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-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-- 
-- PostGIS - Spatial Types for PostgreSQL
-- http://postgis.net
--
-- Copyright (C) 2010, 2011, 2012, 2013 Sandro Santilli <strk@keybit.net>
-- Copyright (C) 2005 Refractions Research Inc.
--
-- This is free software; you can redistribute and/or modify it under
-- the terms of the GNU General Public Licence. See the COPYING file.
--
-- Author: Sandro Santilli <strk@keybit.net>
--  
-- 

/* #define POSTGIS_TOPOLOGY_DEBUG 1 */

--={ ----------------------------------------------------------------
--  SQL/MM block
--
--  This part contains function in the SQL/MM specification
--
---------------------------------------------------------------------

--
-- Type returned by ST_GetFaceEdges
--
CREATE TYPE topology.GetFaceEdges_ReturnType AS (
  sequence integer,
  edge integer
);


--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.5
--
--  ST_GetFaceEdges(atopology, aface)
--
--
-- 
CREATE OR REPLACE FUNCTION topology.ST_GetFaceEdges(toponame varchar, face_id integer)
  RETURNS SETOF topology.GetFaceEdges_ReturnType
AS
$$
DECLARE
  rec RECORD;
  bounds geometry;
  retrec topology.GetFaceEdges_ReturnType;
  n int;
  sql TEXT;
BEGIN
  --
  -- toponame and face_id are required
  -- 
  IF toponame IS NULL OR face_id IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  IF NOT EXISTS(SELECT name FROM topology.topology WHERE name = toponame)  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END IF;

  n := 1;

  -- Construct the face geometry, then for each ring of each polygon:
  sql := 'SELECT (ST_DumpRings((ST_Dump(ST_ForceRHR('
    || 'ST_BuildArea(ST_Collect(geom))))).geom)).geom FROM '
    || quote_ident(toponame) || '.edge_data WHERE left_face = '
    || face_id || ' OR right_face = ' || face_id;
  FOR rec IN EXECUTE sql 
  LOOP -- {

    -- Find the edges constituting its boundary
    bounds = ST_Boundary(rec.geom);


    sql := 'WITH er2 AS ( ' 
      || 'WITH er AS ( SELECT ' 
      || 'min(e.edge_id) over (), count(*) over () as cnt, e.edge_id, '
      || 'ST_LineLocatePoint('
      || quote_literal(bounds::text)
      || ', ST_LineInterpolatePoint(e.geom, 0.2)) as pos'
      || ', ST_LineLocatePoint('
      || quote_literal(bounds::text)
      || ', ST_LineInterpolatePoint(e.geom, 0.8)) as pos2 FROM '
      || quote_ident(toponame)
      || '.edge e WHERE ( e.left_face = ' || face_id
      || ' OR e.right_face = ' || face_id
      || ') AND ST_Covers('
      || quote_literal(bounds::text)
      || ', e.geom)';
    IF face_id = 0 THEN
      sql := sql || ' ORDER BY POS ASC) ';
    ELSE
      sql := sql || ' ORDER BY POS DESC) ';
    END IF;

    -- Reorder rows so to start with the one with smaller edge_id
    sql := sql || 'SELECT row_number() over () - 1 as rn, * FROM er ) '
               || 'SELECT *, ( rn + cnt - ( select rn FROM er2 WHERE edge_id = min ) ) % cnt AS reord FROM er2 ORDER BY reord';


    --RAISE DEBUG 'SQL: %', sql;

    FOR rec IN EXECUTE sql
    LOOP

#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'rn:%, n:%, edg:%, cnt:%, min:%, reord:%',
         rec.rn, n, rec.edge_id, rec.cnt, rec.min, rec.reord;
#endif

      retrec.sequence = n;
      retrec.edge = rec.edge_id;

      IF face_id = 0 THEN
        -- if this edge goes in opposite direction to the
        --       ring bounds, make it with negative orientation
        IF rec.pos2 < rec.pos THEN -- edge goes in opposite direction
          retrec.edge = -retrec.edge;
        END IF;
      ELSE
        -- if this edge goes in same direction to the
        --       ring bounds, make it with negative orientation
        IF rec.pos2 > rec.pos THEN -- edge goes in same direction
          retrec.edge = -retrec.edge;
        END IF;
      END IF;

      RETURN NEXT retrec;

      n = n+1;

    END LOOP;
  END LOOP; -- }

  RETURN;
EXCEPTION
  WHEN INVALID_SCHEMA_NAME THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
END
$$
LANGUAGE 'plpgsql' STABLE;
--} ST_GetFaceEdges

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.10
--
--  ST_NewEdgeHeal(atopology, anedge, anotheredge)
--
-- Not in the specs:
-- * Refuses to heal two edges if any of the two is closed 
-- * Raise an exception when trying to heal an edge with itself
-- * Raise an exception if any TopoGeometry is defined by only one
--   of the two edges
-- * Update references in the Relation table.
-- 
CREATE OR REPLACE FUNCTION topology.ST_NewEdgeHeal(toponame varchar, e1id integer, e2id integer)
  RETURNS int
AS
$$
DECLARE
  e1rec RECORD;
  e2rec RECORD;
  rec RECORD;
  newedgeid int;
  connectededges int[];
  commonnode int;
  caseno int;
  topoid int;
  sql text;
  e2sign int;
  eidary int[];
BEGIN
  --
  -- toponame and face_id are required
  -- 
  IF toponame IS NULL OR e1id IS NULL OR e2id IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  -- NOT IN THE SPECS: see if the same edge is given twice..
  IF e1id = e2id THEN
    RAISE EXCEPTION 'Cannot heal edge % with itself, try with another', e1id;
  END IF;

  -- Get topology id
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = toponame;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(toponame)
      || '.edge_data WHERE edge_id = ' || e1id
      INTO STRICT e1rec;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', e1id;
      WHEN INVALID_SCHEMA_NAME THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
      WHEN UNDEFINED_TABLE THEN
        RAISE EXCEPTION 'corrupted topology "%" (missing edge_data table)',
          toponame;
  END;

  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(toponame)
      || '.edge_data WHERE edge_id = ' || e2id
      INTO STRICT e2rec;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', e2id;
    -- NOTE: checks for INVALID_SCHEMA_NAME or UNDEFINED_TABLE done before
  END;


  -- NOT IN THE SPECS: See if any of the two edges are closed.
  IF e1rec.start_node = e1rec.end_node THEN
    RAISE EXCEPTION 'Edge % is closed, cannot heal to edge %', e1id, e2id;
  END IF;
  IF e2rec.start_node = e2rec.end_node THEN
    RAISE EXCEPTION 'Edge % is closed, cannot heal to edge %', e2id, e1id;
  END IF;

  -- Find common node

  IF e1rec.end_node = e2rec.start_node THEN
    commonnode = e1rec.end_node;
    caseno = 1;
  ELSIF e1rec.end_node = e2rec.end_node THEN
    commonnode = e1rec.end_node;
    caseno = 2;
  END IF;

  -- Check if any other edge is connected to the common node
  IF commonnode IS NOT NULL THEN
    FOR rec IN EXECUTE 'SELECT edge_id FROM ' || quote_ident(toponame)
      || '.edge_data WHERE ( edge_id != ' || e1id
      || ' AND edge_id != ' || e2id || ') AND ( start_node = '
      || commonnode || ' OR end_node = ' || commonnode || ' )'
    LOOP
      commonnode := NULL;
      connectededges = connectededges || rec.edge_id;
    END LOOP;
  END IF;

  IF commonnode IS NULL THEN
    IF e1rec.start_node = e2rec.start_node THEN
      commonnode = e1rec.start_node;
      caseno = 3;
    ELSIF e1rec.start_node = e2rec.end_node THEN
      commonnode = e1rec.start_node;
      caseno = 4;
    END IF;

    -- Check if any other edge is connected to the common node
    IF commonnode IS NOT NULL THEN
      FOR rec IN EXECUTE 'SELECT edge_id FROM ' || quote_ident(toponame)
        || '.edge_data WHERE ( edge_id != ' || e1id
        || ' AND edge_id != ' || e2id || ') AND ( start_node = '
        || commonnode || ' OR end_node = ' || commonnode || ' )'
      LOOP
        commonnode := NULL;
        connectededges = connectededges || rec.edge_id;
      END LOOP;
    END IF;
  END IF;

  IF commonnode IS NULL THEN
    IF connectededges IS NOT NULL THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - other edges connected (%)', array_to_string(connectededges, ',');
    ELSE
      RAISE EXCEPTION 'SQL/MM Spatial exception - non-connected edges';
    END IF;
  END IF;

  -- NOT IN THE SPECS:
  -- check if any topo_geom is defined only by one of the
  -- input edges. In such case there would be no way to adapt
  -- the definition in case of healing, so we'd have to bail out
  eidary = ARRAY[e1id, e2id];
  sql := 'SELECT t.* from ('
    || 'SELECT r.topogeo_id, r.layer_id'
    || ', l.schema_name, l.table_name, l.feature_column'
    || ', array_agg(abs(r.element_id)) as elems '
    || 'FROM topology.layer l INNER JOIN '
    || quote_ident(toponame)
    || '.relation r ON (l.layer_id = r.layer_id) '
    || 'WHERE l.level = 0 AND l.feature_type = 2 '
    || ' AND l.topology_id = ' || topoid
    || ' AND abs(r.element_id) IN (' || e1id || ',' || e2id || ') '
    || 'group by r.topogeo_id, r.layer_id, l.schema_name, l.table_name, '
    || ' l.feature_column ) t WHERE NOT t.elems @> '
    || quote_literal(eidary);
  --RAISE DEBUG 'SQL: %', sql;
  FOR rec IN EXECUTE sql LOOP
    RAISE EXCEPTION 'TopoGeom % in layer % (%.%.%) cannot be represented healing edges % and %',
          rec.topogeo_id, rec.layer_id,
          rec.schema_name, rec.table_name, rec.feature_column,
          e1id, e2id;
  END LOOP;

  -- Create new edge {
  rec := e1rec;
  IF caseno = 1 THEN -- e1.end = e2.start
    rec.geom = ST_MakeLine(e1rec.geom, e2rec.geom);
    rec.end_node = e2rec.end_node;
    rec.next_left_edge = e2rec.next_left_edge;
    e2sign = 1;
  ELSIF caseno = 2 THEN -- e1.end = e2.end
    rec.geom = ST_MakeLine(e1rec.geom, st_reverse(e2rec.geom));
    rec.end_node = e2rec.start_node;
    rec.next_left_edge = e2rec.next_right_edge;
    e2sign = -1;
  ELSIF caseno = 3 THEN -- e1.start = e2.start
    rec.geom = ST_MakeLine(st_reverse(e2rec.geom), e1rec.geom);
    rec.start_node = e2rec.end_node;
    rec.next_right_edge = e2rec.next_left_edge;
    e2sign = -1;
  ELSIF caseno = 4 THEN -- e1.start = e2.end
    rec.geom = ST_MakeLine(e2rec.geom, e1rec.geom);
    rec.start_node = e2rec.start_node;
    rec.next_right_edge = e2rec.next_right_edge;
    e2sign = 1;
  END IF;
  -- }

  -- Insert new edge {
  EXECUTE 'SELECT nextval(' || quote_literal(
      quote_ident(toponame) || '.edge_data_edge_id_seq'
    ) || ')' INTO STRICT newedgeid;
  EXECUTE 'INSERT INTO ' || quote_ident(toponame)
    || '.edge VALUES(' || newedgeid
    || ',' || rec.start_node
    || ',' || rec.end_node
    || ',' || rec.next_left_edge
    || ',' || rec.next_right_edge
    || ',' || rec.left_face
    || ',' || rec.right_face
    || ',' || quote_literal(rec.geom::text)
    || ')';
  -- End of new edge insertion }

  -- Update next_left_edge/next_right_edge for
  -- any edge having them still pointing at the edges being removed
  -- (e2id)
  --
  -- NOTE:
  -- *(next_XXX_edge/e2id) serves the purpose of extracting existing
  -- sign from the value, while *e2sign changes that sign again if we
  -- reverted edge2 direction
  --
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET abs_next_left_edge = ' || newedgeid
    || ', next_left_edge = ' || e2sign*newedgeid
    || '*(next_left_edge/'
    || e2id || ')  WHERE abs_next_left_edge = ' || e2id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET abs_next_right_edge = ' || newedgeid
    || ', next_right_edge = ' || e2sign*newedgeid
    || '*(next_right_edge/'
    || e2id || ') WHERE abs_next_right_edge = ' || e2id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;

  -- New edge has the same direction as old edge 1
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET abs_next_left_edge = ' || newedgeid
    || ', next_left_edge = ' || newedgeid
    || '*(next_left_edge/'
    || e1id || ')  WHERE abs_next_left_edge = ' || e1id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET abs_next_right_edge = ' || newedgeid
    || ', next_right_edge = ' || newedgeid
    || '*(next_right_edge/'
    || e1id || ') WHERE abs_next_right_edge = ' || e1id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;

  --
  -- NOT IN THE SPECS:
  -- Replace composition rows involving the two
  -- edges as one involving the new edge.
  -- It takes a DELETE and an UPDATE to do all
  sql := 'DELETE FROM ' || quote_ident(toponame)
    || '.relation r USING topology.layer l '
    || 'WHERE l.level = 0 AND l.feature_type = 2'
    || ' AND l.topology_id = ' || topoid
    || ' AND l.layer_id = r.layer_id AND abs(r.element_id) = '
    || e2id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.relation r '
    || ' SET element_id = ' || newedgeid || '*(element_id/'
    || e1id
    || ') FROM topology.layer l WHERE l.level = 0 AND l.feature_type = 2'
    || ' AND l.topology_id = ' || topoid
    || ' AND l.layer_id = r.layer_id AND abs(r.element_id) = '
    || e1id
  ;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'SQL: %', sql;
#endif
  EXECUTE sql;


  -- Delete both edges
  EXECUTE 'DELETE FROM ' || quote_ident(toponame)
    || '.edge_data WHERE edge_id = ' || e2id;
  EXECUTE 'DELETE FROM ' || quote_ident(toponame)
    || '.edge_data WHERE edge_id = ' || e1id;

  -- Delete the common node 
  BEGIN
    EXECUTE 'DELETE FROM ' || quote_ident(toponame)
            || '.node WHERE node_id = ' || commonnode;
    EXCEPTION
      WHEN UNDEFINED_TABLE THEN
        RAISE EXCEPTION 'corrupted topology "%" (missing node table)',
          toponame;
  END;

  RETURN newedgeid;
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_NewEdgeHeal

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.11
--
--  ST_ModEdgeHeal(atopology, anedge, anotheredge)
--
-- Not in the specs:
-- * Returns the id of the node being removed
-- * Refuses to heal two edges if any of the two is closed 
-- * Raise an exception when trying to heal an edge with itself
-- * Raise an exception if any TopoGeometry is defined by only one
--   of the two edges
-- * Update references in the Relation table.
-- 
CREATE OR REPLACE FUNCTION topology.ST_ModEdgeHeal(toponame varchar, e1id integer, e2id integer)
  RETURNS int
AS
$$
DECLARE
  e1rec RECORD;
  e2rec RECORD;
  rec RECORD;
  connectededges int[];
  commonnode int;
  caseno int;
  topoid int;
  sql text;
  e2sign int;
  eidary int[];
BEGIN
  --
  -- toponame and face_id are required
  -- 
  IF toponame IS NULL OR e1id IS NULL OR e2id IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  -- NOT IN THE SPECS: see if the same edge is given twice..
  IF e1id = e2id THEN
    RAISE EXCEPTION 'Cannot heal edge % with itself, try with another', e1id;
  END IF;

  -- Get topology id
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = toponame;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(toponame)
      || '.edge_data WHERE edge_id = ' || e1id
      INTO STRICT e1rec;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', e1id;
      WHEN INVALID_SCHEMA_NAME THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
      WHEN UNDEFINED_TABLE THEN
        RAISE EXCEPTION 'corrupted topology "%" (missing edge_data table)',
          toponame;
  END;

  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(toponame)
      || '.edge_data WHERE edge_id = ' || e2id
      INTO STRICT e2rec;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', e2id;
    -- NOTE: checks for INVALID_SCHEMA_NAME or UNDEFINED_TABLE done before
  END;


  -- NOT IN THE SPECS: See if any of the two edges are closed.
  IF e1rec.start_node = e1rec.end_node THEN
    RAISE EXCEPTION 'Edge % is closed, cannot heal to edge %', e1id, e2id;
  END IF;
  IF e2rec.start_node = e2rec.end_node THEN
    RAISE EXCEPTION 'Edge % is closed, cannot heal to edge %', e2id, e1id;
  END IF;

  -- Find common node

  IF e1rec.end_node = e2rec.start_node THEN
    commonnode = e1rec.end_node;
    caseno = 1;
  ELSIF e1rec.end_node = e2rec.end_node THEN
    commonnode = e1rec.end_node;
    caseno = 2;
  END IF;

  -- Check if any other edge is connected to the common node
  IF commonnode IS NOT NULL THEN
    FOR rec IN EXECUTE 'SELECT edge_id FROM ' || quote_ident(toponame)
      || '.edge_data WHERE ( edge_id != ' || e1id
      || ' AND edge_id != ' || e2id || ') AND ( start_node = '
      || commonnode || ' OR end_node = ' || commonnode || ' )'
    LOOP
      commonnode := NULL;
      connectededges = connectededges || rec.edge_id;
    END LOOP;
  END IF;

  IF commonnode IS NULL THEN
    IF e1rec.start_node = e2rec.start_node THEN
      commonnode = e1rec.start_node;
      caseno = 3;
    ELSIF e1rec.start_node = e2rec.end_node THEN
      commonnode = e1rec.start_node;
      caseno = 4;
    END IF;

    -- Check if any other edge is connected to the common node
    IF commonnode IS NOT NULL THEN
      FOR rec IN EXECUTE 'SELECT edge_id FROM ' || quote_ident(toponame)
        || '.edge_data WHERE ( edge_id != ' || e1id
        || ' AND edge_id != ' || e2id || ') AND ( start_node = '
        || commonnode || ' OR end_node = ' || commonnode || ' )'
      LOOP
        commonnode := NULL;
        connectededges = connectededges || rec.edge_id;
      END LOOP;
    END IF;
  END IF;

  IF commonnode IS NULL THEN
    IF connectededges IS NOT NULL THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - other edges connected (%)', array_to_string(connectededges, ',');
    ELSE
      RAISE EXCEPTION 'SQL/MM Spatial exception - non-connected edges';
    END IF;
  END IF;

  -- NOT IN THE SPECS:
  -- check if any topo_geom is defined only by one of the
  -- input edges. In such case there would be no way to adapt
  -- the definition in case of healing, so we'd have to bail out
  eidary = ARRAY[e1id, e2id];
  sql := 'SELECT t.* from ('
    || 'SELECT r.topogeo_id, r.layer_id'
    || ', l.schema_name, l.table_name, l.feature_column'
    || ', array_agg(abs(r.element_id)) as elems '
    || 'FROM topology.layer l INNER JOIN '
    || quote_ident(toponame)
    || '.relation r ON (l.layer_id = r.layer_id) '
    || 'WHERE l.level = 0 AND l.feature_type = 2 '
    || ' AND l.topology_id = ' || topoid
    || ' AND abs(r.element_id) IN (' || e1id || ',' || e2id || ') '
    || 'group by r.topogeo_id, r.layer_id, l.schema_name, l.table_name, '
    || ' l.feature_column ) t WHERE NOT t.elems @> '
    || quote_literal(eidary);
  --RAISE DEBUG 'SQL: %', sql;
  FOR rec IN EXECUTE sql LOOP
    RAISE EXCEPTION 'TopoGeom % in layer % (%.%.%) cannot be represented healing edges % and %',
          rec.topogeo_id, rec.layer_id,
          rec.schema_name, rec.table_name, rec.feature_column,
          e1id, e2id;
  END LOOP;

  -- Update data of the first edge {
  rec := e1rec;
  IF caseno = 1 THEN -- e1.end = e2.start
    rec.geom = ST_MakeLine(e1rec.geom, e2rec.geom);
    rec.end_node = e2rec.end_node;
    rec.next_left_edge = e2rec.next_left_edge;
    e2sign = 1;
  ELSIF caseno = 2 THEN -- e1.end = e2.end
    rec.geom = ST_MakeLine(e1rec.geom, st_reverse(e2rec.geom));
    rec.end_node = e2rec.start_node;
    rec.next_left_edge = e2rec.next_right_edge;
    e2sign = -1;
  ELSIF caseno = 3 THEN -- e1.start = e2.start
    rec.geom = ST_MakeLine(st_reverse(e2rec.geom), e1rec.geom);
    rec.start_node = e2rec.end_node;
    rec.next_right_edge = e2rec.next_left_edge;
    e2sign = -1;
  ELSIF caseno = 4 THEN -- e1.start = e2.end
    rec.geom = ST_MakeLine(e2rec.geom, e1rec.geom);
    rec.start_node = e2rec.start_node;
    rec.next_right_edge = e2rec.next_right_edge;
    e2sign = 1;
  END IF;
  EXECUTE 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET geom = ' || quote_literal(rec.geom::text)
    || ', start_node = ' || rec.start_node
    || ', end_node = ' || rec.end_node
    || ', next_left_edge = ' || rec.next_left_edge
    || ', abs_next_left_edge = ' || abs(rec.next_left_edge)
    || ', next_right_edge = ' || rec.next_right_edge
    || ', abs_next_right_edge = ' || abs(rec.next_right_edge)
    || ' WHERE edge_id = ' || e1id;
  -- End of first edge update }

  -- Update next_left_edge/next_right_edge for
  -- any edge having them still pointing at the edge being removed (e2id)
  --
  -- NOTE:
  -- *(next_XXX_edge/e2id) serves the purpose of extracting existing
  -- sign from the value, while *e2sign changes that sign again if we
  -- reverted edge2 direction
  --
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET abs_next_left_edge = ' || e1id
    || ', next_left_edge = ' || e2sign*e1id
    || '*(next_left_edge/'
    || e2id || ')  WHERE abs_next_left_edge = ' || e2id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET abs_next_right_edge = ' || e1id
    || ', next_right_edge = ' || e2sign*e1id
    || '*(next_right_edge/'
    || e2id || ') WHERE abs_next_right_edge = ' || e2id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;

  -- Delete the second edge
  EXECUTE 'DELETE FROM ' || quote_ident(toponame)
    || '.edge_data WHERE edge_id = ' || e2id;

  -- Delete the common node 
  BEGIN
    EXECUTE 'DELETE FROM ' || quote_ident(toponame)
            || '.node WHERE node_id = ' || commonnode;
    EXCEPTION
      WHEN UNDEFINED_TABLE THEN
        RAISE EXCEPTION 'corrupted topology "%" (missing node table)',
          toponame;
  END;

  --
  -- NOT IN THE SPECS:
  -- Drop composition rows involving second
  -- edge, as the first edge took its space,
  -- and all affected TopoGeom have been previously checked
  -- for being composed by both edges.
  sql := 'DELETE FROM ' || quote_ident(toponame)
    || '.relation r USING topology.layer l '
    || 'WHERE l.level = 0 AND l.feature_type = 2'
    || ' AND l.topology_id = ' || topoid
    || ' AND l.layer_id = r.layer_id AND abs(r.element_id) = '
    || e2id;
  --RAISE DEBUG 'SQL: %', sql;
  EXECUTE sql;

  RETURN commonnode;
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_ModEdgeHeal

-- {
-- _ST_RemEdgeCheck - check that the given edge is not needed
--                    by the definition of any TopoGeometry
--
CREATE OR REPLACE FUNCTION topology._ST_RemEdgeCheck(tname varchar, tid integer, eid integer, lf integer, rf integer)
RETURNS VOID
AS
$$
DECLARE
  sql text;
  fidary int[];
  rec RECORD;
BEGIN
  -- Check that no TopoGeometry references the edge being removed
  sql := 'SELECT r.topogeo_id, r.layer_id'
      || ', l.schema_name, l.table_name, l.feature_column '
      || 'FROM topology.layer l INNER JOIN '
      || quote_ident(tname)
      || '.relation r ON (l.layer_id = r.layer_id) '
      || 'WHERE l.level = 0 AND l.feature_type = 2 '
      || ' AND l.topology_id = ' || tid
      || ' AND abs(r.element_id) = ' || eid ;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Checking TopoGeometry definitions: %', sql;
#endif
  FOR rec IN EXECUTE sql LOOP
    RAISE EXCEPTION 'TopoGeom % in layer % (%.%.%) cannot be represented dropping edge %',
            rec.topogeo_id, rec.layer_id,
            rec.schema_name, rec.table_name, rec.feature_column,
            eid;
  END LOOP;

  IF lf != rf THEN -- {

    RAISE NOTICE 'Deletion of edge % joins faces % and %',
                    eid, lf, rf;

    -- check if any topo_geom is defined only by one of the
    -- joined faces. In such case there would be no way to adapt
    -- the definition in case of healing, so we'd have to bail out
    -- 
    fidary = ARRAY[lf, rf];
    sql := 'SELECT t.* from ('
      || 'SELECT r.topogeo_id, r.layer_id'
      || ', l.schema_name, l.table_name, l.feature_column'
      || ', array_agg(r.element_id) as elems '
      || 'FROM topology.layer l INNER JOIN '
      || quote_ident(tname)
      || '.relation r ON (l.layer_id = r.layer_id) '
      || 'WHERE l.level = 0 AND l.feature_type = 3 '
      || ' AND l.topology_id = ' || tid
      || ' AND r.element_id = ANY (' || quote_literal(fidary)
      || ') group by r.topogeo_id, r.layer_id, l.schema_name, l.table_name, '
      || ' l.feature_column ) t';

    -- No surface can be defined by universal face 
    IF lf != 0 AND rf != 0 THEN -- {
      sql := sql || ' WHERE NOT t.elems @> ' || quote_literal(fidary);
    END IF; -- }

#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'SQL: %', sql;
#endif

    FOR rec IN EXECUTE sql LOOP
      RAISE EXCEPTION 'TopoGeom % in layer % (%.%.%) cannot be represented healing faces % and %',
            rec.topogeo_id, rec.layer_id,
            rec.schema_name, rec.table_name, rec.feature_column,
            rf, lf;
    END LOOP;

  END IF; -- } two faces healed...
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} _ST_RemEdgeCheck

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.14
--
--  ST_RemEdgeNewFace(atopology, anedge)
--
-- Not in the specs:
-- * Raise an exception if any TopoGeometry is defined by only one
--   of the two faces that will dissolve.
-- * Raise an exception if any TopoGeometry is defined by 
--   the edge being removed.
-- * Properly set containg_face on nodes that remains isolated by the drop
-- * Update containg_face for isolated nodes in the dissolved faces
-- * Update references in the Relation table
-- 
-- }{
CREATE OR REPLACE FUNCTION topology.ST_RemEdgeNewFace(toponame varchar, e1id integer)
  RETURNS int
AS
$$
DECLARE
  e1rec RECORD;
  rec RECORD;
  fidary int[];
  topoid int;
  sql text;
  newfaceid int;
  newfacecreated bool;
  elink int;
BEGIN
  --
  -- toponame and face_id are required
  -- 
  IF toponame IS NULL OR e1id IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  -- Get topology id
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = toponame;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(toponame)
      || '.edge_data WHERE edge_id = ' || e1id
      INTO STRICT e1rec;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', e1id;
      WHEN INVALID_SCHEMA_NAME THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
      WHEN UNDEFINED_TABLE THEN
        RAISE EXCEPTION 'corrupted topology "%" (missing edge_data table)',
          toponame;
  END;

  -- NOT IN THE SPECS:
  -- Check that no TopoGeometry references the edge being removed
  PERFORM topology._ST_RemEdgeCheck(toponame, topoid, e1id, e1rec.left_face, e1rec.right_face);

  -- Update next_left_edge and next_right_edge face
  -- for all edges bounding the new face
  RAISE NOTICE 'Updating next_{right,left}_face of ring edges...';

  -- TODO: reduce the following to 2 UPDATE rather than 4

  -- Update next_left_edge of previous edges in left face -- {

  elink := e1rec.next_left_edge;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_left_edge = '
    || elink
    || ', abs_next_left_edge = '
    || abs(elink)
    || ' WHERE next_left_edge < 0 AND abs(next_left_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_left_edge update: %', sql;
#endif
  EXECUTE sql;

  -- If the edge being removed links to self,
  -- we use the other face
  IF e1rec.abs_next_right_edge = e1rec.edge_id THEN
    elink := e1rec.next_left_edge;
  ELSE
    elink := e1rec.next_right_edge;
  END IF;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_left_edge = '
    || elink
    || ', abs_next_left_edge = '
    || abs(elink)
    || ' WHERE next_left_edge > 0 AND abs(next_left_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_left_edge update: %', sql;
#endif
  EXECUTE sql;

  -- }

  -- Update next_right_edge of previous edges in right face -- {

  elink := e1rec.next_left_edge;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_right_edge = '
    || elink
    || ', abs_next_right_edge = '
    || abs(elink)
    || ' WHERE next_right_edge < 0 AND abs(next_right_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_right_edge update: %', sql;
#endif
  EXECUTE sql;

  -- If the edge being removed links to self,
  -- we use the other face
  IF e1rec.abs_next_right_edge = e1rec.edge_id THEN
    elink := e1rec.next_left_edge;
  ELSE
    elink := e1rec.next_right_edge;
  END IF;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_right_edge = '
    || elink
    || ', abs_next_right_edge = '
    || abs(elink)
    || ' WHERE next_right_edge > 0 AND abs(next_right_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_right_edge update: %', sql;
#endif
  EXECUTE sql;

  -- }

  IF e1rec.left_face = e1rec.right_face THEN -- {

    newfaceid := e1rec.left_face; -- TODO: or what should we return ?
    newfacecreated := false;

  ELSE -- }{

    IF e1rec.left_face = 0 OR e1rec.right_face = 0 THEN -- {

      --
      -- We won't add any new face, but rather let the universe
      -- flood the removed face.
      --

      newfaceid := 0;
      newfacecreated := false;

    ELSE -- }{

      --
      -- Insert the new face 
      --

      sql := 'SELECT nextval(' || quote_literal(
          quote_ident(toponame) || '.face_face_id_seq'
        ) || ')';

      EXECUTE sql INTO STRICT newfaceid;
      newfacecreated := true;

      sql := 'INSERT INTO '
        || quote_ident(toponame)
        || '.face(face_id, mbr) SELECT '
        -- face_id
        || newfaceid  || ', '
        -- minimum bounding rectangle is the union of the old faces mbr
        -- (doing this without GEOS would be faster)
        || 'ST_Envelope(ST_Union(mbr)) FROM '
        || quote_ident(toponame)
        || '.face WHERE face_id IN (' 
        || e1rec.left_face || ',' || e1rec.right_face 
        || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'SQL: %', sql;
#endif
      EXECUTE sql;

    END IF; -- }

    -- Update left_face for all edges still referencing old faces
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.edge_data SET left_face = ' || newfaceid 
      || ' WHERE left_face IN ('
      || e1rec.left_face || ',' || e1rec.right_face 
      || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'left_face update: %', sql;
#endif
    EXECUTE sql;

    -- Update right_face for all edges still referencing old faces
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.edge_data SET right_face = ' || newfaceid 
      || ' WHERE right_face IN ('
      || e1rec.left_face || ',' || e1rec.right_face 
      || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'right_face update: %', sql;
#endif
    EXECUTE sql;

    -- Update containing_face for all nodes still referencing old faces
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.node SET containing_face = ' || newfaceid 
      || ' WHERE containing_face IN ('
      || e1rec.left_face || ',' || e1rec.right_face 
      || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Isolated nodes update: %', sql;
#endif
    EXECUTE sql;

    -- NOT IN THE SPECS:
    -- Replace composition rows involving the two
    -- faces as one involving the new face.
    -- It takes a DELETE and an UPDATE to do all
    sql := 'DELETE FROM ' || quote_ident(toponame)
      || '.relation r USING topology.layer l '
      || 'WHERE l.level = 0 AND l.feature_type = 3'
      || ' AND l.topology_id = ' || topoid
      || ' AND l.layer_id = r.layer_id AND abs(r.element_id) = '
      || e1rec.left_face;
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'SQL: %', sql;
#endif
    EXECUTE sql;
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.relation r '
      || ' SET element_id = ' || newfaceid 
      || ' FROM topology.layer l WHERE l.level = 0 AND l.feature_type = 3'
      || ' AND l.topology_id = ' || topoid
      || ' AND l.layer_id = r.layer_id AND r.element_id = '
      || e1rec.right_face;
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'SQL: %', sql;
#endif
    EXECUTE sql;

  END IF; -- } two faces healed...

  -- Delete the edge
  sql := 'DELETE FROM ' || quote_ident(toponame)
    || '.edge_data WHERE edge_id = ' || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Edge deletion: %', sql;
#endif
  EXECUTE sql;

  -- Check if any of the edge nodes remains isolated, 
  -- set containing_face  = newfaceid in that case
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.node n SET containing_face = ' || newfaceid
    || ' WHERE node_id IN ('
    || e1rec.start_node || ','
    || e1rec.end_node || ') AND NOT EXISTS (SELECT edge_id FROM '
    || quote_ident(toponame)
    || '.edge_data WHERE start_node = n.node_id OR end_node = n.node_id)';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Checking for nodes left isolated: %', sql;
#endif
  EXECUTE sql;

  IF e1rec.right_face != e1rec.left_face THEN -- {

    -- Delete left face, if not universe
    IF e1rec.left_face != 0 THEN
      sql := 'DELETE FROM ' || quote_ident(toponame)
        || '.face WHERE face_id = ' || e1rec.left_face; 
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'Left face deletion: %', sql;
#endif
      EXECUTE sql;
    END IF;

    -- Delete right face, if not universe
    IF e1rec.right_face != 0
    THEN
      sql := 'DELETE FROM ' || quote_ident(toponame)
        || '.face WHERE face_id = ' || e1rec.right_face;
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'Right face deletion: %', sql;
#endif
      EXECUTE sql;
    END IF;

  END IF; -- }

  IF newfacecreated THEN
    RETURN newfaceid;
  ELSE
    RETURN NULL; -- -newfaceid;
  END IF;
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_RemEdgeNewFace

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.15
--
--  ST_RemEdgeModFace(atopology, anedge)
--
-- Not in the specs:
-- * Raise an exception if any TopoGeometry is defined by only one
--   of the two faces that will dissolve.
-- * Raise an exception if any TopoGeometry is defined by 
--   the edge being removed.
-- * Properly set containg_face on nodes that remains isolated by the drop
-- * Update containg_face for isolated nodes in the dissolved faces
-- * Update references in the Relation table
-- * Return id of the face taking up the removed edge space
--
-- }{
CREATE OR REPLACE FUNCTION topology.ST_RemEdgeModFace(toponame varchar, e1id integer)
  RETURNS int
AS
$$
DECLARE
  e1rec RECORD;
  rec RECORD;
  fidary int[];
  topoid int;
  sql text;
  floodfaceid int;
  elink int;
BEGIN
  --
  -- toponame and face_id are required
  -- 
  IF toponame IS NULL OR e1id IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  -- Get topology id
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = toponame;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(toponame)
      || '.edge_data WHERE edge_id = ' || e1id
      INTO STRICT e1rec;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', e1id;
      WHEN INVALID_SCHEMA_NAME THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
      WHEN UNDEFINED_TABLE THEN
        RAISE EXCEPTION 'corrupted topology "%" (missing edge_data table)',
          toponame;
  END;

  -- NOT IN THE SPECS:
  -- Check that no TopoGeometry references the edge being removed
  PERFORM topology._ST_RemEdgeCheck(toponame, topoid, e1id, e1rec.left_face, e1rec.right_face);

  -- Update next_left_edge and next_right_edge face
  -- for all edges bounding the new face
  RAISE NOTICE 'Updating next_{right,left}_face of ring edges...';

  -- TODO: reduce the following to 2 UPDATE rather than 4

  -- Update next_left_edge of previous edges in left face -- {

  elink := e1rec.next_left_edge;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_left_edge = '
    || elink
    || ', abs_next_left_edge = '
    || abs(elink)
    || ' WHERE next_left_edge < 0 AND abs(next_left_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_left_edge update: %', sql;
#endif
  EXECUTE sql;

  -- If the edge being removed links to self,
  -- we use the other face
  IF e1rec.abs_next_right_edge = e1rec.edge_id THEN
    elink := e1rec.next_left_edge;
  ELSE
    elink := e1rec.next_right_edge;
  END IF;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_left_edge = '
    || elink
    || ', abs_next_left_edge = '
    || abs(elink)
    || ' WHERE next_left_edge > 0 AND abs(next_left_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_left_edge update: %', sql;
#endif
  EXECUTE sql;

  -- }

  -- Update next_right_edge of previous edges in right face -- {

  elink := e1rec.next_left_edge;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_right_edge = '
    || elink
    || ', abs_next_right_edge = '
    || abs(elink)
    || ' WHERE next_right_edge < 0 AND abs(next_right_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_right_edge update: %', sql;
#endif
  EXECUTE sql;

  -- If the edge being removed links to self,
  -- we use the other face
  IF e1rec.abs_next_right_edge = e1rec.edge_id THEN
    elink := e1rec.next_left_edge;
  ELSE
    elink := e1rec.next_right_edge;
  END IF;

  sql := 'UPDATE ' || quote_ident(toponame)
    || '.edge_data SET next_right_edge = '
    || elink
    || ', abs_next_right_edge = '
    || abs(elink)
    || ' WHERE next_right_edge > 0 AND abs(next_right_edge) = '
    || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'next_right_edge update: %', sql;
#endif
  EXECUTE sql;

  -- }

  IF e1rec.left_face = e1rec.right_face THEN -- {

    floodfaceid = e1rec.left_face; 

  ELSE -- }{

    IF e1rec.left_face = 0 OR e1rec.right_face = 0 THEN -- {

      --
      -- We won't add any new face, but rather let the universe
      -- flood the removed face.
      --

      floodfaceid = 0;

    ELSE -- }{

      -- we choose right face as the face that will remain
      -- to be symmetric with ST_AddEdgeModFace 
      floodfaceid = e1rec.right_face;

      sql := 'UPDATE '
        || quote_ident(toponame)
        || '.face SET mbr = (SELECT '
        -- minimum bounding rectangle is the union of the old faces mbr
        -- (doing this without GEOS would be faster)
        || 'ST_Envelope(ST_Union(mbr)) FROM '
        || quote_ident(toponame)
        || '.face WHERE face_id IN (' 
        || e1rec.left_face || ',' || e1rec.right_face 
        || ') ) WHERE face_id = ' || floodfaceid ;
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'SQL: %', sql;
#endif
      EXECUTE sql;

    END IF; -- }

    -- Update left_face for all edges still referencing old faces
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.edge_data SET left_face = ' || floodfaceid 
      || ' WHERE left_face IN ('
      || e1rec.left_face || ',' || e1rec.right_face 
      || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'left_face update: %', sql;
#endif
    EXECUTE sql;

    -- Update right_face for all edges still referencing old faces
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.edge_data SET right_face = ' || floodfaceid 
      || ' WHERE right_face IN ('
      || e1rec.left_face || ',' || e1rec.right_face 
      || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'right_face update: %', sql;
#endif
    EXECUTE sql;

    -- Update containing_face for all nodes still referencing old faces
    sql := 'UPDATE ' || quote_ident(toponame)
      || '.node SET containing_face = ' || floodfaceid 
      || ' WHERE containing_face IN ('
      || e1rec.left_face || ',' || e1rec.right_face 
      || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Isolated nodes update: %', sql;
#endif
    EXECUTE sql;

    -- NOT IN THE SPECS:
    -- Replace composition rows involving the two
    -- faces as one involving the new face.
    -- It takes a single DELETE to do that.
    sql := 'DELETE FROM ' || quote_ident(toponame)
      || '.relation r USING topology.layer l '
      || 'WHERE l.level = 0 AND l.feature_type = 3'
      || ' AND l.topology_id = ' || topoid
      || ' AND l.layer_id = r.layer_id AND abs(r.element_id) IN ('
      || e1rec.left_face || ',' || e1rec.right_face
      || ') AND abs(r.element_id) != '
      || floodfaceid; -- could be optimized..
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'SQL: %', sql;
#endif
    EXECUTE sql;

  END IF; -- } two faces healed...

  -- Delete the edge
  sql := 'DELETE FROM ' || quote_ident(toponame)
    || '.edge_data WHERE edge_id = ' || e1id;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Edge deletion: %', sql;
#endif
  EXECUTE sql;

  -- Check if any of the edge nodes remains isolated, 
  -- set containing_face  = floodfaceid in that case
  sql := 'UPDATE ' || quote_ident(toponame)
    || '.node n SET containing_face = ' || floodfaceid
    || ' WHERE node_id IN ('
    || e1rec.start_node || ','
    || e1rec.end_node || ') AND NOT EXISTS (SELECT edge_id FROM '
    || quote_ident(toponame)
    || '.edge_data WHERE start_node = n.node_id OR end_node = n.node_id)';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Checking for nodes left isolated: %', sql;
#endif
  EXECUTE sql;

  IF e1rec.right_face != e1rec.left_face THEN -- {

    -- Delete left face, if not universe and not "flood" face
    IF e1rec.left_face != 0 AND e1rec.left_face != floodfaceid
    THEN
      sql := 'DELETE FROM ' || quote_ident(toponame)
        || '.face WHERE face_id = ' || e1rec.left_face; 
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'Left face deletion: %', sql;
#endif
      EXECUTE sql;
    END IF;

    -- Delete right face, if not universe and not "flood" face
    IF e1rec.right_face != 0 AND e1rec.right_face != floodfaceid
    THEN
      sql := 'DELETE FROM ' || quote_ident(toponame)
        || '.face WHERE face_id = ' || e1rec.right_face;
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'Right face deletion: %', sql;
#endif
      EXECUTE sql;
    END IF;

  END IF; -- }

  RETURN floodfaceid;
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_RemEdgeModFace


--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.16
--
--  ST_GetFaceGeometry(atopology, aface)
-- 
CREATE OR REPLACE FUNCTION topology.ST_GetFaceGeometry(toponame varchar, aface integer)
  RETURNS GEOMETRY AS
$$
DECLARE
  rec RECORD;
  sql TEXT;
BEGIN

  --
  -- toponame and aface are required
  -- 
  IF toponame IS NULL OR aface IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  IF NOT EXISTS(SELECT name FROM topology.topology WHERE name = toponame)  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END IF;

  IF aface = 0 THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - universal face has no geometry';
  END IF;

  BEGIN

    -- No such face
    sql := 'SELECT NOT EXISTS (SELECT * from ' || quote_ident(toponame)
      || '.face WHERE face_id = ' || aface
      || ') as none';
    EXECUTE sql INTO rec;
    IF rec.none THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent face.';
    END IF;

    --
    -- Construct face 
    -- 
    sql :=
      'SELECT ST_BuildArea(ST_Collect(geom)) as geom FROM '
      || quote_ident(toponame)
      || '.edge_data WHERE left_face = ' || aface
      || ' OR right_face = ' || aface;
    FOR rec IN EXECUTE sql
    LOOP
      RETURN rec.geom;
    END LOOP;

  EXCEPTION
    WHEN INVALID_SCHEMA_NAME THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
    WHEN UNDEFINED_TABLE THEN
      RAISE EXCEPTION 'corrupted topology "%"', toponame;
  END;

  RETURN NULL;
END
$$
LANGUAGE 'plpgsql' STABLE;
--} ST_GetFaceGeometry


--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.1 
--
--  ST_AddIsoNode(atopology, aface, apoint)
--
CREATE OR REPLACE FUNCTION topology.ST_AddIsoNode(atopology varchar, aface integer, apoint geometry)
  RETURNS INTEGER AS
$$
DECLARE
  rec RECORD;
  nodeid integer;
  sql text;
  containingface integer;
BEGIN

  --
  -- Atopology and apoint are required
  -- 
  IF atopology IS NULL OR apoint IS NULL THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Atopology must  be registered
  -- 
  IF NOT EXISTS(SELECT name FROM topology.topology WHERE topology.name = atopology) THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - invalid topology name';
  END IF;
  --
  -- Apoint must be a point
  --
  IF substring(geometrytype(apoint), 1, 5) != 'POINT'
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - invalid point';
  END IF;

  --
  -- Check if a coincident node already exists
  -- 
  -- We use index AND x/y equality
  --
  FOR rec IN EXECUTE 'SELECT node_id FROM '
    || quote_ident(atopology) || '.node ' ||
    'WHERE ST_Equals(geom, ' || quote_literal(apoint::text) || '::geometry)'
  LOOP
    RAISE EXCEPTION
     'SQL/MM Spatial exception - coincident node';
  END LOOP;

  --
  -- Check if any edge crosses (intersects) this node
  -- I used _intersects_ here to include boundaries (endpoints)
  --
  FOR rec IN EXECUTE 'SELECT edge_id FROM '
    || quote_ident(atopology) || '.edge ' 
    || 'WHERE ST_Intersects(geom, ' || quote_literal(apoint::text)
    || '::geometry)'
  LOOP
    RAISE EXCEPTION
    'SQL/MM Spatial exception - edge crosses node.';
  END LOOP;

  -- retrieve the face that contains (eventually) the point
  
  --
  -- first test is to check if there is inside an mbr (more fast)
  --
  sql := 'SELECT f.face_id FROM ' 
        || quote_ident(atopology) 
        || '.face f WHERE f.face_id > 0 AND f.mbr && '
        || quote_literal(apoint::text)
        || '::geometry AND ST_Contains(topology.ST_GetFaceGeometry('
        || quote_literal(atopology) 
        || ', f.face_id), '
        || quote_literal(apoint::text)
        || '::geometry)';
  IF aface IS NOT NULL AND aface != 0 THEN
    sql := sql || ' AND f.face_id = ' || aface;
  END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG '%', sql;
#endif
  EXECUTE sql INTO containingface;

  -- If aface was specified, check that it was correct
  IF aface IS NOT NULL THEN -- {
    IF aface = 0 THEN -- {
      IF containingface IS NOT NULL THEN -- {
        RAISE EXCEPTION
          'SQL/MM Spatial exception - within face % (not universe)',
          containingface;
      ELSE -- }{
        containingface := 0;
      END IF; -- }
    ELSE -- }{ -- aface != 0
      IF containingface IS NULL OR containingface != aface THEN -- {
        RAISE EXCEPTION 'SQL/MM Spatial exception - not within face';
      END IF; -- }
    END IF; -- }
  ELSE -- }{ -- aface is null
    containingface := COALESCE(containingface, 0);
  END IF; -- }

  --
  -- Insert the new row
  --
  sql := 'INSERT INTO '
      || quote_ident(atopology)
      || '.node(node_id, geom, containing_face) SELECT nextval('
      || quote_literal( quote_ident(atopology) || '.node_node_id_seq' )
      || '),'
      ||quote_literal(apoint::text)
      || '::geometry,' || containingface
      || ' RETURNING node_id';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG '%', sql;
#endif

  EXECUTE sql INTO nodeid;

  RETURN nodeid;
EXCEPTION
  -- TODO: avoid the EXCEPTION handling here ?
  WHEN INVALID_SCHEMA_NAME THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_AddIsoNode

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.2 
--
--  ST_MoveIsoNode(atopology, anode, apoint)
--
CREATE OR REPLACE FUNCTION topology.ST_MoveIsoNode(atopology character varying, anode integer, apoint geometry)
  RETURNS text AS
$$
DECLARE
  rec RECORD;
BEGIN

  --
  -- All arguments are required
  -- 
  IF atopology IS NULL OR anode IS NULL OR apoint IS NULL THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Apoint must be a point
  --
  IF substring(geometrytype(apoint), 1, 5) != 'POINT'
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - invalid point';
  END IF;

  --
  -- Check node isolation.
  -- 
  FOR rec IN EXECUTE 'SELECT edge_id FROM '
    || quote_ident(atopology) || '.edge ' ||
    ' WHERE start_node =  ' || anode ||
    ' OR end_node = ' || anode 
  LOOP
    RAISE EXCEPTION
     'SQL/MM Spatial exception - not isolated node';
  END LOOP;

  --
  -- Check if a coincident node already exists
  -- 
  -- We use index AND x/y equality
  --
  FOR rec IN EXECUTE 'SELECT node_id FROM '
    || quote_ident(atopology) || '.node ' ||
    'WHERE geom && ' || quote_literal(apoint::text) || '::geometry'
    ||' AND ST_X(geom) = ST_X('||quote_literal(apoint::text)||'::geometry)'
    ||' AND ST_Y(geom) = ST_Y('||quote_literal(apoint::text)||'::geometry)'
  LOOP
    RAISE EXCEPTION
     'SQL/MM Spatial exception - coincident node';
  END LOOP;

  --
  -- Check if any edge crosses (intersects) this node
  -- I used _intersects_ here to include boundaries (endpoints)
  --
  FOR rec IN EXECUTE 'SELECT edge_id FROM '
    || quote_ident(atopology) || '.edge ' 
    || 'WHERE geom && ' || quote_literal(apoint::text) 
    || ' AND ST_Intersects(geom, ' || quote_literal(apoint::text)
    || '::geometry)'
  LOOP
    RAISE EXCEPTION
    'SQL/MM Spatial exception - edge crosses node.';
  END LOOP;

  --
  -- Update node point
  --
  EXECUTE 'UPDATE ' || quote_ident(atopology) || '.node '
    || ' SET geom = ' || quote_literal(apoint::text) 
    || ' WHERE node_id = ' || anode;

  RETURN 'Isolated Node ' || anode || ' moved to location '
    || ST_X(apoint) || ',' || ST_Y(apoint);
END
$$
  LANGUAGE plpgsql VOLATILE;
--} ST_MoveIsoNode

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.3 
--
--  ST_RemoveIsoNode(atopology, anode)
--
CREATE OR REPLACE FUNCTION topology.ST_RemoveIsoNode(atopology varchar, anode integer)
  RETURNS TEXT AS
$$
DECLARE
  rec RECORD;
BEGIN

  --
  -- Atopology and apoint are required
  -- 
  IF atopology IS NULL OR anode IS NULL THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Check node isolation.
  -- 
  FOR rec IN EXECUTE 'SELECT edge_id FROM '
    || quote_ident(atopology) || '.edge_data ' ||
    ' WHERE start_node =  ' || anode ||
    ' OR end_node = ' || anode 
  LOOP
    RAISE EXCEPTION
     'SQL/MM Spatial exception - not isolated node';
  END LOOP;

  EXECUTE 'DELETE FROM ' || quote_ident(atopology) || '.node '
    || ' WHERE node_id = ' || anode;

  RETURN 'Isolated node ' || anode || ' removed';
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_RemoveIsoNode

--{
-- According to http://trac.osgeo.org/postgis/ticket/798
-- ST_RemoveIsoNode was renamed to ST_RemIsoNode in the final ISO
-- document
--
CREATE OR REPLACE FUNCTION topology.ST_RemIsoNode(varchar, integer)
  RETURNS TEXT AS
$$
  SELECT topology.ST_RemoveIsoNode($1, $2)
$$ LANGUAGE 'sql' VOLATILE;

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.7 
--
--  ST_RemoveIsoEdge(atopology, anedge)
--
CREATE OR REPLACE FUNCTION topology.ST_RemoveIsoEdge(atopology varchar, anedge integer)
  RETURNS TEXT AS
$$
DECLARE
  edge RECORD;
  rec RECORD;
  ok BOOL;
BEGIN

  --
  -- Atopology and anedge are required
  -- 
  IF atopology IS NULL OR anedge IS NULL THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Check node existance
  -- 
  ok = false;
  FOR edge IN EXECUTE 'SELECT * FROM '
    || quote_ident(atopology) || '.edge_data ' ||
    ' WHERE edge_id =  ' || anedge
  LOOP
    ok = true;
  END LOOP;
  IF NOT ok THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - non-existent edge';
  END IF;

  --
  -- Check node isolation
  -- 
  IF edge.left_face != edge.right_face THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - not isolated edge';
  END IF;

  FOR rec IN EXECUTE 'SELECT * FROM '
    || quote_ident(atopology) || '.edge_data ' 
    || ' WHERE edge_id !=  ' || anedge
    || ' AND ( start_node = ' || edge.start_node
    || ' OR start_node = ' || edge.end_node
    || ' OR end_node = ' || edge.start_node
    || ' OR end_node = ' || edge.end_node
    || ' ) '
  LOOP
    RAISE EXCEPTION
      'SQL/MM Spatial exception - not isolated edge';
  END LOOP;

  --
  -- Delete the edge
  --
  EXECUTE 'DELETE FROM ' || quote_ident(atopology) || '.edge_data '
    || ' WHERE edge_id = ' || anedge;

  RETURN 'Isolated edge ' || anedge || ' removed';
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_RemoveIsoEdge

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.8 
--
--  ST_NewEdgesSplit(atopology, anedge, apoint)
--
-- Not in the specs:
-- * Update references in the Relation table.
--
CREATE OR REPLACE FUNCTION topology.ST_NewEdgesSplit(atopology varchar, anedge integer, apoint geometry)
  RETURNS INTEGER AS
$$
DECLARE
  oldedge RECORD;
  rec RECORD;
  tmp integer;
  topoid integer;
  nodeid integer;
  nodepos float8;
  edgeid1 integer;
  edgeid2 integer;
  edge1 geometry;
  edge2 geometry;
  ok BOOL;
BEGIN

  --
  -- All args required
  -- 
  IF atopology IS NULL OR anedge IS NULL OR apoint IS NULL THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;
  
  -- Get topology id
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = atopology;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  --
  -- Check node existance
  -- 
  ok = false;
  FOR oldedge IN EXECUTE 'SELECT * FROM '
    || quote_ident(atopology) || '.edge_data ' ||
    ' WHERE edge_id =  ' || anedge
  LOOP
    ok = true;
  END LOOP;
  IF NOT ok THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - non-existent edge';
  END IF;

  --
  -- Check that given point is Within(anedge.geom)
  -- 
  IF NOT ST_Within(apoint, oldedge.geom) THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - point not on edge';
  END IF;

  --
  -- Check if a coincident node already exists
  --
  FOR rec IN EXECUTE 'SELECT node_id FROM '
    || quote_ident(atopology) || '.node '
    || 'WHERE geom && '
    || quote_literal(apoint::text) || '::geometry'
    || ' AND ST_X(geom) = ST_X('
    || quote_literal(apoint::text) || '::geometry)'
    || ' AND ST_Y(geom) = ST_Y('
    || quote_literal(apoint::text) || '::geometry)'
  LOOP
    RAISE EXCEPTION
     'SQL/MM Spatial exception - coincident node';
  END LOOP;

  --
  -- Get new node id
  --
  FOR rec IN EXECUTE 'SELECT nextval(''' ||
    atopology || '.node_node_id_seq'')'
  LOOP
    nodeid = rec.nextval;
  END LOOP;

  --RAISE NOTICE 'Next node id = % ', nodeid;

  --
  -- Add the new node 
  --
  EXECUTE 'INSERT INTO ' || quote_ident(atopology)
    || '.node(node_id, geom) 
    VALUES(' || nodeid || ','
    || quote_literal(apoint::text)
    || ')';

  --
  -- Delete the old edge
  --
  EXECUTE 'DELETE FROM ' || quote_ident(atopology) || '.edge_data '
    || ' WHERE edge_id = ' || anedge;

  --
  -- Compute new edges
  --
  edge2 := ST_Split(oldedge.geom, apoint);
  edge1 := ST_GeometryN(edge2, 1);
  edge2 := ST_GeometryN(edge2, 2);

  --
  -- Get ids for the new edges 
  --
  FOR rec IN EXECUTE 'SELECT nextval(''' ||
    atopology || '.edge_data_edge_id_seq'')'
  LOOP
    edgeid1 = rec.nextval;
  END LOOP;
  FOR rec IN EXECUTE 'SELECT nextval(''' ||
    atopology || '.edge_data_edge_id_seq'')'
  LOOP
    edgeid2 = rec.nextval;
  END LOOP;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' inserting new edges % and % split from %', edgeid1, edgeid2, anedge;
#endif

  --RAISE NOTICE 'EdgeId1 % EdgeId2 %', edgeid1, edgeid2;

  --RAISE DEBUG 'oldedge.next_left_edge: %', oldedge.next_left_edge;
  --RAISE DEBUG 'oldedge.next_right_edge: %', oldedge.next_right_edge;

  --
  -- Insert the two new edges
  --
  EXECUTE 'INSERT INTO ' || quote_ident(atopology)
    || '.edge VALUES('
    || edgeid1                                -- edge_id
    || ',' || oldedge.start_node              -- start_node
    || ',' || nodeid                          -- end_node
    || ',' || edgeid2                         -- next_left_edge
    || ',' || CASE                            -- next_right_edge
               WHEN 
                oldedge.next_right_edge = anedge
               THEN edgeid1
               WHEN
                oldedge.next_right_edge = -anedge
               THEN -edgeid2
               ELSE oldedge.next_right_edge
              END
    || ',' || oldedge.left_face               -- left_face
    || ',' || oldedge.right_face              -- right_face
    || ',' || quote_literal(edge1::text)      -- geom
    ||')';

  EXECUTE 'INSERT INTO ' || quote_ident(atopology)
    || '.edge VALUES('
    || edgeid2                                -- edge_id
    || ',' || nodeid                          -- start_node
    || ',' || oldedge.end_node                -- end_node
    || ',' || CASE                            -- next_left_edge
               WHEN 
                oldedge.next_left_edge =
                -anedge
               THEN -edgeid2
               WHEN 
                oldedge.next_left_edge =
                anedge
               THEN edgeid1
               ELSE oldedge.next_left_edge
              END
    || ',' || -edgeid1                        -- next_right_edge
    || ',' || oldedge.left_face               -- left_face
    || ',' || oldedge.right_face              -- right_face
    || ',' || quote_literal(edge2::text)      -- geom
    ||')';

  --
  -- Update all next edge references to match new layout
  --

  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.edge_data SET next_right_edge = '
    || edgeid2
    || ','
    || ' abs_next_right_edge = ' || edgeid2
    || ' WHERE next_right_edge = ' || anedge
    || ' AND edge_id NOT IN (' || edgeid1 || ',' || edgeid2 || ')'
    ;
  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.edge_data SET next_right_edge = '
    || -edgeid1
    || ','
    || ' abs_next_right_edge = ' || edgeid1
    || ' WHERE next_right_edge = ' || -anedge
    || ' AND edge_id NOT IN (' || edgeid1 || ',' || edgeid2 || ')'
    ;

  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.edge_data SET next_left_edge = '
    || edgeid1
    || ','
    || ' abs_next_left_edge = ' || edgeid1
    || ' WHERE next_left_edge = ' || anedge
    || ' AND edge_id NOT IN (' || edgeid1 || ',' || edgeid2 || ')'
    ;
  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.edge_data SET '
    || ' next_left_edge = ' || -edgeid2
    || ','
    || ' abs_next_left_edge = ' || edgeid2
    || ' WHERE next_left_edge = ' || -anedge
    || ' AND edge_id NOT IN (' || edgeid1 || ',' || edgeid2 || ')'
    ;

  --
  -- Update references in the Relation table.
  -- We only take into considerations non-hierarchical
  -- TopoGeometry here, for obvious reasons.
  --
  FOR rec IN EXECUTE 'SELECT r.* FROM '
    || quote_ident(atopology)
    || '.relation r, topology.layer l '
    || ' WHERE '
    || ' l.topology_id = ' || topoid
    || ' AND l.level = 0 '
    || ' AND l.layer_id = r.layer_id '
    || ' AND abs(r.element_id) = ' || anedge
    || ' AND r.element_type = 2'
  LOOP
    --RAISE NOTICE 'TopoGeometry % in layer % contains the edge being split', rec.topogeo_id, rec.layer_id;

    -- Delete old reference
    EXECUTE 'DELETE FROM ' || quote_ident(atopology)
      || '.relation '
      || ' WHERE '
      || 'layer_id = ' || rec.layer_id
      || ' AND '
      || 'topogeo_id = ' || rec.topogeo_id
      || ' AND '
      || 'element_type = ' || rec.element_type
      || ' AND '
      || 'abs(element_id) = ' || anedge;

    -- Add new reference to edge1
    IF rec.element_id < 0 THEN
      tmp = -edgeid1;
    ELSE
      tmp = edgeid1;
    END IF;
    EXECUTE 'INSERT INTO ' || quote_ident(atopology)
      || '.relation '
      || ' VALUES( '
      || rec.topogeo_id
      || ','
      || rec.layer_id
      || ','
      || tmp
      || ','
      || rec.element_type
      || ')';

    -- Add new reference to edge2
    IF rec.element_id < 0 THEN
      tmp = -edgeid2;
    ELSE
      tmp = edgeid2;
    END IF;
    EXECUTE 'INSERT INTO ' || quote_ident(atopology)
      || '.relation '
      || ' VALUES( '
      || rec.topogeo_id
      || ','
      || rec.layer_id
      || ','
      || tmp
      || ','
      || rec.element_type
      || ')';
      
  END LOOP;

  --RAISE NOTICE 'Edge % split in edges % and % by node %',
  --  anedge, edgeid1, edgeid2, nodeid;

  RETURN nodeid; 
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_NewEdgesSplit

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.9 
--
--  ST_ModEdgeSplit(atopology, anedge, apoint)
--
-- Not in the specs:
-- * Update references in the Relation table.
--
CREATE OR REPLACE FUNCTION topology.ST_ModEdgeSplit(atopology varchar, anedge integer, apoint geometry)
  RETURNS INTEGER AS
$$
DECLARE
  oldedge RECORD;
  rec RECORD;
  tmp integer;
  topoid integer;
  nodeid integer;
  nodepos float8;
  newedgeid integer;
  newedge1 geometry;
  newedge2 geometry;
  query text;
  ok BOOL;
BEGIN

  --
  -- All args required
  -- 
  IF atopology IS NULL OR anedge IS NULL OR apoint IS NULL THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  -- Get topology id
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = atopology;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  --
  -- Check node existance
  -- 
  ok = false;
  FOR oldedge IN EXECUTE 'SELECT * FROM '
    || quote_ident(atopology) || '.edge_data ' ||
    ' WHERE edge_id =  ' || anedge
  LOOP
    ok = true;
  END LOOP;
  IF NOT ok THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - non-existent edge';
  END IF;

  --
  -- Check that given point is Within(anedge.geom)
  -- 
  IF NOT ST_Within(apoint, oldedge.geom) THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - point not on edge';
  END IF;

  --
  -- Check if a coincident node already exists
  --
  FOR rec IN EXECUTE 'SELECT node_id FROM '
    || quote_ident(atopology) || '.node ' ||
    'WHERE geom && '
    || quote_literal(apoint::text) || '::geometry'
    ||' AND ST_X(geom) = ST_X('
    || quote_literal(apoint::text) || '::geometry)'
    ||' AND ST_Y(geom) = ST_Y('
    ||quote_literal(apoint::text)||'::geometry)'
  LOOP
    RAISE EXCEPTION
     'SQL/MM Spatial exception - coincident node';
  END LOOP;

  --
  -- Get new node id
  --
  FOR rec IN EXECUTE 'SELECT nextval(''' ||
    atopology || '.node_node_id_seq'')'
  LOOP
    nodeid = rec.nextval;
  END LOOP;

  --RAISE NOTICE 'Next node id = % ', nodeid;

  --
  -- Add the new node 
  --
  EXECUTE 'INSERT INTO ' || quote_ident(atopology)
    || '.node(node_id, geom) 
    VALUES('||nodeid||','||quote_literal(apoint::text)||
    ')';

  --
  -- Compute new edge
  --
  newedge2 := ST_Split(oldedge.geom, apoint);
  newedge1 := ST_GeometryN(newedge2, 1);
  newedge2 := ST_GeometryN(newedge2, 2);

  --
  -- Get ids for the new edge
  --
  FOR rec IN EXECUTE 'SELECT nextval(''' ||
    atopology || '.edge_data_edge_id_seq'')'
  LOOP
    newedgeid = rec.nextval;
  END LOOP;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' inserting new edge % split from %', newedgeid, anedge;
#endif

  --
  -- Insert the new edge
  --
  EXECUTE 'INSERT INTO ' || quote_ident(atopology)
    || '.edge '
    || '(edge_id, start_node, end_node,'
    || 'next_left_edge, next_right_edge,'
    || 'left_face, right_face, geom) '
    || 'VALUES('
    || newedgeid
    || ',' || nodeid
    || ',' || oldedge.end_node
    || ',' || COALESCE(                      -- next_left_edge
                NULLIF(
                  oldedge.next_left_edge,
                  -anedge
                ),
                -newedgeid
              )
    || ',' || -anedge                        -- next_right_edge
    || ',' || oldedge.left_face              -- left_face
    || ',' || oldedge.right_face             -- right_face
    || ',' || quote_literal(newedge2::text)  -- geom
    ||')';

  --
  -- Update the old edge
  --
  EXECUTE 'UPDATE ' || quote_ident(atopology) || '.edge_data '
    || ' SET geom = ' || quote_literal(newedge1::text)
    || ','
    || ' next_left_edge = ' || newedgeid
    || ', abs_next_left_edge = ' || newedgeid
    || ','
    || ' end_node = ' || nodeid
    || ' WHERE edge_id = ' || anedge;


  --
  -- Update all next edge references to match new layout
  --

  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.edge_data SET next_right_edge = '
    || -newedgeid 
    || ','
    || ' abs_next_right_edge = ' || newedgeid
    || ' WHERE edge_id != ' || newedgeid
    || ' AND next_right_edge = ' || -anedge;

  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.edge_data SET '
    || ' next_left_edge = ' || -newedgeid
    || ','
    || ' abs_next_left_edge = ' || newedgeid
    || ' WHERE edge_id != ' || newedgeid
    || ' AND next_left_edge = ' || -anedge;

  --
  -- Update references in the Relation table.
  -- We only take into considerations non-hierarchical
  -- TopoGeometry here, for obvious reasons.
  --
  FOR rec IN EXECUTE 'SELECT r.* FROM '
    || quote_ident(atopology)
    || '.relation r, topology.layer l '
    || ' WHERE '
    || ' l.topology_id = ' || topoid
    || ' AND l.level = 0 '
    || ' AND l.layer_id = r.layer_id '
    || ' AND abs(r.element_id) = ' || anedge
    || ' AND r.element_type = 2'
  LOOP
    --RAISE NOTICE 'TopoGeometry % in layer % contains the edge being split (%) - updating to add new edge %', rec.topogeo_id, rec.layer_id, anedge, newedgeid;

    -- Add new reference to edge1
    IF rec.element_id < 0 THEN
      tmp = -newedgeid;
    ELSE
      tmp = newedgeid;
    END IF;
    query = 'INSERT INTO ' || quote_ident(atopology)
      || '.relation '
      || ' VALUES( '
      || rec.topogeo_id
      || ','
      || rec.layer_id
      || ','
      || tmp
      || ','
      || rec.element_type
      || ')';

    --RAISE NOTICE '%', query;
    EXECUTE query;
  END LOOP;

  --RAISE NOTICE 'Edge % split in edges % and % by node %',
  --  anedge, anedge, newedgeid, nodeid;

  RETURN nodeid; 
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_ModEdgesSplit

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.4 
--
--  ST_AddIsoEdge(atopology, anode, anothernode, acurve)
-- 
-- Not in the specs:
-- * Reset containing_face for starting and ending point,
--   as they stop being isolated nodes
-- * Refuse to add a closed edge, as it would not be isolated
--   (ie: would create a ring)
--
-- }{
--
CREATE OR REPLACE FUNCTION topology.ST_AddIsoEdge(atopology varchar, anode integer, anothernode integer, acurve geometry)
  RETURNS INTEGER AS
$$
DECLARE
  aface INTEGER;
  face GEOMETRY;
  snodegeom GEOMETRY;
  enodegeom GEOMETRY;
  count INTEGER;
  rec RECORD;
  edgeid INTEGER;
BEGIN

  --
  -- All arguments required
  -- 
  IF atopology IS NULL
     OR anode IS NULL
     OR anothernode IS NULL
     OR acurve IS NULL
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  -- NOT IN THE SPECS:
  -- A closed edge is never isolated (as it forms a face)
  IF anode = anothernode THEN
      RAISE EXCEPTION
       'Closed edges would not be isolated, try ST_AddEdgeNewFaces';
  END IF;

  --
  -- Acurve must be a LINESTRING
  --
  IF substring(geometrytype(acurve), 1, 4) != 'LINE'
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - invalid curve';
  END IF;

  --
  -- Acurve must be simple
  --
  IF NOT ST_IsSimple(acurve)
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - curve not simple';
  END IF;

  --
  -- Check for:
  --    existence of nodes
  --    nodes faces match
  -- Extract:
  --    nodes face id
  --    nodes geoms
  --
  aface := NULL;
  count := 0;
  FOR rec IN EXECUTE 'SELECT geom, containing_face, node_id FROM '
    || quote_ident(atopology) || '.node
    WHERE node_id = ' || anode ||
    ' OR node_id = ' || anothernode
  LOOP 

    IF rec.containing_face IS NULL THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - not isolated node';
    END IF;

    IF aface IS NULL THEN
      aface := rec.containing_face;
    ELSE
      IF aface != rec.containing_face THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - nodes in different faces';
      END IF;
    END IF;

    -- Get nodes geom
    IF rec.node_id = anode THEN
      snodegeom = rec.geom;
    ELSE
      enodegeom = rec.geom;
    END IF;

    count = count+1;

  END LOOP;

  -- TODO: don't need count, can do with snodegeom/enodegeom instead..
  IF count < 2 THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent node';
  END IF;


  --
  -- l) Check that start point of acurve match start node
  -- geoms.
  -- 
  IF ST_X(snodegeom) != ST_X(ST_StartPoint(acurve)) OR
     ST_Y(snodegeom) != ST_Y(ST_StartPoint(acurve))
  THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - start node not geometry start point.';
  END IF;

  --
  -- m) Check that end point of acurve match end node
  -- geoms.
  -- 
  IF ST_X(enodegeom) != ST_X(ST_EndPoint(acurve)) OR
     ST_Y(enodegeom) != ST_Y(ST_EndPoint(acurve))
  THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - end node not geometry end point.';
  END IF;

  --
  -- n) Check if curve crosses (contains) any node
  -- I used _contains_ here to leave endpoints out
  -- 
  FOR rec IN EXECUTE 'SELECT node_id FROM '
    || quote_ident(atopology) || '.node '
    || ' WHERE geom && ' || quote_literal(acurve::text) 
    || ' AND ST_Contains(' || quote_literal(acurve::text)
    || ',geom)'
  LOOP
    RAISE EXCEPTION
      'SQL/MM Spatial exception - geometry crosses a node';
  END LOOP;

  --
  -- o) Check if curve intersects any other edge
  -- 
  FOR rec IN EXECUTE 'SELECT * FROM '
    || quote_ident(atopology) || '.edge_data
    WHERE ST_Intersects(geom, ' || quote_literal(acurve::text) || '::geometry)'
  LOOP
    RAISE EXCEPTION 'SQL/MM Spatial exception - geometry intersects an edge';
  END LOOP;

  --
  -- Get new edge id from sequence
  --
  FOR rec IN EXECUTE 'SELECT nextval(''' ||
    atopology || '.edge_data_edge_id_seq'')'
  LOOP
    edgeid = rec.nextval;
  END LOOP;

  -- TODO: this should likely be an exception instead !
  IF aface IS NULL THEN
    aface := 0;
  END IF;

  --
  -- Insert the new row
  --
  EXECUTE 'INSERT INTO ' || quote_ident(atopology)
    || '.edge VALUES(' || edgeid || ',' || anode
    || ',' || anothernode || ',' || (-edgeid)
    || ',' || edgeid || ','
    || aface || ',' || aface || ','
    || quote_literal(acurve::text) || ')';

  --
  -- Update Node containing_face values
  --
  -- the nodes anode and anothernode are no more isolated
  -- because now there is an edge connecting them
  -- 
  EXECUTE 'UPDATE ' || quote_ident(atopology)
    || '.node SET containing_face = NULL where (node_id ='
    || anode
    || ' OR node_id='
    || anothernode
    || ')';

  RETURN edgeid;

END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_AddIsoEdge

-- Internal function used by ST_ChangeEdgeGeom to compare
-- adjacent edges of an edge endpoint
--
-- @param anode the node to use edge end star of
-- @param anedge the directed edge to get adjacents from
--        if positive `anode' is assumed to be its start node
--        if negative `anode' is assumed to be its end node
--      
-- {
CREATE OR REPLACE FUNCTION topology._ST_AdjacentEdges(atopology varchar, anode integer, anedge integer)
RETURNS integer[] AS
$$
DECLARE
  ret integer[];
BEGIN
  WITH edgestar AS (
    SELECT *, count(*) over () AS cnt
    FROM topology.GetNodeEdges(atopology, anode)
  )
  SELECT ARRAY[ (
      SELECT p.edge AS prev FROM edgestar p
      WHERE p.sequence = CASE WHEN m.sequence-1 < 1 THEN cnt
                         ELSE m.sequence-1 END
    ), (
      SELECT p.edge AS prev FROM edgestar p WHERE p.sequence = ((m.sequence)%cnt)+1
    ) ]
  FROM edgestar m
  WHERE edge = anedge
  INTO ret;

  RETURN ret;
END
$$
LANGUAGE 'plpgsql' STABLE;
--}

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.6
--
--  ST_ChangeEdgeGeom(atopology, anedge, acurve)
--
-- Not in the specs:
-- * Raise an exception if given a non-existent edge
-- * Raise an exception if movement is not topologically isomorphic
--
-- }{
CREATE OR REPLACE FUNCTION topology.ST_ChangeEdgeGeom(atopology varchar, anedge integer, acurve geometry)
  RETURNS TEXT AS
$$
DECLARE
  rec RECORD;
  rng_info RECORD; -- movement range info
  oldedge RECORD;
  range GEOMETRY; -- movement range
  tmp1 GEOMETRY;
  snode_info RECORD;
  enode_info RECORD;
  sql TEXT;
  iscw BOOLEAN;
BEGIN

  --
  -- All arguments required
  -- 
  IF atopology IS NULL
     OR anedge IS NULL
     OR acurve IS NULL
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Acurve must be a LINESTRING
  --
  IF substring(geometrytype(acurve), 1, 4) != 'LINE'
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - invalid curve';
  END IF;

  --
  -- Acurve must be a simple
  --
  IF NOT ST_IsSimple(acurve)
  THEN
    RAISE EXCEPTION
     'SQL/MM Spatial exception - curve not simple';
  END IF;

  --
  -- Get data about existing edge
  --
  BEGIN
    EXECUTE 'SELECT * FROM ' || quote_ident(atopology) || '.edge_data  '
      || ' WHERE edge_id = ' || anedge
    INTO STRICT oldedge;
  EXCEPTION
    -- NOT IN THE SPECS: check given edge existance
    WHEN NO_DATA_FOUND THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent edge %', anedge;
  END;

  --
  -- e) Check StartPoint consistency
  --
  IF NOT ST_Equals(ST_StartPoint(acurve), ST_StartPoint(oldedge.geom)) THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - start node not geometry start point.';
  END IF;

  IF oldedge.start_node = oldedge.end_node THEN -- {

    -- Not in the specs:
    -- if the edge is closed, check we didn't change winding !
    --       (should be part of isomorphism checking)
    range := ST_MakePolygon(oldedge.geom);
    iscw := ST_OrderingEquals(range, ST_ForceRHR(range));

    IF ST_NumPoints(ST_RemoveRepeatedPoints(acurve)) < 3 THEN
      RAISE EXCEPTION 'Invalid edge (no two distinct vertices exist)';
    END IF;
    range := ST_MakePolygon(acurve);

    IF iscw != ST_OrderingEquals(range, ST_ForceRHR(range)) THEN
      RAISE EXCEPTION 'Edge twist at node %',
        ST_AsText(ST_StartPoint(oldedge.geom));
    END IF;

  ELSE -- }{

    --
    -- f) Check EndPoint consistency
    --
    IF NOT ST_Equals(ST_EndPoint(acurve), ST_EndPoint(oldedge.geom)) THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - end node not geometry end point.';
    END IF;

  END IF; -- }

  --
  -- g) Check if curve crosses any node
  -- 
  FOR rec IN EXECUTE
    'SELECT node_id, ST_Relate(geom, '
    || quote_literal(acurve::text) || '::geometry, 2) as relate FROM '
    || quote_ident(atopology)
    || '.node WHERE geom && '
    || quote_literal(acurve::text)
    || '::geometry AND node_id NOT IN ('
    || oldedge.start_node || ',' || oldedge.end_node
    || ')'
  LOOP
    IF ST_RelateMatch(rec.relate, 'T********') THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - geometry crosses a node';
    END IF;
  END LOOP;

  --
  -- h) Check if this geometry has any interaction with any existing edge
  --
  sql := 'SELECT edge_id, ST_Relate(geom,' 
    || quote_literal(acurve::text)
    || '::geometry, 2) as im FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE edge_id != ' || anedge || ' AND geom && '
    || quote_literal(acurve::text) || '::geometry';
  FOR rec IN EXECUTE sql LOOP -- {

    --RAISE DEBUG 'IM=%',rec.im;

    IF ST_RelateMatch(rec.im, 'F********') THEN
      CONTINUE; -- no interior-interior intersection
    END IF;

    IF ST_RelateMatch(rec.im, '1FFF*FFF2') THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - coincident edge %', rec.edge_id;
    END IF;

    -- NOT IN THE SPECS: geometry touches an edge
    IF ST_RelateMatch(rec.im, '1********') THEN
      RAISE EXCEPTION
        'Spatial exception - geometry intersects edge %', rec.edge_id;
    END IF;

    IF ST_RelateMatch(rec.im, 'T********') THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - geometry crosses edge %', rec.edge_id;
    END IF;

  END LOOP; -- }

  --
  -- Not in the specs:
  -- Check topological isomorphism 
  --

  -- Check that the "motion range" doesn't include any node 
  --{

  sql := 'SELECT ST_Collect(geom) as nodes, '
    || 'null::geometry as r1, null::geometry as r2 FROM '
    || quote_ident(atopology)
    || '.node WHERE geom && '
    || quote_literal(ST_Collect(ST_Envelope(oldedge.geom),
                                ST_Envelope(acurve))::text)
    || '::geometry AND node_id NOT IN ( '
    || oldedge.start_node || ',' || oldedge.end_node || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG '%', sql;
#endif
  EXECUTE sql INTO rng_info;

  -- There's no collision if there's no nodes in the combined
  -- bbox of old and new edges.
  --
  IF NOT ST_IsEmpty(rng_info.nodes) THEN -- {

#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG '% nodes in the edge movement range bbox: %',
                              ST_NumGeometries(rng_info.nodes),
                              ST_AsText(rng_info.nodes)
                              ;
#endif

    tmp1 := ST_MakeLine(ST_EndPoint(oldedge.geom), ST_StartPoint(oldedge.geom));
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'end-to-start: %', ST_AsText(tmp1);
#endif

    rng_info.r1 := ST_MakeLine(oldedge.geom, tmp1);
    IF ST_NumPoints(rng_info.r1) < 4 THEN
      rng_info.r1 := ST_AddPoint(rng_info.r1, ST_StartPoint(oldedge.geom));
    END IF;
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Old-ring: %', ST_AsText(rng_info.r1);
#endif
    rng_info.r1 := ST_CollectionExtract(
                       ST_MakeValid(ST_MakePolygon(rng_info.r1)), 3);
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Old-ring (poly): %', ST_AsText(rng_info.r1);
#endif

    rng_info.r2 := ST_MakeLine(acurve, tmp1);
    IF ST_NumPoints(rng_info.r2) < 4 THEN
      rng_info.r2 := ST_AddPoint(rng_info.r2, ST_StartPoint(oldedge.geom));
    END IF;
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'New-ring: %', ST_AsText(rng_info.r2);
#endif
    rng_info.r2 := ST_CollectionExtract(
                       ST_MakeValid(ST_MakePolygon(rng_info.r2)), 3);
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'New-ring (poly): %', ST_AsText(rng_info.r2);
#endif

    FOR rec IN WITH
      nodes AS ( SELECT * FROM ST_Dump(rng_info.nodes) ),
      inr1 AS ( SELECT path[1] FROM nodes WHERE ST_Contains(rng_info.r1, geom) ),
      inr2 AS ( SELECT path[1] FROM nodes WHERE ST_Contains(rng_info.r2, geom) )
      ( SELECT * FROM inr1
          EXCEPT
        SELECT * FROM inr2
      ) UNION 
      ( SELECT * FROM inr2
          EXCEPT
        SELECT * FROM inr1
      )
    LOOP
      RAISE EXCEPTION 'Edge motion collision at %',
                     ST_AsText(ST_GeometryN(rng_info.nodes, rec.path));
    END LOOP;

  END IF; -- }

  --} motion range checking end

  -- 
  -- Check edge adjacency before
  --{

  SELECT topology._ST_AdjacentEdges(
      atopology, oldedge.start_node, anedge
    ) as pre, NULL::integer[] as post
  INTO STRICT snode_info;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Bs:%', snode_info.pre;
#endif

  SELECT topology._ST_AdjacentEdges(
      atopology, oldedge.end_node, -anedge
    ) as pre, NULL::integer[] as post
  INTO STRICT enode_info;
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Be:%', enode_info.pre;
#endif

  --}

  --
  -- Update edge geometry
  --
  EXECUTE 'UPDATE ' || quote_ident(atopology) || '.edge_data '
    || ' SET geom = ' || quote_literal(acurve::text) 
    || ' WHERE edge_id = ' || anedge;

  -- 
  -- Check edge adjacency after
  --{

  snode_info.post := topology._ST_AdjacentEdges(
      atopology, oldedge.start_node, anedge
    );
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'As:%', snode_info.post;
#endif

  enode_info.post := topology._ST_AdjacentEdges(
      atopology, oldedge.end_node, -anedge
    );
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Ae:%', enode_info.post;
#endif

  IF snode_info.pre != snode_info.post THEN
    RAISE EXCEPTION 'Edge changed disposition around start node %',
      oldedge.start_node;
  END IF;

  IF enode_info.pre != enode_info.post THEN
    RAISE EXCEPTION 'Edge changed disposition around end node %',
      oldedge.end_node;
  END IF;

  --}

  -- Update faces MBR of left and right faces
  -- TODO: think about ways to optimize this part, like see if
  --       the old edge geometry partecipated in the definition
  --       of the current MBR (for shrinking) or the new edge MBR
  --       would be larger than the old face MBR...
  --
  IF oldedge.left_face != 0 THEN
    sql := 'UPDATE ' || quote_ident(atopology) || '.face '
      || ' SET mbr = ' || quote_literal(
        ST_Envelope(topology.ST_GetFaceGeometry(atopology, oldedge.left_face))::text
        )
      || '::geometry WHERE face_id = ' || oldedge.left_face;
    EXECUTE sql;
  END IF;
  IF oldedge.right_face != 0 AND oldedge.right_face != oldedge.left_face THEN
    sql := 'UPDATE ' || quote_ident(atopology) || '.face '
      || ' SET mbr = ' || quote_literal(
        ST_Envelope(topology.ST_GetFaceGeometry(atopology, oldedge.right_face))::text
        )
      || '::geometry WHERE face_id = ' || oldedge.right_face;
    EXECUTE sql;
  END IF;
  

  RETURN 'Edge ' || anedge || ' changed';

END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_ChangeEdgeGeom

--
-- _ST_AddFaceSplit
--
-- Add a split face by walking on the edge side.
--
-- @param atopology topology name
-- @param anedge edge id and walking side (left:positive right:negative)
-- @param oface the face in which the edge identifier is known to be
-- @param mbr_only do not create a new face but update MBR of the current
--
-- The created face, if any, will be at the left hand of the walking path
--
-- Return:
--  NULL: if mbr_only was requested
--     0: if the edge does not form a ring
--  NULL: if it is impossible to create a face on the requested side
--        ( new face on the side is the universe )
--   >0 : id of newly added face
--
-- {
CREATE OR REPLACE FUNCTION topology._ST_AddFaceSplit(atopology varchar, anedge integer, oface integer, mbr_only bool)
  RETURNS INTEGER AS
$$
DECLARE
  fan RECORD;
  newface INTEGER;
  sql TEXT;
  isccw BOOLEAN;
  ishole BOOLEAN;

BEGIN

  IF oface = 0 AND mbr_only THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Universal face has no MBR, doing nothing';
#endif
    RETURN NULL;
  END IF;

  SELECT null::int[] as newring_edges,
         null::geometry as shell
  INTO fan;

  SELECT array_agg(edge)
  FROM topology.getringedges(atopology, anedge)
  INTO STRICT fan.newring_edges;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'ring: %', fan.newring_edges;
#endif

  -- You can't get to the other side of an edge forming a ring 
  IF fan.newring_edges @> ARRAY[-anedge] THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'not a ring';
#endif
    RETURN 0;
  END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Edge % splitted face %', anedge, oface;
#endif

  sql := 'WITH ids as ( select row_number() over () as seq, edge from unnest('
    || quote_literal(fan.newring_edges::text)
    || '::int[] ) u(edge) ), edges AS ( select CASE WHEN i.edge < 0 THEN ST_Reverse(e.geom) ELSE e.geom END as g FROM ids i left join '
    || quote_ident(atopology) || '.edge_data e ON(e.edge_id = abs(i.edge)) ORDER BY seq) SELECT ST_MakePolygon(ST_MakeLine(g.g)) FROM edges g;';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG '%', sql;
#endif
  EXECUTE sql INTO fan.shell;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'got shell'; 
#endif

  isccw := NOT ST_OrderingEquals(fan.shell, ST_ForceRHR(fan.shell));

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'winding: %', CASE WHEN isccw THEN 'CCW' ELSE 'CW' END;
#endif

  IF oface = 0 THEN
    IF NOT isccw THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'Not considering CW ring in universe face';
#endif
      RETURN NULL;
    END IF;
  END IF;

  IF mbr_only AND oface != 0 THEN
    -- Update old face mbr (nothing to do if we're opening an hole)
    IF isccw THEN -- {
      sql := 'UPDATE '
        || quote_ident(atopology) || '.face SET mbr = '
        || quote_literal(ST_Envelope(fan.shell)::text)
        || '::geometry WHERE face_id = ' || oface;
#ifdef POSTGIS_TOPOLOGY_DEBUG
    	RAISE DEBUG 'Updating old face mbr'; 
#endif
    	EXECUTE sql;
    END IF; -- }
    RETURN NULL;
  END IF;

  IF oface != 0 AND NOT isccw THEN -- {
    -- Face created an hole in an outer face
    sql := 'INSERT INTO '
      || quote_ident(atopology) || '.face(mbr) SELECT mbr FROM '
      || quote_ident(atopology)
      || '.face WHERE face_id = ' || oface
      || ' RETURNING face_id';
  ELSE
    sql := 'INSERT INTO '
      || quote_ident(atopology) || '.face(mbr) VALUES ('
      || quote_literal(ST_Envelope(fan.shell)::text)
      || '::geometry) RETURNING face_id';
  END IF; -- }

  -- Insert new face
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Inserting new face'; 
#endif
  EXECUTE sql INTO STRICT newface;

  -- Update forward edges
  sql := 'UPDATE '
    || quote_ident(atopology) || '.edge_data SET left_face = ' || newface
    || ' WHERE left_face = ' || oface || ' AND edge_id = ANY ('
    || quote_literal(array( select +(x) from unnest(fan.newring_edges) u(x) )::text)
    || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Updating forward edges in new ring';
#endif
  EXECUTE sql;

  -- Update backward edges
  sql := 'UPDATE '
    || quote_ident(atopology) || '.edge_data SET right_face = ' || newface
    || ' WHERE right_face = ' || oface || ' AND edge_id = ANY ('
    || quote_literal(array( select -(x) from unnest(fan.newring_edges) u(x) )::text)
    || ')';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Updating backward edges in new ring';
#endif
  EXECUTE sql;

  IF oface != 0 AND NOT isccw THEN -- {
    -- face shrinked, must update all non-contained edges and nodes
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Updating rings in former shell';
#endif
    ishole := true;
  ELSE
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Updating contained edges';
#endif
    ishole := false;
  END IF; -- }

  -- Update edges bounding the old face
  sql := 'UPDATE '
    || quote_ident(atopology)
    || '.edge_data SET left_face = CASE WHEN left_face = '
    || oface || ' THEN ' || newface
    || ' ELSE left_face END, right_face = CASE WHEN right_face = '
    || oface || ' THEN ' || newface
    || ' ELSE right_face END WHERE ( left_face = ' || oface
    || ' OR right_face = ' || oface
    || ') AND NOT edge_id = ANY ('
    || quote_literal( array(
        select abs(x) from unnest(fan.newring_edges) u(x)
       )::text )
    || ') AND ';
  IF ishole THEN sql := sql || 'NOT '; END IF;
  sql := sql || '( ' || quote_literal(fan.shell::text)
    || ' && geom AND _ST_Contains(' || quote_literal(fan.shell::text)
    -- We only need to check a single point, but must not be an endpoint
    || '::geometry, ST_LineInterpolatePoint(geom, 0.2)) )';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Updating edges bounding the old face: %', sql;
#endif
  EXECUTE sql;

  -- Update isolated nodes in new new face 
  sql := 'UPDATE '
    || quote_ident(atopology) || '.node SET containing_face = ' || newface
    || ' WHERE containing_face = ' || oface 
    || ' AND ';
  IF ishole THEN sql := sql || 'NOT '; END IF;
  sql := sql || 'ST_Contains(' || quote_literal(fan.shell::text) || '::geometry, geom)';
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Updating isolated nodes in old face';
#endif
  EXECUTE sql;

  RETURN newface;

END
$$
LANGUAGE 'plpgsql' VOLATILE;
--}

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.12
--
--  ST_AddEdgeNewFaces(atopology, anode, anothernode, acurve)
--
-- Not in the specs:
-- * Reset containing_face for starting and ending point,
--   as they stop being isolated nodes
-- * Update references in the Relation table.
--
CREATE OR REPLACE FUNCTION topology.ST_AddEdgeNewFaces(atopology varchar, anode integer, anothernode integer, acurve geometry)
  RETURNS INTEGER AS
$$
DECLARE
  rec RECORD;
  i INTEGER;
  topoid INTEGER;
  az FLOAT8;
  span RECORD; -- start point analysis data
  epan RECORD; --   end point analysis data
  fan RECORD; -- face analisys
  newedge RECORD; -- informations about new edge
  sql TEXT;
  newfaces INTEGER[];
  newface INTEGER;
BEGIN

  --
  -- All args required
  -- 
  IF atopology IS NULL
    OR anode IS NULL
    OR anothernode IS NULL
    OR acurve IS NULL
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Acurve must be a LINESTRING
  --
  IF substring(geometrytype(acurve), 1, 4) != 'LINE'
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - invalid curve';
  END IF;
  
  --
  -- Curve must be simple
  --
  IF NOT ST_IsSimple(acurve) THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - curve not simple';
  END IF;

  --
  -- Get topology id
  --
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = atopology;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  -- Initialize new edge info (will be filled up more later)
  SELECT anode as start_node, anothernode as end_node, acurve as geom,
    NULL::int as next_left_edge, NULL::int as next_right_edge,
    NULL::int as left_face, NULL::int as right_face, NULL::int as edge_id,
    NULL::int as prev_left_edge, NULL::int as prev_right_edge, -- convenience
    anode = anothernode as isclosed, -- convenience
    false as start_node_isolated, -- convenience
    false as end_node_isolated, -- convenience
    NULL::geometry as start_node_geom, -- convenience
    NULL::geometry as end_node_geom, -- convenience
    ST_RemoveRepeatedPoints(acurve) as cleangeom -- convenience
  INTO newedge;

  -- Compute azimuth of first edge end on start node
  SELECT null::int AS nextCW, null::int AS nextCCW,
         null::float8 AS minaz, null::float8 AS maxaz,
         false AS was_isolated,
         ST_Azimuth(ST_StartPoint(newedge.cleangeom),
                    ST_PointN(newedge.cleangeom, 2)) AS myaz
  INTO span;
  IF span.myaz IS NULL THEN
    RAISE EXCEPTION 'Invalid edge (no two distinct vertices exist)';
  END IF;

  -- Compute azimuth of last edge end on end node
  SELECT null::int AS nextCW, null::int AS nextCCW,
         null::float8 AS minaz, null::float8 AS maxaz,
         false AS was_isolated,
         ST_Azimuth(ST_EndPoint(newedge.cleangeom),
                    ST_PointN(newedge.cleangeom,
                              ST_NumPoints(newedge.cleangeom)-1)) AS myaz
  INTO epan;
  IF epan.myaz IS NULL THEN
    RAISE EXCEPTION 'Invalid edge (no two distinct vertices exist)';
  END IF;


  -- 
  -- Check endpoints existance, match with Curve geometry
  -- and get face information (if any)
  --
  i := 0;
  FOR rec IN EXECUTE 'SELECT node_id, containing_face, geom FROM '
    || quote_ident(atopology)
    || '.node WHERE node_id IN ( '
    || anode || ',' || anothernode
    || ')'
  LOOP
    IF rec.containing_face IS NOT NULL THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG  'containing_face for node %:%',
        rec.node_id, rec.containing_face;
#endif
      IF newedge.left_face IS NULL THEN
        newedge.left_face := rec.containing_face;
        newedge.right_face := rec.containing_face;
      ELSE
        IF newedge.left_face != rec.containing_face THEN
          RAISE EXCEPTION
            'SQL/MM Spatial exception - geometry crosses an edge (endnodes in faces % and %)', newedge.left_face, rec.containing_face;
        END IF;
      END IF;
    END IF;

    IF rec.node_id = anode THEN
      newedge.start_node_geom = rec.geom;
    END IF;

    IF rec.node_id = anothernode THEN
      newedge.end_node_geom = rec.geom;
    END IF;

    i := i + 1;
  END LOOP;

  IF newedge.start_node_geom IS NULL
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent node';
  ELSIF NOT ST_Equals(newedge.start_node_geom, ST_StartPoint(acurve))
  THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - start node not geometry start point.';
  END IF;

  IF newedge.end_node_geom IS NULL
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent node';
  ELSIF NOT ST_Equals(newedge.end_node_geom, ST_EndPoint(acurve))
  THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - end node not geometry end point.';
  END IF;

  RAISE DEBUG 'All Checked !';

  --
  -- Check if this geometry crosses any node
  --
  FOR rec IN EXECUTE
    'SELECT node_id, ST_Relate(geom, '
    || quote_literal(acurve::text) || '::geometry, 2) as relate FROM '
    || quote_ident(atopology)
    || '.node WHERE geom && '
    || quote_literal(acurve::text)
    || '::geometry'
  LOOP
    IF ST_RelateMatch(rec.relate, 'T********') THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - geometry crosses a node';
    END IF;
  END LOOP;

  --
  -- Check if this geometry has any interaction with any existing edge
  --
  FOR rec IN EXECUTE 'SELECT edge_id, ST_Relate(geom,' 
    || quote_literal(acurve::text)
    || '::geometry, 2) as im FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE geom && '
    || quote_literal(acurve::text) || '::geometry'
  LOOP

    --RAISE DEBUG 'IM=%',rec.im;

    IF ST_RelateMatch(rec.im, 'F********') THEN
      CONTINUE; -- no interior intersection
    END IF;

    IF ST_RelateMatch(rec.im, '1FFF*FFF2') THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - coincident edge %', rec.edge_id;
    END IF;

    -- NOT IN THE SPECS: geometry touches an edge
    IF ST_RelateMatch(rec.im, '1********') THEN
      RAISE EXCEPTION
        'Spatial exception - geometry intersects edge %', rec.edge_id;
    END IF;

    IF ST_RelateMatch(rec.im, 'T********') THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - geometry crosses edge %', rec.edge_id;
    END IF;

  END LOOP;

  ---------------------------------------------------------------
  --
  -- All checks passed, time to prepare the new edge
  --
  ---------------------------------------------------------------

  EXECUTE 'SELECT nextval(' || quote_literal(
      quote_ident(atopology) || '.edge_data_edge_id_seq') || ')'
  INTO STRICT newedge.edge_id;


  -- Find links on start node -- {

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'My start-segment azimuth: %', span.myaz;
#endif

  sql :=
    'SELECT edge_id, -1 AS end_node, start_node, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) as geom FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE start_node = ' || anode
    || ' UNION SELECT edge_id, end_node, -1, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE end_node = ' || anode;
  IF newedge.isclosed THEN
    sql := sql || ' UNION SELECT '
      || newedge.edge_id || ',' || newedge.end_node
      || ',-1,0,0,' -- pretend we start elsewhere
      || quote_literal(newedge.cleangeom::text);
  END IF;
  i := 0;
  FOR rec IN EXECUTE sql
  LOOP -- incident edges {

    i := i + 1;

    IF rec.start_node = anode THEN
      --
      -- Edge starts at our node, we compute
      -- azimuth from node to its second point
      --
      az := ST_Azimuth(ST_StartPoint(rec.geom), ST_PointN(rec.geom, 2));

    ELSE
      --
      -- Edge ends at our node, we compute
      -- azimuth from node to its second-last point
      --
      az := ST_Azimuth(ST_EndPoint(rec.geom),
                       ST_PointN(rec.geom, ST_NumPoints(rec.geom)-1));
      rec.edge_id := -rec.edge_id;

    END IF;

    IF az IS NULL THEN
      RAISE EXCEPTION 'Invalid edge % found (no two distinct nodes exist)',
        rec.edge_id;
    END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Edge % - az % (%) - fl:% fr:%',
      rec.edge_id, az, az - span.myaz, rec.left_face, rec.right_face;
#endif

    az = az - span.myaz;
    IF az < 0 THEN
      az := az + 2*PI();
    END IF;

    -- RAISE DEBUG ' normalized az %', az;

    IF span.maxaz IS NULL OR az > span.maxaz THEN
      span.maxaz := az;
      span.nextCCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.left_face := rec.left_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.left_face := rec.right_face;
        END IF;
      END IF;
    END IF;

    IF span.minaz IS NULL OR az < span.minaz THEN
      span.minaz := az;
      span.nextCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.right_face := rec.right_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.right_face := rec.left_face;
        END IF;
      END IF;
    END IF;

    --RAISE DEBUG 'Closest edges: CW:%(%) CCW:%(%)', span.nextCW, span.minaz, span.nextCCW, span.maxaz;

  END LOOP; -- incident edges }

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'span ROW_COUNT: %', i;
#endif
  IF newedge.isclosed THEN
    IF i < 2 THEN span.was_isolated = true; END IF;
  ELSE
    IF i < 1 THEN span.was_isolated = true; END IF;
  END IF;

  IF span.nextCW IS NULL THEN
    -- This happens if the destination node is isolated
    newedge.next_right_edge := newedge.edge_id;
    newedge.prev_left_edge := -newedge.edge_id;
  ELSE
    newedge.next_right_edge := span.nextCW;
    newedge.prev_left_edge := -span.nextCCW;
  END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'edge:%', newedge.edge_id;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' left:%, next:%, prev:%',
    newedge.left_face, newedge.next_left_edge, newedge.prev_left_edge;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' right:%, next:%, prev:%',
    newedge.right_face, newedge.next_right_edge, newedge.prev_right_edge;
#endif

  -- } start_node analysis


  -- Find links on end_node {
      
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'My end-segment azimuth: %', epan.myaz;
#endif

  sql :=
    'SELECT edge_id, -1 as end_node, start_node, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) as geom FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE start_node = ' || anothernode
    || 'UNION SELECT edge_id, end_node, -1, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE end_node = ' || anothernode;
  IF newedge.isclosed THEN
    sql := sql || ' UNION SELECT '
      || newedge.edge_id || ',' || -1 -- pretend we end elsewhere
      || ',' || newedge.start_node || ',0,0,'
      || quote_literal(newedge.cleangeom::text);
  END IF;
  i := 0;
  FOR rec IN EXECUTE sql
  LOOP -- incident edges {

    i := i + 1;

    IF rec.start_node = anothernode THEN
      --
      -- Edge starts at our node, we compute
      -- azimuth from node to its second point
      --
      az := ST_Azimuth(ST_StartPoint(rec.geom),
                       ST_PointN(rec.geom, 2));

    ELSE
      --
      -- Edge ends at our node, we compute
      -- azimuth from node to its second-last point
      --
      az := ST_Azimuth(ST_EndPoint(rec.geom),
        ST_PointN(rec.geom, ST_NumPoints(rec.geom)-1));
      rec.edge_id := -rec.edge_id;

    END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Edge % - az % (%)', rec.edge_id, az, az - epan.myaz;
#endif

    az := az - epan.myaz;
    IF az < 0 THEN
      az := az + 2*PI();
    END IF;

    -- RAISE DEBUG ' normalized az %', az;

    IF epan.maxaz IS NULL OR az > epan.maxaz THEN
      epan.maxaz := az;
      epan.nextCCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.right_face := rec.left_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.right_face := rec.right_face;
        END IF;
      END IF;
    END IF;

    IF epan.minaz IS NULL OR az < epan.minaz THEN
      epan.minaz := az;
      epan.nextCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.left_face := rec.right_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.left_face := rec.left_face;
        END IF;
      END IF;
    END IF;

    --RAISE DEBUG 'Closest edges: CW:%(%) CCW:%(%)', epan.nextCW, epan.minaz, epan.nextCCW, epan.maxaz;

  END LOOP; -- incident edges }

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'epan ROW_COUNT: %', i;
#endif
  IF newedge.isclosed THEN
    IF i < 2 THEN epan.was_isolated = true; END IF;
  ELSE
    IF i < 1 THEN epan.was_isolated = true; END IF;
  END IF;

  IF epan.nextCW IS NULL THEN
    -- This happens if the destination node is isolated
    newedge.next_left_edge := -newedge.edge_id;
    newedge.prev_right_edge := newedge.edge_id;
  ELSE
    newedge.next_left_edge := epan.nextCW;
    newedge.prev_right_edge := -epan.nextCCW;
  END IF;

  -- } end_node analysis

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'edge:%', newedge.edge_id;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' left:%, next:%, prev:%',
    newedge.left_face, newedge.next_left_edge, newedge.prev_left_edge;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' right:%, next:%, prev:%',
    newedge.right_face, newedge.next_right_edge, newedge.prev_right_edge;
#endif

  ----------------------------------------------------------------------
  --
  -- If we don't have faces setup by now we must have encountered
  -- a malformed topology (no containing_face on isolated nodes, no
  -- left/right faces on adjacent edges or mismatching values)
  --
  ----------------------------------------------------------------------
  IF newedge.left_face != newedge.right_face THEN
    RAISE EXCEPTION 'Left(%)/right(%) faces mismatch: invalid topology ?', 
      newedge.left_face, newedge.right_face;
  END IF;
  IF newedge.left_face IS NULL THEN
    RAISE EXCEPTION 'Could not derive edge face from linked primitives: invalid topology ?';
  END IF;

  ----------------------------------------------------------------------
  --
  -- Insert the new edge, and update all linking
  --
  ----------------------------------------------------------------------

  -- Insert the new edge with what we have so far
  EXECUTE 'INSERT INTO ' || quote_ident(atopology) 
    || '.edge VALUES(' || newedge.edge_id
    || ',' || newedge.start_node
    || ',' || newedge.end_node
    || ',' || newedge.next_left_edge
    || ',' || newedge.next_right_edge
    || ',' || newedge.left_face
    || ',' || newedge.right_face
    || ',' || quote_literal(newedge.geom::geometry::text)
    || ')';

  -- Link prev_left_edge to us 
  -- (if it's not us already)
  IF abs(newedge.prev_left_edge) != newedge.edge_id THEN
    IF newedge.prev_left_edge > 0 THEN
      -- its next_left_edge is us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_left_edge = '
        || newedge.edge_id
        || ', abs_next_left_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || newedge.prev_left_edge;
    ELSE
      -- its next_right_edge is us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_right_edge = '
        || newedge.edge_id
        || ', abs_next_right_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || -newedge.prev_left_edge;
    END IF;
  END IF;

  -- Link prev_right_edge to us 
  -- (if it's not us already)
  IF abs(newedge.prev_right_edge) != newedge.edge_id THEN
    IF newedge.prev_right_edge > 0 THEN
      -- its next_left_edge is -us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_left_edge = '
        || -newedge.edge_id
        || ', abs_next_left_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || newedge.prev_right_edge;
    ELSE
      -- its next_right_edge is -us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_right_edge = '
        || -newedge.edge_id
        || ', abs_next_right_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || -newedge.prev_right_edge;
    END IF;
  END IF;

  -- NOT IN THE SPECS...
  -- set containing_face = null for start_node and end_node
  -- if they where isolated 
  IF span.was_isolated OR epan.was_isolated THEN
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.node SET containing_face = null WHERE node_id IN ('
        || anode || ',' || anothernode || ')';
  END IF;

  --------------------------------------------
  -- Check face splitting
  --------------------------------------------

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Checking right face';
#endif

  SELECT topology._ST_AddFaceSplit(atopology, -newedge.edge_id, newedge.left_face, false)
  INTO newface;

  IF newface = 0 THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG ' No split';
#endif
    RETURN newedge.edge_id; 
  END IF;

  newfaces[1] := newface;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Checking left face';
#endif
  SELECT topology._ST_AddFaceSplit(atopology, newedge.edge_id, newedge.left_face, false)
  INTO newface;

  newfaces[2] := newface;

  IF newedge.left_face != 0 THEN -- {

    -- NOT IN THE SPECS:
    -- update TopoGeometry compositions to substitute oldface with newfaces
    sql := 'UPDATE '
      || quote_ident(atopology)
      || '.relation r set element_id = ' || newfaces[1]
      || ' FROM topology.layer l '
      || ' WHERE l.topology_id = ' || topoid
      || ' AND l.level = 0 '
      || ' AND l.layer_id = r.layer_id '
      || ' AND r.element_id = ' || newedge.left_face
      || ' AND r.element_type = 3 RETURNING r.topogeo_id, r.layer_id';
    --RAISE DEBUG 'SQL: %', sql;
    FOR rec IN EXECUTE sql
    LOOP
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'TopoGeometry % in layer % contained the face being split (%) - updating to contain both new faces %', rec.topogeo_id, rec.layer_id, newedge.left_face, newfaces;
#endif

      -- Add reference to the other face
      sql := 'INSERT INTO ' || quote_ident(atopology)
        || '.relation VALUES( ' || rec.topogeo_id
        || ',' || rec.layer_id || ',' || newfaces[2] || ', 3)';
      --RAISE DEBUG 'SQL: %', sql;
      EXECUTE sql;

    END LOOP;

    -- drop old face from faces table
    sql := 'DELETE FROM ' || quote_ident(atopology)
      || '.face WHERE face_id = ' || newedge.left_face;
    EXECUTE sql;

  END IF; -- }

  RETURN newedge.edge_id;
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_AddEdgeNewFaces

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.13
--
--  ST_AddEdgeModFace(atopology, anode, anothernode, acurve)
--
-- Not in the specs:
-- * Reset containing_face for starting and ending point,
--   as they stop being isolated nodes
-- * Update references in the Relation table.
--
CREATE OR REPLACE FUNCTION topology.ST_AddEdgeModFace(atopology varchar, anode integer, anothernode integer, acurve geometry)
  RETURNS INTEGER AS
$$
DECLARE
  rec RECORD;
  rrec RECORD;
  i INTEGER;
  topoid INTEGER;
  az FLOAT8;
  span RECORD; -- start point analysis data
  epan RECORD; --   end point analysis data
  fan RECORD; -- face analisys
  newedge RECORD; -- informations about new edge
  sql TEXT;
  newfaces INTEGER[];
  newface INTEGER;
BEGIN

  --
  -- All args required
  -- 
  IF atopology IS NULL
    OR anode IS NULL
    OR anothernode IS NULL
    OR acurve IS NULL
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  --
  -- Acurve must be a LINESTRING
  --
  IF substring(geometrytype(acurve), 1, 4) != 'LINE'
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - invalid curve';
  END IF;
  
  --
  -- Curve must be simple
  --
  IF NOT ST_IsSimple(acurve) THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - curve not simple';
  END IF;

  --
  -- Get topology id
  --
  BEGIN
    SELECT id FROM topology.topology
      INTO STRICT topoid WHERE name = atopology;
    EXCEPTION
      WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  -- Initialize new edge info (will be filled up more later)
  SELECT anode as start_node, anothernode as end_node, acurve as geom,
    NULL::int as next_left_edge, NULL::int as next_right_edge,
    NULL::int as left_face, NULL::int as right_face, NULL::int as edge_id,
    NULL::int as prev_left_edge, NULL::int as prev_right_edge, -- convenience
    anode = anothernode as isclosed, -- convenience
    false as start_node_isolated, -- convenience
    false as end_node_isolated, -- convenience
    NULL::geometry as start_node_geom, -- convenience
    NULL::geometry as end_node_geom, -- convenience
    ST_RemoveRepeatedPoints(acurve) as cleangeom -- convenience
  INTO newedge;

  -- Compute azimut of first edge end on start node
  SELECT null::int AS nextCW, null::int AS nextCCW,
         null::float8 AS minaz, null::float8 AS maxaz,
         false AS was_isolated,
         ST_Azimuth(ST_StartPoint(newedge.cleangeom),
                    ST_PointN(newedge.cleangeom, 2)) AS myaz
  INTO span;
  IF span.myaz IS NULL THEN
    RAISE EXCEPTION 'Invalid edge (no two distinct vertices exist)';
  END IF;

  -- Compute azimuth of last edge end on end node
  SELECT null::int AS nextCW, null::int AS nextCCW,
         null::float8 AS minaz, null::float8 AS maxaz,
         false AS was_isolated,
         ST_Azimuth(ST_EndPoint(newedge.cleangeom),
                    ST_PointN(newedge.cleangeom,
                              ST_NumPoints(newedge.cleangeom)-1)) AS myaz
  INTO epan;
  IF epan.myaz IS NULL THEN
    RAISE EXCEPTION 'Invalid edge (no two distinct vertices exist)';
  END IF;


  -- 
  -- Check endpoints existance, match with Curve geometry
  -- and get face information (if any)
  --
  i := 0;
  FOR rec IN EXECUTE 'SELECT node_id, containing_face, geom FROM '
    || quote_ident(atopology)
    || '.node WHERE node_id IN ( '
    || anode || ',' || anothernode
    || ')'
  LOOP
    IF rec.containing_face IS NOT NULL THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG  'containing_face for node %:%',
        rec.node_id, rec.containing_face;
#endif
      IF newedge.left_face IS NULL THEN
        newedge.left_face := rec.containing_face;
        newedge.right_face := rec.containing_face;
      ELSE
        IF newedge.left_face != rec.containing_face THEN
          RAISE EXCEPTION
            'SQL/MM Spatial exception - geometry crosses an edge (endnodes in faces % and %)', newedge.left_face, rec.containing_face;
        END IF;
      END IF;
    END IF;

    IF rec.node_id = anode THEN
      newedge.start_node_geom = rec.geom;
    END IF;

    IF rec.node_id = anothernode THEN
      newedge.end_node_geom = rec.geom;
    END IF;

    i := i + 1;
  END LOOP;

  IF newedge.start_node_geom IS NULL
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent node';
  ELSIF NOT ST_Equals(newedge.start_node_geom, ST_StartPoint(acurve))
  THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - start node not geometry start point.';
  END IF;

  IF newedge.end_node_geom IS NULL
  THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent node';
  ELSIF NOT ST_Equals(newedge.end_node_geom, ST_EndPoint(acurve))
  THEN
    RAISE EXCEPTION
      'SQL/MM Spatial exception - end node not geometry end point.';
  END IF;

  --
  -- Check if this geometry crosses any node
  --
  FOR rec IN EXECUTE
    'SELECT node_id, ST_Relate(geom, '
    || quote_literal(acurve::text) || '::geometry, 2) as relate FROM '
    || quote_ident(atopology)
    || '.node WHERE geom && '
    || quote_literal(acurve::text)
    || '::geometry'
  LOOP
    IF ST_RelateMatch(rec.relate, 'T********') THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - geometry crosses a node';
    END IF;
  END LOOP;

  --
  -- Check if this geometry has any interaction with any existing edge
  --
  FOR rec IN EXECUTE 'SELECT edge_id, ST_Relate(geom,' 
    || quote_literal(acurve::text)
    || '::geometry, 2) as im FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE geom && '
    || quote_literal(acurve::text) || '::geometry'
  LOOP

    --RAISE DEBUG 'IM=%',rec.im;

    IF ST_RelateMatch(rec.im, 'F********') THEN
      CONTINUE; -- no interior intersection
    END IF;

    IF ST_RelateMatch(rec.im, '1FFF*FFF2') THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - coincident edge %', rec.edge_id;
    END IF;

    -- NOT IN THE SPECS: geometry touches an edge
    IF ST_RelateMatch(rec.im, '1********') THEN
      RAISE EXCEPTION
        'Spatial exception - geometry intersects edge %', rec.edge_id;
    END IF;

    IF ST_RelateMatch(rec.im, 'T********') THEN
      RAISE EXCEPTION
        'SQL/MM Spatial exception - geometry crosses edge %', rec.edge_id;
    END IF;

  END LOOP;

  ---------------------------------------------------------------
  --
  -- All checks passed, time to prepare the new edge
  --
  ---------------------------------------------------------------

  EXECUTE 'SELECT nextval(' || quote_literal(
      quote_ident(atopology) || '.edge_data_edge_id_seq') || ')'
  INTO STRICT newedge.edge_id;


  -- Find links on start node -- {

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'My start-segment azimuth: %', span.myaz;
#endif

  sql :=
    'SELECT edge_id, -1 AS end_node, start_node, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) as geom FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE start_node = ' || anode
    || ' UNION SELECT edge_id, end_node, -1, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE end_node = ' || anode;
  IF newedge.isclosed THEN
    sql := sql || ' UNION SELECT '
      || newedge.edge_id || ',' || newedge.end_node
      || ',-1,0,0,' -- pretend we start elsewhere
      || quote_literal(newedge.cleangeom::text);
  END IF;
  i := 0;
  FOR rec IN EXECUTE sql
  LOOP -- incident edges {

    i := i + 1;

    IF rec.start_node = anode THEN
      --
      -- Edge starts at our node, we compute
      -- azimuth from node to its second point
      --
      az := ST_Azimuth(ST_StartPoint(rec.geom), ST_PointN(rec.geom, 2));

    ELSE
      --
      -- Edge ends at our node, we compute
      -- azimuth from node to its second-last point
      --
      az := ST_Azimuth(ST_EndPoint(rec.geom),
                       ST_PointN(rec.geom, ST_NumPoints(rec.geom)-1));
      rec.edge_id := -rec.edge_id;

    END IF;

    IF az IS NULL THEN
      RAISE EXCEPTION 'Invalid edge % found (no two distinct nodes exist)',
        rec.edge_id;
    END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Edge % - az % (%) - fl:% fr:%',
      rec.edge_id, az, az - span.myaz, rec.left_face, rec.right_face;
#endif

    az = az - span.myaz;
    IF az < 0 THEN
      az := az + 2*PI();
    END IF;

    -- RAISE DEBUG ' normalized az %', az;

    IF span.maxaz IS NULL OR az > span.maxaz THEN
      span.maxaz := az;
      span.nextCCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.left_face := rec.left_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.left_face := rec.right_face;
        END IF;
      END IF;
    END IF;

    IF span.minaz IS NULL OR az < span.minaz THEN
      span.minaz := az;
      span.nextCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.right_face := rec.right_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.right_face := rec.left_face;
        END IF;
      END IF;
    END IF;

    --RAISE DEBUG 'Closest edges: CW:%(%) CCW:%(%)', span.nextCW, span.minaz, span.nextCCW, span.maxaz;

  END LOOP; -- incident edges }

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'span ROW_COUNT: %', i;
#endif
  IF newedge.isclosed THEN
    IF i < 2 THEN span.was_isolated = true; END IF;
  ELSE
    IF i < 1 THEN span.was_isolated = true; END IF;
  END IF;

  IF span.nextCW IS NULL THEN
    -- This happens if the destination node is isolated
    newedge.next_right_edge := newedge.edge_id;
    newedge.prev_left_edge := -newedge.edge_id;
  ELSE
    newedge.next_right_edge := span.nextCW;
    newedge.prev_left_edge := -span.nextCCW;
  END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'edge:%', newedge.edge_id;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' left:%, next:%, prev:%',
    newedge.left_face, newedge.next_left_edge, newedge.prev_left_edge;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' right:%, next:%, prev:%',
    newedge.right_face, newedge.next_right_edge, newedge.prev_right_edge;
#endif

  -- } start_node analysis


  -- Find links on end_node {
      
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'My end-segment azimuth: %', epan.myaz;
#endif

  sql :=
    'SELECT edge_id, -1 as end_node, start_node, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) as geom FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE start_node = ' || anothernode
    || 'UNION SELECT edge_id, end_node, -1, left_face, right_face, '
    || 'ST_RemoveRepeatedPoints(geom) FROM '
    || quote_ident(atopology)
    || '.edge_data WHERE end_node = ' || anothernode;
  IF newedge.isclosed THEN
    sql := sql || ' UNION SELECT '
      || newedge.edge_id || ',' || -1 -- pretend we end elsewhere
      || ',' || newedge.start_node || ',0,0,'
      || quote_literal(newedge.cleangeom::text);
  END IF;
  i := 0;
  FOR rec IN EXECUTE sql
  LOOP -- incident edges {

    i := i + 1;

    IF rec.start_node = anothernode THEN
      --
      -- Edge starts at our node, we compute
      -- azimuth from node to its second point
      --
      az := ST_Azimuth(ST_StartPoint(rec.geom),
                       ST_PointN(rec.geom, 2));

    ELSE
      --
      -- Edge ends at our node, we compute
      -- azimuth from node to its second-last point
      --
      az := ST_Azimuth(ST_EndPoint(rec.geom),
        ST_PointN(rec.geom, ST_NumPoints(rec.geom)-1));
      rec.edge_id := -rec.edge_id;

    END IF;

#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Edge % - az % (%)', rec.edge_id, az, az - epan.myaz;
#endif

    az := az - epan.myaz;
    IF az < 0 THEN
      az := az + 2*PI();
    END IF;

    -- RAISE DEBUG ' normalized az %', az;

    IF epan.maxaz IS NULL OR az > epan.maxaz THEN
      epan.maxaz := az;
      epan.nextCCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.right_face := rec.left_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.right_face := rec.right_face;
        END IF;
      END IF;
    END IF;

    IF epan.minaz IS NULL OR az < epan.minaz THEN
      epan.minaz := az;
      epan.nextCW := rec.edge_id;
      IF abs(rec.edge_id) != newedge.edge_id THEN
        IF rec.edge_id < 0 THEN
          -- TODO: check for mismatch ?
          newedge.left_face := rec.right_face;
        ELSE
          -- TODO: check for mismatch ?
          newedge.left_face := rec.left_face;
        END IF;
      END IF;
    END IF;

    --RAISE DEBUG 'Closest edges: CW:%(%) CCW:%(%)', epan.nextCW, epan.minaz, epan.nextCCW, epan.maxaz;

  END LOOP; -- incident edges }

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'epan ROW_COUNT: %', i;
#endif
  IF newedge.isclosed THEN
    IF i < 2 THEN epan.was_isolated = true; END IF;
  ELSE
    IF i < 1 THEN epan.was_isolated = true; END IF;
  END IF;

  IF epan.nextCW IS NULL THEN
    -- This happens if the destination node is isolated
    newedge.next_left_edge := -newedge.edge_id;
    newedge.prev_right_edge := newedge.edge_id;
  ELSE
    newedge.next_left_edge := epan.nextCW;
    newedge.prev_right_edge := -epan.nextCCW;
  END IF;

  -- } end_node analysis

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'edge:%', newedge.edge_id;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' left:%, next:%, prev:%',
    newedge.left_face, newedge.next_left_edge, newedge.prev_left_edge;
#endif
#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG ' right:%, next:%, prev:%',
    newedge.right_face, newedge.next_right_edge, newedge.prev_right_edge;
#endif

  ----------------------------------------------------------------------
  --
  -- If we don't have faces setup by now we must have encountered
  -- a malformed topology (no containing_face on isolated nodes, no
  -- left/right faces on adjacent edges or mismatching values)
  --
  ----------------------------------------------------------------------
  IF newedge.left_face != newedge.right_face THEN
    RAISE EXCEPTION 'Left(%)/right(%) faces mismatch: invalid topology ?', 
      newedge.left_face, newedge.right_face;
  END IF;
  IF newedge.left_face IS NULL THEN
    RAISE EXCEPTION 'Could not derive edge face from linked primitives: invalid topology ?';
  END IF;

  ----------------------------------------------------------------------
  --
  -- Insert the new edge, and update all linking
  --
  ----------------------------------------------------------------------

  -- Insert the new edge with what we have so far
  EXECUTE 'INSERT INTO ' || quote_ident(atopology) 
    || '.edge VALUES(' || newedge.edge_id
    || ',' || newedge.start_node
    || ',' || newedge.end_node
    || ',' || newedge.next_left_edge
    || ',' || newedge.next_right_edge
    || ',' || newedge.left_face
    || ',' || newedge.right_face
    || ',' || quote_literal(newedge.geom::geometry::text)
    || ')';

  -- Link prev_left_edge to us 
  -- (if it's not us already)
  IF abs(newedge.prev_left_edge) != newedge.edge_id THEN
    IF newedge.prev_left_edge > 0 THEN
      -- its next_left_edge is us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_left_edge = '
        || newedge.edge_id
        || ', abs_next_left_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || newedge.prev_left_edge;
    ELSE
      -- its next_right_edge is us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_right_edge = '
        || newedge.edge_id
        || ', abs_next_right_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || -newedge.prev_left_edge;
    END IF;
  END IF;

  -- Link prev_right_edge to us 
  -- (if it's not us already)
  IF abs(newedge.prev_right_edge) != newedge.edge_id THEN
    IF newedge.prev_right_edge > 0 THEN
      -- its next_left_edge is -us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_left_edge = '
        || -newedge.edge_id
        || ', abs_next_left_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || newedge.prev_right_edge;
    ELSE
      -- its next_right_edge is -us
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.edge_data SET next_right_edge = '
        || -newedge.edge_id
        || ', abs_next_right_edge = '
        || newedge.edge_id
        || ' WHERE edge_id = ' 
        || -newedge.prev_right_edge;
    END IF;
  END IF;

  -- NOT IN THE SPECS...
  -- set containing_face = null for start_node and end_node
  -- if they where isolated 
  IF span.was_isolated OR epan.was_isolated THEN
      EXECUTE 'UPDATE ' || quote_ident(atopology)
        || '.node SET containing_face = null WHERE node_id IN ('
        || anode || ',' || anothernode || ')';
  END IF;

  --------------------------------------------
  -- Check face splitting
  --------------------------------------------

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Checking left face for a split';
#endif
  SELECT topology._ST_AddFaceSplit(atopology, newedge.edge_id, newedge.left_face, false)
  INTO newface;
  IF newface = 0 THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG ' No split';
#endif
    RETURN newedge.edge_id; 
  END IF;

  IF newface IS NULL THEN -- must be forming a maximal ring in universal face
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Checking right face';
#endif
    SELECT topology._ST_AddFaceSplit(atopology, -newedge.edge_id, newedge.left_face, false)
    INTO newface;
  ELSE
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG 'Updating right face mbr';
#endif
    PERFORM topology._ST_AddFaceSplit(atopology, -newedge.edge_id, newedge.left_face, true);
  END IF;

  IF newface IS NULL THEN
#ifdef POSTGIS_TOPOLOGY_DEBUG
    RAISE DEBUG ' No split';
#endif
    RETURN newedge.edge_id; 
  END IF;

  --------------------------------------------
  -- Update topogeometries, if needed
  --------------------------------------------

  IF newedge.left_face != 0 THEN -- {

    -- NOT IN THE SPECS:
    -- update TopoGeometry compositions to add newface
    sql := 'SELECT r.topogeo_id, r.layer_id FROM '
      || quote_ident(atopology)
      || '.relation r, topology.layer l '
      || ' WHERE l.topology_id = ' || topoid
      || ' AND l.level = 0 '
      || ' AND l.layer_id = r.layer_id '
      || ' AND r.element_id = ' || newedge.left_face
      || ' AND r.element_type = 3 ';
    --RAISE DEBUG 'SQL: %', sql;
    FOR rec IN EXECUTE sql
    LOOP
#ifdef POSTGIS_TOPOLOGY_DEBUG
      RAISE DEBUG 'TopoGeometry % in layer % contained the face being split (%) - updating to contain also new face %', rec.topogeo_id, rec.layer_id, newedge.left_face, newface;
#endif

      -- Add reference to the other face
      sql := 'INSERT INTO ' || quote_ident(atopology)
        || '.relation VALUES( ' || rec.topogeo_id
        || ',' || rec.layer_id || ',' || newface || ', 3)';
      --RAISE DEBUG 'SQL: %', sql;
      EXECUTE sql;

    END LOOP;

  END IF; -- }

  RETURN newedge.edge_id;
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_AddEdgeModFace

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.17
--
--  ST_InitTopoGeo(atopology)
--
CREATE OR REPLACE FUNCTION topology.ST_InitTopoGeo(atopology varchar)
RETURNS text
AS
$$
DECLARE
  rec RECORD;
  topology_id numeric;
BEGIN
  IF atopology IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  FOR rec IN SELECT * FROM pg_namespace WHERE text(nspname) = atopology
  LOOP
    RAISE EXCEPTION 'SQL/MM Spatial exception - schema already exists';
  END LOOP;

  FOR rec IN EXECUTE 'SELECT topology.CreateTopology('
    ||quote_literal(atopology)|| ') as id'
  LOOP
    topology_id := rec.id;
  END LOOP;

  RETURN 'Topology-Geometry ' || quote_literal(atopology)
    || ' (id:' || topology_id || ') created.';
END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_InitTopoGeo

--{
-- Topo-Geo and Topo-Net 3: Routine Details
-- X.3.18
--
--  ST_CreateTopoGeo(atopology, acollection)
--}{
CREATE OR REPLACE FUNCTION topology.ST_CreateTopoGeo(atopology varchar, acollection geometry)
RETURNS text
AS
$$
DECLARE
  typ char(4);
  rec RECORD;
  ret int;
  nodededges GEOMETRY;
  points GEOMETRY;
  snode_id int;
  enode_id int;
  tolerance FLOAT8;
  topoinfo RECORD;
BEGIN

  IF atopology IS NULL OR acollection IS NULL THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - null argument';
  END IF;

  -- Get topology information
  BEGIN
    SELECT * FROM topology.topology
      INTO STRICT topoinfo WHERE name = atopology;
  EXCEPTION
    WHEN NO_DATA_FOUND THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
  END;

  -- Check SRID compatibility
  IF ST_SRID(acollection) != topoinfo.SRID THEN
    RAISE EXCEPTION 'Geometry SRID (%) does not match topology SRID (%)',
      ST_SRID(acollection), topoinfo.SRID;
  END IF;

  -- Verify pre-conditions (valid, empty topology schema exists)
  BEGIN -- {

    -- Verify the topology views in the topology schema to be empty
    FOR rec in EXECUTE
      'SELECT count(*) FROM '
      || quote_ident(atopology) || '.edge_data '
      || ' UNION ' ||
      'SELECT count(*) FROM '
      || quote_ident(atopology) || '.node '
    LOOP
      IF rec.count > 0 THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-empty view';
      END IF;
    END LOOP;

    -- face check is separated as it will contain a single (world)
    -- face record
    FOR rec in EXECUTE
      'SELECT count(*) FROM '
      || quote_ident(atopology) || '.face '
    LOOP
      IF rec.count != 1 THEN
    RAISE EXCEPTION 'SQL/MM Spatial exception - non-empty face view';
      END IF;
    END LOOP;

  EXCEPTION
    WHEN INVALID_SCHEMA_NAME THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - invalid topology name';
    WHEN UNDEFINED_TABLE THEN
      RAISE EXCEPTION 'SQL/MM Spatial exception - non-existent view';

  END; -- }

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Noding input linework';
#endif

  --
  -- Node input linework with itself
  --
  WITH components AS ( SELECT geom FROM ST_Dump(acollection) )
  SELECT ST_UnaryUnion(ST_Collect(geom)) FROM (
    SELECT geom FROM components
      WHERE ST_Dimension(geom) = 1
    UNION ALL
    SELECT ST_Boundary(geom) FROM components
      WHERE ST_Dimension(geom) = 2
  ) as linework INTO STRICT nodededges;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Computed % noded edges', ST_NumGeometries(nodededges);
#endif

  --
  -- Linemerge the resulting edges, to reduce the working set
  -- NOTE: this is more of a workaround for GEOS splitting overlapping
  --       lines to each of the segments.
  --
  SELECT ST_LineMerge(nodededges) INTO STRICT nodededges;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Merged edges: %', ST_NumGeometries(nodededges);
#endif


  --
  -- Collect input points and input lines endpoints
  --
  WITH components AS ( SELECT geom FROM ST_Dump(acollection) )
  SELECT ST_Union(geom) FROM (
    SELECT geom FROM components
      WHERE ST_Dimension(geom) = 0
    UNION ALL
    SELECT ST_Boundary(geom) FROM components
      WHERE ST_Dimension(geom) = 1
  ) as nodes INTO STRICT points;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Collected % input points', ST_NumGeometries(points);
#endif

  --
  -- Further split edges by points
  -- TODO: optimize this adding ST_Split support for multiline/multipoint
  --
  FOR rec IN SELECT geom FROM ST_Dump(points)
  LOOP
    -- Use the node to split edges
    SELECT ST_Collect(geom) 
    FROM ST_Dump(ST_Split(nodededges, rec.geom))
    INTO STRICT nodededges;
  END LOOP;
  SELECT ST_UnaryUnion(nodededges) INTO STRICT nodededges;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Noded edges became % after point-split',
    ST_NumGeometries(nodededges);
#endif

  --
  -- Collect all nodes (from points and noded linework endpoints)
  --

  WITH edges AS ( SELECT geom FROM ST_Dump(nodededges) )
  SELECT ST_Union( -- TODO: ST_UnaryUnion ?
          COALESCE(ST_UnaryUnion(ST_Collect(geom)), 
            ST_SetSRID('POINT EMPTY'::geometry, topoinfo.SRID)),
          COALESCE(points,
            ST_SetSRID('POINT EMPTY'::geometry, topoinfo.SRID))
         )
  FROM (
    SELECT ST_StartPoint(geom) as geom FROM edges
      UNION ALL
    SELECT ST_EndPoint(geom) FROM edges
  ) as endpoints INTO points;

#ifdef POSTGIS_TOPOLOGY_DEBUG
  RAISE DEBUG 'Total nodes count: %', ST_NumGeometries(points);
#endif

  --
  -- Add all nodes as isolated so that 
  -- later calls to AddEdgeModFace will tweak their being
  -- isolated or not...
  --
  FOR rec IN SELECT geom FROM ST_Dump(points)
  LOOP
    PERFORM topology.ST_AddIsoNode(atopology, 0, rec.geom);
  END LOOP;
  

  FOR rec IN SELECT geom FROM ST_Dump(nodededges)
  LOOP
    SELECT topology.GetNodeByPoint(atopology, st_startpoint(rec.geom), 0)
      INTO STRICT snode_id;
    SELECT topology.GetNodeByPoint(atopology, st_endpoint(rec.geom), 0)
      INTO STRICT enode_id;
    PERFORM topology.ST_AddEdgeModFace(atopology, snode_id, enode_id, rec.geom);
  END LOOP;

  RETURN 'Topology ' || atopology || ' populated';

END
$$
LANGUAGE 'plpgsql' VOLATILE;
--} ST_CreateTopoGeo

--=}  SQL/MM block