/*
 * viking -- GPS Data and Topo Analyzer, Explorer, and Manager
 *
 * Copyright (C) 2012-2013, Guilhem Bonnefille <guilhem.bonnefille@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/**
 * SECTION:vikrouting
 * @short_description: the routing framework
 * 
 * This module handles the list of #VikRoutingEngine.
 * It also handles the "default" functions.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <glib.h>
#include <glib/gstdio.h>
#include <glib/gi18n.h>

#include "curl_download.h"
#include "babel.h"

#include "preferences.h"

#include "vikrouting.h"
#include "vikroutingengine.h"

/* params will be routing.default */
/* we have to make sure these don't collide. */
#define VIKING_ROUTING_PARAMS_GROUP_KEY "routing"
#define VIKING_ROUTING_PARAMS_NAMESPACE "routing."

/* List to register all routing engines */
static GList *routing_engine_list = NULL;

static VikLayerParam prefs[] = {
  { VIK_LAYER_NUM_TYPES, VIKING_ROUTING_PARAMS_NAMESPACE "default", VIK_LAYER_PARAM_STRING, VIK_LAYER_GROUP_NONE, N_("Default engine:"), VIK_LAYER_WIDGET_COMBOBOX, NULL, NULL, NULL, NULL, NULL, NULL },
};

gchar **routing_engine_labels = NULL;
gchar **routing_engine_ids = NULL;

/**
 * vik_routing_prefs_init:
 * 
 * Initialize the preferences of the routing feature.
 */
void
vik_routing_prefs_init()
{
  a_preferences_register_group ( VIKING_ROUTING_PARAMS_GROUP_KEY, _("Routing") );

  a_preferences_register ( prefs, (VikLayerParamData){0}, VIKING_ROUTING_PARAMS_GROUP_KEY );
}

/* @see g_list_find_custom */
static gint
search_by_id (gconstpointer a,
              gconstpointer b)
{
	const gchar *id = b;
	VikRoutingEngine *engine = (VikRoutingEngine *)a;
	gchar *engineId = vik_routing_engine_get_id (engine);
	if (id && engine)
		return strcmp(id, engineId);
	else
		return -1;
}

/**
 * vik_routing_find_engine:
 * @id: the id of the engine we are looking for
 * 
 * Returns: the found engine or %NULL
 */
VikRoutingEngine *
vik_routing_find_engine ( const gchar *id )
{
	VikRoutingEngine *engine = NULL;
	GList *elem = g_list_find_custom (routing_engine_list, id, search_by_id);
	if (elem)
		engine = elem->data;
	return engine;
}

/**
 * vik_routing_default_engine:
 * 
 * Retrieve the default engine, based on user's preferences.
 * 
 * Returns: the default engine
 */
VikRoutingEngine *
vik_routing_default_engine ( void )
{
  const gchar *id = a_preferences_get ( VIKING_ROUTING_PARAMS_NAMESPACE "default")->s;
  VikRoutingEngine *engine = vik_routing_find_engine(id);
  if (engine == NULL && routing_engine_list != NULL && g_list_first (routing_engine_list) != NULL)
    /* Fallback to first element */
    engine = g_list_first (routing_engine_list)->data;

  return engine;
}

/**
 * vik_routing_default_find:
 * 
 * Route computation with default engine.
 *
 * Return indicates success or not
 */
gboolean
vik_routing_default_find(VikTrwLayer *vt, struct LatLon start, struct LatLon end)
{
  /* The engine */
  VikRoutingEngine *engine = vik_routing_default_engine ( );
  /* The route computation */
  return vik_routing_engine_find ( engine, vt, start, end );
}

/**
 * vik_routing_register:
 * @engine: new routing engine to register
 * 
 * Register a new routing engine.
 */
void
vik_routing_register( VikRoutingEngine *engine )
{
  gchar *label = vik_routing_engine_get_label ( engine );
  gchar *id = vik_routing_engine_get_id ( engine );
  gsize len = 0;

  /* check if id already exists in list */
  GList *elem = g_list_find_custom (routing_engine_list, id, search_by_id);
  if (elem != NULL) {
    g_debug("%s: %s already exists: update", __FUNCTION__, id);

    /* Update main list */
    g_object_unref (elem->data);
    elem->data = g_object_ref ( engine );

    /* Update GUI arrays */
    len = g_strv_length (routing_engine_labels);
    for (; len > 0 ; len--) {
      if (strcmp (routing_engine_ids[len-1], id) == 0)
			break;
	}
    /* Update the label (possibly different */
    g_free (routing_engine_labels[len-1]);
    routing_engine_labels[len-1] = g_strdup (label);
    
  } else {
    g_debug("%s: %s is new: append", __FUNCTION__, id);
    routing_engine_list = g_list_append ( routing_engine_list, g_object_ref ( engine ) );

    if (routing_engine_labels)
      len = g_strv_length (routing_engine_labels);
  
    /* Add the label */
    routing_engine_labels = g_realloc (routing_engine_labels, (len+2)*sizeof(gchar*));
    routing_engine_labels[len] = g_strdup (label);
    routing_engine_labels[len+1] = NULL;

    /* Add the id */
    routing_engine_ids = g_realloc (routing_engine_ids, (len+2)*sizeof(gchar*));
    routing_engine_ids[len] = g_strdup (id);
    routing_engine_ids[len+1] = NULL;
  
    /* Hack
       We have to ensure the mode LayerParam references the up-to-date
       GLists.
    */
    /*
    memcpy(&maps_layer_params[0].widget_data, &params_maptypes, sizeof(gpointer));
    memcpy(&maps_layer_params[0].extra_widget_data, &params_maptypes_ids, sizeof(gpointer));
    */
    prefs[0].widget_data = routing_engine_labels;
    prefs[0].extra_widget_data = routing_engine_ids;
  }
}

/**
 * vik_routing_unregister_all:
 * 
 * Unregister all registered routing engines.
 */
void
vik_routing_unregister_all ()
{
  g_list_foreach ( routing_engine_list, (GFunc) g_object_unref, NULL );
  g_strfreev ( routing_engine_labels );
  g_strfreev ( routing_engine_ids );
}

/**
 * vik_routing_foreach_engine:
 * @func: the function to run on each element
 * @user_data: user's data to give to each call of @func
 *
 * Loop over all registered routing engines.
 */
void
vik_routing_foreach_engine (GFunc func, gpointer user_data)
{
  g_list_foreach ( routing_engine_list, func, user_data );
}

/*
 * This function is called for all routing engine registered.
 * Following result of the predicate function, the current engine
 * is added to the combobox. In order to retrieve the VikRoutingEngine
 * object, we store a list of added engine in a GObject's data "engines".
 *
 * @see g_list_foreach()
 */
static void
fill_engine_box (gpointer data, gpointer user_data)
{
  VikRoutingEngine *engine = (VikRoutingEngine*) data;
  /* Retrieve combo */
  GtkWidget *widget = (GtkWidget*) user_data;

  /* Only register engine fulfilling expected behaviour */
  Predicate predicate = g_object_get_data ( G_OBJECT ( widget ), "func" );
  gpointer predicate_data = g_object_get_data ( G_OBJECT ( widget ), "user_data" );
  /* No predicate means to register all engines */
  gboolean ok = predicate == NULL || predicate (engine, predicate_data);

  if (ok)
  {
    /* Add item in widget */
    const gchar *label = vik_routing_engine_get_label (engine);
    vik_combo_box_text_append (widget, label);
    /* Save engine in internal list */
    GList *engines = (GList*) g_object_get_data ( G_OBJECT ( widget ) , "engines" );
    engines = g_list_append ( engines, engine );
    g_object_set_data ( G_OBJECT ( widget ), "engines", engines );
  }
}

/**
 * vik_routing_ui_selector_new:
 * @func: user function to decide if an engine has to be added or not
 * @user_data: user data for previous function
 *
 * Creates a combo box to allow selection of a routing engine.
 *
 * We use GObject data hashtable to store and retrieve the VikRoutingEngine
 * associated to the selection.
 *
 * Returns: the combo box
 */
GtkWidget *
vik_routing_ui_selector_new (Predicate func, gpointer user_data)
{
  /* Create the combo */
  GtkWidget * combo = vik_combo_box_text_new ();

  /* Save data for foreach function */
  g_object_set_data ( G_OBJECT ( combo ), "func", func );
  g_object_set_data ( G_OBJECT ( combo ), "user_data", user_data );

  /* Filter all engines with given user function */
  vik_routing_foreach_engine (fill_engine_box, combo);

  return combo;
}

/**
 * vik_routing_ui_selector_get_nth:
 * @combo: the GtkWidget combobox
 * @pos: the selected position
 *
 * Retrieve the VikRoutingEngine stored in a list attached to @combo
 * via the "engines" property.
 *
 * Returns: the VikRoutingEngine object associated to @pos
 */
VikRoutingEngine *
vik_routing_ui_selector_get_nth (GtkWidget *combo, int pos)
{
  /* Retrieve engine */
  GList *engines = (GList*) g_object_get_data ( G_OBJECT ( combo ) , "engines" );
  VikRoutingEngine *engine = g_list_nth_data ( engines, pos );

  return engine;
}

// For simplicity a variable with visibility to multiple functions
static guint engine_count = 0;

static void
count_engine_directions (gpointer data, gpointer user_data)
{
  VikRoutingEngine *engine = (VikRoutingEngine*) data;
  if ( vik_routing_engine_supports_direction ( engine ) )
    engine_count++;
}

/**
 * vik_routing_number_of_engines:
 *
 * Returns: the number of engines available
 */
guint vik_routing_number_of_engines ( VikRoutingMethodType method )
{
  engine_count = 0;
  if ( routing_engine_list ) {
    if ( method == VIK_ROUTING_METHOD_DIRECTIONS )
      vik_routing_foreach_engine ( count_engine_directions, NULL );
    else
      // ATM Every engine supports Lat/Lon requests
      engine_count = g_list_length ( routing_engine_list );
  }
  return engine_count;
}