--[[[
-- @module lua_maps
-- This module contains helper functions for managing rspamd maps
--]]

--[[
Copyright (c) 2022, Vsevolod Stakhov <vsevolod@rspamd.com>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
]]--

local rspamd_logger = require "rspamd_logger"
local ts = require("tableshape").types
local lua_util = require "lua_util"

local exports = {}

local maps_cache = {}

local function map_hash_key(data, mtype)
  local hash = require "rspamd_cryptobox_hash"
  local st = hash.create_specific('xxh64')
  st:update(data)
  st:update(mtype)

  return st:hex()
end

local function starts(where, st)
  return string.sub(where, 1, string.len(st)) == st
end

local function cut_prefix(where, st)
  return string.sub(where, #st + 1)
end

local function maybe_adjust_type(data, mtype)
  local function check_prefix(prefix, t)
    if starts(data, prefix) then
      data = cut_prefix(data, prefix)
      mtype = t

      return true
    end

    return false
  end

  local known_types = {
    { 'regexp;', 'regexp' },
    { 're;', 'regexp' },
    { 'regexp_multi;', 'regexp_multi' },
    { 're_multi;', 'regexp_multi' },
    { 'glob;', 'glob' },
    { 'glob_multi;', 'glob_multi' },
    { 'radix;', 'radix' },
    { 'ipnet;', 'radix' },
    { 'set;', 'set' },
    { 'hash;', 'hash' },
    { 'plain;', 'hash' },
    { 'cdb;', 'cdb' },
    { 'cdb:/', 'cdb' },
  }

  if mtype == 'callback' then
    return mtype
  end

  for _, t in ipairs(known_types) do
    if check_prefix(t[1], t[2]) then
      return data, mtype
    end
  end

  -- No change
  return data, mtype
end

local external_map_schema = ts.shape {
  external = ts.equivalent(true), -- must be true
  backend = ts.string:is_optional(), -- where to get data, required for HTTP
  cdb = ts.string:is_optional(), -- path to CDB file, required for CDB
  method = ts.one_of { "body", "header", "query" }:is_optional(), -- how to pass input
  encode = ts.one_of { "json", "messagepack" }:is_optional(), -- how to encode input (if relevant)
  timeout = (ts.number + ts.string / lua_util.parse_time_interval):is_optional(),
}

-- Storage for CDB instances
local cdb_maps = {}
local cdb_finisher_set = false

local rspamd_http = require "rspamd_http"
local ucl = require "ucl"

-- Function to handle CDB maps
local function handle_cdb_map(map_config, key, callback, task)
  local rspamd_cdb = require "rspamd_cdb"
  local hash_key = map_config.cdb

  -- Check if we need to open the CDB file
  if not cdb_maps[hash_key] then
    local cdb_file = map_config.cdb
    -- Provide ev_base to monitor changes
    local cdb_handle = rspamd_cdb.open(cdb_file, task:get_ev_base())

    if not cdb_handle then
      local err_msg = string.format("Failed to open CDB file: %s", cdb_file)
      rspamd_logger.errx(task, err_msg)
      if callback then
        callback(false, err_msg, 500, task)
      end
      return nil
    else
      cdb_maps[hash_key] = cdb_handle
    end
  end

  -- Look up the key in CDB
  local result = cdb_maps[hash_key]:find(key)

  if callback then
    if result then
      callback(true, result, 200, task)
    else
      callback(false, 'not found', 404, task)
    end
    return nil
  end

  return result
end

local function query_external_map(map_config, upstreams, key, callback, task)
  -- Check if this is a CDB map
  if map_config.cdb then
    return handle_cdb_map(map_config, key, callback, task)
  end
  -- Fallback to HTTP
  local http_method = (map_config.method == 'body' or map_config.method == 'form') and 'POST' or 'GET'
  local upstream = upstreams:get_upstream_round_robin()
  local http_headers = {
    ['Accept'] = '*/*'
  }
  local http_body = nil
  local url = map_config.backend

  if type(key) == 'string' or type(key) == 'userdata' then
    if map_config.method == 'body' then
      http_body = key
      http_headers['Content-Type'] = 'text/plain'
    elseif map_config.method == 'header' then
      http_headers = {
        key = key
      }
    elseif map_config.method == 'query' then
      url = string.format('%s?key=%s', url, lua_util.url_encode_string(tostring(key)))
    end
  elseif type(key) == 'table' then
    if map_config.method == 'body' then
      if map_config.encode == 'json' then
        http_body = ucl.to_format(key, 'json-compact', true)
        http_headers['Content-Type'] = 'application/json'
      elseif map_config.encode == 'messagepack' then
        http_body = ucl.to_format(key, 'messagepack', true)
        http_headers['Content-Type'] = 'application/msgpack'
      else
        local caller = debug.getinfo(2) or {}
        rspamd_logger.errx(task,
            "requested external map key with a wrong combination body method and missing encode; caller: %s:%s",
            caller.short_src, caller.currentline)
        callback(false, 'invalid map usage', 500, task)
      end
    else
      -- query/header and no encode
      if map_config.method == 'query' then
        local params_table = {}
        for k, v in pairs(key) do
          if type(v) == 'string' then
            table.insert(params_table,
                string.format('%s=%s', lua_util.url_encode_string(k), lua_util.url_encode_string(v)))
          end
        end
        url = string.format('%s?%s', url, table.concat(params_table, '&'))
      elseif map_config.method == 'header' then
        http_headers = key
      else
        local caller = debug.getinfo(2) or {}
        rspamd_logger.errx(task,
            "requested external map key with a wrong combination of encode and input; caller: %s:%s",
            caller.short_src, caller.currentline)
        callback(false, 'invalid map usage', 500, task)
        return
      end
    end
  end

  local function map_callback(err, code, body, _)
    if err then
      callback(false, err, code, task)
    elseif code == 200 then
      callback(true, body, 200, task)
    else
      callback(false, err, code, task)
    end
  end

  local ret = rspamd_http.request {
    task = task,
    url = url,
    callback = map_callback,
    timeout = map_config.timeout or 1.0,
    keepalive = true,
    upstream = upstream,
    method = http_method,
    headers = http_headers,
    body = http_body,
  }

  if not ret then
    callback(false, 'http request error', 500, task)
  end
end

--[[[
-- @function lua_maps.map_add_from_ucl(opt, mtype, description)
-- Creates a map from static data
-- Returns true if map was added or nil
-- @param {string or table} opt data for map (or URL)
-- @param {string} mtype type of map (`set`, `map`, `radix`, `regexp`)
-- @param {string} description human-readable description of map
-- @param {function} callback optional callback that will be called on map match (required for external maps)
-- @return {bool} true on success, or `nil`
--]]
local function rspamd_map_add_from_ucl(opt, mtype, description, callback)
  local ret = {
    get_key = function(t, k, key_callback, task)
      if t.__data then
        local cb = key_callback or callback
        if t.__external then
          if not cb or not task then
            local caller = debug.getinfo(2) or {}
            rspamd_logger.errx(rspamd_config, "requested external map key without callback or task; caller: %s:%s",
                caller.short_src, caller.currentline)
            return nil
          end
          query_external_map(t.__data, t.__upstreams, k, cb, task)
        else
          local result = t.__data:get_key(k)
          if cb then
            if result then
              cb(true, result, 200, task)
            else
              cb(false, 'not found', 404, task)
            end
          else
            return result
          end
        end
      end

      return nil
    end,
    foreach = function(t, cb)
      return t.__data:foreach(cb)
    end,
    on_load = function(t, cb)
      t.__data:on_load(cb)
    end
  }
  local ret_mt = {
    __index = function(t, k, key_callback, task)
      if t.__data then
        return t.get_key(k, key_callback, task)
      end

      return nil
    end
  }

  if not opt then
    return nil
  end

  local function maybe_register_selector()
    if opt.selector_alias then
      local lua_selectors = require "lua_selectors"
      lua_selectors.add_map(opt.selector_alias, ret)
    end
  end

  if type(opt) == 'string' then
    opt, mtype = maybe_adjust_type(opt, mtype)
    local cache_key = map_hash_key(opt, mtype)
    if not callback and maps_cache[cache_key] then
      rspamd_logger.infox(rspamd_config, 'reuse url for %s(%s)',
          opt, mtype)

      return maps_cache[cache_key]
    end
    -- We have a single string, so we treat it as a map
    local map = rspamd_config:add_map {
      type = mtype,
      description = description,
      url = opt,
    }

    if map then
      ret.__data = map
      ret.hash = cache_key
      setmetatable(ret, ret_mt)
      maps_cache[cache_key] = ret
      return ret
    end
  elseif type(opt) == 'table' then
    local cache_key = lua_util.table_digest(opt)
    if not callback and maps_cache[cache_key] then
      rspamd_logger.infox(rspamd_config, 'reuse url for complex map definition %s: %s',
          cache_key:sub(1, 8), description)

      return maps_cache[cache_key]
    end

    if opt[1] then
      local function check_plain_map(line)
        return lua_util.str_startswith(line, 'http')
            or lua_util.str_startswith(line, 'file:')
            or lua_util.str_startswith(line, '/')
      end
      -- Adjust each element if needed
      local adjusted
      for i, source in ipairs(opt) do
        local nsrc, ntype = maybe_adjust_type(source, mtype)

        if mtype ~= ntype then
          if not adjusted then
            mtype = ntype
          end
          adjusted = true
        end
        opt[i] = nsrc
      end

      if mtype == 'radix' then

        if string.find(opt[1], '^%d') then
          -- List of numeric stuff (hope it's ipnets definitions)
          local map = rspamd_config:radix_from_ucl(opt, description)

          if map then
            ret.__data = map
            setmetatable(ret, ret_mt)
            maps_cache[cache_key] = ret
            maybe_register_selector()

            return ret
          end
        else
          -- Plain table
          local map = rspamd_config:add_map {
            type = mtype,
            description = description,
            url = opt,
          }
          if map then
            ret.__data = map
            setmetatable(ret, ret_mt)
            maps_cache[cache_key] = ret
            maybe_register_selector()

            return ret
          end
        end
      elseif mtype == 'regexp' or mtype == 'glob' then
        if check_plain_map(opt[1]) then
          -- Plain table
          local map = rspamd_config:add_map {
            type = mtype,
            description = description,
            url = opt,
          }
          if map then
            ret.__data = map
            setmetatable(ret, ret_mt)
            maps_cache[cache_key] = ret
            maybe_register_selector()

            return ret
          end
        else
          local map = rspamd_config:add_map {
            type = mtype,
            description = description,
            url = {
              url = 'static',
              data = opt,
            }
          }
          if map then
            ret.__data = map
            setmetatable(ret, ret_mt)
            maps_cache[cache_key] = ret
            maybe_register_selector()

            return ret
          end
        end
      else
        -- Not regexp/glob
        if check_plain_map(opt[1]) then
          -- Plain table
          local map = rspamd_config:add_map {
            type = mtype,
            description = description,
            url = opt,
          }
          if map then
            ret.__data = map
            setmetatable(ret, ret_mt)
            maps_cache[cache_key] = ret
            maybe_register_selector()

            return ret
          end
        else
          local data = {}
          local nelts = 0
          -- Plain array of keys, count merely numeric elts
          for _, elt in ipairs(opt) do
            if type(elt) == 'string' then
              -- Numeric table
              if mtype == 'hash' then
                -- Treat as KV pair
                local pieces = lua_util.str_split(elt, ' ')
                if #pieces > 1 then
                  local key = table.remove(pieces, 1)
                  data[key] = table.concat(pieces, ' ')
                else
                  data[elt] = true
                end
              else
                data[elt] = true
              end

              nelts = nelts + 1
            end
          end

          if nelts > 0 then
            -- Plain Lua table that is used as a map
            ret.__data = data
            ret.get_key = function(t, k)
              if k ~= '__data' then
                return t.__data[k]
              end

              return nil
            end
            ret.foreach = function(_, func)
              for k, v in pairs(ret.__data) do
                if not func(k, v) then
                  return false
                end
              end

              return true
            end
            ret.on_load = function(_, cb)
              rspamd_config:add_on_load(function(_, _, _)
                cb()
              end)
            end

            maps_cache[cache_key] = ret
            maybe_register_selector()

            return ret
          else
            -- Empty map, huh?
            rspamd_logger.errx(rspamd_config, 'invalid map element: %s',
                opt)
          end
        end
      end
    else
      if opt.external then
        -- External map definition, missing fields are handled by schema
        local parse_res, parse_err = external_map_schema(opt)

        if parse_res then
          if opt.cdb then
            ret.__data = opt
            ret.__external = true
            setmetatable(ret, ret_mt)
            maybe_register_selector()

            if not cdb_finisher_set then
              -- Register a finalize script to close all CDB handles when Rspamd stops
              rspamd_config:register_finish_script(function()
                for path, _ in pairs(cdb_maps) do
                  rspamd_logger.infox(rspamd_config, 'closing CDB map: %s', path)
                  cdb_maps[path] = nil
                end
              end)
              cdb_finisher_set = true
            end

            return ret
          elseif opt.backend then
            ret.__upstreams = lua_util.http_upstreams_by_url(rspamd_config:get_mempool(), opt.backend)
            if ret.__upstreams then
              ret.__data = opt
              ret.__external = true
              setmetatable(ret, ret_mt)
              maybe_register_selector()

              return ret
            else
              rspamd_logger.errx(rspamd_config, 'cannot parse external map upstreams: %s',
                  opt.backend)
            end
          else
            rspamd_logger.errx(rspamd_config, 'external map requires either "cdb" or "backend" parameter')
          end
        else
          rspamd_logger.errx(rspamd_config, 'cannot parse external map: %s',
              parse_err)
        end
      else
        -- Adjust lua specific augmentations in a trivial case
        if type(opt.url) == 'string' then
          local nsrc, ntype = maybe_adjust_type(opt.url, mtype)
          if nsrc and ntype then
            opt.url = nsrc
            mtype = ntype
          end
        end
        -- We have some non-trivial object so let C code to deal with it somehow...
        local map = rspamd_config:add_map {
          type = mtype,
          description = description,
          url = opt,
        }
        if map then
          ret.__data = map
          setmetatable(ret, ret_mt)
          maps_cache[cache_key] = ret
          maybe_register_selector()

          return ret
        end
      end
    end -- opt[1]
  end

  return nil
end

--[[[
-- @function lua_maps.map_add(mname, optname, mtype, description)
-- Creates a map from configuration elements (static data or URL)
-- Returns true if map was added or nil
-- @param {string} mname config section to use
-- @param {string} optname option name to use
-- @param {string} mtype type of map ('set', 'hash', 'radix', 'regexp', 'glob')
-- @param {string} description human-readable description of map
-- @param {function} callback optional callback that will be called on map match (required for external maps)
-- @return {bool} true on success, or `nil`
--]]

local function rspamd_map_add(mname, optname, mtype, description, callback)
  local opt = rspamd_config:get_module_opt(mname, optname)

  return rspamd_map_add_from_ucl(opt, mtype, description, callback)
end

exports.rspamd_map_add = rspamd_map_add
exports.map_add = rspamd_map_add
exports.rspamd_map_add_from_ucl = rspamd_map_add_from_ucl
exports.map_add_from_ucl = rspamd_map_add_from_ucl

-- Check `what` for being lua_map name, otherwise just compares key with what
local function rspamd_maybe_check_map(key, what)
  local fun = require "fun"

  if type(what) == "table" then
    return fun.any(function(elt)
      return rspamd_maybe_check_map(key, elt)
    end, what)
  end
  if type(rspamd_maps) == "table" and starts(key, "map:") then
    local mn = string.sub(key, 5)
    if starts(mn, "//") then
      mn = string.sub(mn, 3)
    end
    if rspamd_maps[mn] then
      return rspamd_maps[mn]:get_key(what)
    end
  end

  return what:lower() == key
end

exports.rspamd_maybe_check_map = rspamd_maybe_check_map

--[[[
-- @function lua_maps.fill_config_maps(mname, options, defs)
-- Fill maps that could be defined in defs, from the config in the options
-- Defs is a table indexed by a map's parameter name and defining it's config,
-- @example
-- defs = {
--   my_map = {
--     type = 'map',
--     description = 'my cool map',
--     optional = true,
--   }
-- }
-- -- Then this function will look for opts.my_map parameter and try to replace it with
-- -- a map with the specific type, description but not failing if it was empty.
-- -- It will also set options.my_map_orig to the original value defined in the map.
--]]
exports.fill_config_maps = function(mname, opts, map_defs)
  assert(type(opts) == 'table')
  assert(type(map_defs) == 'table')
  for k, v in pairs(map_defs) do
    if opts[k] then
      local map = rspamd_map_add_from_ucl(opts[k], v.type or 'map', v.description)
      if not map then
        rspamd_logger.errx(rspamd_config, 'map add error %s for module %s', k, mname)
        return false
      end
      opts[k .. '_orig'] = opts[k]
      opts[k] = map
    elseif not v.optional then
      rspamd_logger.errx(rspamd_config, 'cannot find non optional map %s for module %s', k, mname)
      return false
    end
  end

  return true
end

local direct_map_schema = ts.shape { -- complex object
  name = ts.string:is_optional(),
  description = ts.string:is_optional(),
  selector_alias = ts.string:is_optional(), -- an optional alias for the selectos framework
  timeout = ts.number,
  data = ts.array_of(ts.string):is_optional(),
  -- Tableshape has no options support for something like key1 or key2?
  upstreams = ts.one_of {
    ts.string,
    ts.array_of(ts.string),
  }             :is_optional(),
  url = ts.one_of {
    ts.string,
    ts.array_of(ts.string),
  }       :is_optional(),
}

exports.map_schema = ts.one_of {
  ts.string, -- 'http://some_map'
  ts.array_of(ts.string), -- ['foo', 'bar']
  ts.one_of { direct_map_schema, external_map_schema }
}

return exports