--[[[
-- @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

--[[[
-- @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
-- @return {bool} true on success, or `nil`
--]]

local function rspamd_map_add_from_ucl(opt, mtype, description)
  local ret = {
    get_key = function(t, k)
      if t.__data then
        return t.__data:get_key(k)
      end

      return nil
    end
  }
  local ret_mt = {
    __index = function(t, k)
      if t.__data then
        return t.get_key(k)
      end

      return nil
    end
  }

  if not opt then
    return nil
  end

  if type(opt) == 'string' then
    opt,mtype = maybe_adjust_type(opt, mtype)
    local cache_key = map_hash_key(opt, mtype)
    if 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 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
      -- 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
          local map = rspamd_config:radix_from_ucl(opt)

          if map then
            ret.__data = map
            setmetatable(ret, ret_mt)
            maps_cache[cache_key] = ret
            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
            return ret
          end
        end
      elseif mtype == 'regexp' or mtype == 'glob' then
        if string.find(opt[1], '^/%a') or string.find(opt[1], '^http') 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
            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
            return ret
          end
        end
      else
        if string.find(opt[1], '^/%a') or string.find(opt[1], '^http') 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
            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

            maps_cache[cache_key] = ret
            return ret
          else
            -- Empty map, huh?
            rspamd_logger.errx(rspamd_config, 'invalid map element: %s',
                opt)
          end
        end
      end
    else
      -- 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
        return ret
      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
-- @return {bool} true on success, or `nil`
--]]

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

  return rspamd_map_add_from_ucl(opt, mtype, description)
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" then
    local mn
    if starts(what, "map:") then
      mn = string.sub(what, 4)
    elseif starts(what, "map://") then
      mn = string.sub(what, 6)
    end

    if mn and rspamd_maps[mn] then
      return rspamd_maps[mn]:get_key(key)
    else
      return what:lower() == key
    end
  else
    return what:lower() == key
  end

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,
-- for 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's 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

exports.map_schema = ts.one_of{
  ts.string, -- 'http://some_map'
  ts.array_of(ts.string), -- ['foo', 'bar']
  ts.shape{ -- complex object
    name = ts.string:is_optional(),
    description = ts.string:is_optional(),
    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(),
  }
}

return exports