var extend = require('extend');

var TYPE_TO_SOURCE = {
  'geoname': 'gn',
  'osmnode': 'osm',
  'osmway': 'osm',
  'admin0': 'qs',
  'admin1': 'qs',
  'admin2': 'qs',
  'neighborhood': 'qs',
  'locality': 'qs',
  'local_admin': 'qs',
  'osmaddress': 'osm',
  'openaddresses': 'oa'
};

/*
 * This doesn't include alias layers such as coarse
 */
var TYPE_TO_LAYER = {
  'geoname': 'venue',
  'osmnode': 'venue',
  'osmway': 'venue',
  'admin0': 'country',
  'admin1': 'region',
  'admin2': 'county',
  'neighborhood': 'neighbourhood',
  'locality': 'locality',
  'local_admin': 'localadmin',
  'osmaddress': 'address',
  'openaddresses': 'address'
};

var SOURCE_TO_TYPE = {
  'gn'            : ['geoname'],
  'geonames'      : ['geoname'],
  'oa'            : ['openaddresses'],
  'openaddresses' : ['openaddresses'],
  'qs'            : ['admin0', 'admin1', 'admin2', 'neighborhood', 'locality', 'local_admin'],
  'quattroshapes' : ['admin0', 'admin1', 'admin2', 'neighborhood', 'locality', 'local_admin'],
  'osm'           : ['osmaddress', 'osmnode', 'osmway'],
  'openstreetmap' : ['osmaddress', 'osmnode', 'osmway']
};

/**
 * This does not included alias layers, those are built separately
 */
var LAYER_TO_TYPE = {
  'venue': ['geoname','osmnode','osmway'],
  'address': ['osmaddress','openaddresses', 'geoname'],
  'country': ['admin0', 'geoname'],
  'region': ['admin1', 'geoname'],
  'county': ['admin2', 'geoname'],
  'locality': ['locality', 'geoname'],
  'localadmin': ['local_admin'],
  'neighbourhood': ['neighborhood', 'geoname']
};

var LAYER_ALIASES = {
  'coarse': ['admin0','admin1','admin2','neighborhood','locality','local_admin']
};

var LAYER_WITH_ALIASES_TO_TYPE = extend({}, LAYER_ALIASES, LAYER_TO_TYPE);

/*
 * derive the list of types, sources, and layers from above mappings
 */
var TYPES   = Object.keys(TYPE_TO_SOURCE);
var SOURCES = Object.keys(SOURCE_TO_TYPE);
var LAYERS  = Object.keys(LAYER_TO_TYPE);

/**
 * Calculate the set-style intersection of two arrays
 */
var intersection = function intersection(set1, set2) {
  return set2.filter(function(value) {
    return set1.indexOf(value) !== -1;
  });
};

var sourceAndLayerToType = function sourceAndLayerToType(source, layer) {
  return intersection(SOURCE_TO_TYPE[source], LAYER_WITH_ALIASES_TO_TYPE[layer]);
};

module.exports = {
  types: TYPES,
  sources: SOURCES,
  layers: LAYERS,
  type_to_source: TYPE_TO_SOURCE,
  type_to_layer: TYPE_TO_LAYER,
  source_to_type: SOURCE_TO_TYPE,
  layer_to_type: LAYER_TO_TYPE,
  layer_with_aliases_to_type: LAYER_WITH_ALIASES_TO_TYPE,
  source_and_layer_to_type: sourceAndLayerToType
};