/**
 * Create a new [Mapbox GL JS plugin](https://www.mapbox.com/blog/build-mapbox-gl-js-plugins/) that
 * modifies the layers of the map style to use the 'text-field' that matches the browser language.
 * @constructor
 * @param {object} options - Options to configure the plugin.
 * @param {string[]} [options.supportedLanguages] - List of supported languages
 * @param {Function} [options.languageTransform] - Custom style transformation to apply
 * @param {RegExp} [options.languageField=/^\{name/] - RegExp to match if a text-field is a language field
 * @param {Function} [options.getLanguageField] - Given a language choose the field in the vector tiles
 * @param {string} [options.languageSource] - Name of the source that contains the different languages.
 * @param {string} [options.defaultLanguage] - Name of the default language to initialize style after loading.
 * @param {string[]} [options.excludedLayerIds] - Name of the layers that should be excluded from translation.
 */
 function MapboxLanguage(options) {
    options = Object.assign({}, options);
    if (!(this instanceof MapboxLanguage)) {
      throw new Error('MapboxLanguage needs to be called with the new keyword');
    }
  
    this.setLanguage = this.setLanguage.bind(this);
    this._initialStyleUpdate = this._initialStyleUpdate.bind(this);
  
    this._defaultLanguage = options.defaultLanguage;
    this._isLanguageField = options.languageField || /^\{name/;
    this._getLanguageField = options.getLanguageField || function nameField(language) {
      return language === 'mul' ? '{name}' : '{name_' + language + '}';
    };
    this._languageSource = options.languageSource || null;
    this._languageTransform = options.languageTransform || function (style, language) {
      if (language === 'ar') {
        return noSpacing(style);
      } else {
        return standardSpacing(style);
      }
    };
    this._excludedLayerIds = options.excludedLayerIds || [];
    this.supportedLanguages = options.supportedLanguages || ['ar', 'en', 'es', 'fr', 'de', 'ja', 'ko', 'mul', 'pt', 'ru', 'zh'];
  }
  
  function standardSpacing(style) {
    var changedLayers = style.layers.map(function (layer) {
      if (!(layer.layout || {})['text-field']) return layer;
      var spacing = 0;
      if (layer['source-layer'] === 'state_label') {
        spacing = 0.15;
      }
      if (layer['source-layer'] === 'marine_label') {
        if (/-lg/.test(layer.id)) {
          spacing = 0.25;
        }
        if (/-md/.test(layer.id)) {
          spacing = 0.15;
        }
        if (/-sm/.test(layer.id)) {
          spacing = 0.1;
        }
      }
      if (layer['source-layer'] === 'place_label') {
        if (/-suburb/.test(layer.id)) {
          spacing = 0.15;
        }
        if (/-neighbour/.test(layer.id)) {
          spacing = 0.1;
        }
        if (/-islet/.test(layer.id)) {
          spacing = 0.01;
        }
      }
      if (layer['source-layer'] === 'airport_label') {
        spacing = 0.01;
      }
      if (layer['source-layer'] === 'rail_station_label') {
        spacing = 0.01;
      }
      if (layer['source-layer'] === 'poi_label') {
        if (/-scalerank/.test(layer.id)) {
          spacing = 0.01;
        }
      }
      if (layer['source-layer'] === 'road_label') {
        if (/-label-/.test(layer.id)) {
          spacing = 0.01;
        }
        if (/-shields/.test(layer.id)) {
          spacing = 0.05;
        }
      }
      return Object.assign({}, layer, {
        layout: Object.assign({}, layer.layout, {
          'text-letter-spacing': spacing
        })
      });
    });
  
    return Object.assign({}, style, {
      layers: changedLayers
    });
  }
  
  function noSpacing(style) {
    var changedLayers = style.layers.map(function (layer) {
      if (!(layer.layout || {})['text-field']) return layer;
      var spacing = 0;
      return Object.assign({}, layer, {
        layout: Object.assign({}, layer.layout, {
          'text-letter-spacing': spacing
        })
      });
    });
  
    return Object.assign({}, style, {
      layers: changedLayers
    });
  }
  
  function isNameStringField(isLangField, property) {
    return typeof property === 'string' && isLangField.test(property);
  }
  
  function isNameFunctionField(isLangField, property) {
    return property.stops && property.stops.filter(function (stop) {
      return isLangField.test(stop[1]);
    }).length > 0;
  }
  
  function adaptPropertyLanguage(isLangField, property, languageFieldName) {
    if (isNameStringField(isLangField, property)) return languageFieldName;
    if (isNameFunctionField(isLangField, property)) {
      var newStops = property.stops.map(function (stop) {
        if (isLangField.test(stop[1])) {
          return [stop[0], languageFieldName];
        }
        return stop;
      });
      return Object.assign({}, property, {
        stops: newStops
      });
    }
    return property;
  }
  
  function changeLayerTextProperty(isLangField, layer, languageFieldName, excludedLayerIds) {
    if (layer.layout && layer.layout['text-field'] && excludedLayerIds.indexOf(layer.id) === -1) {
      return Object.assign({}, layer, {
        layout: Object.assign({}, layer.layout, {
          'text-field': adaptPropertyLanguage(isLangField, layer.layout['text-field'], languageFieldName)
        })
      });
    }
    return layer;
  }
  
  function findStreetsSource(style) {
    var sources = Object.keys(style.sources).filter(function (sourceName) {
      var source = style.sources[sourceName];
      return /mapbox-streets-v\d/.test(source.url);
    });
    return sources[0];
  }
  
  /**
   * Explicitly change the language for a style.
   * @param {object} style - Mapbox GL style to modify
   * @param {string} language - The language iso code
   * @returns {object} the modified style
   */
  MapboxLanguage.prototype.setLanguage = function (style, language) {
    if (this.supportedLanguages.indexOf(language) < 0) throw new Error('Language ' + language + ' is not supported');
    var streetsSource = this._languageSource || findStreetsSource(style);
    if (!streetsSource) return style;
  
    var field = this._getLanguageField(language);
    var isLangField = this._isLanguageField;
    var excludedLayerIds = this._excludedLayerIds;
    var changedLayers = style.layers.map(function (layer) {
      if (layer.source === streetsSource) return changeLayerTextProperty(isLangField, layer, field, excludedLayerIds);
      return layer;
    });
  
    var languageStyle = Object.assign({}, style, {
      layers: changedLayers
    });
  
    return this._languageTransform(languageStyle, language);
  };
  
  MapboxLanguage.prototype._initialStyleUpdate = function () {
    var style = this._map.getStyle();
    var language = this._defaultLanguage || browserLanguage(this.supportedLanguages);
  
    // We only update the style once
    this._map.off('styledata', this._initialStyleUpdate);
    this._map.setStyle(this.setLanguage(style, language));
  };
  
  function browserLanguage(supportedLanguages) {
    var language = navigator.languages ? navigator.languages[0] : (navigator.language || navigator.userLanguage);
    var parts = language.split('-');
    var languageCode = language;
    if (parts.length > 1) {
      languageCode = parts[0];
    }
    if (supportedLanguages.indexOf(languageCode) > -1) {
      return languageCode;
    }
    return null;
  }
  
  MapboxLanguage.prototype.onAdd = function (map) {
    this._map = map;
    this._map.on('styledata', this._initialStyleUpdate);
    this._container = document.createElement('div');
    return this._container;
  };
  
  MapboxLanguage.prototype.onRemove = function () {
    this._map.off('styledata', this._initialStyleUpdate);
    this._map = undefined;
  };
  
  function ie11Polyfill() {
    if (typeof Object.assign != 'function') {
      // Must be writable: true, enumerable: false, configurable: true
      Object.defineProperty(Object, 'assign', {
        // eslint-disable-next-line no-unused-vars
        value: function assign(target, varArgs) { // .length of function is 2
          // eslint-disable-next-line strict
          'use strict';
          if (target === null) { // TypeError if undefined or null
            throw new TypeError('Cannot convert undefined or null to object');
          }
  
          var to = Object(target);
  
          for (var index = 1; index < arguments.length; index++) {
            var nextSource = arguments[index];
  
            if (nextSource !== null) { // Skip over if undefined or null
              for (var nextKey in nextSource) {
                // Avoid bugs when hasOwnProperty is shadowed
                if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
                  to[nextKey] = nextSource[nextKey];
                }
              }
            }
          }
          return to;
        },
        writable: true,
        configurable: true
      });
    }
  }
  
  if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') {
    module.exports = MapboxLanguage;
  } else {
    ie11Polyfill();
    window.MapboxLanguage = MapboxLanguage;
  }