"use strict";

/* global module, define */

function mapEach(map, operation){
  var keys = map.keys();
  var next;
  while(!(next = keys.next()).done) {
    operation(map.get(next.value), next.value, map);
  }
}

var Multimap = (function() {
  var mapCtor;
  if (typeof Map !== 'undefined') {
    mapCtor = Map;

    if (!Map.prototype.keys) {
      Map.prototype.keys = function() {
        var keys = [];
        this.forEach(function(item, key) {
          keys.push(key);
        });
        return keys;
      };
    }
  }

  function Multimap(iterable) {
    var self = this;

    self._map = mapCtor;

    if (Multimap.Map) {
      self._map = Multimap.Map;
    }

    self._ = self._map ? new self._map() : {};

    if (iterable) {
      iterable.forEach(function(i) {
        self.set(i[0], i[1]);
      });
    }
  }

  /**
   * @param {Object} key
   * @return {Array} An array of values, undefined if no such a key;
   */
  Multimap.prototype.get = function(key) {
    return this._map ? this._.get(key) : this._[key];
  };

  /**
   * @param {Object} key
   * @param {Object} val...
   */
  Multimap.prototype.set = function(key, val) {
    var args = Array.prototype.slice.call(arguments);

    key = args.shift();

    var entry = this.get(key);
    if (!entry) {
      entry = [];
      if (this._map)
        this._.set(key, entry);
      else
        this._[key] = entry;
    }

    Array.prototype.push.apply(entry, args);
    return this;
  };

  /**
   * @param {Object} key
   * @param {Object=} val
   * @return {boolean} true if any thing changed
   */
  Multimap.prototype.delete = function(key, val) {
    if (!this.has(key))
      return false;

    if (arguments.length == 1) {
      this._map ? (this._.delete(key)) : (delete this._[key]);
      return true;
    } else {
      var entry = this.get(key);
      var idx = entry.indexOf(val);
      if (idx != -1) {
        entry.splice(idx, 1);
        return true;
      }
    }

    return false;
  };

  /**
   * @param {Object} key
   * @param {Object=} val
   * @return {boolean} whether the map contains 'key' or 'key=>val' pair
   */
  Multimap.prototype.has = function(key, val) {
    var hasKey = this._map ? this._.has(key) : this._.hasOwnProperty(key);

    if (arguments.length == 1 || !hasKey)
      return hasKey;

    var entry = this.get(key) || [];
    return entry.indexOf(val) != -1;
  };


  /**
   * @return {Array} all the keys in the map
   */
  Multimap.prototype.keys = function() {
    if (this._map)
      return makeIterator(this._.keys());

    return makeIterator(Object.keys(this._));
  };

  /**
   * @return {Array} all the values in the map
   */
  Multimap.prototype.values = function() {
    var vals = [];
    this.forEachEntry(function(entry) {
      Array.prototype.push.apply(vals, entry);
    });

    return makeIterator(vals);
  };

  /**
   *
   */
  Multimap.prototype.forEachEntry = function(iter) {
    mapEach(this, iter);
  };

  Multimap.prototype.forEach = function(iter) {
    var self = this;
    self.forEachEntry(function(entry, key) {
      entry.forEach(function(item) {
        iter(item, key, self);
      });
    });
  };


  Multimap.prototype.clear = function() {
    if (this._map) {
      this._.clear();
    } else {
      this._ = {};
    }
  };

  Object.defineProperty(
    Multimap.prototype,
    "size", {
      configurable: false,
      enumerable: true,
      get: function() {
        var total = 0;

        mapEach(this, function(value){
          total += value.length;
        });

        return total;
      }
    });

  Object.defineProperty(
    Multimap.prototype,
    "count", {
      configurable: false,
      enumerable: true,
      get: function() {
        return this._.size;
      }
    });

  var safariNext;

  try{
    safariNext = new Function('iterator', 'makeIterator', 'var keysArray = []; for(var key of iterator){keysArray.push(key);} return makeIterator(keysArray).next;');
  }catch(error){
    // for of not implemented;
  }

  function makeIterator(iterator){
    if(Array.isArray(iterator)){
      var nextIndex = 0;

      return {
        next: function(){
          return nextIndex < iterator.length ?
            {value: iterator[nextIndex++], done: false} :
          {done: true};
        }
      };
    }

    // Only an issue in safari
    if(!iterator.next && safariNext){
      iterator.next = safariNext(iterator, makeIterator);
    }

    return iterator;
  }

  return Multimap;
})();


if(typeof exports === 'object' && module && module.exports)
  module.exports = Multimap;
else if(typeof define === 'function' && define.amd)
  define(function() { return Multimap; });