var Hash = function(obj) {
  Object.extend(this, obj || {});
};

Object.extend(Hash, {
  toQueryString: function(obj) {
    var parts = [];
    
	  this.prototype._each.call(obj, function(pair) {
      if (!pair.key) return;
      
      if (pair.value && pair.value.constructor == Array) {
        var values = pair.value.compact();
        if (values.length < 2) pair.value = values.reduce();
        else {
        	key = encodeURIComponent(pair.key);
          values.each(function(value) {
            value = value != undefined ? encodeURIComponent(value) : '';
            parts.push(key + '=' + encodeURIComponent(value));
          });
          return;
        }
      }
      if (pair.value == undefined) pair[1] = '';
      parts.push(pair.map(encodeURIComponent).join('='));
	  });
    
    return parts.join('&');
  }
});

Object.extend(Hash.prototype, Enumerable);
Object.extend(Hash.prototype, {
  _each: function(iterator) {
    for (var key in this) {
      var value = this[key];
      if (value && value == Hash.prototype[key]) continue;
      
      var pair = [key, value];
      pair.key = key;
      pair.value = value;
      iterator(pair);
    }
  },
  
  keys: function() {
    return this.pluck('key');
  },
  
  values: function() {
    return this.pluck('value');
  },
  
  merge: function(hash) {
    return $H(hash).inject(this, function(mergedHash, pair) {
      mergedHash[pair.key] = pair.value;
      return mergedHash;
    });
  },

  remove: function() {
    var result;
    for(var i = 0, length = arguments.length; i < length; i++) {
      var value = this[arguments[i]];
      if (value !== undefined){
        if (result === undefined) result = value;
        else {
          if (result.constructor != Array) result = [result];
          result.push(value)
        }
      }
      delete this[arguments[i]];
    }
    return result;
  },
  
  toQueryString: function() {
    return Hash.toQueryString(this);
  },
  
  inspect: function() {
    return '#<Hash:{' + this.map(function(pair) {
      return pair.map(Object.inspect).join(': ');
    }).join(', ') + '}>';
  }
});

function $H(object) {
  if (object && object.constructor == Hash) return object;
  return new Hash(object);
};