// GPG4Browsers - An OpenPGP implementation in javascript
// Copyright (C) 2011 Recurity Labs GmbH
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

/** 
 * @class
 * @classdesc Implementation of the User Attribute Packet (Tag 17)
 *  The User Attribute packet is a variation of the User ID packet.  It
 *  is capable of storing more types of data than the User ID packet,
 *  which is limited to text.  Like the User ID packet, a User Attribute
 *  packet may be certified by the key owner ("self-signed") or any other
 *  key owner who cares to certify it.  Except as noted, a User Attribute
 *  packet may be used anywhere that a User ID packet may be used.
 *
 *  While User Attribute packets are not a required part of the OpenPGP
 *  standard, implementations SHOULD provide at least enough
 *  compatibility to properly handle a certification signature on the
 *  User Attribute packet.  A simple way to do this is by treating the
 *  User Attribute packet as a User ID packet with opaque contents, but
 *  an implementation may use any method desired.
 */
module.exports = function packet_user_attribute() {
  this.tag = 17;
  this.attributes = [];

  /**
   * parsing function for a user attribute packet (tag 17).
   * @param {String} input payload of a tag 17 packet
   * @param {Integer} position position to start reading from the input string
   * @param {Integer} len length of the packet or the remaining length of input at position
   * @return {openpgp_packet_encrypteddata} object representation
   */
  this.read = function(bytes) {
    var i = 0;
    while (i < bytes.length) {
      var len = openpgp_packet.read_simple_length(bytes);

      i += len.offset;
      this.attributes.push(bytes.substr(i, len.len));
      i += len.len;
    }
  }
};