/* global bridge,
          streamClient,
          Thread
*/

(function(exports) {
  'use strict';

  const debug = 0 ?
    (arg1, ...args) => console.log(`[ConversationClient] ${arg1}`, ...args):
    () => {};

  const mark = 0 ?
    (...args) => exports.performance.mark(`[ConversationClient] ${args}`):
    () => {};

  const priv = {
    client: Symbol('client'),
    appInstanceId: Symbol('appInstanceId')
  };

  /**
   * Name of the service that is responsible for managing conversation.
   * @type {string}
   */
  const SERVICE_NAME = 'conversation-service';

  /**
   * ConversationClient is a wrapper around bridge client connected to the
   * bridge service hosted in a Shared Worker.
   * @type {Object}
   */
  var ConversationClient = {
    /**
     * Reference to active bridge client instance.
     * @type {Client}
     */
    [priv.client]: null,

    /**
     * Unique identifier of app instance where client resides in.
     * @type {string}
     */
    [priv.appInstanceId]: null,

    /**
     * Initialized conversation service client bridge.
     * @param {string} appInstanceId Unique identifier of app instance where
     * client resides in.
     */
    init(appInstanceId) {
      if (!appInstanceId) {
        throw new Error('AppInstanceId is required!');
      }

      this[priv.client] = bridge.client({
        service: SERVICE_NAME,
        endpoint: new SharedWorker(
          '/services/js/conversation/conversation_service.js'
        ),
        timeout: false
      }).plugin(streamClient);

      this[priv.appInstanceId] = appInstanceId;
    },

    /**
     * Retrieves all conversations and drafts.
     * @param {Function} onConversationRetrieved Callback that is called for
     * every retrieved conversation.
     * @returns {Promise} Promise is resolved once all conversations are
     * retrieved and rejected if conversation stream is closed unexpectedly.
     */
    getAllConversations(onConversationRetrieved) {
      mark('start retrieving conversations');

      var getAllConversationsStream = this[priv.client].stream(
        'getAllConversations', this[priv.appInstanceId]
      );

      var index = 0;
      getAllConversationsStream.listen((thread) => {
        mark(++index, ' conversation retrieved');
        debug('Conversation with id %s is retrieved from stream', thread.id);

        onConversationRetrieved(new Thread(thread));
      });

      return getAllConversationsStream.closed.then(() => {
        mark('all conversations retrieved');
      }).catch((e) => {
        console.error('Conversation stream is closed unexpectedly', e);
        throw e;
      });
    }
  };

  exports.ConversationClient = Object.seal(ConversationClient);
})(window);