'use strict';

/**
 * Licensed Materials - Property of IBM
 * IBM Cognos Products: BI Cloud (C) Copyright IBM Corp. 2014, 2017
 * US Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
 */
define(['underscore', '../../lib/@waca/dashboard-common/dist/core/Collection'], function (_, Collection) {

	var TransactionalCollection = null;

	/**
  * A collection which allow changes to be made within the context of a transaction
  *
  * @see Collection
  *
  */
	TransactionalCollection = Collection.extend({

		init: function init() {
			TransactionalCollection.inherited('init', this, arguments);
		},

		/**
   * Start a transaction on this collection. During a transaction modifications will be silent and the
   * user of the collection can be notified of all the changes during the transaction at the end of the transaction
   * by calling stopTransaction(...)
   */
		startTransaction: function startTransaction() {
			if (this._transactionLog) {
				throw new Error('A transaction is already started');
			}
			this._transactionLog = new Collection(this.toJSON(), { modelClass: this.model });
		},

		/**
   * Stop the transaction on this collection. If changes were made to this collection in the context of the transaction
   * then a 'reset' event will be emitted describing the changes.
   */
		stopTransaction: function stopTransaction() {
			if (!this._transactionLog) {
				throw new Error('No transaction to stop');
			}

			var transactionLog = this._transactionLog;
			this._transactionLog = null;

			TransactionalCollection.inherited('reset', this, [transactionLog.toJSON()]);
		}

	});

	// Mix-in an override for all the collection methods that delegate to the transaction log collection when
	// we are in the context of a transaction
	var collectionFns = _.union(['add', 'remove', 'reset', 'set', 'getModels', 'get', 'toJSON'], Collection._underscoreMethods, Collection._underscoreAttributeMethods);
	_.each(collectionFns, function (method) {
		TransactionalCollection.prototype[method] = function () {
			if (this._transactionLog) {
				return this._transactionLog[method].apply(this._transactionLog, arguments);
			}
			return TransactionalCollection.inherited(method, this, arguments);
		};
	});

	return TransactionalCollection;
});
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