text: ﻿/*
   *
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   *
  */
  
  var exec = require('cordova/exec'),
      Promise = require('./Promise');
  
  /**
   * Performs an asynchronous download operation in the background.
   *
   * @param {string} uri The location of the resource.
   * @param {File} resultFile The file that the response will be written to.
   */
  var DownloadOperation = function (uri, resultFile, title) {
  
      if (uri == null || resultFile == null) {
          throw new Error("missing or invalid argument");
      }
      
      this.uri = uri;
      this.resultFile = resultFile;
      this.title = title;
  };
  
  /**
   * Starts an asynchronous download operation.
   */
  DownloadOperation.prototype.startAsync = function() {
  
      var deferral = new Promise.Deferral(),
          me = this,
          successCallback = function(result) {
  
              // success callback is used to both report operation progress and 
              // as operation completeness handler
              
              if (result && typeof result.progress != 'undefined') {
                  deferral.notify(result.progress);
              } else {
                  deferral.resolve(result);
              }
          },
          errorCallback = function(err) {
              deferral.reject(err);
          };
  
      exec(successCallback, errorCallback, "BackgroundDownload", "startAsync", [this.uri, this.resultFile.toURL(), this.title]);
  
      // custom mechanism to trigger stop when user cancels pending operation
      deferral.promise.onCancelled = function () {
          me.stop();
      };
  
      return deferral.promise;
  };
  
  /**
   * Stops a download operation.
   */
  DownloadOperation.prototype.stop = function() {
      // TODO return promise
      exec(null, null, "BackgroundDownload", "stop", [this.uri]);
  
  };
  
  module.exports = DownloadOperation;
  