/* global exports, require */
'use strict';

/**
 * DownloadManager is a tool for downloading file from internet.
 * When downloads a https url which uses self-signed certificate,
 * DownloadManager fallbacks to "http" protocol to download it.
 *
 */

var utils = require('./utils');

const { Cc, Ci, Cu, Cr } = require('chrome');
const { Services } = Cu.import('resource://gre/modules/Services.jsm');

var DownloadManager = {
  debug: false,
  count: 0,
  download: function dm_download(url, targetFolder, targetName,
                                finishedCallback, errorCallback) {

    var tmpFile;
    var isTemp;
    var isHttps = url.substring(0, 5) === 'https';

    function logLine(msg) {
      if (DownloadManager.debug) {
        utils.log('download-manager', msg);
      }
    }

    function downloadFinished() {
      logLine(url + ' is successfully downloaded.');
      try {
        if (finishedCallback) {
          finishedCallback(url, tmpFile.path);
        }
      } finally {
        DownloadManager.count -= 1;
      }
    }

    function downloadError(reason) {
      try {
        if (isHttps) {
          // If we failed with https protocol, it may be self-signed
          // certificate. We fallback to use http protocol to download it.
          // XXX find a way to bypass the self-signed certificate error.
          var httpUrl = 'http' + url.substring(5);
          logLine('fallback to ' + httpUrl);
          DownloadManager.download(httpUrl, targetFolder, targetName,
                                   finishedCallback, errorCallback);
        } else if (errorCallback) {
          logLine('Unable to download ' + url + '\n' + reason);
          errorCallback(url, tmpFile.path);
        } else {
          logLine('Unable to download ' + url + '\n' + reason);
        }
      } finally {
        DownloadManager.count -= 1;
      }
    }

    // normalize file for saving.
    if (targetFolder && targetName) {
      isTemp = false;
      utils.ensureFolderExists(utils.getFile(targetFolder));
      tmpFile = utils.getFile(targetFolder, targetName);
    } else {
      isTemp = true;
      tmpFile = DownloadManager._getTempFolder('gaia').clone();
      tmpFile.append((new Date()).getTime() + '.tmp');
      tmpFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt('0644', 8));
    }

    DownloadManager.count += 1;

    var listener = {
      QueryInterface: function(iid) {
       if (!iid.equals(Ci.nsIDownloadObserver) &&
           !iid.equals(Ci.nsISupports)) {
          throw Cr.NS_ERROR_NO_INTERFACE;
        }
        return this;
      },

      onDownloadComplete: function(downloader, request, ctxt, status, file) {
        if (!file || status !== 0) {
          downloadError('failed to download "' + url + '" with error code: ' +
                        status);
        } else {
          downloadFinished();
        }
      }
    };

    var downloader = Cc['@mozilla.org/network/downloader;1']
                   .createInstance(Ci.nsIDownloader);
    downloader.init(listener, tmpFile);
    var principal = Services.scriptSecurityManager.getSystemPrincipal();

    let channel = Services.io.newChannel2(url,
                                          null,
                                          null,
                                          null,  // aLoadingNode
                                          principal,
                                          null,  // aTriggeringPrincipal
                                          Ci.nsILoadInfo.SEC_NORMAL,
                                          Ci.nsIContentPolicy.TYPE_OTHER);

    channel.asyncOpen(downloader, null);
  },
  // private functions and variables
  _tempFolder: null,
  _getTempFolder: function dm_get_temp_folder(name) {
    if (!DownloadManager._tempFolder) {
      var file = Cc['@mozilla.org/file/directory_service;1']
                   .getService(Ci.nsIProperties).get('TmpD', Ci.nsIFile);
      file.append(name);
      file.createUnique(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0755', 8));
      DownloadManager._tempFolder = file;
    }
    return DownloadManager._tempFolder;
  }
};

exports.getDownloadManager = function() {
  return DownloadManager;
};