// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

cr.define('downloads', function() {
  /**
   * @param {string} chromeSendName
   * @return {function(string):void} A chrome.send() callback with curried name.
   */
  function chromeSendWithId(chromeSendName) {
    return function(id) { chrome.send(chromeSendName, [id]); };
  }

  /** @constructor */
  function ActionService() {
    /** @private {Array<string>} */
    this.searchTerms_ = [];
  }

  /**
   * @param {string} s
   * @return {string} |s| without whitespace at the beginning or end.
   */
  function trim(s) { return s.trim(); }

  /**
   * @param {string|undefined} value
   * @return {boolean} Whether |value| is truthy.
   */
  function truthy(value) { return !!value; }

  /**
   * @param {string} searchText Input typed by the user into a search box.
   * @return {Array<string>} A list of terms extracted from |searchText|.
   */
  ActionService.splitTerms = function(searchText) {
    // Split quoted terms (e.g., 'The "lazy" dog' => ['The', 'lazy', 'dog']).
    return searchText.split(/"([^"]*)"/).map(trim).filter(truthy);
  };

  ActionService.prototype = {
    /** @param {string} id ID of the download to cancel. */
    cancel: chromeSendWithId('cancel'),

    /** Instructs the browser to clear all finished downloads. */
    clearAll: function() {
      if (loadTimeData.getBoolean('allowDeletingHistory')) {
        chrome.send('clearAll');
        this.search('');
      }
    },

    /** @param {string} id ID of the dangerous download to discard. */
    discardDangerous: chromeSendWithId('discardDangerous'),

    /** @param {string} url URL of a file to download. */
    download: function(url) {
      var a = document.createElement('a');
      a.href = url;
      a.setAttribute('download', '');
      a.click();
    },

    /** @param {string} id ID of the download that the user started dragging. */
    drag: chromeSendWithId('drag'),

    /** Loads more downloads with the current search terms. */
    loadMore: function() {
      chrome.send('getDownloads', this.searchTerms_);
    },

    /**
     * @return {boolean} Whether the user is currently searching for downloads
     *     (i.e. has a non-empty search term).
     */
    isSearching: function() {
      return this.searchTerms_.length > 0;
    },

    /** Opens the current local destination for downloads. */
    openDownloadsFolder: chrome.send.bind(chrome, 'openDownloadsFolder'),

    /**
     * @param {string} id ID of the download to run locally on the user's box.
     */
    openFile: chromeSendWithId('openFile'),

    /** @param {string} id ID the of the progressing download to pause. */
    pause: chromeSendWithId('pause'),

    /** @param {string} id ID of the finished download to remove. */
    remove: chromeSendWithId('remove'),

    /** @param {string} id ID of the paused download to resume. */
    resume: chromeSendWithId('resume'),

    /**
     * @param {string} id ID of the dangerous download to save despite
     *     warnings.
     */
    saveDangerous: chromeSendWithId('saveDangerous'),

    /**
     * @param {string} searchText What to search for.
     * @return {boolean} Whether |searchText| resulted in new search terms.
     */
    search: function(searchText) {
      var searchTerms = ActionService.splitTerms(searchText);
      var sameTerms = searchTerms.length == this.searchTerms_.length;

      for (var i = 0; sameTerms && i < searchTerms.length; ++i) {
        if (searchTerms[i] != this.searchTerms_[i])
          sameTerms = false;
      }

      if (sameTerms)
        return false;

      this.searchTerms_ = searchTerms;
      this.loadMore();
      return true;
    },

    /**
     * Shows the local folder a finished download resides in.
     * @param {string} id ID of the download to show.
     */
    show: chromeSendWithId('show'),

    /** Undo download removal. */
    undo: chrome.send.bind(chrome, 'undo'),
  };

  cr.addSingletonGetter(ActionService);

  return {ActionService: ActionService};
});