/* Copyright 2013 Mozilla Foundation
 *
 * Licensed 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.
 */
/* globals chrome */

'use strict';

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define('pdfjs-web/chromecom', ['exports', 'pdfjs-web/app',
      'pdfjs-web/overlay_manager', 'pdfjs-web/preferences', 'pdfjs-web/pdfjs'],
      factory);
  } else if (typeof exports !== 'undefined') {
    factory(exports, require('./app.js'), require('./overlay_manager.js'),
      require('./preferences.js'), require('./pdfjs.js'));
  } else {
    factory((root.pdfjsWebChromeCom = {}), root.pdfjsWebApp,
      root.pdfjsWebOverlayManager, root.pdfjsWebPreferences,
      root.pdfjsWebPDFJS);
  }
}(this, function (exports, app, overlayManager, preferences, pdfjsLib) {
  if (typeof PDFJSDev === 'undefined' || !PDFJSDev.test('CHROME')) {
    throw new Error('Module "pdfjs-web/chromecom" shall not be used outside ' +
                    'CHROME build.');
  }

  var PDFViewerApplication = app.PDFViewerApplication;
  var DefaultExernalServices = app.DefaultExernalServices;
  var OverlayManager = overlayManager.OverlayManager;
  var Preferences = preferences.Preferences;

  var ChromeCom = {};
  /**
   * Creates an event that the extension is listening for and will
   * asynchronously respond by calling the callback.
   *
   * @param {String} action The action to trigger.
   * @param {String} data Optional data to send.
   * @param {Function} callback Optional response callback that will be called
   * with one data argument. When the request cannot be handled, the callback
   * is immediately invoked with no arguments.
   */
  ChromeCom.request = function ChromeCom_request(action, data, callback) {
    var message = {
      action: action,
      data: data
    };
    if (!chrome.runtime) {
      console.error('chrome.runtime is undefined.');
      if (callback) {
        callback();
      }
    } else if (callback) {
      chrome.runtime.sendMessage(message, callback);
    } else {
      chrome.runtime.sendMessage(message);
    }
  };

  /**
   * Resolves a PDF file path and attempts to detects length.
   *
   * @param {String} file Absolute URL of PDF file.
   * @param {Function} callback A callback with resolved URL and file length.
   */
  ChromeCom.resolvePDFFile = function ChromeCom_resolvePDFFile(file, callback) {
    // Expand drive:-URLs to filesystem URLs (Chrome OS)
    file = file.replace(/^drive:/i,
        'filesystem:' + location.origin + '/external/');

    if (/^filesystem:/.test(file) && !pdfjsLib.PDFJS.disableWorker) {
      // The security origin of filesystem:-URLs are not preserved when the
      // URL is passed to a Web worker, (http://crbug.com/362061), so we have
      // to create an intermediate blob:-URL as a work-around.
      var resolveLocalFileSystemURL = window.resolveLocalFileSystemURL ||
                                      window.webkitResolveLocalFileSystemURL;
      resolveLocalFileSystemURL(file, function onResolvedFSURL(fileEntry) {
        fileEntry.file(function(fileObject) {
          var blobUrl = URL.createObjectURL(fileObject);
          callback(blobUrl, fileObject.size);
        });
      }, function onFileSystemError(error) {
        // This should not happen. When it happens, just fall back to the
        // usual way of getting the File's data (via the Web worker).
        console.warn('Cannot resolve file ' + file + ', ' + error.name + ' ' +
                     error.message);
        callback(file);
      });
      return;
    }
    if (/^https?:/.test(file)) {
      // Assumption: The file being opened is the file that was requested.
      // There is no UI to input a different URL, so this assumption will hold
      // for now.
      setReferer(file, function() {
        callback(file);
      });
      return;
    }
    if (/^file?:/.test(file)) {
      getEmbedderOrigin(function(origin) {
        // If the origin cannot be determined, let Chrome decide whether to
        // allow embedding files. Otherwise, only allow local files to be
        // embedded from local files or Chrome extensions.
        // Even without this check, the file load in frames is still blocked,
        // but this may change in the future (https://crbug.com/550151).
        if (origin && !/^file:|^chrome-extension:/.test(origin)) {
          PDFViewerApplication.error('Blocked ' + origin + ' from loading ' +
              file + '. Refused to load a local file in a non-local page ' +
              'for security reasons.');
          return;
        }
        isAllowedFileSchemeAccess(function(isAllowedAccess) {
          if (isAllowedAccess) {
            callback(file);
          } else {
            requestAccessToLocalFile(file);
          }
        });
      });
      return;
    }
    callback(file);
  };

  function getEmbedderOrigin(callback) {
    var origin = window === top ? location.origin : location.ancestorOrigins[0];
    if (origin === 'null') {
      // file:-URLs, data-URLs, sandboxed frames, etc.
      getParentOrigin(callback);
    } else {
      callback(origin);
    }
  }

  function getParentOrigin(callback) {
    ChromeCom.request('getParentOrigin', null, callback);
  }

  function isAllowedFileSchemeAccess(callback) {
    ChromeCom.request('isAllowedFileSchemeAccess', null, callback);
  }

  function isRuntimeAvailable() {
    try {
      // When the extension is reloaded, the extension runtime is destroyed and
      // the extension APIs become unavailable.
      if (chrome.runtime && chrome.runtime.getManifest()) {
        return true;
      }
    } catch (e) {}
    return false;
  }

  function reloadIfRuntimeIsUnavailable() {
    if (!isRuntimeAvailable()) {
      location.reload();
    }
  }

  var chromeFileAccessOverlayPromise;
  function requestAccessToLocalFile(fileUrl) {
    var onCloseOverlay = null;
    if (top !== window) {
      // When the extension reloads after receiving new permissions, the pages
      // have to be reloaded to restore the extension runtime. Auto-reload
      // frames, because users should not have to reload the whole page just to
      // update the viewer.
      // Top-level frames are closed by Chrome upon reload, so there is no need
      // for detecting unload of the top-level frame. Should this ever change
      // (crbug.com/511670), then the user can just reload the tab.
      window.addEventListener('focus', reloadIfRuntimeIsUnavailable);
      onCloseOverlay = function() {
        window.removeEventListener('focus', reloadIfRuntimeIsUnavailable);
        reloadIfRuntimeIsUnavailable();
        OverlayManager.close('chromeFileAccessOverlay');
      };
    }
    if (!chromeFileAccessOverlayPromise) {
      chromeFileAccessOverlayPromise = OverlayManager.register(
        'chromeFileAccessOverlay',
        document.getElementById('chromeFileAccessOverlay'),
        onCloseOverlay, true);
    }
    chromeFileAccessOverlayPromise.then(function() {
      var iconPath = chrome.runtime.getManifest().icons[48];
      document.getElementById('chrome-pdfjs-logo-bg').style.backgroundImage =
        'url(' + chrome.runtime.getURL(iconPath) + ')';

      // Use Chrome's definition of UI language instead of PDF.js's #lang=...,
      // because the shown string should match the UI at chrome://extensions.
      // These strings are from chrome/app/resources/generated_resources_*.xtb.
      /* eslint-disable no-unexpected-multiline */
      var i18nFileAccessLabel =
        PDFJSDev.json('$ROOT/web/chrome-i18n-allow-access-to-file-urls.json')
        [chrome.i18n.getUILanguage && chrome.i18n.getUILanguage()];
      /* eslint-enable no-unexpected-multiline */

      if (i18nFileAccessLabel) {
        document.getElementById('chrome-file-access-label').textContent =
          i18nFileAccessLabel;
      }

      var link = document.getElementById('chrome-link-to-extensions-page');
      link.href = 'chrome://extensions/?id=' + chrome.runtime.id;
      link.onclick = function(e) {
        // Direct navigation to chrome:// URLs is blocked by Chrome, so we
        // have to ask the background page to open chrome://extensions/?id=...
        e.preventDefault();
        // Open in the current tab by default, because toggling the file access
        // checkbox causes the extension to reload, and Chrome will close all
        // tabs upon reload.
        ChromeCom.request('openExtensionsPageForFileAccess', {
          newTab: e.ctrlKey || e.metaKey || e.button === 1 || window !== top
        });
      };

      // Show which file is being opened to help the user with understanding
      // why this permission request is shown.
      document.getElementById('chrome-url-of-local-file').textContent = fileUrl;

      OverlayManager.open('chromeFileAccessOverlay');
    });
  }

  if (window === top) {
    // Chrome closes all extension tabs (crbug.com/511670) when the extension
    // reloads. To counter this, the tab URL and history state is saved to
    // localStorage and restored by extension-router.js.
    // Unfortunately, the window and tab index are not restored. And if it was
    // the only tab in an incognito window, then the tab is not restored either.
    addEventListener('unload', function() {
      // If the runtime is still available, the unload is most likely a normal
      // tab closure. Otherwise it is most likely an extension reload.
      if (!isRuntimeAvailable()) {
        localStorage.setItem(
          'unload-' + Date.now() + '-' + document.hidden + '-' + location.href,
          JSON.stringify(history.state));
      }
    });
  }

  // This port is used for several purposes:
  // 1. When disconnected, the background page knows that the frame has unload.
  // 2. When the referrer was saved in history.state.chromecomState, it is sent
  //    to the background page.
  // 3. When the background page knows the referrer of the page, the referrer is
  //    saved in history.state.chromecomState.
  var port;
  // Set the referer for the given URL.
  // 0. Background: If loaded via a http(s) URL: Save referer.
  // 1. Page -> background: send URL and referer from history.state
  // 2. Background: Bind referer to URL (via webRequest).
  // 3. Background -> page: Send latest referer and save to history.
  // 4. Page: Invoke callback.
  function setReferer(url, callback) {
    if (!port) {
      // The background page will accept the port, and keep adding the Referer
      // request header to requests to |url| until the port is disconnected.
      port = chrome.runtime.connect({name: 'chromecom-referrer'});
    }
    port.onDisconnect.addListener(onDisconnect);
    port.onMessage.addListener(onMessage);
    // Initiate the information exchange.
    port.postMessage({
      referer: window.history.state && window.history.state.chromecomState,
      requestUrl: url
    });

    function onMessage(referer) {
      if (referer) {
        // The background extracts the Referer from the initial HTTP request for
        // the PDF file. When the viewer is reloaded or when the user navigates
        // back and forward, the background page will not observe a HTTP request
        // with Referer. To make sure that the Referer is preserved, store it in
        // history.state, which is preserved across reloads/navigations.
        var state = window.history.state || {};
        state.chromecomState = referer;
        window.history.replaceState(state, '');
      }
      onCompleted();
    }
    function onDisconnect() {
      // When the connection fails, ignore the error and call the callback.
      port = null;
      callback();
    }
    function onCompleted() {
      port.onDisconnect.removeListener(onDisconnect);
      port.onMessage.removeListener(onMessage);
      callback();
    }
  }

  // chrome.storage.sync is not supported in every Chromium-derivate.
  // Note: The background page takes care of migrating values from
  // chrome.storage.local to chrome.storage.sync when needed.
  var storageArea = chrome.storage.sync || chrome.storage.local;

  Preferences._writeToStorage = function (prefObj) {
    return new Promise(function (resolve) {
      if (prefObj === Preferences.defaults) {
        var keysToRemove = Object.keys(Preferences.defaults);
        // If the storage is reset, remove the keys so that the values from
        // managed storage are applied again.
        storageArea.remove(keysToRemove, function() {
          resolve();
        });
      } else {
        storageArea.set(prefObj, function() {
          resolve();
        });
      }
    });
  };

  Preferences._readFromStorage = function (prefObj) {
    return new Promise(function (resolve) {
      if (chrome.storage.managed) {
        // Get preferences as set by the system administrator.
        // See extensions/chromium/preferences_schema.json for more information.
        // These preferences can be overridden by the user.
        chrome.storage.managed.get(Preferences.defaults, getPreferences);
      } else {
        // Managed storage not supported, e.g. in old Chromium versions.
        getPreferences(Preferences.defaults);
      }

      function getPreferences(defaultPrefs) {
        if (chrome.runtime.lastError) {
          // Managed storage not supported, e.g. in Opera.
          defaultPrefs = Preferences.defaults;
        }
        storageArea.get(defaultPrefs, function(readPrefs) {
          resolve(readPrefs);
        });
      }
    });
  };

  var ChromeExternalServices = Object.create(DefaultExernalServices);
  ChromeExternalServices.initPassiveLoading = function (callbacks) {
    var appConfig = PDFViewerApplication.appConfig;
    ChromeCom.resolvePDFFile(appConfig.defaultUrl,
        function (url, length, originalURL) {
      callbacks.onOpenWithURL(url, length, originalURL);
    });
  };
  PDFViewerApplication.externalServices = ChromeExternalServices;

  exports.ChromeCom = ChromeCom;
}));
