Introduce concept of provisional destinations to print preview

chrome/browser/resources/print_preview/search/provisional_destination_resolver.js

+// 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('print_preview', function() {
+  'use strict';
+
+  /** @enum {string} */
+  var ResolverState = {
+    INITIAL: 'INITIAL',
+    ACTIVE: 'ACTIVE',
+    GRANTING_PERMISSION: 'GRANTING_PERMISSION',
+    ERROR: 'ERROR',
+    DONE: 'DONE'
+  };
+
+  /**
+   * Utility class for bundling a promise object with it's resolver methods.
+   * @param {!Promise<!print_preview.Destination>} promise A promise returning
+   *     a destination.
+   * @param {function(!print_preview.Destination)} resolve Function resolving
+   *     the promise.
+   * @param {function()} reject Function for rejecting the promise.
+   * @constructor @struct
+   */
+  function PromiseResolver(promise, resolve, reject) {
+    /** @type {!Promise<!print_preview.Destination>} */
+    this.promise = promise;
+    /** @type {function(!print_preview.Destination)} */
+    this.resolve = resolve;
+    /** @type {function()} */
+    this.reject = reject;
+  }
+
+  /**
+   * Create a Promise and an associated PromiseResolver.
+   * @return {!PromiseResolver}
+   */
+  PromiseResolver.create = function() {
+    var reject = null;
+    var resolve = null;
+    /** @type {!Promise<!print_preview.Destination>} */
+    var promise = new Promise(function(resolvePromise, rejectPromise) {
+      resolve = /** @type {function(!print_preview.Destination)}*/(
+          resolvePromise);
+      reject = /** @type {function()} */(rejectPromise);
+    });
+
+    return new PromiseResolver(promise, resolve, reject);
+  };
+
+  /**
+   * Overlay used to resolve a provisional extension destination. The user is
+   * prompted to allow print preview to grant a USB device access to an
+   * extension associated with the destination. If user agrees destination
+   * resolvement is attempted (which includes granting the extension USB access
+   * and requesting destination description from the extension). The overlay is
+   * hidden when destination resolving is done.
+   *
+   * @param {!print_preview.DestinationStore} destinationStore The destination
+   *    store containing the destination. Used as a proxy to native layer for
+   *    resolving the destination.
+   * @param {!print_preview.Destination} destination The destination that has
+   *     to be resolved.
+   * @constructor
+   * @extends {print_preview.Overlay}
+   */
+  function ProvisionalDestinationResolver(destinationStore, destination) {
+    print_preview.Overlay.call(this);
+
+    /** @private {!print_preview.DestinationStore} */
+    this.destinationStore_ = destinationStore;
+    /** @private {!print_preview.Destination} */
+    this.destination_ = destination;
+
+    /** @private {ResolverState} */
+    this.state_ = ResolverState.INITIAL;
+
+    /**
+     * Promise resolver for promise returned by {@code this.run}.
+     * @private {?PromiseResolver}
+     */
+    this.promiseResolver_ = null;
+  }
+
+  /**
+   * @param {!print_preview.DestinationStore} store
+   * @param {!print_preview.Destination} destination
+   * @return {?ProvisionalDestinationResolver}
+   */
+  ProvisionalDestinationResolver.create = function(store, destination) {
+    if (destination.provisionalType !=
+            print_preview.Destination.ProvisionalType.NEEDS_USB_PERMISSION) {
+      return null;
+    }
+    return new ProvisionalDestinationResolver(store, destination);
+  };
+
+  ProvisionalDestinationResolver.prototype = {
+    __proto__: print_preview.Overlay.prototype,
+
+    /** @override */
+    enterDocument: function() {
+      print_preview.Overlay.prototype.enterDocument.call(this);
+
+      this.tracker.add(
+          this.getChildElement('.usb-permission-ok-button'),
+          'click',
+          this.startResolveDestination_.bind(this));
+      this.tracker.add(
+          this.getChildElement('.cancel'),
+          'click',
+          this.cancel.bind(this));
+
+      this.tracker.add(
+          this.destinationStore_,
+          print_preview.DestinationStore.EventType
+              .PROVISIONAL_DESTINATION_RESOLVED,
+          this.onDestinationResolved_.bind(this));
+    },
+
+    /** @override */
+    onSetVisibleInternal: function(visible) {
+      if (visible) {
+        assert(this.state_ == ResolverState.INITIAL,
+               'Showing overlay while not in initial state.');
+        assert(!this.promiseResolver_, 'Promise resolver already set.');
+        this.setState_(ResolverState.ACTIVE);
+        this.promiseResolver_ = PromiseResolver.create();
+        this.getChildElement('.default').focus();
+      } else if (this.state_ != ResolverState.DONE) {
+        assert(this.state_ != ResolverState.INITIAL, 'Hiding in initial state');
+        this.setState_(ResolverState.DONE);
+        this.promiseResolver_.reject();
+        this.promiseResolver_ = null;
+      }
+    },
+
+    /** @override */
+    createDom: function() {
+      this.setElementInternal(this.cloneTemplateInternal(
+          'extension-usb-resolver'));
+
+      var extNameEl = this.getChildElement('.usb-permission-extension-name');
+      extNameEl.title = this.destination_.extensionName;
+      extNameEl.textContent = this.destination_.extensionName;
+
+      var extIconEl = this.getChildElement('.usb-permission-extension-icon');
+      extIconEl.style.backgroundImage = '-webkit-image-set(' +
+          'url(chrome://extension-icon/' +
+               this.destination_.extensionId + '/24/1) 1x,' +
+          'url(chrome://extension-icon/' +
+               this.destination_.extensionId + '/48/1) 2x)';
+    },
+
+    /**
+     * Handler for click on OK button. It initiates destination resolving.
+     * @private
+     */
+    startResolveDestination_: function() {
+      assert(this.state_ == ResolverState.ACTIVE,
+             'Invalid state in request grant permission');
+
+      this.setState_(ResolverState.GRANTING_PERMISSION);
+      this.destinationStore_.resolveProvisionalDestination(this.destination_);
+    },
+
+    /**
+     * Handler for PROVISIONAL_DESTINATION_RESOLVED event. It finalizes the
+     * resolver state once the destination associated with the resolver gets
+     * resolved.
+     * @param {Event} event
+     * @private
+     */
+    onDestinationResolved_: function(event) {
+      if (this.state_ == ResolverState.DONE)
+        return;
+
+      if (event.provisionalId != this.destination_.id)
+        return;
+
+      if (event.destination) {
+        this.setState_(ResolverState.DONE);
+        this.promiseResolver_.resolve(event.destination);
+        this.promiseResolver_ = null;
+        this.setIsVisible(false);
+      } else {
+        this.setState_(ResolverState.ERROR);
+      }
+    },
+
+    /**
+     * Sets new resolver state and updates the UI accordingly.
+     * @param {ResolverState} state
+     * @private
+     */
+    setState_: function(state) {
+      if (this.state_ == state)
+        return;
+
+      this.state_ = state;
+      this.updateUI_();
+    },
+
+    /**
+     * Updates the resolver overlay UI to match the resolver state.
+     * @private
+     */
+    updateUI_: function() {
+      this.getChildElement('.usb-permission-ok-button').hidden =
+          this.state_ == ResolverState.ERROR;
+      this.getChildElement('.usb-permission-ok-button').disabled =
+          this.state_ != ResolverState.ACTIVE;
+
+      // If OK button is disabled, make sure Cancel button gets focus.
+      if (this.state_ != ResolverState.ACTIVE)
+        this.getChildElement('.cancel').focus();
+
+      this.getChildElement('.throbber-placeholder').classList.toggle(
+          'throbber',
+          this.state_ == ResolverState.GRANTING_PERMISSION);
+
+      this.getChildElement('.usb-permission-extension-desc').hidden =
+          this.state_ == ResolverState.ERROR;
+
+      this.getChildElement('.usb-permission-message').textContent =
+          this.state_ == ResolverState.ERROR ?
+              loadTimeData.getStringF('resolveExtensionUSBErrorMessage',
+                                      this.destination_.extensionName) :
+              loadTimeData.getString('resolveExtensionUSBPermissionMessage');
+    },
+
+    /**
+     * Initiates and shows the resolver overlay.
+     * @param {!HTMLElement} parent The element that should parent the resolver
+     *     UI.
+     * @return {!Promise<!print_preview.Destination>} Promise that will be
+     * fulfilled when the destination resolving is finished.
+     */
+    run: function(parent) {
+      this.render(parent);
+      this.setIsVisible(true);
+
+      assert(this.promiseResolver_, 'Promise resolver not created.');
+      return this.promiseResolver_.promise;
+    }
+  };
+
+  return {
+    ProvisionalDestinationResolver: ProvisionalDestinationResolver
+  };
+});