Save most recent 3 destinations across multiple sessions

chrome/browser/resources/print_preview/data/app_state.js

Index: chrome/browser/resources/print_preview/data/app_state.js
diff --git a/chrome/browser/resources/print_preview/data/app_state.js b/chrome/browser/resources/print_preview/data/app_state.js
index b782f4ea3d1543fc1b8edb23ba6fdb842778570c..0a53f70a7b5f7796cf52daf9dfe0afb31620e477 100644
--- a/chrome/browser/resources/print_preview/data/app_state.js
+++ b/chrome/browser/resources/print_preview/data/app_state.js
@@ -6,9 +6,23 @@ cr.define('print_preview', function() {
   'use strict';
 
   /**
-   * Object used to get and persist the print preview application state.
+   * Object used to represent a recent destination in the app state.
    * @constructor
    */
+  function RecentDestination(destination) {
+    this.id_ = destination.id;
+    this.origin_ = destination.origin;
+    this.account_ = destination.account || '';
+    this.capabilities_ = destination.capabilities;
+    this.name_ = destination.name || '';
+    this.extension_id_ = destination.extension_id || '';

[dpapad, 2016/09/21 20:44:18]

Nit: Per JS styleguide naming, this should be this.extensionId_ (similar for
extensionName below).

[rbpotter, 2016/09/21 23:19:14]

Done.

+    this.extension_name_ = destination.extension_name || '';
+  };
+
+  /**
+  * Object used to get and persist the print preview application state.
+  * @constructor
+  */
   function AppState() {
     /**
      * Internal representation of application state.
@@ -18,6 +32,7 @@ cr.define('print_preview', function() {
     this.state_ = {};
     this.state_[AppState.Field.VERSION] = AppState.VERSION_;
     this.state_[AppState.Field.IS_GCP_PROMO_DISMISSED] = true;
+    this.state_[AppState.Field.RECENT_DESTINATIONS] = [];
 
     /**
      * Whether the app state has been initialized. The app state will ignore all
@@ -29,18 +44,19 @@ cr.define('print_preview', function() {
   };
 
   /**
+    * Number of recent print destinations to store across browser sessions.
+    * @const {number}
+    */
+  AppState.NUM_DESTINATIONS_ = 3;
+
+
+  /**
    * Enumeration of field names for serialized app state.
    * @enum {string}
    */
   AppState.Field = {
     VERSION: 'version',
-    SELECTED_DESTINATION_ID: 'selectedDestinationId',
-    SELECTED_DESTINATION_ACCOUNT: 'selectedDestinationAccount',
-    SELECTED_DESTINATION_ORIGIN: 'selectedDestinationOrigin',
-    SELECTED_DESTINATION_CAPABILITIES: 'selectedDestinationCapabilities',
-    SELECTED_DESTINATION_NAME: 'selectedDestinationName',
-    SELECTED_DESTINATION_EXTENSION_ID: 'selectedDestinationExtensionId',
-    SELECTED_DESTINATION_EXTENSION_NAME: 'selectedDestinationExtensionName',
+    RECENT_DESTINATIONS: 'recentDestinations',
     IS_GCP_PROMO_DISMISSED: 'isGcpPromoDismissed',
     DPI: 'dpi',
     MEDIA_SIZE: 'mediaSize',
@@ -74,14 +90,27 @@ cr.define('print_preview', function() {
   AppState.NATIVE_FUNCTION_NAME_ = 'saveAppState';
 
   AppState.prototype = {
+
+    /**
+      * Helper function to get the most recent destination.
+      * @return {?RecentDestination} The most recent value of the
+      *     destination.
+      */
+    getSelectedDestination_: function() {
+      return (this.state_[AppState.Field.RECENT_DESTINATIONS].length > 0) ?
+          this.state_[AppState.Field.RECENT_DESTINATIONS][0] : null;
+    },
+
     /** @return {?string} ID of the selected destination. */
     get selectedDestinationId() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_ID];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.id : null;
     },
 
     /** @return {?string} Account the selected destination is registered for. */
     get selectedDestinationAccount() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_ACCOUNT];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.account : null;
     },
 
     /**
@@ -89,24 +118,28 @@ cr.define('print_preview', function() {
      *     selected destination.
      */
     get selectedDestinationOrigin() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_ORIGIN];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.origin : null;
     },
 
     /** @return {?print_preview.Cdd} CDD of the selected destination. */
     get selectedDestinationCapabilities() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_CAPABILITIES];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.capabilities : null;
     },
 
     /** @return {?string} Name of the selected destination. */
     get selectedDestinationName() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_NAME];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.name : null;
     },
 
     /**
      * @return {?string} Extension ID associated with the selected destination.
      */
     get selectedDestinationExtensionId() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_EXTENSION_ID];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.extension_id : null;
     },
 
     /**
@@ -114,7 +147,24 @@ cr.define('print_preview', function() {
      *     destination.
      */
     get selectedDestinationExtensionName() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_EXTENSION_NAME];
+      return this.getSelectedDestination_ ?
+          this.getSelectedDestination_.extension_name : null;
+    },
+
+    /**
+     * @return {?RecentDestination} The most recent destination, which is
+     *     currently the selected destination.
+     */
+    get selectedDestination() {
+      return this.getSelectedDestination_;
+    },
+
+    /**
+     * @return {?Array<RecentDestination>} The AppState.NUM_DESTINATIONS_ most

[dpapad, 2016/09/21 20:44:18]

Nit: ?Array<!RecentDestination>

[rbpotter, 2016/09/21 23:19:15]

Done.

+     *     recent destinations.
+     */
+    get recentDestinations() {
+      return this.state_[AppState.Field.RECENT_DESTINATIONS];
     },
 
     /** @return {boolean} Whether the GCP promotion has been dismissed. */
@@ -164,6 +214,18 @@ cr.define('print_preview', function() {
       } else {
         // Set some state defaults.
         this.state_[AppState.Field.IS_GCP_PROMO_DISMISSED] = false;
+        this.state_[AppState.Field.RECENT_DESTINATIONS] = [];
+      }
+      if (!this.state_[AppState.Field.RECENT_DESTINATIONS])
+        this.state_[AppState.Field.RECENT_DESTINATIONS] = [];
+      else if (!(this.state_[AppState.Field.RECENT_DESTINATIONS] instanceof
+            Array)) {
+        var tmp = this.state_[AppState.Field.RECENT_DESTINATIONS];
+        this.state_[AppState.Field.RECENT_DESTINATIONS] = [tmp];
+      } else if (this.state_[AppState.Field.RECENT_DESTINATIONS].length >
+          AppState.NUM_DESTINATIONS_) {
+        this.state_[AppState.Field.RECENT_DESTINATIONS].length =
+            AppState.NUM_DESTINATIONS_;
       }
     },
 
@@ -197,16 +259,35 @@ cr.define('print_preview', function() {
     persistSelectedDestination: function(dest) {
       if (!this.isInitialized_)
         return;
-      this.state_[AppState.Field.SELECTED_DESTINATION_ID] = dest.id;
-      this.state_[AppState.Field.SELECTED_DESTINATION_ACCOUNT] = dest.account;
-      this.state_[AppState.Field.SELECTED_DESTINATION_ORIGIN] = dest.origin;
-      this.state_[AppState.Field.SELECTED_DESTINATION_CAPABILITIES] =
-          dest.capabilities;
-      this.state_[AppState.Field.SELECTED_DESTINATION_NAME] = dest.displayName;
-      this.state_[AppState.Field.SELECTED_DESTINATION_EXTENSION_ID] =
-          dest.extensionId;
-      this.state_[AppState.Field.SELECTED_DESTINATION_EXTENSION_NAME] =
-          dest.extensionName;
+
+      // Determine if this destination is already in the recent destinations,
+      // and where in the array it is located.
+      var newDestination = new RecentDestination(dest);
+      var indexFound = this.state_[
+          AppState.Field.RECENT_DESTINATIONS].findIndex(function(recent) {
+            return (this.id_ == recent.id_ && this.origin_ == recent.origin_);
+          }, newDestination);

[dpapad, 2016/09/21 20:44:18]

No need to use newDestination as "this" here. Just refer to newDestination
directly, it already exists in the scope.

[rbpotter, 2016/09/21 23:19:15]

Done.

+
+      // No change
+      if (indexFound == 0) {
+        this.persist_();
+        return;
+      }
+
+      // Shift the array so that the nth most recent destination is located at
+      // index n.
+      if (indexFound == -1 &&
+          this.state_[AppState.Field.RECENT_DESTINATIONS].length ==
+          AppState.NUM_DESTINATIONS_) {
+        indexFound = AppState.NUM_DESTINATIONS_ - 1;
+      }
+      if (indexFound != -1)
+        this.state_[AppState.Field.RECENT_DESTINATIONS].splice(indexFound, 1);
+
+      // Add the most recent destination
+      this.state_[AppState.Field.RECENT_DESTINATIONS].splice(0, 0,
+          newDestination);

[dpapad, 2016/09/21 20:44:18]

Nit: Probably more readable to break line right after "(".

[rbpotter, 2016/09/21 23:19:15]

Done.

+
       this.persist_();
     },