Save most recent 3 destinations across multiple sessions

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

 // Copyright (c) 2012 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';
 
   /**
    * Object used to get and persist the print preview application state.
    * @constructor
@@ skipping 11 matching lines @@
     /**
      * Whether the app state has been initialized. The app state will ignore all
      * writes until it has been initialized.
      * @type {boolean}
      * @private
      */
     this.isInitialized_ = false;
   };
 
   /**
+    * 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_DESTINATION_IDS: 'recentDestinationIds',
+    RECENT_DESTINATION_ACCOUNTS: 'recentDestinationAccounts',
+    RECENT_DESTINATION_ORIGINS: 'recentDestinationOrigins',
+    RECENT_DESTINATION_CAPABILITIES: 'recentDestinationCapabilities',
+    RECENT_DESTINATION_NAMES: 'recentDestinationNames',
+    RECENT_DESTINATION_EXTENSION_IDS: 'recentDestinationExtensionIds',
+    RECENT_DESTINATION_EXTENSION_NAMES: 'recentDestinationExtensionNames',
     IS_GCP_PROMO_DISMISSED: 'isGcpPromoDismissed',
     DPI: 'dpi',
     MEDIA_SIZE: 'mediaSize',
     MARGINS_TYPE: 'marginsType',
     CUSTOM_MARGINS: 'customMargins',
     IS_COLOR_ENABLED: 'isColorEnabled',
     IS_DUPLEX_ENABLED: 'isDuplexEnabled',
     IS_HEADER_FOOTER_ENABLED: 'isHeaderFooterEnabled',
     IS_LANDSCAPE_ENABLED: 'isLandscapeEnabled',
     IS_COLLATE_ENABLED: 'isCollateEnabled',
@@ skipping 13 matching lines @@
 
   /**
    * Name of C++ layer function to persist app state.
    * @type {string}
    * @const
    * @private
    */
   AppState.NATIVE_FUNCTION_NAME_ = 'saveAppState';
 
   AppState.prototype = {
+
+    /**
+      * Helper function to get the most recent value of one of the destination
+      * fields in the app state.
+      * @param {?print_preview.AppState.field} The state field to return the

[dpapad, 2016/09/19 22:16:19]

Type annotation is missing the parameter name, and has a small typo. Should be:

* @param {!print_preview.AppState.Field} fieldName The state field to return the

[rbpotter, 2016/09/20 23:47:37]

Done.

+      *     value of.
+      * @return {?string or ?print_preview.Cdd} The most recent value of the

[dpapad, 2016/09/19 22:16:19]

This is not a valid type annotation. I am not sure if print_preview code is
actually compiled by the JS compiler, or if these annotations server mostly as
documentation, but a valid annotation for returning a union of types looks as
follows

{?string|?print_preview.Cdd}

If this code, was actually compiled, the compiler would throw a "Bad type
annotation" error.

[rbpotter, 2016/09/20 23:47:37]

Done - I did not realize there was actually a compiler, thought that these
comments were just for documentation... sorry.

+      *     destination state field. ?print_preview.Cdd if the state field is
+      *     RECENT_DESTINATION_CAPABILIITIES, ?string otherwise.
+      */
+    getStateValue_: function(fieldName) {
+      return (this.state_[fieldName] && this.state_[fieldName].length > 0) ?
+          this.state_[fieldName][0] : null;
+    },
+
     /** @return {?string} ID of the selected destination. */
     get selectedDestinationId() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_ID];
+      return this.getStateValue_(AppState.Field.RECENT_DESTINATION_IDS);
     },
 
     /** @return {?string} Account the selected destination is registered for. */
     get selectedDestinationAccount() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_ACCOUNT];
+      return this.getStateValue_(AppState.Field.RECENT_DESTINATION_ACCOUNTS);
     },
 
     /**
      * @return {?print_preview.Destination.Origin<string>} Origin of the
      *     selected destination.
      */
     get selectedDestinationOrigin() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_ORIGIN];
+      return this.getStateValue_(AppState.Field.RECENT_DESTINATION_ORIGINS);
     },
 
     /** @return {?print_preview.Cdd} CDD of the selected destination. */
     get selectedDestinationCapabilities() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_CAPABILITIES];
+      return this.getStateValue_(
+          AppState.Field.RECENT_DESTINATION_CAPABILITIES);
     },
 
     /** @return {?string} Name of the selected destination. */
     get selectedDestinationName() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_NAME];
+      return this.getStateValue_(AppState.Field.RECENT_DESTINATION_NAMES);
     },
 
     /**
      * @return {?string} Extension ID associated with the selected destination.
      */
     get selectedDestinationExtensionId() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_EXTENSION_ID];
+      return this.getStateValue_(
+          AppState.Field.RECENT_DESTINATION_EXTENSION_IDS);
     },
 
     /**
      * @return {?string} Extension name associated with the selected
      *     destination.
      */
     get selectedDestinationExtensionName() {
-      return this.state_[AppState.Field.SELECTED_DESTINATION_EXTENSION_NAME];
+      return this.getStateValue_(
+          AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES);
+    },
+
+   /** @return {?Array<string>} IDs of the recent destinations. */
+    get recentDestinationIds() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_IDS];
+    },
+
+    /**
+     * @return {?Array<string>} Accounts the recent destinations are registered
+     *     for.
+     */
+    get recentDestinationAccounts() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_ACCOUNTS];
+    },
+
+    /** @return {?Array<string>} Origins of the recent destinations. */
+    get recentDestinationOrigins() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_ORIGINS];
+    },
+
+    /** @return {?Array<print_preview.Cdd>} CDDs of the recent destinations. */
+    get recentDestinationCapabilities() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_CAPABILITIES];
+    },
+
+    /** @return {?Array<string>} Names of the recent destinations. */
+    get recentDestinationNames() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_NAMES];
+    },
+
+    /**
+     * @return {?Array<string>} Extension IDs associated with the recent
+     * destinations.
+     */
+    get recentDestinationExtensionIds() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_IDS];
+    },
+
+    /**
+     * @return {?Array<string>} Extension names associated with the recent
+     *     destinations.
+     */
+    get recentDestinationExtensionNames() {
+      return this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES];
     },
 
     /** @return {boolean} Whether the GCP promotion has been dismissed. */
     get isGcpPromoDismissed() {
       return this.state_[AppState.Field.IS_GCP_PROMO_DISMISSED];
     },
 
     /**
      * @param {!print_preview.AppState.Field} field App state field to check if
      *     set.
@@ skipping 10 matching lines @@
     getField: function(field) {
       if (field == AppState.Field.CUSTOM_MARGINS) {
         return this.state_[field] ?
             print_preview.Margins.parse(this.state_[field]) : null;
       } else {
         return this.state_[field];
       }
     },
 
     /**
+     * Helper function to set up the recent destination fields in case they are
+     * empty or only contain one value.
+     * @param {print_preview.AppState.field} stateFieldName The state field to

[dpapad, 2016/09/19 22:16:19]

!print_preview.AppState.Field

[rbpotter, 2016/09/20 23:47:37]

Done.

+     *     be set up.
+     */
+    setUpState_: function(stateFieldName) {
+      if (!this.state_[stateFieldName]) {

[dpapad, 2016/09/19 22:16:19]

Is this check robust? Could this.state_[stateFieldName] have a valid value of 0
or '' (empty string) for example? If so this check would succeed, but
accidentally it seems. Or is this.state_[stateFieldName] expected to only have
Array instances as values?

[rbpotter, 2016/09/20 23:47:37]

Done - fields other than IDs could be a single element with a value of '' or
null. IDs should always be non empty strings or an array of nonempty strings.

+        this.state_[stateFieldName] = [];
+      } else if (!(this.state_[stateFieldName] instanceof Array)) {
+        var tmp = this.state_[stateFieldName];
+        this.state_[stateFieldName][0] = tmp;

[dpapad, 2016/09/19 22:16:19]

This assignment seems a odd but also wrong. Are you simply trying to convert the
single value to an array with a single element that has that value? If so could
you do the following instead:

var tmp = this.state_[stateFieldName];
this.state_[stateFieldName] = [tmp];

[rbpotter, 2016/09/20 23:47:37]

Done - yes, I was trying to convert the value to an array with an element that
has that value.

+      } else if (this.state_[stateFieldName].length >
+          AppState.NUM_DESTINATIONS_) {
+        this.state_[stateFieldName].splice(AppState.NUM_DESTINATIONS_,
+            this.state_[stateFieldName].length - AppState.NUM_DESTINATIONS_);
+      }
+    },
+
+    /**
      * Initializes the app state from a serialized string returned by the native
      * layer.
      * @param {?string} serializedAppStateStr Serialized string representation
      *     of the app state.
      */
     init: function(serializedAppStateStr) {
       if (serializedAppStateStr) {
         try {
           var state = JSON.parse(serializedAppStateStr);
           if (state[AppState.Field.VERSION] == AppState.VERSION_) {
             this.state_ = state;
           }
         } catch(e) {
           console.error('Unable to parse state: ' + e);
           // Proceed with default state.
         }
       } else {
         // Set some state defaults.
         this.state_[AppState.Field.IS_GCP_PROMO_DISMISSED] = false;
       }
+
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_IDS);
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_ACCOUNTS);
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_ORIGINS);
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_CAPABILITIES);
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_NAMES);
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_EXTENSION_IDS);
+      this.setUpState_(AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES);
+

[dpapad, 2016/09/19 22:16:19]

Nit: Remove blank line.

[rbpotter, 2016/09/20 23:47:37]

Done.

     },
 
     /**
      * Sets to initialized state. Now object will accept persist requests.
      */
     setInitialized: function() {
       this.isInitialized_ = true;
     },
 
     /**
      * Persists the given value for the given field.
      * @param {!print_preview.AppState.Field} field Field to persist.
      * @param {?} value Value of field to persist.
      */
     persistField: function(field, value) {
       if (!this.isInitialized_)
         return;
       if (field == AppState.Field.CUSTOM_MARGINS) {
         this.state_[field] = value ? value.serialize() : null;
       } else {
         this.state_[field] = value;
       }
       this.persist_();
     },
 
     /**
+     * Shifts the desired recent destination field's values as needed and places
+     * the most recent value, destVal, in position 0 in the array.
+     * @param {number} indexFound the index where the destination already exists
+     *     in the array, or -1 if it is not in the array.
+     * @param {!print_preview.AppState.Field} fieldName the field array to
+     *     adjust
+     * @param {string or print_preview.Cdd} the value that should be added as
+     *     the most recent value in the array.
+     */
+    shiftStateField_: function(indexFound, fieldName, destVal) {
+      if (indexFound == -1 &&
+          this.state_[fieldName].length == AppState.NUM_DESTINATIONS_)
+        indexFound = AppState.NUM_DESTINATIONS_ - 1;
+      if (indexFound != -1)
+        this.state_[fieldName].splice(indexFound, 1);
+      this.state_[fieldName].reverse();

[dpapad, 2016/09/19 22:16:19]

No need to reverse, push, reverse. You can insert a single element in the front
of an array with splice(), as follows

myArray.splice(0, 0, 'foo');

[rbpotter, 2016/09/20 23:47:37]

Done.

+      this.state_[fieldName].push(destVal);
+      this.state_[fieldName].reverse();
+    },
+
+    /**
      * Persists the selected destination.
      * @param {!print_preview.Destination} dest Destination to persist.
      */
     persistSelectedDestination: function(dest) {

[rbpotter, 2016/09/19 21:16:19]

Does this function (with the helper above) look better? If so I will remove the
commented code below.

-      if (!this.isInitialized_)
+      if (!this.isInitialized_ || !dest)
         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 idIndexFound = this.state_[
+          AppState.Field.RECENT_DESTINATION_IDS].indexOf(dest.id);
+      var originIndexFound = this.state_[
+          AppState.Field.RECENT_DESTINATION_ORIGINS].indexOf(dest.origin);
+
+      if (idIndexFound != originIndexFound ||
+          idIndexFound >= AppState.NUM_DESTINATIONS_)
+        idIndexFound = -1;
+
+      if (idIndexFound == 0) {
+        this.persist_();
+        return;
+      }
+
+      // Shift all the destination state fields so that the are always ordered
+      // from most recent (entry 0) to least recent.
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_IDS, dest.id);
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_ACCOUNTS, dest.account || '');
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_ORIGINS, dest.origin);
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_CAPABILITIES,
+          dest.capabilities);
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_NAMES, dest.name || '');
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_EXTENSION_IDS,
+          dest.extension_id || '');
+      this.shiftStateField_(idIndexFound,
+          AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES,
+          dest.extension_name || '');
+
+      /*
+
+      // Shift destinations so that they are always ordered from most recent
+      // (entry 0) to least recent (entry AppState.NUM_DESTINATIONS_ -1).
+      for (var i = AppState.NUM_DESTINATIONS - 1; i > 0; i--) {
+        var shiftDestination = true;
+        // If the selected destination is one of the destinations more recent
+        // than destination i there is no need to move destination i-1 to i, as
+        // only the more recent destinations need to be reordered and the ith
+        // entry remains the ith most recently used.
+        for (var j = i - 1; j >= 0; j--) {
+          if (!this.state_[AppState.Field.RECENT_DESTINATION_IDS] ||
+              dest.id == this.state_[AppState.Field.RECENT_DESTINATION_IDS][j])
+            shiftDestination = false;
+        }
+        // Shift destination i-1 to i.
+        if (shiftDestination) {
+          this.state_[AppState.Field.RECENT_DESTINATION_IDS][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_IDS][i - 1];
+          this.state_[AppState.Field.RECENT_DESTINATION_ACCOUNTS][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_ACCOUNTS][i - 1];
+          this.state_[AppState.Field.RECENT_DESTINATION_ORIGINS][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_ORIGINS][i - 1];
+          this.state_[AppState.Field.RECENT_DESTINATION_CAPABILITIES][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_CAPABILITIES][
+              i - 1];
+          this.state_[AppState.Field.RECENT_DESTINATION_NAMES][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_NAMES][i - 1];
+          this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_IDS][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_IDS][
+              i - 1];
+          this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES][i] =
+              this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES][
+              i - 1];
+        }
+      }
+      // Set the most recent destination (currently selected destination) to
+      // dest.
+      this.state_[AppState.Field.RECENT_DESTINATION_IDS][0] = dest.id;
+      this.state_[AppState.Field.RECENT_DESTINATION_ACCOUNTS][0] =
+          dest.account || '';
+      this.state_[AppState.Field.RECENT_DESTINATION_ORIGINS][0] =
+          dest.origin;
+      this.state_[AppState.Field.RECENT_DESTINATION_CAPABILITIES][0] =
+          dest.capabilities || '';
+      this.state_[AppState.Field.RECENT_DESTINATION_NAMES][0] =
+          dest.name || '';
+      this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_IDS][0] =
+          dest.extensionId || '';
+      this.state_[AppState.Field.RECENT_DESTINATION_EXTENSION_NAMES][0] =
+          dest.extensionName || '';*/
       this.persist_();
     },
 
     /**
      * Persists whether the GCP promotion has been dismissed.
      * @param {boolean} isGcpPromoDismissed Whether the GCP promotion has been
      *     dismissed.
      */
     persistIsGcpPromoDismissed: function(isGcpPromoDismissed) {
       if (!this.isInitialized_)
         return;
       this.state_[AppState.Field.IS_GCP_PROMO_DISMISSED] = isGcpPromoDismissed;
       this.persist_();
     },
 
     /**
      * Calls into the native layer to persist the application state.
      * @private
      */
     persist_: function() {
       chrome.send(AppState.NATIVE_FUNCTION_NAME_,
                   [JSON.stringify(this.state_)]);
     }
   };
 
   return {
     AppState: AppState
   };
 });