Added support for resetting settings via revision number (#52)

This is the first step in adding migrations. This commit adds the
support for resetting the user settings when you change the
"__revision__" value of a settings namespace.

src/config.js

@@ -131,7 +131,9 @@ export const defaultConfiguration = {
     defaults: {
       'osjs/default-application': {},
       'osjs/session': [],
-      'osjs/desktop': {},
+      'osjs/desktop': {
+        __revision__: 0
+      },
       'osjs/locale': {}
     }
   },

src/core.js

@@ -144,7 +144,7 @@ export default class Core extends CoreBase {
             this.user = user;
 
             if (this.has('osjs/settings')) {
-              this.make('osjs/settings').load()
+              this.make('osjs/settings').load(true)
                 .then(() => done())
                 .catch(() => done());
             } else {

src/providers/settings.js

@@ -58,7 +58,7 @@ export default class SettingsServiceProvider extends ServiceProvider {
   init() {
     this.core.singleton('osjs/settings', () => ({
       save: () => this.settings.save(),
-      load: () => this.settings.load(),
+      load: migrate => this.settings.load(migrate),
       clear: (...args) => this.settings.clear(...args),
       get: (...args) => this.settings.get(...args),
       set: (...args) => this.settings.set(...args)

src/settings.js

@@ -106,9 +106,10 @@ export default class Settings {
 
   /**
    * Loads settings
+   * @param {boolean} [migrate] Run migrations
    * @return {Promise<boolean,  Error>}
    */
-  load() {
+  load(migrate) {
     const defaults = this.core.config('settings.defaults', {});
 
     return this.adapter.load()
@@ -117,6 +118,9 @@ export default class Settings {
           arrayMerge: (dest, source) => source
         });
 
+        return migrate ? this.migrate() : Promise.resolve();
+      })
+      .then(() => {
         this.core.emit('osjs/settings:load');
 
         return true;
@@ -128,6 +132,38 @@ export default class Settings {
       });
   }
 
+  /**
+   * Runs migrations for settings
+   */
+  migrate() {
+    const defaults = this.core.config('settings.defaults', {});
+
+    const revisionsChanged = Object.keys(defaults)
+      .filter(key => {
+        const currentRevision = defaults[key].__revision__;
+        const userRevision = this.settings[key]
+          ? this.settings[key].__revision__
+          : undefined;
+
+        if (typeof currentRevision === 'undefined') {
+          return false;
+        }
+
+        return userRevision < currentRevision;
+      });
+
+    if (revisionsChanged.length > 0) {
+      revisionsChanged.forEach(key => {
+        this.settings[key] = merge(defaults[key], {});
+      });
+
+      return this.save()
+        .catch(err => console.warn('Settings#migrate', 'failed to save after migration', err));
+    }
+
+    return Promise.resolve();
+  }
+
   /**
    * Gets a settings entry by key
    *