[gnome-shell] extensionSystem: Add canChange property to extensions

[Florian Müllner <fmuellner src gnome org>]

commit 4a3476266fbf4c132ea66455193b39e4188c69bc
Author: Didier Roche <didrocks ubuntu com>
Date:   Tue Dec 4 09:31:27 2018 +0100

    extensionSystem: Add canChange property to extensions
    
    Whether or not an extension can be enabled/disabled depends on various
    factors: Whether the extension is in error state, whether user extensions
    are disabled and whether the underlying GSettings keys are writable.
    
    This is complex enough to share the logic, so add it to the extension
    properties that are exposed over D-Bus.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=789852

 js/misc/extensionUtils.js |  3 ++-
 js/ui/extensionSystem.js  | 44 ++++++++++++++++++++++++++++++++++++++------
 2 files changed, 40 insertions(+), 7 deletions(-)
---
diff --git a/js/misc/extensionUtils.js b/js/misc/extensionUtils.js
index ea094ba73..96431b1f2 100644
--- a/js/misc/extensionUtils.js
+++ b/js/misc/extensionUtils.js
@@ -30,7 +30,7 @@ var ExtensionState = {
     UNINSTALLED: 99
 };
 
-const SERIALIZED_PROPERTIES = ['type', 'state', 'path', 'error', 'hasPrefs'];
+const SERIALIZED_PROPERTIES = ['type', 'state', 'path', 'error', 'hasPrefs', 'canChange'];
 
 // Maps uuid -> metadata object
 var extensions = {};
@@ -219,6 +219,7 @@ function createExtensionObject(uuid, dir, type) {
     extension.path = dir.get_path();
     extension.error = '';
     extension.hasPrefs = dir.get_child('prefs.js').query_exists(null);
+    extension.canChange = false;
 
     extensions[uuid] = extension;
 
diff --git a/js/ui/extensionSystem.js b/js/ui/extensionSystem.js
index 84a79170b..6d842dc16 100644
--- a/js/ui/extensionSystem.js
+++ b/js/ui/extensionSystem.js
@@ -189,6 +189,7 @@ var ExtensionManager = class {
             }
         }
 
+        this._updateCanChange(extension);
         this.emit('extension-state-changed', extension);
     }
 
@@ -267,12 +268,28 @@ var ExtensionManager = class {
         return true;
     }
 
-    _getEnabledExtensions() {
-        let extensions;
+    _getModeExtensions() {
         if (Array.isArray(Main.sessionMode.enabledExtensions))
-            extensions = Main.sessionMode.enabledExtensions;
-        else
-            extensions = [];
+            return Main.sessionMode.enabledExtensions;
+        return [];
+    }
+
+    _updateCanChange(extension) {
+        let hasError =
+            extension.state == ExtensionState.ERROR ||
+            extension.state == ExtensionState.OUT_OF_DATE;
+
+        let isMode = this._getModeExtensions().includes(extension.uuid);
+        let modeOnly = global.settings.get_boolean(DISABLE_USER_EXTENSIONS_KEY);
+
+        extension.canChange =
+            !hasError &&
+            global.settings.is_writable(ENABLED_EXTENSIONS_KEY) &&
+            (isMode || !modeOnly);
+    }
+
+    _getEnabledExtensions() {
+        let extensions = this._getModeExtensions();
 
         if (global.settings.get_boolean(DISABLE_USER_EXTENSIONS_KEY))
             return extensions;
@@ -280,6 +297,11 @@ var ExtensionManager = class {
         return extensions.concat(global.settings.get_strv(ENABLED_EXTENSIONS_KEY));
     }
 
+    _onUserExtensionsEnabledChanged() {
+        this._onEnabledExtensionsChanged();
+        this._onSettingsWritableChanged();
+    }
+
     _onEnabledExtensionsChanged() {
         let newEnabledExtensions = this._getEnabledExtensions();
 
@@ -305,6 +327,14 @@ var ExtensionManager = class {
         this._enabledExtensions = newEnabledExtensions;
     }
 
+    _onSettingsWritableChanged() {
+        for (let uuid in ExtensionUtils.extensions) {
+            let extension = ExtensionUtils.extensions[uuid];
+            this._updateCanChange(extension);
+            this.emit('extension-state-changed', extension);
+        }
+    }
+
     _onVersionValidationChanged() {
         // we want to reload all extensions, but only enable
         // extensions when allowed by the sessionMode, so
@@ -325,9 +355,11 @@ var ExtensionManager = class {
         global.settings.connect(`changed::${ENABLED_EXTENSIONS_KEY}`,
             this._onEnabledExtensionsChanged.bind(this));
         global.settings.connect(`changed::${DISABLE_USER_EXTENSIONS_KEY}`,
-            this._onEnabledExtensionsChanged.bind(this));
+            this._onUserExtensionsEnabledChanged.bind(this));
         global.settings.connect(`changed::${EXTENSION_DISABLE_VERSION_CHECK_KEY}`,
             this._onVersionValidationChanged.bind(this));
+        global.settings.connect(`writable-changed::${ENABLED_EXTENSIONS_KEY}`,
+            this._onSettingsWritableChanged.bind(this));
 
         this._enabledExtensions = this._getEnabledExtensions();