[gnome-shell] Add app introspection API

[Florian Müllner <fmuellner src gnome org>]

commit 8be0c5a58a923e57be88f073341cf72cffd9c3d1
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Sep 5 11:15:30 2018 +0200

    Add app introspection API
    
    Add a D-Bus API that allows the API user to introspect the application
    state of the shell. Currently the only exposed information is list of
    running applications and which one is active (i.e. has focus).
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/326

 data/dbus-interfaces/meson.build                   |   1 +
 .../dbus-interfaces/org.gnome.Shell.Introspect.xml |  37 +++++++
 data/gnome-shell-dbus-interfaces.gresource.xml     |   1 +
 data/org.gnome.shell.gschema.xml.in                |   8 ++
 js/js-resources.gresource.xml                      |   1 +
 js/misc/introspect.js                              | 111 +++++++++++++++++++++
 js/ui/main.js                                      |   4 +
 7 files changed, 163 insertions(+)
---
diff --git a/data/dbus-interfaces/meson.build b/data/dbus-interfaces/meson.build
index 4ba832661..c96bbbb4d 100644
--- a/data/dbus-interfaces/meson.build
+++ b/data/dbus-interfaces/meson.build
@@ -1,5 +1,6 @@
 dbus_interfaces = [
   'org.gnome.Shell.Extensions.xml',
+  'org.gnome.Shell.Introspect.xml',
   'org.gnome.Shell.PadOsd.xml',
   'org.gnome.Shell.Screencast.xml',
   'org.gnome.Shell.Screenshot.xml',
diff --git a/data/dbus-interfaces/org.gnome.Shell.Introspect.xml 
b/data/dbus-interfaces/org.gnome.Shell.Introspect.xml
new file mode 100644
index 000000000..10c48d635
--- /dev/null
+++ b/data/dbus-interfaces/org.gnome.Shell.Introspect.xml
@@ -0,0 +1,37 @@
+<!DOCTYPE node PUBLIC
+'-//freedesktop//DTD D-BUS Object Introspection 1.0//EN'
+'http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd'>
+<node>
+
+  <!--
+      org.gnome.Shell.Introspect:
+      @short_description: Introspection interface
+
+      The interface used to introspect the state of Shell, such as running
+      applications, currently active application, etc.
+  -->
+  <interface name="org.gnome.Shell.Introspect">
+
+    <!--
+        RunningApplicationsChanged:
+        @short_description: Notifies when the running applications changes
+    -->
+    <signal name="RunningApplicationsChanged" />
+
+    <!--
+        GetRunningApplications:
+        @short_description: Retrieves the description of all running applications
+
+        Each application is associated by an application ID. The details of
+        each application consists of a varlist of keys and values. Available
+        keys are listed below.
+
+        'active-on-seats' - (as)   list of seats the application is active on
+                                   (a seat only has at most one active
+                                   application)
+    -->
+    <method name="GetRunningApplications">
+      <arg name="apps" direction="out" type="a{sa{sv}}" />
+    </method>
+  </interface>
+</node>
diff --git a/data/gnome-shell-dbus-interfaces.gresource.xml b/data/gnome-shell-dbus-interfaces.gresource.xml
index 5183672c9..ba148ca1f 100644
--- a/data/gnome-shell-dbus-interfaces.gresource.xml
+++ b/data/gnome-shell-dbus-interfaces.gresource.xml
@@ -40,6 +40,7 @@
     <file preprocess="xml-stripblanks">org.gnome.SettingsDaemon.Wacom.xml</file>
     <file preprocess="xml-stripblanks">org.gnome.Shell.AudioDeviceSelection.xml</file>
     <file preprocess="xml-stripblanks">org.gnome.Shell.Extensions.xml</file>
+    <file preprocess="xml-stripblanks">org.gnome.Shell.Introspect.xml</file>
     <file preprocess="xml-stripblanks">org.gnome.Shell.HotplugSniffer.xml</file>
     <file preprocess="xml-stripblanks">org.gnome.Shell.PerfHelper.xml</file>
     <file preprocess="xml-stripblanks">org.gnome.Shell.PortalHelper.xml</file>
diff --git a/data/org.gnome.shell.gschema.xml.in b/data/org.gnome.shell.gschema.xml.in
index a7251cd06..87898a36e 100644
--- a/data/org.gnome.shell.gschema.xml.in
+++ b/data/org.gnome.shell.gschema.xml.in
@@ -90,6 +90,14 @@
         adapter is ever seen not to have devices associated to it.
       </description>
     </key>
+    <key name="introspect" type="b">
+      <default>false</default>
+      <summary>Enable introspection API</summary>
+      <description>
+        Enables a D-Bus API that allows to introspect the application state of
+        the shell.
+      </description>
+    </key>
     <child name="keybindings" schema="org.gnome.shell.keybindings"/>
     <child name="keyboard" schema="org.gnome.shell.keyboard"/>
   </schema>
diff --git a/js/js-resources.gresource.xml b/js/js-resources.gresource.xml
index 75a6c3b12..a3dd2be08 100644
--- a/js/js-resources.gresource.xml
+++ b/js/js-resources.gresource.xml
@@ -16,6 +16,7 @@
     <file>misc/history.js</file>
     <file>misc/ibusManager.js</file>
     <file>misc/inputMethod.js</file>
+    <file>misc/introspect.js</file>
     <file>misc/jsParse.js</file>
     <file>misc/keyboardManager.js</file>
     <file>misc/loginManager.js</file>
diff --git a/js/misc/introspect.js b/js/misc/introspect.js
new file mode 100644
index 000000000..fa0a66e00
--- /dev/null
+++ b/js/misc/introspect.js
@@ -0,0 +1,111 @@
+const Gio = imports.gi.Gio;
+const GLib = imports.gi.GLib;
+const Lang = imports.lang;
+const Meta = imports.gi.Meta;
+const Shell = imports.gi.Shell;
+
+const INTROSPECT_SCHEMA = 'org.gnome.shell';
+const INTROSPECT_KEY = 'introspect';
+const APP_WHITELIST = ['org.freedesktop.impl.portal.desktop.gtk'];
+
+const { loadInterfaceXML } = imports.misc.fileUtils;
+
+const IntrospectDBusIface = loadInterfaceXML('org.gnome.Shell.Introspect');
+
+var IntrospectService = new Lang.Class({
+    Name: 'IntrospectService',
+
+    _init() {
+        this._dbusImpl = Gio.DBusExportedObject.wrapJSObject(IntrospectDBusIface,
+                                                             this);
+        this._dbusImpl.export(Gio.DBus.session, '/org/gnome/Shell/Introspect');
+        Gio.DBus.session.own_name('org.gnome.Shell.Introspect',
+                                  Gio.BusNameOwnerFlags.REPLACE,
+                                  null, null);
+
+        this._runningApplications = {};
+        this._runningApplicationsDirty = true;
+        this._activeApplication = null;
+        this._activeApplicationDirty = true;
+
+        this._appSystem = Shell.AppSystem.get_default();
+        this._appSystem.connect('app-state-changed',
+                                () => {
+                                    this._runningApplicationsDirty = true;
+                                    this._syncRunningApplications();
+                                });
+
+        this._settings = new Gio.Settings({ schema_id: INTROSPECT_SCHEMA });
+
+        let tracker = Shell.WindowTracker.get_default();
+        tracker.connect('notify::focus-app',
+                        () => {
+                            this._activeApplicationDirty = true;
+                            this._syncRunningApplications();
+                        });
+
+        this._syncRunningApplications();
+    },
+
+    _isStandaloneApp(app) {
+        let windows = app.get_windows();
+
+        return app.get_windows().some(w => w.transient_for == null);
+    },
+
+    _isIntrospectEnabled() {
+       return this._settings.get_boolean(INTROSPECT_KEY);
+    },
+
+    _isSenderWhitelisted(sender) {
+       return APP_WHITELIST.includes(sender);
+    },
+
+    _syncRunningApplications() {
+        let tracker = Shell.WindowTracker.get_default();
+        let apps = this._appSystem.get_running();
+        let seatName = "seat0";
+        let newRunningApplications = {};
+
+        let newActiveApplication = null;
+        let focusedApp = tracker.focus_app;
+
+        for (let app of apps) {
+            let appInfo = {};
+            let isAppActive = (focusedApp == app);
+
+            if (!this._isStandaloneApp(app))
+                continue;
+
+            if (isAppActive) {
+                appInfo['active-on-seats'] = new GLib.Variant('as', [seatName]);
+                newActiveApplication = app.get_id();
+            }
+
+            newRunningApplications[app.get_id()] = appInfo;
+        }
+
+        if (this._runningApplicationsDirty ||
+            (this._activeApplicationDirty &&
+             this._activeApplication != newActiveApplication)) {
+            this._runningApplications = newRunningApplications;
+            this._activeApplication = newActiveApplication;
+
+            this._dbusImpl.emit_signal('RunningApplicationsChanged', null);
+        }
+        this._runningApplicationsDirty = false;
+        this._activeApplicationDirty = false;
+    },
+
+    GetRunningApplicationsAsync(params, invocation) {
+        if (!this._isIntrospectEnabled() &&
+            !this._isSenderWhitelisted(invocation.get_sender())) {
+            invocation.return_error_literal(Gio.DBusError,
+                                            Gio.DBusError.ACCESS_DENIED,
+                                            'App introspection not allowed');
+            return;
+        }
+
+        invocation.return_value(new GLib.Variant('(a{sa{sv}})', [this._runningApplications]));
+    }
+});
diff --git a/js/ui/main.js b/js/ui/main.js
index 9e7ce8706..f87b1ad02 100644
--- a/js/ui/main.js
+++ b/js/ui/main.js
@@ -20,6 +20,7 @@ const Environment = imports.ui.environment;
 const ExtensionSystem = imports.ui.extensionSystem;
 const ExtensionDownloader = imports.ui.extensionDownloader;
 const InputMethod = imports.misc.inputMethod;
+const Introspect = imports.misc.introspect;
 const Keyboard = imports.ui.keyboard;
 const MessageTray = imports.ui.messageTray;
 const ModalDialog = imports.ui.modalDialog;
@@ -82,6 +83,7 @@ var keyboard = null;
 var layoutManager = null;
 var kbdA11yDialog = null;
 var inputMethod = null;
+var introspectService = null;
 let _startDate;
 let _defaultCssStylesheet = null;
 let _cssStylesheet = null;
@@ -187,6 +189,8 @@ function _initializeUI() {
     windowAttentionHandler = new WindowAttentionHandler.WindowAttentionHandler();
     componentManager = new Components.ComponentManager();
 
+    introspectService = new Introspect.IntrospectService();
+
     layoutManager.init();
     overview.init();