Add global.log, global.logError functions

These log to a display in lookingGlass; rough equivalent of
the Firebug "console.log".

https://bugzilla.gnome.org/show_bug.cgi?id=599661

js/ui/lookingGlass.js

@@ -308,6 +308,42 @@ Inspector.prototype = {
 
 Signals.addSignalMethods(Inspector.prototype);
 
+function ErrorLog() {
+    this._init();
+}
+
+ErrorLog.prototype = {
+    _init: function() {
+        this.actor = new St.BoxLayout();
+        this.text = new St.Label();
+        this.actor.add(this.text);
+        this.text.clutter_text.line_wrap = true;
+        this.text.connect('notify::mapped', Lang.bind(this, this._onMappedNotify));
+    },
+
+    _formatTime: function(d){
+        function pad(n) { return n < 10 ? '0' + n : n };
+        return d.getUTCFullYear()+'-'
+            + pad(d.getUTCMonth()+1)+'-'
+            + pad(d.getUTCDate())+'T'
+            + pad(d.getUTCHours())+':'
+            + pad(d.getUTCMinutes())+':'
+            + pad(d.getUTCSeconds())+'Z'
+    },
+
+    _onMappedNotify: function() {
+        if (!(this.actor.mapped && Main._errorLogStack.length > 0))
+            return;
+        let text = this.text.text;
+        let stack = Main._getAndClearErrorStack();
+        for (let i = 0; i < stack.length; i++) {
+            let logItem = stack[i];
+            text += logItem.category + " t=" + this._formatTime(new Date(logItem.timestamp)) + " " + logItem.message + "\n";
+        }
+        this.text.text = text;
+    }
+}
+
 function LookingGlass() {
     this._init();
 }
@@ -406,6 +442,9 @@ LookingGlass.prototype = {
             notebook.selectIndex(0);
         }));
 
+        this._errorLog = new ErrorLog();
+        notebook.appendPage('Errors', this._errorLog.actor);
+
         this._entry.clutter_text.connect('activate', Lang.bind(this, function (o, e) {
             let text = o.get_text();
             // Ensure we don't get newlines in the command; the history file is

js/ui/main.js

@@ -38,6 +38,8 @@ let recorder = null;
 let shellDBusService = null;
 let modalCount = 0;
 let modalActorFocusStack = [];
+let _errorLogStack = [];
+let _startDate;
 
 function start() {
     // Add a binding for "global" in the global JS namespace; (gjs
@@ -45,6 +47,12 @@ function start() {
     // called "window".)
     window.global = Shell.Global.get();
 
+    // Now monkey patch utility functions into the global proxy;
+    // This is easier and faster than indirecting down into global
+    // if we want to call back up into JS.
+    global.logError = _logError;
+    global.log = _logDebug;
+
     Gio.DesktopAppInfo.set_desktop_env("GNOME");
 
     global.grab_dbus_service();
@@ -105,6 +113,8 @@ function start() {
     sidebar = new Sidebar.Sidebar();
     wm = new WindowManager.WindowManager();
 
+    _startDate = new Date();
+
     global.screen.connect('toggle-recording', function() {
         if (recorder == null) {
             recorder = new Shell.Recorder({ stage: global.stage });
@@ -127,9 +137,52 @@ function start() {
 
     global.stage.connect('captured-event', _globalKeyPressHandler);
 
+    _log('info', 'loaded at ' + _startDate);
+
     Mainloop.idle_add(_removeUnusedWorkspaces);
 }
 
+/**
+ * _log:
+ * @category: string message type ('info', 'error')
+ * @msg: A message string
+ * ...: Any further arguments are converted into JSON notation,
+ *      and appended to the log message, separated by spaces.
+ *
+ * Log a message into the LookingGlass error
+ * stream.  This is primarily intended for use by the
+ * extension system as well as debugging.
+ */
+function _log(category, msg) {
+    let text = msg;
+    if (arguments.length > 2) {
+        text += ': ';
+        for (let i = 2; i < arguments.length; i++) {
+            text += JSON.stringify(arguments[i]);
+            if (i < arguments.length - 1)
+                text += " ";
+        }
+    }
+    _errorLogStack.push({timestamp: new Date().getTime(),
+                         category: category,
+                         message: text });
+}
+
+function _logError(msg) {
+    return _log('error', msg);
+}
+
+function _logDebug(msg) {
+    return _log('debug', msg);
+}
+
+// Used by the error display in lookingGlass.js
+function _getAndClearErrorStack() {
+    let errors = _errorLogStack;
+    _errorLogStack = [];
+    return errors;
+}
+
 function _relayout() {
     let primary = global.get_primary_monitor();
     panel.actor.set_position(primary.x, primary.y);