Capture trace output during start-up and display in HUD page

src/Cassette.Web/Cassette.Web.csproj

@@ -56,6 +56,7 @@
       <Link>SharedAssemblyInfo.cs</Link>
     </Compile>
     <Compile Include="CassetteApplication.cs" />
+    <Compile Include="StringBuilderTraceListener.cs" />
     <None Include="CassetteConfiguration.cs.pp" />
     <Compile Include="CassetteHttpModule.cs" />
     <Compile Include="AssetRequestHandler.cs" />

src/Cassette.Web/HudRequestHandler.cs

@@ -50,7 +50,8 @@ string CreateJson()
             {
                 Scripts = scripts.Select(ScriptData),
                 Stylesheets = stylesheets.Select(StylesheetData),
-                HtmlTemplates = htmlTemplates.Select(HtmlTemplateData)
+                HtmlTemplates = htmlTemplates.Select(HtmlTemplateData),
+                StartupTrace = StartUp.TraceOutput
             };
             var json = new JavaScriptSerializer().Serialize(data);
             return json;

src/Cassette.Web/Resources/hud.htm

@@ -63,6 +63,8 @@ <h1>Cassette</h1>
         </li>
     </ul>
 
+    <pre data-bind="text: StartupTrace"></pre>
+
     <script type="text/javascript" src="?knockout.js"></script>
     <script type="text/javascript">
         var data = $json$;

src/Cassette.Web/StartUp.cs

@@ -55,7 +55,15 @@ public static class StartUp
         static IsolatedStorageFile _storage;
         static CassetteApplicationContainer<CassetteApplication> _applicationContainer;
         static Stopwatch _startupTimer;
-        readonly static object CreationLock = new object();
+        static readonly object CreationLock = new object();
+        /// <summary>
+        /// Collects all of Cassette's trace output during start-up.
+        /// </summary>
+        static readonly TraceListener StartupTraceListener = new StringBuilderTraceListener
+        {
+            TraceOutputOptions = TraceOptions.DateTime,
+            Filter = new EventTypeFilter(SourceLevels.All)
+        };
 
         /// <summary>
         /// The function delegate used to create Cassette configuration objects for the application.
@@ -71,11 +79,12 @@ static StartUp()
             CreateConfigurations = CreateConfigurationsByScanningAssembliesForType;
         }
 
-
 // ReSharper disable UnusedMember.Global
         public static void PreApplicationStart()
 // ReSharper restore UnusedMember.Global
         {
+            Trace.Source.Listeners.Add(StartupTraceListener);
+
             _startupTimer = Stopwatch.StartNew();
             Trace.Source.TraceInformation("Registering CassetteHttpModule.");
             DynamicModuleUtility.RegisterModule(typeof(CassetteHttpModule));
@@ -102,6 +111,9 @@ public static void PostApplicationStart()
 
             Trace.Source.TraceInformation("Cassette startup completed. It took " + _startupTimer.ElapsedMilliseconds + "ms.");
             _startupTimer.Stop();
+
+            StartupTraceListener.Flush();
+            Trace.Source.Listeners.Remove(StartupTraceListener);
         }
 
 // ReSharper disable UnusedMember.Global
@@ -113,6 +125,11 @@ public static void ApplicationShutdown()
             _applicationContainer.Dispose();
         }
 
+        static internal string TraceOutput
+        {
+            get { return StartupTraceListener.ToString(); }
+        }
+
         static IEnumerable<ICassetteConfiguration> CreateConfigurationsByScanningAssembliesForType()
         {
             Trace.Source.TraceInformation("Creating CassetteConfigurations by scanning assemblies.");

src/Cassette.Web/StringBuilderTraceListener.cs

@@ -0,0 +1,50 @@
+using System.Diagnostics;
+using System.Text;
+
+namespace Cassette.Web
+{
+    class StringBuilderTraceListener : TraceListener
+    {
+        readonly StringBuilder builder = new StringBuilder();
+
+        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string message)
+        {
+            if (eventType == TraceEventType.Information)
+            {
+                WriteLine(eventCache.DateTime.TimeOfDay + " - " + message);
+            }
+            else
+            {
+                base.TraceEvent(eventCache, source, eventType, id, message);
+            }
+        }
+
+        public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string format, params object[] args)
+        {
+            var message = args == null ? format : string.Format(format, args);
+            if (eventType == TraceEventType.Information)
+            {
+                WriteLine(eventCache.DateTime.TimeOfDay + " - " + message);
+            }
+            else
+            {
+                base.TraceEvent(eventCache, source, eventType, id, message);
+            }
+        }
+
+        public override void Write(string message)
+        {
+            builder.Append(message);
+        }
+
+        public override void WriteLine(string message)
+        {
+            builder.AppendLine(message);
+        }
+
+        public override string ToString()
+        {
+            return builder.ToString();
+        }
+    }
+}