Unhandled exception handler

AideDeJeu/AideDeJeu.Android/MainActivity.cs

@@ -6,6 +6,8 @@ using Android.Runtime;
 using Android.Views;
 using Android.Widget;
 using Android.OS;
+using System.Threading.Tasks;
+using System.Diagnostics;
 
 namespace AideDeJeu.Droid
 {
@@ -19,6 +21,10 @@ namespace AideDeJeu.Droid
             ToolbarResource = Resource.Layout.Toolbar;
 
             base.OnCreate(bundle);
+
+            AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;
+            TaskScheduler.UnobservedTaskException += TaskSchedulerOnUnobservedTaskException;
+
             Xamarin.Essentials.Platform.Init(this, bundle);
             Xamarin.Essentials.ExperimentalFeatures.Enable(Xamarin.Essentials.ExperimentalFeatures.ShareFileRequest);
 
@@ -30,6 +36,8 @@ namespace AideDeJeu.Droid
             //global::Xamarin.Forms.FormsMaterial.Init(this, bundle);
             SQLitePCL.raw.SetProvider(new SQLitePCL.SQLite3Provider_e_sqlite3());
 
+            DisplayCrashReport();
+
             LoadApplication(new App());
         }
 
@@ -52,6 +60,71 @@ namespace AideDeJeu.Droid
 
             base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
         }
+
+
+        private static void TaskSchedulerOnUnobservedTaskException(object sender, UnobservedTaskExceptionEventArgs unobservedTaskExceptionEventArgs)
+        {
+            var newExc = new Exception("TaskSchedulerOnUnobservedTaskException", unobservedTaskExceptionEventArgs.Exception);
+            LogUnhandledException(newExc);
+        }
+
+        private static void CurrentDomainOnUnhandledException(object sender, UnhandledExceptionEventArgs unhandledExceptionEventArgs)
+        {
+            var newExc = new Exception("CurrentDomainOnUnhandledException", unhandledExceptionEventArgs.ExceptionObject as Exception);
+            LogUnhandledException(newExc);
+        }
+
+        internal static void LogUnhandledException(Exception exception)
+        {
+            try
+            {
+                const string errorFileName = "Fatal.log";
+                var libraryPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal); // iOS: Environment.SpecialFolder.Resources
+                var errorFilePath = System.IO.Path.Combine(libraryPath, errorFileName);
+                var errorMessage = String.Format("Time: {0}\r\nError: Unhandled Exception\r\n{1}",
+                DateTime.Now, exception.ToString());
+                System.IO.File.WriteAllText(errorFilePath, errorMessage);
+
+                // Log to Android Device Logging.
+                Android.Util.Log.Error("Crash Report", errorMessage);
+            }
+            catch
+            {
+                // just suppress any error logging exceptions
+            }
+        }
+
+        /// <summary>
+        // If there is an unhandled exception, the exception information is diplayed 
+        // on screen the next time the app is started (only in debug configuration)
+        /// </summary>
+        [Conditional("DEBUG")]
+        private void DisplayCrashReport()
+        {
+            const string errorFilename = "Fatal.log";
+            var libraryPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
+            var errorFilePath = System.IO.Path.Combine(libraryPath, errorFilename);
+
+            if (!System.IO.File.Exists(errorFilePath))
+            {
+                return;
+            }
+
+            var errorText = System.IO.File.ReadAllText(errorFilePath);
+            new AlertDialog.Builder(this)
+                .SetPositiveButton("Clear", (sender, args) =>
+                {
+                    System.IO.File.Delete(errorFilePath);
+                })
+                .SetNegativeButton("Close", (sender, args) =>
+                {
+                    // User pressed Close.
+                })
+                .SetMessage(errorText)
+                .SetTitle("Crash Report")
+                .Show();
+        }
+
     }
 }