Fix losing widget state on restart

app/src/main/java/org/solovyev/android/calculator/DisplayState.java

@@ -26,7 +26,7 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.text.TextUtils;
 import android.view.ContextMenu;
-import jscl.math.Generic;
+
 import org.json.JSONException;
 import org.json.JSONObject;
 import org.solovyev.android.calculator.jscl.JsclOperation;
@@ -34,6 +34,8 @@ import org.solovyev.android.calculator.jscl.JsclOperation;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import jscl.math.Generic;
+
 public class DisplayState implements Parcelable, ContextMenu.ContextMenuInfo {
 
     public static final Creator<DisplayState> CREATOR = new Creator<DisplayState>() {
@@ -143,4 +145,8 @@ public class DisplayState implements Parcelable, ContextMenu.ContextMenuInfo {
         dest.writeString(text);
         dest.writeByte((byte) (valid ? 1 : 0));
     }
+
+    public boolean isEmpty() {
+        return valid && TextUtils.isEmpty(text);
+    }
 }

app/src/main/java/org/solovyev/android/calculator/WidgetReceiver.java

@@ -4,8 +4,11 @@ import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Vibrator;
+import android.support.annotation.NonNull;
 import android.text.TextUtils;
+
 import org.solovyev.android.calculator.buttons.CppButton;
+import org.solovyev.android.calculator.history.History;
 
 import javax.annotation.Nonnull;
 import javax.inject.Inject;
@@ -19,6 +22,8 @@ public final class WidgetReceiver extends BroadcastReceiver {
 
     @Inject
     Keyboard keyboard;
+    @Inject
+    History history;
 
     @Nonnull
     public static Intent newButtonClickedIntent(@Nonnull Context context, @Nonnull CppButton button) {
@@ -43,9 +48,21 @@ public final class WidgetReceiver extends BroadcastReceiver {
             return;
         }
 
+        if (history.isLoaded()) {
             if (!keyboard.buttonPressed(button.action)) {
+                // prevent vibrate
                 return;
             }
+        } else {
+            // if app has been killed we need first to restore the state and only after doing this
+            // to apply actions. Otherwise, we will apply actions on the empty editor
+            history.runWhenLoaded(new MyRunnable(keyboard, button.action));
+        }
+
+        vibrate(context);
+    }
+
+    private void vibrate(@NonNull Context context) {
         if (!keyboard.isVibrateOnKeypress()) {
             return;
         }
@@ -55,4 +72,21 @@ public final class WidgetReceiver extends BroadcastReceiver {
         }
         vibrator.vibrate(10);
     }
+
+    private static class MyRunnable implements Runnable {
+        @NonNull
+        private final Keyboard keyboard;
+        @NonNull
+        private final String action;
+
+        public MyRunnable(@NonNull Keyboard keyboard, @NonNull String action) {
+            this.keyboard = keyboard;
+            this.action = action;
+        }
+
+        @Override
+        public void run() {
+            keyboard.buttonPressed(action);
+        }
+    }
 }

app/src/main/java/org/solovyev/android/calculator/history/History.java

@@ -77,6 +77,9 @@ public class History {
     private final RecentHistory recent = new RecentHistory();
     @Nonnull
     private final List<HistoryState> saved = new ArrayList<>();
+    @Nonnull
+    private final List<Runnable> whenLoadedRunnables = new ArrayList<>();
+    private boolean loaded;
     @Inject
     Application application;
     @Inject
@@ -217,15 +220,32 @@ public class History {
         handler.post(new Runnable() {
             @Override
             public void run() {
-                Check.isTrue(recent.isEmpty());
+                onLoaded(recentStates, savedStates);
-                Check.isTrue(saved.isEmpty());
-                recent.addInitial(recentStates);
-                saved.addAll(savedStates);
-                editor.onHistoryLoaded(recent);
             }
         });
     }
 
+    private void onLoaded(@NonNull List<HistoryState> recentStates, @NonNull List<HistoryState> savedStates) {
+        Check.isTrue(saved.isEmpty());
+        Check.isMainThread();
+        final boolean wasEmpty = recent.isEmpty();
+        recent.addInitial(recentStates);
+        saved.addAll(savedStates);
+        if (wasEmpty) {
+            // user has typed nothing while we were loading, let's use recent history to restore
+            // editor state
+            editor.onHistoryLoaded(recent);
+        } else {
+            // user has types something => we should schedule save
+            postRecentWrite();
+        }
+        loaded = true;
+        for (Runnable runnable : whenLoadedRunnables) {
+            runnable.run();
+        }
+        whenLoadedRunnables.clear();
+    }
+
     @Nonnull
     private List<HistoryState> tryLoadStates(@NonNull File file) {
         try {
@@ -238,6 +258,10 @@ public class History {
 
     public void addRecent(@Nonnull HistoryState state) {
         Check.isMainThread();
+        if (recent.isEmpty() && state.isEmpty()) {
+            // don't add empty states to empty history
+            return;
+        }
         recent.add(state);
         onRecentChanged(new AddedEvent(state, true));
     }
@@ -255,15 +279,23 @@ public class History {
     }
 
     private void onRecentChanged(@Nonnull Object event) {
-        handler.removeCallbacks(writeRecent);
+        postRecentWrite();
-        handler.postDelayed(writeRecent, 5000);
         bus.post(event);
     }
 
+    private void postRecentWrite() {
+        handler.removeCallbacks(writeRecent);
+        handler.postDelayed(writeRecent, 5000);
+    }
+
     private void onSavedChanged(@Nonnull Object event) {
+        postSavedWrite();
+        bus.post(event);
+    }
+
+    private void postSavedWrite() {
         handler.removeCallbacks(writeSaved);
         handler.postDelayed(writeSaved, 500);
-        bus.post(event);
     }
 
     @Nonnull
@@ -359,6 +391,15 @@ public class History {
         addRecent(HistoryState.builder(editorState, displayState).build());
     }
 
+    public boolean isLoaded() {
+        return loaded;
+    }
+
+    public void runWhenLoaded(@NonNull Runnable runnable) {
+        Check.isTrue(!loaded);
+        whenLoadedRunnables.add(runnable);
+    }
+
     public static class ClearedEvent {
         public final boolean recent;
 
@@ -406,6 +447,9 @@ public class History {
         @Override
         public void run() {
             Check.isMainThread();
+            if (!loaded) {
+                return;
+            }
             // don't need to save intermediate states, thus {@link History#getRecent}
             final List<HistoryState> states = recent ? getRecent(false) : getSaved();
             backgroundThread.execute(new Runnable() {

app/src/main/java/org/solovyev/android/calculator/history/HistoryState.java

@@ -3,6 +3,7 @@ package org.solovyev.android.calculator.history;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.support.annotation.NonNull;
+import android.text.TextUtils;
 
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -15,8 +16,6 @@ import org.solovyev.android.calculator.json.Jsonable;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
-import static android.text.TextUtils.isEmpty;
-
 public class HistoryState implements Parcelable, Jsonable {
 
     public static final Creator<HistoryState> CREATOR = new Creator<HistoryState>() {
@@ -103,7 +102,7 @@ public class HistoryState implements Parcelable, Jsonable {
         json.put(JSON_EDITOR, editor.toJson());
         json.put(JSON_DISPLAY, display.toJson());
         json.put(JSON_TIME, time);
-        if (!isEmpty(comment)) {
+        if (!TextUtils.isEmpty(comment)) {
             json.put(JSON_COMMENT, comment);
         }
         return json;
@@ -173,6 +172,10 @@ public class HistoryState implements Parcelable, Jsonable {
         dest.writeString(comment);
     }
 
+    public boolean isEmpty() {
+        return display.isEmpty() && editor.isEmpty() && TextUtils.isEmpty(comment);
+    }
+
     public static final class Builder {
 
         @NonNull