Restore editor state from recent history

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

@@ -27,7 +27,10 @@ import android.text.TextUtils;
 
 import com.squareup.otto.Bus;
 import com.squareup.otto.Subscribe;
+
 import org.solovyev.android.Check;
+import org.solovyev.android.calculator.history.HistoryState;
+import org.solovyev.android.calculator.history.RecentHistory;
 import org.solovyev.android.calculator.text.TextProcessorEditorResult;
 import org.solovyev.android.calculator.view.EditorTextProcessor;
 
@@ -234,6 +237,17 @@ public class Editor {
         onTextChanged(getState(), true);
     }
 
+    public void onHistoryLoaded(@Nonnull RecentHistory history) {
+        if (!state.isEmpty()) {
+            return;
+        }
+        final HistoryState state = history.getCurrent();
+        if (state == null) {
+            return;
+        }
+        setState(state.editor);
+    }
+
     public static class ChangedEvent {
         @Nonnull
         public final EditorState oldState;

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

@@ -106,6 +106,10 @@ public class EditorState implements Parcelable {
         return TextUtils.equals(text, that.text) && selection == that.selection;
     }
 
+    public boolean isEmpty() {
+        return TextUtils.isEmpty(text);
+    }
+
     @Override
     public String toString() {
         return "EditorState{" +

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

@@ -22,8 +22,6 @@
 
 package org.solovyev.android.calculator.history;
 
-import static android.text.TextUtils.isEmpty;
-
 import android.app.Application;
 import android.content.SharedPreferences;
 import android.os.Handler;
@@ -62,6 +60,8 @@ import javax.inject.Inject;
 import javax.inject.Named;
 import javax.inject.Singleton;
 
+import static android.text.TextUtils.isEmpty;
+
 @Singleton
 public class History {
 
@@ -219,8 +219,9 @@ public class History {
             public void run() {
                 Check.isTrue(recent.isEmpty());
                 Check.isTrue(saved.isEmpty());
-                recent.addAll(recentStates);
+                recent.addInitial(recentStates);
                 saved.addAll(savedStates);
+                editor.onHistoryLoaded(recent);
             }
         });
     }
@@ -267,6 +268,11 @@ public class History {
 
     @Nonnull
     public List<HistoryState> getRecent() {
+        return getRecent(true);
+    }
+
+    @Nonnull
+    private List<HistoryState> getRecent(boolean forUi) {
         Check.isMainThread();
 
         final List<HistoryState> result = new LinkedList<>();
@@ -291,7 +297,7 @@ public class History {
         if (statesCount > 0) {
             // try add last state if not empty
             final HistoryState state = states.get(statesCount - 1);
-            if (!isEmpty(state.editor.getTextString())) {
+            if (!state.editor.isEmpty() || !forUi) {
                 result.add(0, state);
             }
         }
@@ -401,7 +407,7 @@ public class History {
         public void run() {
             Check.isMainThread();
             // don't need to save intermediate states, thus {@link History#getRecent}
-            final List<HistoryState> states = recent ? getRecent() : getSaved();
+            final List<HistoryState> states = recent ? getRecent(false) : getSaved();
             backgroundThread.execute(new Runnable() {
                 @Override
                 public void run() {

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

@@ -2,13 +2,9 @@ package org.solovyev.android.calculator.history;
 
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
-import android.util.Log;
+
-import org.json.JSONArray;
-import org.json.JSONException;
-import org.json.JSONObject;
 import org.solovyev.android.Check;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
@@ -31,16 +27,23 @@ public class RecentHistory {
         }
         list.add(state);
         current++;
-        if (list.size() > MAX_HISTORY) {
+        trim();
+    }
+
+    private void trim() {
+        while (list.size() > MAX_HISTORY) {
             current--;
             list.remove(0);
         }
     }
 
-    public void addAll(@NonNull List<HistoryState> states) {
+    public void addInitial(@NonNull List<HistoryState> states) {
+        Check.isMainThread();
         for (HistoryState state : states) {
-            add(state);
+            list.add(0, state);
         }
+        current += states.size();
+        trim();
     }
 
     public void remove(@NonNull HistoryState state) {