Save history states

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

@@ -70,6 +70,7 @@ import java.util.Arrays;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -136,6 +137,15 @@ public final class App {
             return new Thread(r, "Init");
         }
     });
+    @Nonnull
+    private static final Executor background = Executors.newFixedThreadPool(5, new ThreadFactory() {
+        @NonNull
+        private final AtomicInteger counter = new AtomicInteger();
+        @Override
+        public Thread newThread(@Nonnull Runnable r) {
+            return new Thread(r, "Background #" + counter.getAndIncrement());
+        }
+    });
 
     private App() {
         throw new AssertionError();
@@ -271,6 +281,11 @@ public final class App {
         return initThread;
     }
 
+    @Nonnull
+    public static Executor getBackground() {
+        return background;
+    }
+
     @Nonnull
     public static Preferences.Gui.Theme getThemeFor(@Nonnull Context context) {
         if (context instanceof CalculatorOnscreenService) {

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

@@ -105,4 +105,13 @@ public class DisplayState {
         json.put(JSON_TEXT, text);
         return json;
     }
+
+    @Override
+    public String toString() {
+        return "DisplayState{" +
+                "valid=" + valid +
+                ", sequence=" + sequence +
+                ", operation=" + operation +
+                '}';
+    }
 }

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

@@ -23,9 +23,11 @@
 package org.solovyev.android.calculator;
 
 import android.text.TextUtils;
+
 import org.json.JSONException;
 import org.json.JSONObject;
-import org.solovyev.android.Check;
+
+import java.util.concurrent.atomic.AtomicLong;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
@@ -35,7 +37,7 @@ public class EditorState {
     public static final long NO_SEQUENCE = -1;
     private static final String JSON_TEXT = "t";
     private static final String JSON_SELECTION = "s";
-    private static long counter = NO_SEQUENCE + 1;
+    private static AtomicLong counter = new AtomicLong(NO_SEQUENCE + 1);
 
     public final long sequence;
     @Nonnull
@@ -49,8 +51,7 @@ public class EditorState {
     }
 
     private EditorState(@Nonnull CharSequence text, int selection) {
-        Check.isMainThread();
+        this.sequence = counter.getAndIncrement();
-        this.sequence = counter++;
         this.text = text;
         this.selection = selection;
     }
@@ -91,11 +92,20 @@ public class EditorState {
         return TextUtils.equals(text, that.text) && selection == that.selection;
     }
 
+    @Override
+    public String toString() {
+        return "EditorState{" +
+                "sequence=" + sequence +
+                ", text=" + text +
+                ", selection=" + selection +
+                '}';
+    }
+
     @Nonnull
-    public String toJson() throws JSONException {
+    public JSONObject toJson() throws JSONException {
         final JSONObject json = new JSONObject();
         json.put(JSON_TEXT, getTextString());
         json.put(JSON_SELECTION, selection);
-        return json.toString();
+        return json;
     }
 }

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

@@ -23,6 +23,7 @@
 package org.solovyev.android.calculator.history;
 
 import android.content.SharedPreferences;
+import android.os.Handler;
 import android.support.annotation.NonNull;
 import android.text.TextUtils;
 
@@ -54,10 +55,16 @@ import javax.annotation.Nullable;
 public class History {
 
     public static final String TAG = App.subTag("History");
+    @NonNull
+    private final Runnable writeCurrent = new WriteTask(true);
+    @NonNull
+    private final Runnable writeSaved = new WriteTask(false);
     @Nonnull
     private final HistoryList current = new HistoryList();
     @Nonnull
     private final List<HistoryState> saved = new ArrayList<>();
+    @Nonnull
+    private final Handler handler = App.getHandler();
     @Nullable
     private EditorState lastEditorState;
     private boolean initialized;
@@ -131,9 +138,11 @@ public class History {
         migrateOldHistory();
         final List<HistoryState> currentStates = loadStates(getCurrentHistoryFile());
         final List<HistoryState> savedStates = loadStates(getSavedHistoryFile());
-        App.getHandler().post(new Runnable() {
+        handler.post(new Runnable() {
             @Override
             public void run() {
+                Check.isTrue(current.isEmpty());
+                Check.isTrue(saved.isEmpty());
                 current.addAll(currentStates);
                 saved.addAll(savedStates);
                 initialized = true;
@@ -155,11 +164,13 @@ public class History {
     }
 
     private void onCurrentChanged() {
-        // todo serso: implement
+        handler.removeCallbacks(writeCurrent);
+        handler.postDelayed(writeCurrent, 500);
     }
 
     private void onSavedChanged() {
-        // todo serso: implement
+        handler.removeCallbacks(writeSaved);
+        handler.postDelayed(writeSaved, 500);
     }
 
     @Nonnull
@@ -184,10 +195,10 @@ public class History {
     @Nonnull
     public List<HistoryState> getSaved() {
         Check.isMainThread();
-        return Collections.unmodifiableList(saved);
+        return new ArrayList<>(saved);
     }
 
-    private boolean isIntermediate(@Nonnull String newerText,
+    private static boolean isIntermediate(@Nonnull String newerText,
                                    @Nonnull String olderText) {
         final int diff = newerText.length() - olderText.length();
         if (diff == 1) {
@@ -268,4 +279,27 @@ public class History {
         addCurrent(HistoryState.newBuilder(lastEditorState, e.newState).build());
         lastEditorState = null;
     }
+
+    private class WriteTask implements Runnable {
+        private final boolean current;
+
+        public WriteTask(boolean current) {
+            this.current = current;
+        }
+
+        @Override
+        public void run() {
+            Check.isMainThread();
+            // don't need to save intermediate states, thus {@link History#getCurrent}
+            final List<HistoryState> states = current ? getCurrent() : getSaved();
+            App.getBackground().execute(new Runnable() {
+                @Override
+                public void run() {
+                    final File file = current ? getCurrentHistoryFile() : getSavedHistoryFile();
+                    final JSONArray array = HistoryList.toJson(states);
+                    FileSaver.save(file, array.toString());
+                }
+            });
+        }
+    }
 }

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

@@ -81,6 +81,16 @@ public class HistoryState {
         return this.editor.same(that.editor) && this.display.same(that.display);
     }
 
+    @Override
+    public String toString() {
+        return "HistoryState{" +
+                "editor=" + editor +
+                ", display=" + display +
+                ", time=" + time +
+                ", comment='" + comment + '\'' +
+                '}';
+    }
+
     public static final class Builder extends HistoryState {
 
         private boolean built;

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

@@ -26,7 +26,6 @@ import org.solovyev.android.calculator.CalculatorFragmentType;
 import org.solovyev.android.calculator.Locator;
 import org.solovyev.android.calculator.R;
 
-import java.util.ArrayList;
 import java.util.List;
 
 import javax.annotation.Nonnull;
@@ -45,7 +44,7 @@ public class SavedHistoryFragment extends BaseHistoryFragment {
     @Nonnull
     @Override
     protected List<HistoryState> getHistoryItems() {
-        return new ArrayList<>(Locator.getInstance().getHistory().getSaved());
+        return Locator.getInstance().getHistory().getSaved();
     }
 
     @Override