/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.app;

import static android.app.ActivityManager.START_CANCELED;

import android.content.Context;
import android.content.ContextWrapper;
import android.content.IIntentSender;
import android.content.Intent;
import android.content.IntentSender;
import android.graphics.SurfaceTexture;
import android.os.IBinder;
import android.os.Message;
import android.os.OperationCanceledException;
import android.os.RemoteException;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.InputDevice;
import android.view.InputEvent;
import android.view.MotionEvent;
import android.view.Surface;
import android.view.TextureView;
import android.view.TextureView.SurfaceTextureListener;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import dalvik.system.CloseGuard;

import java.lang.ref.WeakReference;
import java.util.ArrayDeque;
import java.util.concurrent.Executor;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import com.android.internal.annotations.GuardedBy;


/** @hide */
public class ActivityView extends ViewGroup {
    private static final String TAG = "ActivityView";
    private static final boolean DEBUG = false;

    private static final int MSG_SET_SURFACE = 1;

    private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
    private static final int MINIMUM_POOL_SIZE = 1;
    private static final int MAXIMUM_POOL_SIZE = CPU_COUNT * 2 + 1;
    private static final int KEEP_ALIVE = 1;

    private static final ThreadFactory sThreadFactory = new ThreadFactory() {
        private final AtomicInteger mCount = new AtomicInteger(1);

        public Thread newThread(Runnable r) {
            return new Thread(r, "ActivityView #" + mCount.getAndIncrement());
        }
    };

    private static final BlockingQueue<Runnable> sPoolWorkQueue =
            new LinkedBlockingQueue<Runnable>(128);

    /**
     * An {@link Executor} that can be used to execute tasks in parallel.
     */
    private static final Executor sExecutor = new ThreadPoolExecutor(MINIMUM_POOL_SIZE,
            MAXIMUM_POOL_SIZE, KEEP_ALIVE, TimeUnit.SECONDS, sPoolWorkQueue, sThreadFactory);


    private static class SerialExecutor implements Executor {
        private final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>();
        private Runnable mActive;

        public synchronized void execute(final Runnable r) {
            mTasks.offer(new Runnable() {
                public void run() {
                    try {
                        r.run();
                    } finally {
                        scheduleNext();
                    }
                }
            });
            if (mActive == null) {
                scheduleNext();
            }
        }

        protected synchronized void scheduleNext() {
            if ((mActive = mTasks.poll()) != null) {
                sExecutor.execute(mActive);
            }
        }
    }

    private final SerialExecutor mExecutor = new SerialExecutor();

    private final int mDensityDpi;
    private final TextureView mTextureView;

    @GuardedBy("mActivityContainerLock")
    private ActivityContainerWrapper mActivityContainer;
    private Object mActivityContainerLock = new Object();

    private Activity mActivity;
    private int mWidth;
    private int mHeight;
    private Surface mSurface;
    private int mLastVisibility;
    private ActivityViewCallback mActivityViewCallback;


    public ActivityView(Context context) {
        this(context, null);
    }

    public ActivityView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ActivityView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        while (context instanceof ContextWrapper) {
            if (context instanceof Activity) {
                mActivity = (Activity)context;
                break;
            }
            context = ((ContextWrapper)context).getBaseContext();
        }
        if (mActivity == null) {
            throw new IllegalStateException("The ActivityView's Context is not an Activity.");
        }

        try {
            mActivityContainer = new ActivityContainerWrapper(
                    ActivityManager.getService().createVirtualActivityContainer(
                            mActivity.getActivityToken(), new ActivityContainerCallback(this)));
        } catch (RemoteException e) {
            throw new RuntimeException("ActivityView: Unable to create ActivityContainer. "
                    + e);
        }

        mTextureView = new TextureView(context);
        mTextureView.setSurfaceTextureListener(new ActivityViewSurfaceTextureListener());
        addView(mTextureView);

        WindowManager wm = (WindowManager)mActivity.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics metrics = new DisplayMetrics();
        wm.getDefaultDisplay().getMetrics(metrics);
        mDensityDpi = metrics.densityDpi;

        mLastVisibility = getVisibility();

        if (DEBUG) Log.v(TAG, "ctor()");
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        mTextureView.layout(0, 0, r - l, b - t);
    }

    @Override
    protected void onVisibilityChanged(View changedView, final int visibility) {
        super.onVisibilityChanged(changedView, visibility);

        if (mSurface != null && (visibility == View.GONE || mLastVisibility == View.GONE)) {
            if (DEBUG) Log.v(TAG, "visibility changed; enqueing runnable");
            final Surface surface = (visibility == View.GONE) ? null : mSurface;
            setSurfaceAsync(surface, mWidth, mHeight, mDensityDpi, false);
        }
        mLastVisibility = visibility;
    }

    private boolean injectInputEvent(InputEvent event) {
        return mActivityContainer != null && mActivityContainer.injectEvent(event);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return injectInputEvent(event) || super.onTouchEvent(event);
    }

    @Override
    public boolean onGenericMotionEvent(MotionEvent event) {
        if (event.isFromSource(InputDevice.SOURCE_CLASS_POINTER)) {
            if (injectInputEvent(event)) {
                return true;
            }
        }
        return super.onGenericMotionEvent(event);
    }

    @Override
    public void onAttachedToWindow() {
        if (DEBUG) Log.v(TAG, "onAttachedToWindow(): mActivityContainer=" + mActivityContainer +
                " mSurface=" + mSurface);
    }

    @Override
    public void onDetachedFromWindow() {
        if (DEBUG) Log.v(TAG, "onDetachedFromWindow(): mActivityContainer=" + mActivityContainer +
                " mSurface=" + mSurface);
    }

    public boolean isAttachedToDisplay() {
        return mSurface != null;
    }

    public void startActivity(Intent intent) {
        if (mActivityContainer == null) {
            throw new IllegalStateException("Attempt to call startActivity after release");
        }
        if (mSurface == null) {
            throw new IllegalStateException("Surface not yet created.");
        }
        if (DEBUG) Log.v(TAG, "startActivity(): intent=" + intent + " " +
                (isAttachedToDisplay() ? "" : "not") + " attached");
        if (mActivityContainer.startActivity(intent) == START_CANCELED) {
            throw new OperationCanceledException();
        }
    }

    public void startActivity(IntentSender intentSender) {
        if (mActivityContainer == null) {
            throw new IllegalStateException("Attempt to call startActivity after release");
        }
        if (mSurface == null) {
            throw new IllegalStateException("Surface not yet created.");
        }
        if (DEBUG) Log.v(TAG, "startActivityIntentSender(): intentSender=" + intentSender + " " +
                (isAttachedToDisplay() ? "" : "not") + " attached");
        final IIntentSender iIntentSender = intentSender.getTarget();
        if (mActivityContainer.startActivityIntentSender(iIntentSender) == START_CANCELED) {
            throw new OperationCanceledException();
        }
    }

    public void startActivity(PendingIntent pendingIntent) {
        if (mActivityContainer == null) {
            throw new IllegalStateException("Attempt to call startActivity after release");
        }
        if (mSurface == null) {
            throw new IllegalStateException("Surface not yet created.");
        }
        if (DEBUG) Log.v(TAG, "startActivityPendingIntent(): PendingIntent=" + pendingIntent + " "
                + (isAttachedToDisplay() ? "" : "not") + " attached");
        final IIntentSender iIntentSender = pendingIntent.getTarget();
        if (mActivityContainer.startActivityIntentSender(iIntentSender) == START_CANCELED) {
            throw new OperationCanceledException();
        }
    }

    public void release() {
        if (DEBUG) Log.v(TAG, "release() mActivityContainer=" + mActivityContainer +
                " mSurface=" + mSurface);
        if (mActivityContainer == null) {
            Log.e(TAG, "Duplicate call to release");
            return;
        }
        synchronized (mActivityContainerLock) {
            mActivityContainer.release();
            mActivityContainer = null;
        }

        if (mSurface != null) {
            mSurface.release();
            mSurface = null;
        }

        mTextureView.setSurfaceTextureListener(null);
    }

    private void setSurfaceAsync(final Surface surface, final int width, final int height,
            final int densityDpi, final boolean callback) {
        mExecutor.execute(new Runnable() {
            public void run() {
                try {
                    synchronized (mActivityContainerLock) {
                        if (mActivityContainer != null) {
                            mActivityContainer.setSurface(surface, width, height, densityDpi);
                        }
                    }
                } catch (RemoteException e) {
                    throw new RuntimeException(
                        "ActivityView: Unable to set surface of ActivityContainer. ",
                        e);
                }
                if (callback) {
                    post(new Runnable() {
                        @Override
                        public void run() {
                            if (mActivityViewCallback != null) {
                                if (surface != null) {
                                    mActivityViewCallback.onSurfaceAvailable(ActivityView.this);
                                } else {
                                    mActivityViewCallback.onSurfaceDestroyed(ActivityView.this);
                                }
                            }
                        }
                    });
                }
            }
        });
    }

    /**
     * Set the callback to use to report certain state changes.
     *
     * Note: If the surface has been created prior to this call being made, then
     * ActivityViewCallback.onSurfaceAvailable will be called from within setCallback.
     *
     *  @param callback The callback to report events to.
     *
     * @see ActivityViewCallback
     */
    public void setCallback(ActivityViewCallback callback) {
        mActivityViewCallback = callback;

        if (mSurface != null) {
            mActivityViewCallback.onSurfaceAvailable(this);
        }
    }

    public static abstract class ActivityViewCallback {
        /**
         * Called when all activities in the ActivityView have completed and been removed. Register
         * using {@link ActivityView#setCallback(ActivityViewCallback)}. Each ActivityView may
         * have at most one callback registered.
         */
        public abstract void onAllActivitiesComplete(ActivityView view);
        /**
         * Called when the surface is ready to be drawn to. Calling startActivity prior to this
         * callback will result in an IllegalStateException.
         */
        public abstract void onSurfaceAvailable(ActivityView view);
        /**
         * Called when the surface has been removed. Calling startActivity after this callback
         * will result in an IllegalStateException.
         */
        public abstract void onSurfaceDestroyed(ActivityView view);
    }

    private class ActivityViewSurfaceTextureListener implements SurfaceTextureListener {
        @Override
        public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width,
                int height) {
            if (mActivityContainer == null) {
                return;
            }
            if (DEBUG) Log.d(TAG, "onSurfaceTextureAvailable: width=" + width + " height="
                    + height);
            mWidth = width;
            mHeight = height;
            mSurface = new Surface(surfaceTexture);
            setSurfaceAsync(mSurface, mWidth, mHeight, mDensityDpi, true);
        }

        @Override
        public void onSurfaceTextureSizeChanged(SurfaceTexture surfaceTexture, int width,
                int height) {
            if (mActivityContainer == null) {
                return;
            }
            if (DEBUG) Log.d(TAG, "onSurfaceTextureSizeChanged: w=" + width + " h=" + height);
        }

        @Override
        public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
            if (mActivityContainer == null) {
                return true;
            }
            if (DEBUG) Log.d(TAG, "onSurfaceTextureDestroyed");
            mSurface.release();
            mSurface = null;
            setSurfaceAsync(null, mWidth, mHeight, mDensityDpi, true);
            return true;
        }

        @Override
        public void onSurfaceTextureUpdated(SurfaceTexture surfaceTexture) {
//            Log.d(TAG, "onSurfaceTextureUpdated");
        }

    }

    private static class ActivityContainerCallback extends IActivityContainerCallback.Stub {
        private final WeakReference<ActivityView> mActivityViewWeakReference;

        ActivityContainerCallback(ActivityView activityView) {
            mActivityViewWeakReference = new WeakReference<>(activityView);
        }

        @Override
        public void setVisible(IBinder container, boolean visible) {
            if (DEBUG) Log.v(TAG, "setVisible(): container=" + container + " visible=" + visible +
                    " ActivityView=" + mActivityViewWeakReference.get());
        }

        @Override
        public void onAllActivitiesComplete(IBinder container) {
            final ActivityView activityView = mActivityViewWeakReference.get();
            if (activityView != null) {
                final ActivityViewCallback callback = activityView.mActivityViewCallback;
                if (callback != null) {
                    final WeakReference<ActivityViewCallback> callbackRef =
                            new WeakReference<>(callback);
                    activityView.post(new Runnable() {
                        @Override
                        public void run() {
                            ActivityViewCallback callback = callbackRef.get();
                            if (callback != null) {
                                callback.onAllActivitiesComplete(activityView);
                            }
                        }
                    });
                }
            }
        }
    }

    private static class ActivityContainerWrapper {
        private final IActivityContainer mIActivityContainer;
        private final CloseGuard mGuard = CloseGuard.get();
        boolean mOpened; // Protected by mGuard.

        ActivityContainerWrapper(IActivityContainer container) {
            mIActivityContainer = container;
            mOpened = true;
            mGuard.open("release");
        }

        void setSurface(Surface surface, int width, int height, int density)
                throws RemoteException {
            mIActivityContainer.setSurface(surface, width, height, density);
        }

        int startActivity(Intent intent) {
            try {
                return mIActivityContainer.startActivity(intent);
            } catch (RemoteException e) {
                throw new RuntimeException("ActivityView: Unable to startActivity. " + e);
            }
        }

        int startActivityIntentSender(IIntentSender intentSender) {
            try {
                return mIActivityContainer.startActivityIntentSender(intentSender);
            } catch (RemoteException e) {
                throw new RuntimeException(
                        "ActivityView: Unable to startActivity from IntentSender. " + e);
            }
        }

        int getDisplayId() {
            try {
                return mIActivityContainer.getDisplayId();
            } catch (RemoteException e) {
                return -1;
            }
        }

        boolean injectEvent(InputEvent event) {
            try {
                return mIActivityContainer.injectEvent(event);
            } catch (RemoteException e) {
                return false;
            }
        }

        void release() {
            synchronized (mGuard) {
                if (mOpened) {
                    if (DEBUG) Log.v(TAG, "ActivityContainerWrapper: release called");
                    try {
                        mIActivityContainer.release();
                        mGuard.close();
                    } catch (RemoteException e) {
                    }
                    mOpened = false;
                }
            }
        }

        @Override
        protected void finalize() throws Throwable {
            if (DEBUG) Log.v(TAG, "ActivityContainerWrapper: finalize called");
            try {
                if (mGuard != null) {
                    mGuard.warnIfOpen();
                    release();
                }
            } finally {
                super.finalize();
            }
        }

    }
}