/*
 * Copyright (C) 2018 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.gameperformance;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Trace;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/**
 * Minimal SurfaceView that sends buffer on request.
 */
public class CustomSurfaceView extends SurfaceView implements SurfaceHolder.Callback {
    // Tag for trace when buffer is requested.
    public final static String LOCAL_REQUEST_BUFFER = "localRequestBuffer";
    // Tag for trace when buffer is posted.
    public final static String LOCAL_POST_BUFFER = "localPostBuffer";

    private final Object mSurfaceLock = new Object();
    // Keeps frame times. Used to calculate fps.
    private List<Long> mFrameTimes;
    // Surface to send.
    private Surface mSurface;
    private Handler mHandler;

    private Runnable mInvalidateSurfaceTask = new Runnable() {
        @Override
        public void run() {
            synchronized (mSurfaceLock) {
                if (mSurface == null) {
                    return;
                }
                invalidateSurface(true, true);
                mHandler.post(this);
            }
        }
    };

    public CustomSurfaceView(Context context) {
        super(context);
        mFrameTimes = new ArrayList<Long>();
        getHolder().addCallback(this);
        getHolder().setFormat(PixelFormat.OPAQUE);

        HandlerThread thread = new HandlerThread("SurfaceInvalidator");
        thread.start();
        mHandler = new Handler(thread.getLooper());
    }

    /**
     * Resets frame times in order to calculate fps for different test pass.
     */
    public void resetFrameTimes() {
        synchronized (mSurfaceLock) {
            mFrameTimes.clear();
        }
    }

    /**
     * Returns current fps based on collected frame times.
     */
    public double getFps() {
        synchronized (mSurfaceLock) {
            if (mFrameTimes.size() < 2) {
                return 0.0f;
            }
            return 1000.0 * mFrameTimes.size() /
                    (mFrameTimes.get(mFrameTimes.size() - 1) - mFrameTimes.get(0));
        }
    }

    /**
     * Invalidates surface.
     * @param traceCalls set to true in case we need register trace calls. Not used for warm-up.
     * @param drawFps perform drawing current fps on surface to have some payload on surface.
     */
    public void invalidateSurface(boolean traceCalls, boolean drawFps) {
        synchronized (mSurfaceLock) {
            if (mSurface == null) {
                throw new IllegalStateException("Surface is not ready");
            }
            if (traceCalls) {
                Trace.traceBegin(Trace.TRACE_TAG_GRAPHICS, LOCAL_REQUEST_BUFFER);
            }
            Canvas canvas = mSurface.lockHardwareCanvas();
            if (traceCalls) {
                Trace.traceEnd(Trace.TRACE_TAG_GRAPHICS);
            }

            if (drawFps) {
                int textSize = canvas.getHeight() / 24;
                Paint paint = new Paint();
                paint.setTextSize(textSize);
                paint.setColor(0xFFFF8040);
                canvas.drawARGB(92, 255, 255, 255);
                canvas.drawText("FPS: " + String.format("%.2f", getFps()), 10, 300, paint);
            }

            if (traceCalls) {
                Trace.traceBegin(Trace.TRACE_TAG_GRAPHICS, LOCAL_POST_BUFFER);
            }
            mSurface.unlockCanvasAndPost(canvas);
            if (traceCalls) {
                Trace.traceEnd(Trace.TRACE_TAG_GRAPHICS);
            }

            mFrameTimes.add(System.currentTimeMillis());
        }
    }

    /**
     * Wait until surface is created and ready to use or return immediately if surface
     * already exists.
     */
    public void waitForSurfaceReady() {
        synchronized (mSurfaceLock) {
            if (mSurface == null) {
                try {
                    mSurfaceLock.wait(5000);
                } catch(InterruptedException e) {
                    e.printStackTrace();
                }
            }
            if (mSurface == null)
                throw new IllegalStateException("Surface is not ready.");
        }
    }

    /**
     * Waits until surface is destroyed or return immediately if surface does not exist.
     */
    public void waitForSurfaceDestroyed() {
        synchronized (mSurfaceLock) {
            if (mSurface != null) {
                try {
                    mSurfaceLock.wait(5000);
                } catch(InterruptedException e) {
                }
            }
            if (mSurface != null)
                throw new IllegalStateException("Surface still exists.");
        }
    }


    @Override
    public void surfaceCreated(SurfaceHolder holder) {
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // This method is always called at least once, after surfaceCreated.
        synchronized (mSurfaceLock) {
            mSurface = holder.getSurface();
            mSurfaceLock.notify();
            mHandler.post(mInvalidateSurfaceTask);
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        synchronized (mSurfaceLock) {
            mHandler.removeCallbacks(mInvalidateSurfaceTask);
            mSurface = null;
            mSurfaceLock.notify();
        }
    }
}