/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.mozilla.gecko.media;

import android.media.MediaCodec;
import android.media.MediaFormat;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.os.Message;
import android.util.Log;
import android.view.Surface;

import java.io.IOException;
import java.nio.ByteBuffer;

// Implement async API using MediaCodec sync mode (API v16).
// This class uses internal worker thread/handler (mBufferPoller) to poll
// input and output buffer and notifies the client through callbacks.
final class JellyBeanAsyncCodec implements AsyncCodec {
    private static final String LOGTAG = "GeckoAsyncCodecAPIv16";
    private static final boolean DEBUG = false;

    private static final int ERROR_CODEC = -10000;

    private abstract class CancelableHandler extends Handler {
        private static final int MSG_CANCELLATION = 0x434E434C; // 'CNCL'

        protected CancelableHandler(Looper looper) {
            super(looper);
        }

        protected void cancel() {
            removeCallbacksAndMessages(null);
            sendEmptyMessage(MSG_CANCELLATION);
            // Wait until handleMessageLocked() is done.
            synchronized (this) { }
        }

        protected boolean isCanceled() {
            return hasMessages(MSG_CANCELLATION);
        }

        // Subclass should implement this and return true if it handles msg.
        // Warning: Never, ever call super.handleMessage() in this method!
        protected abstract boolean handleMessageLocked(Message msg);

        public final void handleMessage(Message msg) {
            // Block cancel() during handleMessageLocked().
            synchronized (this) {
                if (isCanceled() || handleMessageLocked(msg)) {
                    return;
                }
            }

            switch (msg.what) {
                case MSG_CANCELLATION:
                    // Just a marker. Nothing to do here.
                    if (DEBUG) Log.d(LOGTAG, "handler " + this + " done cancellation, codec=" + JellyBeanAsyncCodec.this);
                    break;
                default:
                    super.handleMessage(msg);
                    break;
            }
        }
     }

    // A handler to invoke AsyncCodec.Callbacks methods.
    private final class CallbackSender extends CancelableHandler {
        private static final int MSG_INPUT_BUFFER_AVAILABLE = 1;
        private static final int MSG_OUTPUT_BUFFER_AVAILABLE = 2;
        private static final int MSG_OUTPUT_FORMAT_CHANGE = 3;
        private static final int MSG_ERROR = 4;
        private Callbacks mCallbacks;

        private CallbackSender(Looper looper, Callbacks callbacks) {
          super(looper);
          mCallbacks = callbacks;
        }

        public void notifyInputBuffer(int index) {
            if (isCanceled()) {
                return;
            }

            Message msg = obtainMessage(MSG_INPUT_BUFFER_AVAILABLE);
            msg.arg1 = index;
            processMessage(msg);
        }

        private void processMessage(Message msg) {
            if (Looper.myLooper() == getLooper()) {
                handleMessage(msg);
            } else {
                sendMessage(msg);
            }
        }

        public void notifyOutputBuffer(int index, MediaCodec.BufferInfo info) {
            if (isCanceled()) {
                return;
            }

            Message msg = obtainMessage(MSG_OUTPUT_BUFFER_AVAILABLE, info);
            msg.arg1 = index;
            processMessage(msg);
        }

        public void notifyOutputFormat(MediaFormat format) {
            if (isCanceled()) {
                return;
            }
            processMessage(obtainMessage(MSG_OUTPUT_FORMAT_CHANGE, format));
        }

        public void notifyError(int result) {
            Log.e(LOGTAG, "codec error:" + result);
            processMessage(obtainMessage(MSG_ERROR, result, 0));
        }

        protected boolean handleMessageLocked(Message msg) {
            switch (msg.what) {
                case MSG_INPUT_BUFFER_AVAILABLE: // arg1: buffer index.
                    mCallbacks.onInputBufferAvailable(JellyBeanAsyncCodec.this,
                                                      msg.arg1);
                    break;
                case MSG_OUTPUT_BUFFER_AVAILABLE: // arg1: buffer index, obj: info.
                    mCallbacks.onOutputBufferAvailable(JellyBeanAsyncCodec.this,
                                                       msg.arg1,
                                                       (MediaCodec.BufferInfo)msg.obj);
                    break;
                case MSG_OUTPUT_FORMAT_CHANGE: // obj: output format.
                    mCallbacks.onOutputFormatChanged(JellyBeanAsyncCodec.this,
                                                     (MediaFormat)msg.obj);
                    break;
                case MSG_ERROR: // arg1: error code.
                    mCallbacks.onError(JellyBeanAsyncCodec.this, msg.arg1);
                    break;
                default:
                    return false;
            }

            return true;
        }
    }

    // Handler to poll input and output buffers using dequeue(Input|Output)Buffer(),
    // with 10ms time-out. Once triggered and successfully gets a buffer, it
    // will schedule next polling until EOS or failure. To prevent it from
    // automatically polling more buffer, use cancel() it inherits from
    // CancelableHandler.
    private final class BufferPoller extends CancelableHandler {
        private static final int MSG_POLL_INPUT_BUFFERS = 1;
        private static final int MSG_POLL_OUTPUT_BUFFERS = 2;

        private static final long DEQUEUE_TIMEOUT_US = 10000;

        public BufferPoller(Looper looper) {
            super(looper);
        }

        private void schedulePollingIfNotCanceled(int what) {
            if (isCanceled()) {
                return;
            }

            schedulePolling(what);
        }

        private void schedulePolling(int what) {
            if (needsBuffer(what)) {
                sendEmptyMessage(what);
            }
        }

        private boolean needsBuffer(int what) {
            if (mOutputEnded && (what == MSG_POLL_OUTPUT_BUFFERS)) {
                return false;
            }

            if (mInputEnded && (what == MSG_POLL_INPUT_BUFFERS)) {
                return false;
            }

            return true;
        }

        protected boolean handleMessageLocked(Message msg) {
            try {
                switch (msg.what) {
                    case MSG_POLL_INPUT_BUFFERS:
                        pollInputBuffer();
                        break;
                    case MSG_POLL_OUTPUT_BUFFERS:
                        pollOutputBuffer();
                        break;
                    default:
                        return false;
                }
            } catch (IllegalStateException e) {
                e.printStackTrace();
                mCallbackSender.notifyError(ERROR_CODEC);
            }

            return true;
        }

        private void pollInputBuffer() {
            int result = mCodec.dequeueInputBuffer(DEQUEUE_TIMEOUT_US);
            if (result >= 0) {
                mCallbackSender.notifyInputBuffer(result);
                schedulePollingIfNotCanceled(BufferPoller.MSG_POLL_INPUT_BUFFERS);
            } else if (result != MediaCodec.INFO_TRY_AGAIN_LATER) {
                mCallbackSender.notifyError(result);
            }
        }

        private void pollOutputBuffer() {
            boolean dequeueMoreBuffer = true;
            MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
            int result = mCodec.dequeueOutputBuffer(info, DEQUEUE_TIMEOUT_US);
            if (result >= 0) {
                if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
                    mOutputEnded = true;
                }
                mCallbackSender.notifyOutputBuffer(result, info);
                if (!hasMessages(MSG_POLL_INPUT_BUFFERS)) {
                    schedulePollingIfNotCanceled(MSG_POLL_INPUT_BUFFERS);
                }
            } else if (result == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
                mOutputBuffers = mCodec.getOutputBuffers();
            } else if (result == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
                mCallbackSender.notifyOutputFormat(mCodec.getOutputFormat());
            } else if (result == MediaCodec.INFO_TRY_AGAIN_LATER) {
                // When input ended, keep polling remaining output buffer until EOS.
                dequeueMoreBuffer = mInputEnded;
            } else {
                mCallbackSender.notifyError(result);
                dequeueMoreBuffer = false;
            }

            if (dequeueMoreBuffer) {
                schedulePollingIfNotCanceled(MSG_POLL_OUTPUT_BUFFERS);
            }
        }
    }

    private MediaCodec mCodec;
    private ByteBuffer[] mInputBuffers;
    private ByteBuffer[] mOutputBuffers;
    private AsyncCodec.Callbacks mCallbacks;
    private CallbackSender mCallbackSender;

    private BufferPoller mBufferPoller;
    private volatile boolean mInputEnded;
    private volatile boolean mOutputEnded;

    // Must be called on a thread with looper.
    /* package */ JellyBeanAsyncCodec(String name) throws IOException {
        mCodec = MediaCodec.createByCodecName(name);
        initBufferPoller(name + " buffer poller");
    }

    private void initBufferPoller(String name) {
        if (mBufferPoller != null) {
            Log.e(LOGTAG, "poller already initialized");
            return;
        }
        HandlerThread thread = new HandlerThread(name);
        thread.start();
        mBufferPoller = new BufferPoller(thread.getLooper());
        if (DEBUG) Log.d(LOGTAG, "start poller for codec:" + this + ", thread=" + thread.getThreadId());
    }

    @Override
    public void setCallbacks(AsyncCodec.Callbacks callbacks, Handler handler) {
        if (callbacks == null) {
            return;
        }

        Looper looper = (handler == null) ? null : handler.getLooper();
        if (looper == null) {
            // Use this thread if no handler supplied.
            looper = Looper.myLooper();
        }
        if (looper == null) {
            // This thread has no looper. Use poller thread.
            looper = mBufferPoller.getLooper();
        }
        mCallbackSender = new CallbackSender(looper, callbacks);
        if (DEBUG) Log.d(LOGTAG, "setCallbacks(): sender=" + mCallbackSender);
    }

    @Override
    public void configure(MediaFormat format, Surface surface, int flags) {
        assertCallbacks();

        mCodec.configure(format, surface, null, flags);
    }

    private void assertCallbacks() {
        if (mCallbackSender == null) {
            throw new IllegalStateException(LOGTAG + ": callback must be supplied with setCallbacks().");
        }
    }

    @Override
    public void start() {
        assertCallbacks();

        mCodec.start();
        mInputEnded = false;
        mOutputEnded = false;
        mInputBuffers = mCodec.getInputBuffers();
        mOutputBuffers = mCodec.getOutputBuffers();
        mBufferPoller.schedulePolling(BufferPoller.MSG_POLL_INPUT_BUFFERS);
    }

    @Override
    public final void queueInputBuffer(int index, int offset, int size, long presentationTimeUs, int flags) {
        assertCallbacks();

        mInputEnded = (flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0;

        try {
            mCodec.queueInputBuffer(index, offset, size, presentationTimeUs, flags);
        } catch (IllegalStateException e) {
            e.printStackTrace();
            mCallbackSender.notifyError(ERROR_CODEC);
            return;
        }

        mBufferPoller.schedulePolling(BufferPoller.MSG_POLL_INPUT_BUFFERS);
        mBufferPoller.schedulePolling(BufferPoller.MSG_POLL_OUTPUT_BUFFERS);
    }

    @Override
    public final void releaseOutputBuffer(int index, boolean render) {
        assertCallbacks();

        mCodec.releaseOutputBuffer(index, render);
    }

    @Override
    public final ByteBuffer getInputBuffer(int index) {
        assertCallbacks();

        return mInputBuffers[index];
    }

    @Override
    public final ByteBuffer getOutputBuffer(int index) {
        assertCallbacks();

        return mOutputBuffers[index];
    }

    @Override
    public void flush() {
        assertCallbacks();

        mInputEnded = false;
        mOutputEnded = false;
        cancelPendingTasks();
        mCodec.flush();
        mBufferPoller.schedulePolling(BufferPoller.MSG_POLL_INPUT_BUFFERS);
    }

    private void cancelPendingTasks() {
        mBufferPoller.cancel();
        mCallbackSender.cancel();
    }

    @Override
    public void stop() {
        assertCallbacks();

        cancelPendingTasks();
        mCodec.stop();
    }

    @Override
    public void release() {
        assertCallbacks();

        cancelPendingTasks();
        mCallbackSender = null;
        mCodec.release();
        stopBufferPoller();
    }

    private void stopBufferPoller() {
        if (mBufferPoller == null) {
            Log.e(LOGTAG, "no initialized poller.");
            return;
        }

        mBufferPoller.getLooper().quit();
        mBufferPoller = null;

        if (DEBUG) Log.d(LOGTAG, "stop poller " + this);
    }
}