/*
 * Copyright 2014, 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 com.android.server.telecom;

import android.media.Ringtone;
import android.net.Uri;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.os.SomeArgs;
import com.android.internal.util.Preconditions;

/**
 * Plays the default ringtone. Uses {@link Ringtone} in a separate thread so that this class can be
 * used from the main thread.
 */
@VisibleForTesting
public class AsyncRingtonePlayer {
    // Message codes used with the ringtone thread.
    private static final int EVENT_PLAY = 1;
    private static final int EVENT_STOP = 2;
    private static final int EVENT_REPEAT = 3;

    // The interval in which to restart the ringer.
    private static final int RESTART_RINGER_MILLIS = 3000;

    /** Handler running on the ringtone thread. */
    private Handler mHandler;

    /** The current ringtone. Only used by the ringtone thread. */
    private Ringtone mRingtone;

    /** Plays the ringtone. */
    public void play(RingtoneFactory factory, Call incomingCall) {
        Log.d(this, "Posting play.");
        SomeArgs args = SomeArgs.obtain();
        args.arg1 = factory;
        args.arg2 = incomingCall;
        postMessage(EVENT_PLAY, true /* shouldCreateHandler */, args);
    }

    /** Stops playing the ringtone. */
    public void stop() {
        Log.d(this, "Posting stop.");
        postMessage(EVENT_STOP, false /* shouldCreateHandler */, null);
    }

    /**
     * Posts a message to the ringtone-thread handler. Creates the handler if specified by the
     * parameter shouldCreateHandler.
     *
     * @param messageCode The message to post.
     * @param shouldCreateHandler True when a handler should be created to handle this message.
     */
    private void postMessage(int messageCode, boolean shouldCreateHandler, SomeArgs args) {
        synchronized(this) {
            if (mHandler == null && shouldCreateHandler) {
                mHandler = getNewHandler();
            }

            if (mHandler == null) {
                Log.d(this, "Message %d skipped because there is no handler.", messageCode);
            } else {
                mHandler.obtainMessage(messageCode, args).sendToTarget();
            }
        }
    }

    /**
     * Creates a new ringtone Handler running in its own thread.
     */
    private Handler getNewHandler() {
        Preconditions.checkState(mHandler == null);

        HandlerThread thread = new HandlerThread("ringtone-player");
        thread.start();

        return new Handler(thread.getLooper()) {
            @Override
            public void handleMessage(Message msg) {
                switch(msg.what) {
                    case EVENT_PLAY:
                        handlePlay((SomeArgs) msg.obj);
                        break;
                    case EVENT_REPEAT:
                        handleRepeat();
                        break;
                    case EVENT_STOP:
                        handleStop();
                        break;
                }
            }
        };
    }

    /**
     * Starts the actual playback of the ringtone. Executes on ringtone-thread.
     */
    private void handlePlay(SomeArgs args) {
        RingtoneFactory factory = (RingtoneFactory) args.arg1;
        Call incomingCall = (Call) args.arg2;
        args.recycle();
        // don't bother with any of this if there is an EVENT_STOP waiting.
        if (mHandler.hasMessages(EVENT_STOP)) {
            return;
        }

        // If the Ringtone Uri is EMPTY, then the "None" Ringtone has been selected. Do not play
        // anything.
        if(Uri.EMPTY.equals(incomingCall.getRingtone())) {
            mRingtone = null;
            return;
        }

        ThreadUtil.checkNotOnMainThread();
        Log.i(this, "Play ringtone.");

        if (mRingtone == null) {
            mRingtone = factory.getRingtone(incomingCall);
            if (mRingtone == null) {
                Uri ringtoneUri = incomingCall.getRingtone();
                String ringtoneUriString = (ringtoneUri == null) ? "null" :
                        ringtoneUri.toSafeString();
                Log.event(null, Log.Events.ERROR_LOG, "Failed to get ringtone from factory. " +
                        "Skipping ringing. Uri was: " + ringtoneUriString);
                return;
            }
        }

        handleRepeat();
    }

    private void handleRepeat() {
        if (mRingtone == null) {
            return;
        }

        if (mRingtone.isPlaying()) {
            Log.d(this, "Ringtone already playing.");
        } else {
            mRingtone.play();
            Log.i(this, "Repeat ringtone.");
        }

        // Repost event to restart ringer in {@link RESTART_RINGER_MILLIS}.
        synchronized(this) {
            if (!mHandler.hasMessages(EVENT_REPEAT)) {
                mHandler.sendEmptyMessageDelayed(EVENT_REPEAT, RESTART_RINGER_MILLIS);
            }
        }
    }

    /**
     * Stops the playback of the ringtone. Executes on the ringtone-thread.
     */
    private void handleStop() {
        ThreadUtil.checkNotOnMainThread();
        Log.i(this, "Stop ringtone.");

        if (mRingtone != null) {
            Log.d(this, "Ringtone.stop() invoked.");
            mRingtone.stop();
            mRingtone = null;
        }

        synchronized(this) {
            // At the time that STOP is handled, there should be no need for repeat messages in the
            // queue.
            mHandler.removeMessages(EVENT_REPEAT);

            if (mHandler.hasMessages(EVENT_PLAY)) {
                Log.v(this, "Keeping alive ringtone thread for subsequent play request.");
            } else {
                mHandler.removeMessages(EVENT_STOP);
                mHandler.getLooper().quitSafely();
                mHandler = null;
                Log.v(this, "Handler cleared.");
            }
        }
    }
}