/*
 * Copyright (C) 2015 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.internal.midi;

import android.media.midi.MidiReceiver;
import android.media.midi.MidiSender;

import java.io.IOException;
import java.util.concurrent.CopyOnWriteArrayList;

Utility class for dispatching MIDI data to a list of MidiReceivers. This class subclasses MidiReceiver and dispatches any data it receives to its receiver list. Any receivers that throw an exception upon receiving data will be automatically removed from the receiver list. If a MidiReceiverFailureHandler has been provided to the MidiDispatcher, it will be notified about the failure, but the exception itself will be swallowed. /**
 * Utility class for dispatching MIDI data to a list of {@link android.media.midi.MidiReceiver}s.
 * This class subclasses {@link android.media.midi.MidiReceiver} and dispatches any data it receives
 * to its receiver list. Any receivers that throw an exception upon receiving data will
 * be automatically removed from the receiver list. If a MidiReceiverFailureHandler has been
 * provided to the MidiDispatcher, it will be notified about the failure, but the exception
 * itself will be swallowed.
 */
public final class MidiDispatcher extends MidiReceiver {

    // MidiDispatcher's client and MidiReceiver's owner can be different
    // classes (e.g. MidiDeviceService is a client, but MidiDeviceServer is
    // the owner), and errors occuring during sending need to be reported
    // to the owner rather than to the sender.
    //
    // Note that the callbacks will be called on the sender's thread.
    public interface MidiReceiverFailureHandler {
        void onReceiverFailure(MidiReceiver receiver, IOException failure);
    }

    private final MidiReceiverFailureHandler mFailureHandler;
    private final CopyOnWriteArrayList<MidiReceiver> mReceivers
            = new CopyOnWriteArrayList<MidiReceiver>();

    private final MidiSender mSender = new MidiSender() {
        @Override
        public void onConnect(MidiReceiver receiver) {
            mReceivers.add(receiver);
        }

        @Override
        public void onDisconnect(MidiReceiver receiver) {
            mReceivers.remove(receiver);
        }
    };

    public MidiDispatcher() {
        this(null);
    }

    public MidiDispatcher(MidiReceiverFailureHandler failureHandler) {
        mFailureHandler = failureHandler;
    }

    
Returns the number of MidiReceivers this dispatcher contains. 
Returns:
the number of receivers/**
     * Returns the number of {@link android.media.midi.MidiReceiver}s this dispatcher contains.
     * @return the number of receivers
     */
    public int getReceiverCount() {
        return mReceivers.size();
    }

    
Returns a MidiSender which is used to add and remove MidiReceivers to the dispatcher's receiver list. 
Returns:
the dispatcher's MidiSender/**
     * Returns a {@link android.media.midi.MidiSender} which is used to add and remove
     * {@link android.media.midi.MidiReceiver}s
     * to the dispatcher's receiver list.
     * @return the dispatcher's MidiSender
     */
    public MidiSender getSender() {
        return mSender;
    }

    @Override
    public void onSend(byte[] msg, int offset, int count, long timestamp) throws IOException {
       for (MidiReceiver receiver : mReceivers) {
            try {
                receiver.send(msg, offset, count, timestamp);
            } catch (IOException e) {
                // If the receiver fails we remove the receiver but do not propagate the exception.
                // Note that this may also happen if the client code stalls, and thus underlying
                // MidiInputPort.onSend has raised IOException for EAGAIN / EWOULDBLOCK error.
                mReceivers.remove(receiver);
                if (mFailureHandler != null) {
                    mFailureHandler.onReceiverFailure(receiver, e);
                }
            }
        }
    }

    @Override
    public void onFlush() throws IOException {
       for (MidiReceiver receiver : mReceivers) {
            try {
                receiver.flush();
            } catch (IOException e) {
                // This is just a special case of 'send' thus handle in the same way.
                mReceivers.remove(receiver);
                if (mFailureHandler != null) {
                    mFailureHandler.onReceiverFailure(receiver, e);
                }
            }
       }
    }
}