Mystify/Lib.Midi/MidiCommunication.cs

// Author: Gockner, Simon
// Created: 2021-04-09
// Copyright(c) 2021 SimonG. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Linq;
using Lib.Driver.Interfaces;
using Lib.Midi.Interfaces;
using Lib.Midi.Messages.Factories;
using Lib.Midi.Messages.Interfaces;
using NAudio.Midi;

namespace Lib.Midi
{
    public class MidiCommunication : IMidiCommunication
    {
        private readonly IDriver _driver;
        private readonly IMidiMessageFactory _midiMessageFactory;
        
        private MidiIn? _midiIn;
        private MidiOut? _midiOut;

        public MidiCommunication(IDriver driver, IMidiMessageFactory midiMessageFactory)
        {
            _driver = driver;
            _midiMessageFactory = midiMessageFactory;
        }

        private IEnumerable<(MidiInCapabilities midiInCapabilities, int index)> MidiInputs 
        {
            get
            {
                for (int i = 0; i < MidiIn.NumberOfDevices; i++)
                    yield return (MidiIn.DeviceInfo(i), i);
            }
        }
        
        private IEnumerable<(MidiOutCapabilities midiOutCapabilities, int index)> MidiOutputs
        {
            get
            {
                for (int i = 0; i < MidiOut.NumberOfDevices; i++)
                    yield return (MidiOut.DeviceInfo(i), i);
            }
        }
        
        public void Open(bool useMidiView)
        {
            int inputProductId = useMidiView ? MidiView.INPUT_PRODUCT_ID : _driver.InputProductId;
            int outputProductId = useMidiView ? MidiView.OUTPUT_PRODUCT_ID : _driver.OutputProductId;
            
            var midiInput = MidiInputs.FirstOrDefault(i => i.midiInCapabilities.ProductId == inputProductId);
            var midiOutput = MidiOutputs.FirstOrDefault(o => o.midiOutCapabilities.ProductId == outputProductId);
            
            _midiIn = new MidiIn(midiInput.index);
            _midiOut = new MidiOut(midiOutput.index);
            
            _midiIn.MessageReceived += OnMidiInMessageReceived;
            _midiIn.ErrorReceived += OnMidiInErrorReceived;
            _midiIn.Start();
        }

        public void Close()
        {
            if (_midiIn != null)
            {
                _midiIn.Stop();
                _midiIn.MessageReceived -= OnMidiInMessageReceived;
                _midiIn.ErrorReceived -= OnMidiInErrorReceived;
                _midiIn.Close();
            }

            _midiOut?.Close();
        }

        public void Send(IMidiMessage message) => _midiOut?.Send(message.RawMessage);
        private void OnMidiInMessageReceived(object? sender, MidiInMessageEventArgs args) => MessageReceived?.Invoke(this, _midiMessageFactory.Create(args.MidiEvent));
        private void OnMidiInErrorReceived(object? sender, MidiInMessageEventArgs args) => ErrorReceived?.Invoke(this, _midiMessageFactory.Create(args.MidiEvent));

        public event EventHandler<IMidiMessage>? MessageReceived;
        public event EventHandler<IMidiMessage>? ErrorReceived;
    }
}