// Author: Gockner, Simon
// Created: 2021-04-07
// Copyright(c) 2021 SimonG. All Rights Reserved.

using System.Collections.Generic;
using System.Linq;
using Lib.Audio.Controls;
using Lib.Audio.Controls.Buttons;
using Lib.Audio.Controls.Buttons.Factories;
using Lib.Audio.Controls.Buttons.Interfaces;
using Lib.Audio.Controls.Factories;
using Lib.Audio.Controls.Interfaces;
using Lib.Audio.Interfaces;
using Lib.Driver.Xml;
using Lib.Midi.Interfaces;
using Lib.Midi.Messages;
using Lib.Midi.Messages.Interfaces;
using Lib.ProcessManaging.Interfaces;

namespace Lib.Audio
{
    public class Channel : IChannel
    {
        private readonly IControllableCollector _controllableCollector;
        private readonly IMidiCommunication _midiCommunication;
        private readonly IProcessManager _processManager;
        
        private readonly int _channelNumber;
        
        private IMidiMessage? _acknowledgeMessage;

        public Channel(XmlChannel xmlChannel,
            IControllableCollector controllableCollector,
            IMidiCommunication midiCommunication,
            IProcessManager processManager,
            IFaderFactory faderFactory,
            IKnobFactory knobFactory,
            IButtonFactory buttonFactory)
        {
            _controllableCollector = controllableCollector;
            _midiCommunication = midiCommunication;
            _processManager = processManager;
            _channelNumber = xmlChannel.ChannelNumber;

            if (xmlChannel.Fader != null)
            {
                Fader = faderFactory.Create(xmlChannel.Fader);
                Fader.PositionChanged += OnFaderPositionChanged;
            }

            if (xmlChannel.Knob != null)
                Knob = knobFactory.Create();

            Buttons = new List<IButton>();
            if (xmlChannel.Buttons != null)
            {
                foreach (var button in xmlChannel.Buttons) 
                    Buttons.Add(buttonFactory.Create(button, _channelNumber));
            }
            
            _processManager.ProcessStarted += OnProcessManagerProcessStarted;
            _processManager.ProcessExited += OnProcessManagerProcessExited;
        }

        public IFader? Fader { get; }
        public IKnob? Knob { get; }
        public List<IButton> Buttons { get; }
        public IControllable? Controllable { get; private set; }
        
        public void MapControllable(IControllable controllable)
        {
            Controllable = controllable;
            ToggleButtonLed<ISelectButton>(LedState.On);

            if (!Controllable.IsValid)
                return;
            
            InitializeFader();
            ToggleButtonLed<IRecordButton>(LedState.On);
        }

        private void UnMapControllable()
        {
            if (Controllable == null)
                return;
            
            ToggleButtonLed<ISelectButton>(LedState.Off);
            ToggleButtonLed<IRecordButton>(LedState.Off);
        }

        public void HandleMessage(IMidiMessage message)
        {
            if (message is NoteOnMessage noteOnMessage)
            {
                if (Fader?.NoteNumber == noteOnMessage.NoteNumber)
                    Fader.IsTouched = true;
                else 
                {
                    IButton? button = Buttons.FirstOrDefault(b => b.NoteNumber == noteOnMessage.NoteNumber);
                    _acknowledgeMessage = button?.HandlePressed(Controllable, (Velocity) noteOnMessage.Velocity);
                }
            }
            else if (message is NoteMessage noteMessage)
            {
                if (Fader?.NoteNumber == noteMessage.NoteNumber)
                {
                    Fader.IsTouched = false;
                    _acknowledgeMessage = new PitchWheelChangeMessage(0, _channelNumber, Fader.Position);
                }
                else 
                {
                    IButton? button = Buttons.FirstOrDefault(b => b.NoteNumber == noteMessage.NoteNumber);
                    _acknowledgeMessage = button?.HandlePressed(Controllable, (Velocity) noteMessage.Velocity);
                }
            }
            else if (message is PitchWheelChangeMessage pitchWheelChangeMessage)
            {
                if (Fader != null) 
                    Fader.Position = pitchWheelChangeMessage.Pitch;
            }
        }

        public void SendAcknowledge()
        {
            if (_acknowledgeMessage == null)
                return;
            
            _midiCommunication.Send(_acknowledgeMessage);
            _acknowledgeMessage = null;
        }

        private void InitializeFader()
        {
            if (Fader == null || Controllable == null)
                return;
            
            float volume = Controllable.GetVolume();
            Fader.RelativePosition = volume;
            
            _midiCommunication.Send(new PitchWheelChangeMessage(0, _channelNumber, Fader.Position));
        }
        
        private void ToggleButtonLed<TButton>(LedState ledState) where TButton : IButton
        {
            TButton? button = Buttons.OfType<TButton>().FirstOrDefault();
            IMidiMessage? selectMessage = button?.ToggleLed(ledState);
            
            if (selectMessage != null)
                _midiCommunication.Send(selectMessage);
        }

        private void OnFaderPositionChanged(object? sender, int position)
        {
            if (sender is not IFader fader)
                return;
            
            Controllable?.SetVolume(fader.RelativePosition);
        }
        
        private void OnProcessManagerProcessStarted(object? sender, IObservedProcess process)
        {
            if (Controllable == null)
                return;
            
            if (!Controllable.ExecutablePath.Equals(process.FileName))
                return;

            Controllable = _controllableCollector.GetControllableForExecutable(Controllable.ExecutablePath);
            if (Controllable == null)
                return;
            
            InitializeFader();
            ToggleButtonLed<IRecordButton>(LedState.On);
        }
        
        private void OnProcessManagerProcessExited(object? sender, IObservedProcess process)
        {
            if (Controllable == null)
                return;
            
            if (!Controllable.ExecutablePath.Equals(process.FileName))
                return;

            Controllable.IsValid = false;
            ToggleButtonLed<IRecordButton>(LedState.Off);
        }

        public override string ToString() => $"Channel {_channelNumber}";

        public void Dispose()
        {
            _processManager.ProcessStarted -= OnProcessManagerProcessStarted;
            _processManager.ProcessExited -= OnProcessManagerProcessExited;
            
            UnMapControllable();
            _midiCommunication.Send(new PitchWheelChangeMessage(0, _channelNumber, 0));

            foreach (IMidiMessage ledOffMessage in Buttons.Select(b => b.ToggleLed(LedState.Off)))
                _midiCommunication.Send(ledOffMessage);
        }
    }
}