// Author: Gockner, Simon
// Created: 2021-04-08
// Copyright(c) 2021 SimonG. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Linq;
using Lib.Audio.Factories;
using Lib.Audio.Interfaces;
using Lib.Logging;
using Lib.ProcessManaging.Interfaces;
using NAudio.CoreAudioApi;
using NAudio.CoreAudioApi.Interfaces;

namespace Lib.Audio
{
    public class ControllableCollector : IControllableCollector
    {
        private readonly IProcessManager _processManager; 
        private readonly IControllableFactory _controllableFactory;

        public ControllableCollector(IProcessManager processManager, IControllableFactory controllableFactory)
        {
            _processManager = processManager;
            _controllableFactory = controllableFactory;
        }

        public List<IControllable> Controllables => CreateControllables();
        
        public IControllable? GetControllableForExecutable(string executablePath) => 
            Controllables.FirstOrDefault(c => c.ExecutablePath.Equals(executablePath));

        private List<IControllable> CreateControllables()
        {
            MMDeviceEnumerator deviceEnumerator = new();
            MMDeviceCollection? audioDevices = deviceEnumerator.EnumerateAudioEndPoints(DataFlow.All, DeviceState.Active);

            List<IControllable> controllables = new();
            controllables.AddRange(audioDevices.Select(a => _controllableFactory.Create(a.AudioEndpointVolume, a.FriendlyName)));

            Dictionary<string, List<AudioSessionControl>> sessionsById = new();
            foreach (var audioDevice in audioDevices)
            {
                if (audioDevice.DataFlow == DataFlow.Capture) //don't add input device to the same controllable than the output device, for now just remove them
                    continue;
                
                SessionCollection sessions = audioDevice.AudioSessionManager.Sessions;
                for (int i = 0; i < sessions.Count; i++)
                {
                    AudioSessionControl session = sessions[i];
                    if (session.State == AudioSessionState.AudioSessionStateExpired)
                        continue;
                    
                    string searchIdentifier = session.GetSessionIdentifier[(session.GetSessionIdentifier.IndexOf("|", StringComparison.Ordinal) + 1)..];

                    if (!sessionsById.ContainsKey(searchIdentifier))
                        sessionsById[searchIdentifier] = new List<AudioSessionControl>();

                    sessionsById[searchIdentifier].Add(session);
                }
            }
            
            foreach (var id in sessionsById.Keys.ToList())
            {
                List<AudioSessionControl> idSessions = sessionsById[id];
                    
                (IObservedProcess? process, AudioSessionControl? audioSessionControl) = FindProcess(idSessions);
                if (audioSessionControl == null || process == default && !idSessions.Any(s => s.IsSystemSoundsSession))
                    continue;

                string name;
                if (idSessions.Any(s => s.IsSystemSoundsSession))
                    name = "System Sounds";
                else if (process != null)
                    name = process.Name;
                else
                    name = id;

                if (process == null)
                {
                    Log.Write<ControllableCollector>($"Could not find process for session id {id}.");
                    continue;
                }
                
                controllables.Add(_controllableFactory.Create(idSessions, process.FileName, name));
            }
            
            return controllables;
        }

        private (IObservedProcess? process, AudioSessionControl? session) FindProcess(List<AudioSessionControl> sessions)
        {
            foreach (var session in sessions)
            {
                IObservedProcess? process = _processManager.GetProcessById((int) session.GetProcessID);
                if (process != null)
                    return (process, session);
            }
            
            return (null, null);
        }
    }
}