using System.Collections.Generic;
using Cysharp.Threading.Tasks;
using Unity.Mathematics;
using UnityEngine;
using UnityEngine.Audio;
using Object = UnityEngine.Object;
#if UNITY_EDITOR
using UnityEditor;
#endif

namespace DanieleMarotta.RiversongCodeShowcase
{
    [Service(typeof(ISoundPlayer))]
    [GameSystemGroup(typeof(AudioSystemGroup))]
    [InitializeAfter(typeof(BackgroundMusicSystem))]
    public class SoundPlayerSystem : GameSystem, IInitializable, IUpdatable, ISoundPlayer, IDrawGizmos
    {
        private const int ChannelCount = 16;

        [InjectService]
        private ITileSpace _tileSpace;

        [InjectService]
        private IScene _scene;

        [InjectService]
        private ICameraProperties _cameraProperties;

        [InjectService]
        private GameConfig _config;

        private AudioSourcePool _poolNonSpatial;

        private AudioSourcePool _poolSpatial;

        private SystemSoundLibrary _systemSoundLibrary;

        public SoundPlayerSystem(IServiceLocator serviceLocator) : base(serviceLocator)
        {
        }

        public async UniTask InitializeAsync()
        {
            var systemSoundLibraryTask = _config.Audio.SystemSoundLibrary.LoadAssetAsync<SystemSoundLibrary>().ToUniTask();
            var audioSourcePrefabTask = _config.Audio.AudioSourcePrefab.LoadAssetAsync().ToUniTask();

            _systemSoundLibrary = await systemSoundLibraryTask;

            var audioSourcePrefab = (await audioSourcePrefabTask).GetComponent<AudioSource>();
            await InitializePoolAsync(audioSourcePrefab);
        }

        private async UniTask InitializePoolAsync(AudioSource audioSourcePrefab)
        {
            _poolNonSpatial = InitializePool(audioSourcePrefab, "Sound_{0:00} (2D)");
            await UniTask.NextFrame();

            _poolSpatial = InitializePool(audioSourcePrefab, "Sound_{0:00} (3D)");
            await UniTask.NextFrame();
        }

        private AudioSourcePool InitializePool(AudioSource audioSourcePrefab, string nameFormat)
        {
            var audioSources = new AudioSource[ChannelCount];

            for (var i = 0; i < ChannelCount; i++)
            {
                var source = Object.Instantiate(audioSourcePrefab, _scene.SceneFolders.AudioSources);
                source.name = string.Format(nameFormat, i);

                audioSources[i] = source;
            }

            return new AudioSourcePool(audioSources);
        }

        public void Update()
        {
            UpdateSpatialAudioSources();
        }

        private void UpdateSpatialAudioSources()
        {
            var cameraPosition = ((float3)_scene.MainCamera.transform.position).xz;

            var horizontalDistanceRange = _config.Audio.SpatialAudioHorizontalDistanceRange;
            var zoomRange = _config.Audio.SpatialAudioZoomRange;

            foreach (var audioSource in _poolSpatial.AudioSources)
            {
#if !UNITY_EDITOR
                if (!audioSource.isPlaying) continue;
#endif

                var p = ((float3)audioSource.transform.position).xz;

                var horizontalDistance = math.distance(cameraPosition, p);

                var t = math.saturate(math.unlerp(horizontalDistanceRange.x, horizontalDistanceRange.y, horizontalDistance));
                var attenuation = 1 - t * t;

                var zoomFactor = 1 - math.unlerp(zoomRange.x, zoomRange.y, _cameraProperties.Zoom);

                audioSource.volume = attenuation * zoomFactor;
            }
        }

        public void Play(AudioResource resource)
        {
            var source = _poolNonSpatial.GetAudioSource();

            source.resource = resource;

            source.Play();
        }

        public void PlayAt(AudioResource resource, float3 position)
        {
            var source = _poolSpatial.GetAudioSource();

            source.resource = resource;
            source.transform.position = position;

            source.Play();
        }

        public void PlayAt(AudioResource resource, int2 tile)
        {
            PlayAt(resource, _tileSpace.TileToWorld(tile));
        }

        public AudioResource GetSystemSound(SystemSoundId soundId)
        {
            return _systemSoundLibrary.Sounds.GetValueOrDefault(soundId);
        }

        public void DrawGizmos(bool selected)
        {
#if UNITY_EDITOR
            const int width = 60;
            const int height = 8;

            var camera = _scene.MainCamera;

            foreach (var audioSource in _poolSpatial.AudioSources)
            {
                var screenPoint = camera.WorldToScreenPoint(audioSource.transform.position);
                if (screenPoint.z < 0) continue;

                var p = new Vector2(screenPoint.x - width * 0.5f, camera.pixelHeight - screenPoint.y);

                Handles.BeginGUI();

                EditorGUI.DrawRect(new Rect(p.x, p.y, width, height), new Color(0, 0, 0, 0.6f));

                var volume = audioSource.volume;
                var color = Color.Lerp(Color.red, Color.green, volume);
                EditorGUI.DrawRect(new Rect(p.x + 0.5f * (width * (1 - volume)), p.y, width * volume, height), color);

                Handles.EndGUI();
            }
#endif
        }

        private class AudioSourcePool
        {
            private int _nextChannel;

            public AudioSourcePool(AudioSource[] audioSources)
            {
                AudioSources = audioSources;
            }

            public AudioSource[] AudioSources { get; }

            public AudioSource GetAudioSource()
            {
                var source = AudioSources[_nextChannel];
                _nextChannel = (_nextChannel + 1) % ChannelCount;
                return source;
            }
        }
    }
}