using LibMMD.Motion;
using LibMMD.Reader;
using LibMMD.Unity3D.Animation;
using System;
using System.Threading.Tasks;
using UnityEngine;

namespace LibMMD.Unity3D
{
    public class MmdCameraObject : MonoBehaviour
    {
        private static readonly object CameraCacheLock = new object();
        private static string _cameraCacheKey;
        private static CameraMotion _cachedCameraMotion;

        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
        private static void ResetCameraCache()
        {
            lock (CameraCacheLock)
            {
                _cameraCacheKey = null;
                _cachedCameraMotion = null;
            }
        }

        private CameraMotion _cameraMotion = null; 
        public bool Playing = false;
        public bool Loop = false;
        private double _playTime;
        private Camera _camera;

        public static GameObject CreateGameObject(string name = "MMDCameraObject")
        {
            var cameraObj = new GameObject("Camera");
            var cameraComponent = cameraObj.AddComponent<Camera>();
            cameraComponent.backgroundColor = Color.black;
            cameraComponent.clearFlags = CameraClearFlags.Color;
            var obj = new GameObject(name);
            cameraComponent.transform.SetParent(obj.transform);
            var mmdCameraObject = obj.AddComponent<MmdCameraObject>();
            mmdCameraObject._camera = cameraComponent;            
            return obj;
        }
        
        public bool LoadCameraMotion(string path)
        {
            if (path == null)
            {
                _cameraMotion = null;
                return false;
            }
            return LoadCameraMotion(LoadCameraMotionData(path));
        }

        public static Task<CameraMotion> LoadCameraMotionAsync(string path)
        {
            if (string.IsNullOrWhiteSpace(path))
                throw new ArgumentException("A camera VMD path is required.", nameof(path));
            return Task.Run(() => LoadCameraMotionData(path));
        }

        public bool LoadCameraMotion(CameraMotion motion)
        {
            _cameraMotion = motion;
            if (_cameraMotion == null || _cameraMotion.KeyFrames.Count == 0) return false;
            ResetMotion();
            return true;
        }

        private static CameraMotion LoadCameraMotionData(string path)
        {
            var key = MmdMotionLoader.BuildKey(path);
            CameraMotion cameraMotion;
            lock (CameraCacheLock)
            {
                cameraMotion = key != null && key == _cameraCacheKey
                    ? _cachedCameraMotion
                    : null;
            }
            if (cameraMotion == null)
            {
                var parsed = new VmdReader().ReadCameraMotion(path);
                var keyAfterRead = MmdMotionLoader.BuildKey(path);
                cameraMotion = parsed;
                if (key != null && key == keyAfterRead)
                {
                    lock (CameraCacheLock)
                    {
                        _cameraCacheKey = key;
                        _cachedCameraMotion = parsed;
                    }
                }
            }
            return cameraMotion;
        }

        public double MotionLength => _cameraMotion != null && _cameraMotion.KeyFrames.Count > 0
            ? _cameraMotion.KeyFrames[_cameraMotion.KeyFrames.Count - 1].Key / 30.0
            : 0.0;

        public double PlayTime => _playTime;

        public void ResetMotion()
        {
            _playTime = 0.0;
            Playing = false;
            Refresh();
        }

        public void SetPlayPos(double pos)
        {
            _playTime = pos;
            Refresh();
        }

        private void Update()
        {
            if (!Playing || _cameraMotion == null)
            {
                return;
            }
            var deltaTime = Time.deltaTime;
            _playTime += deltaTime;
            if (Loop && MotionLength > 0.0 && _playTime >= MotionLength)
            {
                ResetMotion();
                Playing = true;
                return;
            }
            Refresh();
        }

        private void Refresh()
        {
            if (_cameraMotion == null)
            {
                return;
            }
            var cameraPose = _cameraMotion.GetCameraPose(_playTime);
            if (cameraPose == null)
            {
                return;
            }
            transform.position = cameraPose.Position;
            transform.rotation = Quaternion.Euler(- 180 / Mathf.PI * cameraPose.Rotation);
            _camera.transform.localPosition = new Vector3(0.0f, 0.0f, cameraPose.FocalLength);
            _camera.fieldOfView = cameraPose.Fov;
            _camera.orthographic = cameraPose.Orthographic;
        }
    }
}