// ***********************************************************************
// Assembly         : Unity
// Author           : Kimch
// Created          : 2018-04-27
//
// Last Modified By : Kimch
// Last Modified On : 
// ***********************************************************************
// <copyright file= "SceneLoader" company="Kunpo"></copyright>
// <summary></summary>
// ***********************************************************************
#define USE_AddressableAssets

namespace G
{
	using System;
	using System.Collections;
	using UnityEngine;
	using UnityEngine.SceneManagement;

#if USE_AddressableAssets
	using UnityEngine.AddressableAssets;
	using UnityEngine.ResourceManagement.AsyncOperations;
#endif

	/// <summary>
	/// 
	/// </summary>
	public class SceneLoader : MonoBehaviour, F.IAsyncResult
	{
		#region Field

		/// <summary>
		/// 
		/// </summary>
		private string _currentSceneName;

		private bool _loading;
		private float _progress;

#if USE_AddressableAssets
		AsyncOperationHandle _sceneAOHandle;
#endif

		#endregion

		/// <summary>
		/// 
		/// </summary>
		public bool isLoading
		{
			get { return _loading; }
		}

		/// <summary>
		/// 
		/// </summary>
		public bool showLoading
		{
			get;
			set;
		}

		#region Unity Method

		private static SceneLoader _Instance;
		public static SceneLoader Instance
		{
			get
			{
				if (_Instance is null)
				{
					_Instance = new GameObject(nameof(SceneLoader)).AddComponent<SceneLoader>();
				}
				return _Instance;
			}
		}

		private void Awake()
		{
			_Instance = this;
			DontDestroyOnLoad(this.gameObject);
			SceneManager.sceneLoaded += this.OnSceneLoaded;
			SceneManager.sceneUnloaded += this.OnSceneUnloaded;
		}

		private void OnSceneLoaded(Scene arg0, LoadSceneMode arg1)
		{
			//Debug.Log($"OnSceneLoaded {arg0.name}");
		}

		private void OnSceneUnloaded(Scene scene)
		{
			if (_currentSceneName == scene.name)
			{
				_currentSceneName = null;
			}
		}

		#endregion

		#region Method 

		/// <summary>
		/// 
		/// </summary>
		/// <param name="name"></param>
		/// <param name="action"></param>
		public void LoadSceneAsync(string name, Action<int> completed)
		{
			if (_currentSceneName != name)
			{
				_loading = true;
				_progress = 0f;
				StartCoroutine(LoadSceneCoroutine(name, completed));
			}
			else
			{
				completed?.Invoke(0);
			}
		}

		/// <summary>
		/// 
		/// </summary>
		public void UnloadScene()
		{
			if (_currentSceneName != null)
			{
				_loading = true;
				_progress = 0f;
				StartCoroutine(LoadSceneCoroutine(null, null));
			}
		}

		/// <summary>
		/// 
		/// </summary>
		/// <param name="name"></param>
		/// <param name="completed"></param>
		/// <returns></returns>
		private IEnumerator LoadSceneCoroutine(string name, Action<int> completed)
		{
			yield return null;

			if (!string.IsNullOrEmpty(_currentSceneName))
			{
#if USE_AddressableAssets
				var unloadHandle = Addressables.UnloadSceneAsync(_sceneAOHandle);
				while (!unloadHandle.IsDone)
				{
					_progress = unloadHandle.PercentComplete * 0.2f;
					yield return null;
				}
#else
				var asyncOp = SceneManager.UnloadSceneAsync(_currentSceneName);
				if (asyncOp != null)
				{
					while (!asyncOp.isDone)
					{
						_progress = asyncOp.progress * 0.2f;
						yield return null;
					}
				}
#endif
				_currentSceneName = null;
			}

			if (!string.IsNullOrEmpty(name))
			{
#if USE_AddressableAssets
				var asyncOp = Addressables.LoadSceneAsync(name);
				while (!asyncOp.IsDone)
				{
					_progress = asyncOp.PercentComplete * 0.8f + 0.2f;
					yield return null;
				}
				_sceneAOHandle = asyncOp;
#else
				var asyncOp = SceneManager.LoadSceneAsync(name);
				while (!asyncOp.isDone)
				{
					_progress = asyncOp.progress * 0.8f + 0.2f;
					yield return null;
				}
#endif
				_progress = 1f + float.Epsilon;
				_currentSceneName = name;
			}

			completed?.Invoke(0);
			_loading = false;
		}

		bool F.IAsyncResult.isDone
		{
			get { return _progress > 1f; }
		}

		string F.IAsyncResult.errorMsg
		{
			get { return ""; }
		}

		float F.IAsyncResult.progress
		{
			get { return _progress; }
		}

		object F.IAsyncResult.userData
		{
			get { return this; }
		}

		#endregion
	}
}