using System;
using Unity.Netcode;
using UnityEngine;
using UnityEngine.SceneManagement;

namespace Unity.Multiplayer.Samples.Utilities
{
    //场景切换管理。SceneManager、NetworkSceneManager
    public class SceneLoaderWrapper : NetworkBehaviour
    {
        //[SerializeField]
        //ClientLoadingScreen m_ClientLoadingScreen;

        //[SerializeField]
        //LoadingProgressManager m_LoadingProgressManager;

        //是否开启了场景管理
        bool IsNetworkSceneManagementEnabled => NetworkManager != null && NetworkManager.SceneManager != null && NetworkManager.NetworkConfig.EnableSceneManagement;

        public static SceneLoaderWrapper Instance { get; protected set; }

        public virtual void Awake()
        {
            if (Instance != null && Instance != this)
            {
                Destroy(gameObject);
            }
            else
            {
                Instance = this;
            }

            DontDestroyOnLoad(this);
        }

        public virtual void Start()
        {
            SceneManager.sceneLoaded += OnSceneLoaded;
        }

        public override void OnDestroy()
        {
            SceneManager.sceneLoaded -= OnSceneLoaded;
            base.OnDestroy();
        }

        public override void OnNetworkDespawn()
        {
            if (NetworkManager != null && NetworkManager.SceneManager != null)
            {
                NetworkManager.SceneManager.OnSceneEvent -= OnSceneEvent;
            }
        }

        //添加场景加载回调
        public virtual void AddOnSceneEventCallback()
        {
            if (IsNetworkSceneManagementEnabled)
            {
                NetworkManager.SceneManager.OnSceneEvent += OnSceneEvent;
            }
        }

        //异步加载场景，可以用SceneManager（Unity自己的），也可以用NetworkSceneManager（NetCode）
        public virtual void LoadScene(string sceneName, bool useNetworkSceneManager, LoadSceneMode loadSceneMode = LoadSceneMode.Single)
        {
            if (useNetworkSceneManager)
            {
                //使用NetworkSceneManager加载场景
                if(IsSpawned && IsNetworkSceneManagementEnabled && !NetworkManager.ShutdownInProgress)
                {
                    if (NetworkManager.IsServer)
                    {
                        //必须服务端，才能加载场景
                        NetworkManager.SceneManager.LoadScene(sceneName, loadSceneMode);
                    }
                }
            }
            else
            {
                //使用SceneManager异步加载场景
                var loadOperation = SceneManager.LoadSceneAsync(sceneName, loadSceneMode);
                if (loadSceneMode == LoadSceneMode.Single)
                {
                    //m_ClientLoadingScreen.StartLoadingScreen(sceneName);
                    //m_LoadingProgressManager.LocalLoadOperation = loadOperation;
                }
            }
        }

        //Unity的场景切换成功
        void OnSceneLoaded(Scene scene, LoadSceneMode loadSceneMode)
        {
            if (!IsSpawned || NetworkManager.ShutdownInProgress)
            {
                //m_ClientLoadingScreen.StopLoadingScreen();
            }
        }

        //收到其他客户端发来的场景切换消息
        void OnSceneEvent(SceneEvent sceneEvent)
        {
            switch(sceneEvent.SceneEventType)
            {
                case SceneEventType.Load:
                    //服务端通知客户端切换场景
                    if(NetworkManager.IsClient)
                    {
                        //客户端进行UI显示
                        if(sceneEvent.LoadSceneMode == LoadSceneMode.Single)
                        {
                            //m_ClientLoadingScreen.StartLoadingScreen(sceneEvent.SceneName);
                            //m_LoadingProgressManager.LocalLoadOperation = sceneEvent.AsyncOperation;
                        }
                        else
                        {
                            //m_ClientLoadingScreen.UpdateLoadingScreen(sceneEvent.SceneName);
                            //m_LoadingProgressManager.LocalLoadOperation = sceneEvent.AsyncOperation;
                        }
                    }
                    break;
                case SceneEventType.LoadEventCompleted: 
                    //服务端通知客户端，所有的客户端都加载成功
                    if(NetworkManager.IsClient)
                    {
                        //m_ClientLoadingScreen.StopLoadingScreen();
                        //m_LoadingProgressManager.ResetLocalProgress();
                    }
                    break;
                case SceneEventType.Synchronize:
                    {
                        //服务端通知客户端，开始同步场景加载进度
                        if(NetworkManager.IsClient && !NetworkManager.IsHost)
                        {
                            //只有Client才执行（非Host）

                            //卸载其他场景
                            UnloadAdditiveScenes();
                        }
                        break;
                    }
                case SceneEventType.SynchronizeComplete:
                    // 客户端通知服务端，场景同步完成
                    if(NetworkManager.IsServer)
                    {
                        //服务端通知客户端隐藏Loading界面
                        StopLoadingScreenClientRpc(new ClientRpcParams { Send = new ClientRpcSendParams { TargetClientIds = new[] { sceneEvent.ClientId } } });
                    }
                    break;
            }
        }

        //Unity卸载其他场景（非ActiveScene）
        void UnloadAdditiveScenes()
        {
            var activeScene = SceneManager.GetActiveScene();
            for (var i = 0; i < SceneManager.sceneCount; i++)
            {
                var scene = SceneManager.GetSceneAt(i);
                if (scene.isLoaded && scene != activeScene)
                {
                    SceneManager.UnloadSceneAsync(scene);
                }
            }
        }

        //服务端通知客户端隐藏Loading界面
        [ClientRpc]
        void StopLoadingScreenClientRpc(ClientRpcParams clientRpcParams = default)
        {
            //m_ClientLoadingScreen.StopLoadingScreen();
        }
    }
}