using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class DynamicSceneManager : MonoBehaviour
{
    private static DynamicSceneManager _instance;
    public static DynamicSceneManager GetInstance() { return _instance; }

    private Dictionary<GameObject, bool> originalChunkStates = new Dictionary<GameObject, bool>();
    public HashSet<string> loadedScenes = new HashSet<string>(); // Track loaded scenes

    private void Awake()
    {
        if (_instance == null)
        {
            _instance = this;
            DontDestroyOnLoad(gameObject);  // This ensures the object persists across scene loads
        }
        else
        {
            Destroy(gameObject);  // This prevents duplicate instances
        }


        //foreach (string nearbyScene in RoomManager.GetInstance()._nearbyRoomSceneNames)
        //{
        //    RetainScene(nearbyScene);
        //}
    }
    public void EnableChunks(List<GameObject> chunksToEnable, string sceneName)
    {
        Debug.Log($"Starting gradual enabling of {chunksToEnable.Count} chunks for scene {sceneName}");

        foreach (var chunk in chunksToEnable)
        {
            if (!originalChunkStates.ContainsKey(chunk))
            {
                originalChunkStates[chunk] = chunk.activeSelf; // store initial state
            }
        }

        if (!SceneManager.GetSceneByName(sceneName).isLoaded)
        {
            Debug.Log($"Scene {sceneName} is not loaded. Loading it now.");
            LoadSceneAsync(sceneName, chunksToEnable);
        }
        else
        {
            Debug.Log($"Scene {sceneName} is already loaded. Enabling valid chunks.");
            StartCoroutine(GradualEnableChunks(chunksToEnable));
        }
    }

    public void DisableChunksExcept(List<GameObject> chunksToKeep, string sceneName)
    {
        Debug.Log($"Disabling chunks for scene: {sceneName}, keeping {chunksToKeep.Count} chunks.");

        if (!IsSceneLoaded(sceneName))
        {
            Debug.LogWarning($"Attempted to disable chunks for an unloaded scene: {sceneName}");
            return;
        }

        List<GameObject> chunksToDisable = new List<GameObject>();

        foreach (GameObject rootObject in SceneManager.GetSceneByName(sceneName).GetRootGameObjects())
        {
            foreach (Transform child in rootObject.GetComponentsInChildren<Transform>(true))
            {
                if (!chunksToKeep.Contains(child.gameObject) && child.gameObject.activeSelf)
                {
                    chunksToDisable.Add(child.gameObject);
                }
            }
        }
        //
       // StartCoroutine(GradualUnloadChunks(chunksToDisable, sceneName));
    }

    private IEnumerator GradualLoadChunks(List<GameObject> chunksToEnable)
    {
        foreach (GameObject chunk in chunksToEnable)
        {
            if (chunk != null && !chunk.activeSelf)
            {
                chunk.SetActive(true);
                Debug.Log($"Enabled chunk: {chunk.name}");
                yield return null; // Distribute work across frames

            }
        }
    }

    private IEnumerator GradualEnableChunks(List<GameObject> chunksToEnable)
    {
        foreach (GameObject chunk in chunksToEnable)
        {
            if (chunk != null && !chunk.activeSelf)
            {
                if (originalChunkStates.ContainsKey(chunk) && originalChunkStates[chunk])
                {
                    chunk.SetActive(true);
                    Debug.Log($"Enabled chunk: {chunk.name}");
                }
                else
                {
                    Debug.Log($"Skipping chunk {chunk.name} - was originally inactive");
                }
                yield return null;
            }
        }
    }

    private void GradualUnloadChunks(List<GameObject> chunksToUnload)
    {
        StartCoroutine(GradualDisableChunks(chunksToUnload));
    }

    private IEnumerator GradualDisableChunks(List<GameObject> chunksToUnload)
    {
        foreach (GameObject chunk in chunksToUnload)
        {
            if (chunk != null && chunk.activeSelf)
            {
                chunk.SetActive(false);
                Debug.Log($"Disabled chunk: {chunk.name}");
                yield return null; // Spread disabling chunks across frames
            }
        }
    }
    public void RetainScene(string sceneName)
    {
        if (SceneManager.GetSceneByName(sceneName).isLoaded)
        {
            Debug.Log($"Scene {sceneName} is already loaded. Skipping RetainScene.");
            loadedScenes.Add(sceneName);
            return;
        }

        // Add to loadedScenes list and load the scene
        if (!loadedScenes.Contains(sceneName))
            loadedScenes.Add(sceneName);

        SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive);
        Debug.Log($"Scene {sceneName} retained successfully.");
    }
    public void RetainScenes(List<string> nearbyScenes)
    {
        if (nearbyScenes == null || nearbyScenes.Count == 0)
        {
            Debug.LogWarning("RetainScenes called with an empty or null list. No scenes retained.");
            return;
        }

        nearbyScenes.RemoveAll(scene => string.IsNullOrWhiteSpace(scene)); // Αφαίρεση άδειων ή μη έγκυρων ονομάτων

        foreach (string sceneName in nearbyScenes)
        {
            if (!loadedScenes.Contains(sceneName))
            {
                RetainScene(sceneName);
            }
            else
            {
                Debug.Log($"Scene {sceneName} is already loaded. Skipping.");
            }
        }

        // Handle unloading as before
        var scenesToUnload = new HashSet<string>(loadedScenes);
        scenesToUnload.ExceptWith(nearbyScenes);

        foreach (string sceneName in scenesToUnload)
        {
            Debug.Log($"Unloading scene: {sceneName}");
            UnloadSceneAsync(sceneName);
        }
    }

    public void ReleaseScenes(List<string> nearbyScenes)
    {
        var scenesToUnload = new HashSet<string>(loadedScenes);

        // Retain nearby scenes
        scenesToUnload.ExceptWith(nearbyScenes);

        foreach (string sceneName in scenesToUnload)
        {
            Debug.Log($"Unloading scene: {sceneName}");
            UnloadSceneAsync(sceneName);
        }

    }

    private void LoadSceneAsync(string sceneName, List<GameObject> chunksToEnable = null)
    {
        SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive).completed += (op) =>
        {
            if (op.isDone)
            {
                loadedScenes.Add(sceneName);
                Debug.Log($"Scene {sceneName} successfully loaded.");

                if (chunksToEnable != null)
                {
                    StartCoroutine(GradualEnableChunks(chunksToEnable));
                }
            }
        };
    }

    public void UnloadSceneAsync(string sceneName)
    {
        if (string.IsNullOrEmpty(sceneName))
        {
            Debug.LogError("Cannot unload scene: Scene name is null or empty.");
            return;
        }

        if (loadedScenes == null)
        {
            Debug.LogError("loadedScenes list is null!");
            return;
        }

        if (loadedScenes.Contains(sceneName))
        {
            Debug.Log($"Attempting to unload scene: {sceneName}");

            SceneManager.UnloadSceneAsync(sceneName).completed += op =>
            {
                if (op.isDone)
                {
                    loadedScenes.Remove(sceneName);
                    Debug.Log($"Scene {sceneName} successfully unloaded.");
                }
            };
        }
        else
        {
            Debug.LogWarning($"Scene {sceneName} is not loaded. Cannot unload.");
        }
    }

    public bool IsSceneLoaded(string sceneName)
    {
        return loadedScenes.Contains(sceneName);
    }
    public HashSet<string> GetLoadedScenes()
    {
        return new HashSet<string>(loadedScenes);
    }

}