using System;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.Networking;
using Fusion;

public class AssetBundleNetworkDownloader : NetworkBehaviour
{
    [Header("Reference")]
    public GameObject map; // Where to spawn downloaded content

    [Networked, OnChangedRender(nameof(OnUrlChanged))]
    private NetworkString<_512> BundleUrl { get; set; }

    [NonSerialized] public bool serverDownloaded = false;

    private string _previousUrl = null;

    public override void Spawned()
    {
        Debug.Log($"[AssetBundleDownloader] Spawned for {Object.InputAuthority}");

        if (Object.HasInputAuthority)
        {
            string url = EN.instance.mapUrl;
            if (!string.IsNullOrEmpty(url))
            {
                Debug.Log($"[AssetBundleDownloader] Setting BundleUrl to {url}");
                BundleUrl = url;
            }
            else
            {
                Debug.LogWarning("[AssetBundleDownloader] Empty mapUrl in EN.instance");
            }
        }
        else
        {
            // Late joiner: use already set BundleUrl
            if (!string.IsNullOrEmpty(BundleUrl.ToString()))
            {
                _previousUrl = BundleUrl.ToString();
                Debug.Log($"[AssetBundleDownloader] Late joiner loading bundle: {_previousUrl}");
                _ = DownloadAndInstantiate(_previousUrl);
            }
        }
    }

    private void OnUrlChanged()
    {
        Debug.Log($"[AssetBundleDownloader] OnUrlChanged triggered: {BundleUrl}");

        string newUrl = BundleUrl.ToString();
        if (!string.IsNullOrEmpty(newUrl) && newUrl != _previousUrl)
        {
            _previousUrl = newUrl;
            _ = DownloadAndInstantiate(newUrl);
        }
    }

    private async Task DownloadAndInstantiate(string url)
    {
        serverDownloaded = false;

        using (UnityWebRequest uwr = UnityWebRequestAssetBundle.GetAssetBundle(url))
        {
            var op = uwr.SendWebRequest();
            while (!op.isDone)
                await Task.Yield();

            if (uwr.result != UnityWebRequest.Result.Success)
            {
                Debug.LogError($"[AssetBundleDownloader] Download failed: {uwr.error}");
                return;
            }

            AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(uwr);
            if (bundle == null)
            {
                Debug.LogError("[AssetBundleDownloader] Failed to load AssetBundle content");
                return;
            }

            string[] assetNames = bundle.GetAllAssetNames();
            if (assetNames.Length > 0)
            {
                GameObject prefab = bundle.LoadAsset<GameObject>(assetNames[0]);
                if (prefab != null)
                {
                    GameObject obj = Instantiate(prefab, map ? map.transform.position : Vector3.zero, Quaternion.identity);
                    obj.tag = "NetworkAssetBundle";
                    Debug.Log("[AssetBundleDownloader] Asset instantiated.");
                }
            }
            else
            {
                Debug.LogWarning("[AssetBundleDownloader] No assets found in bundle.");
            }

            bundle.Unload(false); // Keep loaded assets in memory
            serverDownloaded = true;
        }
    }
}