using System;
using System.Collections;
using GameServer.Client;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.UI;

public class serverSelector : MonoBehaviour
{
    private const string DefaultServerUrl = "http://47.112.187.172:8080";
    private const float RefreshIntervalSeconds = 5f;
    private const float StatusCacheDurationSeconds = 60f;

    [Header("button")]
    [SerializeField] private Button serverSelectorButton;

    [Header("text")]
    [SerializeField] private Text currentServerName;
    [SerializeField] private Image currentServerStatus;
    [SerializeField] private uServerStatus currentServerStatusDisplay;

    [Header("Server Status Sprites")]
    [SerializeField] private Sprite serverOkaySprite;
    [SerializeField] private Sprite serverBusySprite;
    [SerializeField] private Sprite serverErrorSprite;
    [SerializeField] private Sprite serverSupportingSprite;
    [SerializeField] private Sprite userOfflineSprite;

    [Header("objs")]
    [SerializeField] private GameObject serverSelectorPanel;
    [SerializeField] private Button shutSSPanel;

    [Header("network")]
    [SerializeField] private string fallbackServerUrl = DefaultServerUrl;
    [SerializeField] private float requestTimeoutSeconds = 5f;

    private Coroutine _pollCoroutine;
    private bool _started;
    private static bool s_hasCachedStatus;
    private static uServerStatus.ServerStatus s_cachedStatus;
    private static DateTime s_lastValidationUtc;

    [Serializable]
    private class ServerStatusResponse
    {
        public bool success;
        public string server_state;
        public bool maintenance_enabled;
        public string maintenance_message;
        public float requests_per_second;
        public float busy_qps_threshold;
    }

    private void Awake()
    {
        if (serverSelectorButton != null)
        {
            serverSelectorButton.onClick.RemoveListener(OpenServerSelectorPanel);
            serverSelectorButton.onClick.AddListener(OpenServerSelectorPanel);
        }

        if (shutSSPanel != null)
        {
            shutSSPanel.onClick.RemoveListener(CloseServerSelectorPanel);
            shutSSPanel.onClick.AddListener(CloseServerSelectorPanel);
        }
    }

    private void Start()
    {
        _started = true;

        if (serverSelectorPanel != null)
        {
            serverSelectorPanel.SetActive(false);
        }

        if (OnlineModeSettings.IsLocalOnlyMode)
        {
            ApplyStatus(uServerStatus.ServerStatus.Offline);
            return;
        }

        StartOrRestartPolling(refreshImmediately: true);
    }

    private void OnEnable()
    {
        if (!_started || !Application.isPlaying)
        {
            return;
        }

        if (OnlineModeSettings.IsLocalOnlyMode)
        {
            ApplyStatus(uServerStatus.ServerStatus.Offline);
            return;
        }

        StartOrRestartPolling(refreshImmediately: true);
    }

    private void StartOrRestartPolling(bool refreshImmediately)
    {
        if (_pollCoroutine != null)
        {
            StopCoroutine(_pollCoroutine);
            _pollCoroutine = null;
        }

        _pollCoroutine = StartCoroutine(StatusPollLoop(refreshImmediately));
    }

    private void OnDisable()
    {
        if (_pollCoroutine != null)
        {
            StopCoroutine(_pollCoroutine);
            _pollCoroutine = null;
        }
    }

    private IEnumerator StatusPollLoop(bool refreshImmediately)
    {
        if (refreshImmediately)
        {
            if (TryApplyFreshCachedStatus())
            {
                float remainingLockDuration = GetRemainingCacheLockSeconds();
                if (remainingLockDuration > 0f)
                {
                    yield return new WaitForSecondsRealtime(remainingLockDuration);
                }
            }

            yield return RefreshServerStatus();
        }

        while (true)
        {
            yield return new WaitForSecondsRealtime(RefreshIntervalSeconds);
            yield return RefreshServerStatus();
        }
    }

    private IEnumerator RefreshServerStatus()
    {
        if (OnlineModeSettings.IsLocalOnlyMode)
        {
            ApplyStatus(uServerStatus.ServerStatus.Offline);
            yield break;
        }

        if (Application.internetReachability == NetworkReachability.NotReachable)
        {
            ApplyStatus(uServerStatus.ServerStatus.Offline);
            yield break;
        }

        string statusUrl = BuildServerStatusUrl();
        using (UnityWebRequest request = UnityWebRequest.Get(statusUrl))
        {
            request.timeout = Mathf.Max(1, Mathf.RoundToInt(requestTimeoutSeconds));
            yield return request.SendWebRequest();

            if (request.result != UnityWebRequest.Result.Success)
            {
                CacheAndApplyStatus(uServerStatus.ServerStatus.Unreachable);
                yield break;
            }

            string responseText = request.downloadHandler != null ? request.downloadHandler.text : string.Empty;
            if (string.IsNullOrWhiteSpace(responseText))
            {
                CacheAndApplyStatus(uServerStatus.ServerStatus.Unreachable);
                yield break;
            }

            ServerStatusResponse response;
            try
            {
                response = JsonUtility.FromJson<ServerStatusResponse>(responseText);
            }
            catch
            {
                CacheAndApplyStatus(uServerStatus.ServerStatus.Unreachable);
                yield break;
            }

            if (response == null || !response.success)
            {
                CacheAndApplyStatus(uServerStatus.ServerStatus.Unreachable);
                yield break;
            }

            CacheAndApplyStatus(ResolveStatus(response));
        }
    }

    private void OpenServerSelectorPanel()
    {
        if (serverSelectorPanel != null)
        {
            serverSelectorPanel.SetActive(true);
        }

        if (!OnlineModeSettings.IsLocalOnlyMode)
        {
            StartCoroutine(RefreshServerStatusIfNeeded());
        }
        else
        {
            ApplyStatus(uServerStatus.ServerStatus.Offline);
        }
    }

    private void CloseServerSelectorPanel()
    {
        if (serverSelectorPanel != null)
        {
            serverSelectorPanel.SetActive(false);
        }
    }

    private string ResolveServerBaseUrl()
    {
        NetworkManager manager = NetworkManager.Instance;
        if (manager != null && !string.IsNullOrWhiteSpace(manager.ServerUrl))
        {
            return manager.ServerUrl.TrimEnd('/');
        }

        return string.IsNullOrWhiteSpace(fallbackServerUrl) ? DefaultServerUrl : fallbackServerUrl.TrimEnd('/');
    }

    private string BuildServerStatusUrl()
    {
        return $"{ResolveServerBaseUrl()}/api/server-status";
    }

    private IEnumerator RefreshServerStatusIfNeeded()
    {
        if (TryApplyFreshCachedStatus())
        {
            yield break;
        }

        yield return RefreshServerStatus();
    }

    private uServerStatus.ServerStatus ResolveStatus(ServerStatusResponse response)
    {
        if (response == null)
        {
            return uServerStatus.ServerStatus.Unreachable;
        }

        if (response.maintenance_enabled)
        {
            return uServerStatus.ServerStatus.Maintenance;
        }

        string normalizedState = (response.server_state ?? string.Empty).Trim().ToUpperInvariant();
        switch (normalizedState)
        {
            case "MAINTENANCE":
                return uServerStatus.ServerStatus.Maintenance;
            case "BUSY":
                return uServerStatus.ServerStatus.Fair;
            case "OK":
                if (response.busy_qps_threshold > 0f &&
                    response.requests_per_second >= response.busy_qps_threshold)
                {
                    return uServerStatus.ServerStatus.Fair;
                }

                return uServerStatus.ServerStatus.Good;
            default:
                return uServerStatus.ServerStatus.Unknown;
        }
    }

    private bool TryApplyFreshCachedStatus()
    {
        if (!HasFreshCachedStatus())
        {
            return false;
        }

        ApplyStatus(s_cachedStatus);
        return true;
    }

    private bool HasFreshCachedStatus()
    {
        if (!s_hasCachedStatus)
        {
            return false;
        }

        return (DateTime.UtcNow - s_lastValidationUtc).TotalSeconds < StatusCacheDurationSeconds;
    }

    private float GetRemainingCacheLockSeconds()
    {
        if (!s_hasCachedStatus)
        {
            return 0f;
        }

        double elapsedSeconds = (DateTime.UtcNow - s_lastValidationUtc).TotalSeconds;
        return Mathf.Max(0f, StatusCacheDurationSeconds - (float)elapsedSeconds);
    }

    private void CacheAndApplyStatus(uServerStatus.ServerStatus status)
    {
        s_cachedStatus = status;
        s_lastValidationUtc = DateTime.UtcNow;
        s_hasCachedStatus = true;
        ApplyStatus(status);
    }

    private Sprite ResolveSpriteForStatus(uServerStatus.ServerStatus status)
    {
        switch (status)
        {
            case uServerStatus.ServerStatus.Good:
                return serverOkaySprite;
            case uServerStatus.ServerStatus.Fair:
                return serverBusySprite;
            case uServerStatus.ServerStatus.Maintenance:
                return serverSupportingSprite;
            case uServerStatus.ServerStatus.Offline:
                return userOfflineSprite != null ? userOfflineSprite : serverErrorSprite;
            case uServerStatus.ServerStatus.Unreachable:
            case uServerStatus.ServerStatus.Unknown:
            case uServerStatus.ServerStatus.Test:
            default:
                return serverErrorSprite;
        }
    }

    private void ApplyStatus(uServerStatus.ServerStatus status)
    {
        Sprite sprite = ResolveSpriteForStatus(status);

        if (currentServerStatus == null || sprite == null)
        {
            if (currentServerStatusDisplay != null)
            {
                currentServerStatusDisplay.SetStatus(status);
            }

            return;
        }

        currentServerStatus.sprite = sprite;

        if (currentServerStatusDisplay != null)
        {
            currentServerStatusDisplay.SetStatus(status);
        }
    }
}