using System;
using System.Collections;
using System.Text;
using TMPro;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.SceneManagement;
using UnityEngine.UI;

public class LoginManager : MonoBehaviour
{
    const string AuthBaseUrl = "http://vps.playpoolstudios.com:2612";
    const string PlayerPrefsAuthKey = "WalkInvest.AuthToken";

    const int MIN_USERNAME_LENGTH = 3;
    const int MAX_USERNAME_LENGTH = 16;
    const int MIN_PASSWORD_LENGTH = 8;
    const int MAX_PASSWORD_LENGTH = 20;

    [Header("Login")]
    [SerializeField] private TMP_InputField usernameInputLogin;
    [SerializeField] private TMP_InputField passwordInputLogin;
    [SerializeField] private Button btnLogin;
    [Header("Register")]
    [SerializeField] private TMP_InputField usernameInputRegister;
    [SerializeField] private TMP_InputField passwordInputRegister;
    [SerializeField] private Button btnRegister;

    [Header("UI")]
    [SerializeField] private TMP_Text error_txt;

    bool _authInProgress;

    public static string AuthToken { get; private set; }

    /// <summary>Latest user payload from the server. Reading this schedules a refresh (one in flight at a time).</summary>
    public static UserData CurrentUser
    {
        get
        {
            if (instance != null)
                instance.ScheduleUserDataRefreshOnRead();
            return _currentUser;
        }
    }

    public static Action<UserData> OnUserDataUpdated;

    static UserData _currentUser;
    bool _userDataReadRefreshPending;

    [Serializable]
    class AuthApiResponse
    {
        public bool ok;
        public string error;
        public string token;
    }

    [Serializable]
    class AuthUserApiResponse
    {
        public bool ok;
        public string error;
        public UserData user;
    }

    [Serializable]
    class PurchaseRcApiResponse
    {
        public bool ok;
        public string error;
    }

    public static LoginManager instance;

    void Awake()
    {
        error_txt.text = "";
        AuthToken = PlayerPrefs.GetString(PlayerPrefsAuthKey, "");

        if(instance !=null){
            Destroy(gameObject);
            return;
        }
        instance = this;
        DontDestroyOnLoad(gameObject);
    }

    void Start()
    {
        btnLogin.onClick.AddListener(OnLogin);
        btnRegister.onClick.AddListener(OnRegister);

        if (!string.IsNullOrEmpty(AuthToken))
        {
            SetBusy(true);
            StartCoroutine(ResumeSessionCoroutine());
        }
    }

    IEnumerator ResumeSessionCoroutine()
    {
        yield return StartCoroutine(FetchUserDataCoroutine(null, true));
        ProceedToMainMenu();
        SetBusy(false);
    }

    static void ProceedToMainMenu()
    {
        if (LevelLoadManager.instance != null)
            LevelLoadManager.LoadLevel("MainMenu");
        else
            SceneManager.LoadScene("MainMenu");
    }

    void SetBusy(bool busy)
    {
        _authInProgress = busy;
        if (btnLogin != null) btnLogin.interactable = !busy;
        if (btnRegister != null) btnRegister.interactable = !busy;
    }

    void OnLogin()
    {
        if (_authInProgress) return;

        string username = usernameInputLogin.text;
        string password = passwordInputLogin.text;
        if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
        {
            error_txt.text = "Please fill in all fields";
            return;
        }

        if (username.Length < MIN_USERNAME_LENGTH || username.Length > MAX_USERNAME_LENGTH)
        {
            error_txt.text = "Username must be between " + MIN_USERNAME_LENGTH + " and " + MAX_USERNAME_LENGTH + " characters";
            return;
        }

        if (password.Length < MIN_PASSWORD_LENGTH || password.Length > MAX_PASSWORD_LENGTH)
        {
            error_txt.text = "Password must be between " + MIN_PASSWORD_LENGTH + " and " + MAX_PASSWORD_LENGTH + " characters";
            return;
        }

        string json = "{\"username\":\"" + EscapeJsonString(username) + "\",\"password\":\"" + EscapeJsonString(password) + "\"}";
        StartCoroutine(AuthPostCoroutine(AuthBaseUrl + "/auth/login", json, "Signed in."));
    }

    void OnRegister()
    {
        if (_authInProgress) return;

        string username = usernameInputRegister.text;
        string password = passwordInputRegister.text;
        if (string.IsNullOrEmpty(username) || string.IsNullOrEmpty(password))
        {
            error_txt.text = "Please fill in all fields";
            return;
        }

        if (username.Length < MIN_USERNAME_LENGTH || username.Length > MAX_USERNAME_LENGTH)
        {
            error_txt.text = "Username must be between " + MIN_USERNAME_LENGTH + " and " + MAX_USERNAME_LENGTH + " characters";
            return;
        }

        if (password.Length < MIN_PASSWORD_LENGTH || password.Length > MAX_PASSWORD_LENGTH)
        {
            error_txt.text = "Password must be between " + MIN_PASSWORD_LENGTH + " and " + MAX_PASSWORD_LENGTH + " characters";
            return;
        }

        // Server register endpoint accepts username + password only (email field is optional UI-only).
        string json = "{\"username\":\"" + EscapeJsonString(username) + "\",\"password\":\"" + EscapeJsonString(password) + "\"}";
        StartCoroutine(AuthPostCoroutine(AuthBaseUrl + "/auth/register", json, "Account created."));
    }

    static string EscapeJsonString(string s)
    {
        if (string.IsNullOrEmpty(s)) return s;
        return s.Replace("\\", "\\\\").Replace("\"", "\\\"");
    }

    IEnumerator AuthPostCoroutine(string url, string jsonBody, string successMessage)
    {
        SetBusy(true);
        error_txt.text = "";

        using (var request = new UnityWebRequest(url, UnityWebRequest.kHttpVerbPOST))
        {
            byte[] bodyRaw = Encoding.UTF8.GetBytes(jsonBody);
            request.uploadHandler = new UploadHandlerRaw(bodyRaw);
            request.downloadHandler = new DownloadHandlerBuffer();
            request.SetRequestHeader("Content-Type", "application/json");

            yield return request.SendWebRequest();

            string text = request.downloadHandler != null ? request.downloadHandler.text : "";

            if (request.result != UnityWebRequest.Result.Success &&
                request.result != UnityWebRequest.Result.ProtocolError)
            {
                error_txt.text = string.IsNullOrEmpty(request.error) ? "Network error" : request.error;
                SetBusy(false);
                yield break;
            }

            if (string.IsNullOrEmpty(text))
            {
                error_txt.text = "Empty response from server";
                SetBusy(false);
                yield break;
            }

            AuthApiResponse resp = JsonUtility.FromJson<AuthApiResponse>(text);

            if (resp.ok && !string.IsNullOrEmpty(resp.token))
            {
                AuthToken = resp.token;
                PlayerPrefs.SetString(PlayerPrefsAuthKey, resp.token);
                PlayerPrefs.Save();

                yield return StartCoroutine(FetchUserDataCoroutine(null, true));
                ProceedToMainMenu();
            }
            else
            {
                error_txt.text = string.IsNullOrEmpty(resp.error) ? "Request failed" : resp.error;
            }
        }

        SetBusy(false);
    }

    static void ApplyUserData(UserData u)
    {
        _currentUser = u;
        OnUserDataUpdated?.Invoke(u);
    }

    void ScheduleUserDataRefreshOnRead()
    {
        if (string.IsNullOrEmpty(AuthToken)) return;
        if (_userDataReadRefreshPending) return;
        _userDataReadRefreshPending = true;
        StartCoroutine(UserDataReadRefreshCoroutine());
    }

    IEnumerator UserDataReadRefreshCoroutine()
    {
        try
        {
            yield return StartCoroutine(FetchUserDataCoroutine(null, true));
        }
        finally
        {
            _userDataReadRefreshPending = false;
        }
    }

    /// <summary>GET /auth/user; updates <see cref="CurrentUser"/> when successful. Callback (success, errorOrNull, userOrNull).</summary>
    public void GetUserData(Action<bool, string, UserData> onComplete)
    {
        StartCoroutine(FetchUserDataCoroutine(onComplete, true));
    }

    /// <summary>GET /auth/rc-packs (no auth). Callback (success, errorOrNull, jsonOrNull).</summary>
    public void GetRcPacks(Action<bool, string, string> onComplete)
    {
        StartCoroutine(GetRcPacksCoroutine(onComplete));
    }

    IEnumerator GetRcPacksCoroutine(Action<bool, string, string> onComplete)
    {
        string url = AuthBaseUrl + "/auth/rc-packs";
        using (var request = UnityWebRequest.Get(url))
        {
            request.downloadHandler = new DownloadHandlerBuffer();

            yield return request.SendWebRequest();

            string text = request.downloadHandler != null ? request.downloadHandler.text : "";

            if (request.result != UnityWebRequest.Result.Success &&
                request.result != UnityWebRequest.Result.ProtocolError)
            {
                onComplete?.Invoke(false, string.IsNullOrEmpty(request.error) ? "Network error" : request.error, null);
                yield break;
            }

            if (request.responseCode < 200 || request.responseCode >= 300)
            {
                onComplete?.Invoke(false, string.IsNullOrEmpty(text) ? "Request failed (" + request.responseCode + ")" : text, null);
                yield break;
            }

            onComplete?.Invoke(true, null, text);
        }
    }

    /// <summary>POST /auth/purchase-rc with <c>{"pack":"usd_5"|...}</c>. Refreshes profile on success. Callback (success, errorOrNull).</summary>
    public void PurchaseRcPack(string packId, Action<bool, string> onComplete)
    {
        StartCoroutine(PurchaseRcCoroutine(packId, onComplete));
    }

    IEnumerator PurchaseRcCoroutine(string packId, Action<bool, string> onComplete)
    {
        if (string.IsNullOrEmpty(AuthToken))
        {
            onComplete?.Invoke(false, "Not signed in");
            yield break;
        }

        if (!RcPack.IsValid(packId))
        {
            onComplete?.Invoke(false, "Invalid pack (use " + RcPack.Usd5 + ", " + RcPack.Usd20 + ", or " + RcPack.Usd50 + ")");
            yield break;
        }

        string json = "{\"pack\":\"" + EscapeJsonString(packId) + "\"}";
        string url = AuthBaseUrl + "/auth/purchase-rc";

        using (var request = new UnityWebRequest(url, UnityWebRequest.kHttpVerbPOST))
        {
            byte[] bodyRaw = Encoding.UTF8.GetBytes(json);
            request.uploadHandler = new UploadHandlerRaw(bodyRaw);
            request.downloadHandler = new DownloadHandlerBuffer();
            request.SetRequestHeader("Content-Type", "application/json");
            request.SetRequestHeader("Authorization", "Bearer " + AuthToken);

            yield return request.SendWebRequest();

            string text = request.downloadHandler != null ? request.downloadHandler.text : "";

            if (request.result != UnityWebRequest.Result.Success &&
                request.result != UnityWebRequest.Result.ProtocolError)
            {
                onComplete?.Invoke(false, string.IsNullOrEmpty(request.error) ? "Network error" : request.error);
                yield break;
            }

            if (request.responseCode < 200 || request.responseCode >= 300)
            {
                onComplete?.Invoke(false, string.IsNullOrEmpty(text) ? "Request failed (" + request.responseCode + ")" : text);
                yield break;
            }

            if (string.IsNullOrEmpty(text))
            {
                onComplete?.Invoke(false, "Empty response from server");
                yield break;
            }

            PurchaseRcApiResponse resp = JsonUtility.FromJson<PurchaseRcApiResponse>(text);

            if (resp != null && resp.ok)
            {
                bool refreshOk = false;
                string refreshErr = null;
                yield return StartCoroutine(FetchUserDataCoroutine((ok, err, u) =>
                {
                    refreshOk = ok;
                    refreshErr = err;
                }, true));

                if (refreshOk)
                    onComplete?.Invoke(true, null);
                else
                    onComplete?.Invoke(false, string.IsNullOrEmpty(refreshErr) ? "Purchase ok but profile refresh failed" : refreshErr);
            }
            else
            {
                string err = resp != null && !string.IsNullOrEmpty(resp.error) ? resp.error : "Purchase failed";
                onComplete?.Invoke(false, err);
            }
        }
    }

    IEnumerator FetchUserDataCoroutine(Action<bool, string, UserData> onComplete, bool applyToStatic)
    {
        if (string.IsNullOrEmpty(AuthToken))
        {
            onComplete?.Invoke(false, "Not signed in", null);
            yield break;
        }

        string url = AuthBaseUrl + "/auth/user";
        using (var request = UnityWebRequest.Get(url))
        {
            request.downloadHandler = new DownloadHandlerBuffer();
            request.SetRequestHeader("Authorization", "Bearer " + AuthToken);

            yield return request.SendWebRequest();

            string text = request.downloadHandler != null ? request.downloadHandler.text : "";

            if (request.result != UnityWebRequest.Result.Success &&
                request.result != UnityWebRequest.Result.ProtocolError)
            {
                onComplete?.Invoke(false, string.IsNullOrEmpty(request.error) ? "Network error" : request.error, null);
                yield break;
            }

            if (request.responseCode < 200 || request.responseCode >= 300)
            {
                onComplete?.Invoke(false, string.IsNullOrEmpty(text) ? "Request failed (" + request.responseCode + ")" : text, null);
                yield break;
            }

            if (string.IsNullOrEmpty(text))
            {
                onComplete?.Invoke(false, "Empty response from server", null);
                yield break;
            }

            AuthUserApiResponse resp = JsonUtility.FromJson<AuthUserApiResponse>(text);

            if (resp != null && resp.ok && resp.user != null)
            {
                if (applyToStatic)
                    ApplyUserData(resp.user);
                onComplete?.Invoke(true, null, resp.user);
            }
            else
            {
                string err = resp != null && !string.IsNullOrEmpty(resp.error) ? resp.error : "Request failed";
                onComplete?.Invoke(false, err, null);
            }
        }
    }
}

[Serializable]
public class UserData
{
    public int id;
    public string username;
    public int cc;
    public int rc;
    public string created_at;
    public string last_logged_at;
}

/// <summary>Typical <c>pack</c> ids for <see cref="LoginManager.PurchaseRcPack"/>; prefer <see cref="LoginManager.GetRcPacks"/> for the live list.</summary>
public static class RcPack
{
    public const string Usd5 = "usd_5";
    public const string Usd20 = "usd_20";
    public const string Usd50 = "usd_50";

    public static bool IsValid(string packId)
    {
        return packId == Usd5 || packId == Usd20 || packId == Usd50;
    }
}

public static class CoinHelper{
    public static float Format(int coins){
        int whole = coins / 4;
        int fraction = coins % 4;
        return float.Parse(whole + "." + fraction);
    }

    public static string FormatString(int coins){
        return Format(coins).ToString("N2");
    }
}