using System;
using System.Linq;
using System.Threading.Tasks;
using UnityEngine;
using UnityEngine.UI;
using Vanguard.Api;
using Vanguard.App;
using Vanguard.Auth;

namespace Vanguard.UI
{
    /// <summary>Экран входа/регистрации и выбора адреса сервера.</summary>
    public sealed class LoginView
    {
        private readonly AppConfig _config;
        private readonly AuthService _auth;
        private readonly Action _onAuthenticated;

        private readonly RectTransform _root;
        private readonly InputField _serverUrl;
        private readonly InputField _userName;
        private readonly InputField _password;
        private readonly Button _loginButton;
        private readonly Button _registerButton;
        private readonly Text _status;
        private bool _busy;

        public LoginView(
            Transform parent,
            AppConfig config,
            AuthService auth,
            Action onAuthenticated)
        {
            _config = config;
            _auth = auth;
            _onAuthenticated = onAuthenticated;

            _root = UiKit.CreatePanel(parent, "LoginScreen", new Color(0.035f, 0.045f, 0.065f, 1f));

            var card = UiKit.CreateCenteredCard(
                _root,
                "LoginCard",
                new Vector2(640f, 790f),
                new Color(0.07f, 0.085f, 0.115f, 1f));

            UiKit.AddVerticalLayout(card, 36, 10);

            var title = UiKit.CreateText(
                card, "Title", "VANGUARD", 54, new Color(0.86f, 0.90f, 1f));
            title.fontStyle = FontStyle.Bold;
            UiKit.SetPreferredHeight(title, 64f);

            var subtitle = UiKit.CreateText(
                card, "Subtitle", "ReMaster · сетевой клиент", 20,
                new Color(0.62f, 0.68f, 0.82f));
            UiKit.SetPreferredHeight(subtitle, 34f);

            AddCaption(card, "Сервер");
            _serverUrl = UiKit.CreateInput(card, "ServerUrl", "http://192.168.31.158:18080");
            _serverUrl.text = _config.ServerBaseUrl;
            UiKit.SetPreferredHeight(_serverUrl, 54f);

            AddCaption(card, "Имя игрока");
            _userName = UiKit.CreateInput(card, "UserName", "3–32 символа");
            UiKit.SetPreferredHeight(_userName, 54f);

            AddCaption(card, "Пароль");
            _password = UiKit.CreateInput(card, "Password", "8–128 символов", password: true);
            UiKit.SetPreferredHeight(_password, 54f);

            _loginButton = UiKit.CreateButton(card, "LoginButton", "Войти", OnLoginClicked);
            UiKit.SetPreferredHeight(_loginButton, 56f);

            _registerButton = UiKit.CreateButton(card, "RegisterButton", "Создать аккаунт", OnRegisterClicked, 21);
            UiKit.SetPreferredHeight(_registerButton, 50f);

            _status = UiKit.CreateText(
                card, "Status", string.Empty, 18,
                new Color(0.70f, 0.75f, 0.86f),
                TextAnchor.UpperCenter);
            _status.horizontalOverflow = HorizontalWrapMode.Wrap;
            UiKit.SetPreferredHeight(_status, 72f);

            var footer = UiKit.CreateText(
                card,
                "Footer",
                "Стенд: 192.168.31.158:18080 · локально: localhost:5080",
                15,
                new Color(0.45f, 0.50f, 0.62f));
            UiKit.SetPreferredHeight(footer, 26f);
        }

        public void Show(string status = null)
        {
            UiKit.SetActive(_root, true);
            if (!string.IsNullOrEmpty(status))
                SetStatus(status, new Color(0.70f, 0.75f, 0.86f));
        }

        public void Hide() => UiKit.SetActive(_root, false);

        private static void AddCaption(Transform parent, string text)
        {
            var caption = UiKit.CreateText(
                parent,
                "Caption_" + text,
                text,
                17,
                new Color(0.62f, 0.68f, 0.82f),
                TextAnchor.MiddleLeft);
            UiKit.SetPreferredHeight(caption, 24f);
        }

        private async void OnLoginClicked()
        {
            await SubmitAsync(register: false);
        }

        private async void OnRegisterClicked()
        {
            await SubmitAsync(register: true);
        }

        private async Task SubmitAsync(bool register)
        {
            if (_busy)
                return;

            var userName = (_userName.text ?? string.Empty).Trim();
            var password = _password.text ?? string.Empty;

            if (string.IsNullOrEmpty(userName) || string.IsNullOrEmpty(password))
            {
                SetStatus("Введите имя игрока и пароль.", new Color(1f, 0.70f, 0.35f));
                return;
            }

            _config.SetServerBaseUrl(_serverUrl.text);
            _serverUrl.text = _config.ServerBaseUrl;

            SetBusy(true, register ? "Создаём аккаунт…" : "Подключаемся…");

            try
            {
                if (register)
                    await _auth.RegisterAsync(userName, password);
                else
                    await _auth.LoginAsync(userName, password);

                _password.text = string.Empty;
                SetStatus("Готово.", new Color(0.45f, 0.85f, 0.55f));
                _onAuthenticated();
            }
            catch (ApiException exception)
            {
                SetStatus(FormatError(exception), new Color(1f, 0.55f, 0.45f));
            }
            catch (Exception exception)
            {
                Debug.LogException(exception);
                SetStatus("Не удалось связаться с сервером. Проверьте адрес.", new Color(1f, 0.55f, 0.45f));
            }
            finally
            {
                SetBusy(false, null);
            }
        }

        private static string FormatError(ApiException exception)
        {
            if (exception.StatusCode == 0)
                return "Нет связи с сервером. Проверьте адрес и запущен ли сервер.";

            if (exception.Violations.Count > 0)
            {
                var details = string.Join("\n", exception.Violations.Take(3).Select(item => item.Message));
                return exception.Message + "\n" + details;
            }

            return string.IsNullOrEmpty(exception.Message)
                ? "Сервер вернул ошибку " + exception.StatusCode + "."
                : exception.Message;
        }

        private void SetBusy(bool busy, string status)
        {
            _busy = busy;
            _loginButton.interactable = !busy;
            _registerButton.interactable = !busy;
            _serverUrl.interactable = !busy;
            _userName.interactable = !busy;
            _password.interactable = !busy;

            if (status != null)
                SetStatus(status, new Color(0.70f, 0.75f, 0.86f));
        }

        private void SetStatus(string text, Color color)
        {
            _status.text = text ?? string.Empty;
            _status.color = color;
        }
    }
}