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

namespace Vanguard.UI
{
    /// <summary>Экран входа по референсу: key art, неоновая панель, меню.</summary>
    public sealed class LoginView
    {
        private const int PanelWidth = 560;
        private const int PanelHeight = 420;

        private readonly AppConfig _config;
        private readonly AuthService _auth;
        private readonly Action _onAuthenticated;

        private readonly RectTransform _root;
        private readonly InputField _userName;
        private readonly InputField _password;
        private readonly Image _passwordToggle;
        private readonly Button _loginButton;
        private readonly Text _loginLabel;
        private readonly Button _registerButton;
        private readonly Text _status;
        private readonly StatusTicker _ticker;
        private readonly HamburgerMenu _menu;

        private bool _busy;
        private bool _passwordVisible;

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

            _root = UiKit.CreatePanel(parent, "LoginScreen", new Color(0f, 0f, 0f, 0f));
            _root.GetComponent<Image>().raycastTarget = false;

            LoginBackdrop.Create(_root);

            var panel = CreatePanel(_root);
            _userName = CreateField(panel, "UserName", "Логин", UserIcon(), 110f);
            _password = CreateField(panel, "Password", "Пароль", LockIcon(), 32f, password: true);
            _passwordToggle = CreatePasswordToggle(panel);

            var tabs = _root.gameObject.AddComponent<TabFocusDriver>();
            tabs.First = _userName;
            tabs.Second = _password;
            tabs.Submit = OnSubmitShortcut;
            tabs.Cancel = OnCancelShortcut;

            CreateLink(
                panel,
                "ForgotPassword",
                "Забыли пароль?",
                -14f,
                TextAnchor.MiddleRight,
                new Color(0.37f, 0.69f, 1f),
                OnForgotClicked);

            _loginButton = CreateLoginButton(panel, out _loginLabel);
            _registerButton = CreateLink(
                panel,
                "Register",
                "Создать аккаунт",
                -128f,
                TextAnchor.MiddleCenter,
                new Color(0.50f, 0.66f, 0.88f),
                OnRegisterClicked);

            _status = UiKit.CreateText(
                panel,
                "Status",
                string.Empty,
                15,
                new Color(0.62f, 0.72f, 0.88f),
                TextAnchor.UpperCenter);
            _status.horizontalOverflow = HorizontalWrapMode.Wrap;
            _status.verticalOverflow = VerticalWrapMode.Overflow;
            Place(_status.rectTransform, new Vector2(500f, 44f), new Vector2(0f, -172f));

            CreateTagline(_root);
            CreateCopyright(_root);

            _ticker = _root.gameObject.AddComponent<StatusTicker>();
            _ticker.Hide = () => SetStatus(string.Empty, StatusColor);

            _menu = new HamburgerMenu(_root, _config);
        }

        /// <summary>Enter отправляет форму; в открытом меню не срабатывает.</summary>
        private void OnSubmitShortcut()
        {
            if (_busy || _menu == null || _menu.IsOpen)
                return;

            _ = SubmitAsync(register: false);
        }

        /// <summary>Esc закрывает меню, если оно открыто.</summary>
        private void OnCancelShortcut()
        {
            if (_menu != null && _menu.IsOpen)
                _menu.Close();
        }

        public void Show(string status = null)
        {
            UiKit.SetActive(_root, true);
            if (!string.IsNullOrEmpty(status))
                SetStatus(status, StatusColor);
        }

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

        // ------------------------------------------------------------ построение

        private static RectTransform CreatePanel(Transform parent)
        {
            var glow = NeonUi.AddImage(
                parent,
                "PanelGlow",
                NeonUi.Glow(
                    PanelWidth + 48,
                    PanelHeight + 48,
                    24,
                    24,
                    new Color(0.18f, 0.49f, 1f, 0.24f)),
                new Vector2(PanelWidth + 48, PanelHeight + 48),
                new Vector2(0f, -170f));

            var panel = UiKit.CreateCenteredCard(
                parent,
                "LoginPanel",
                new Vector2(PanelWidth, PanelHeight),
                Color.white);
            panel.anchoredPosition = new Vector2(0f, -170f);
            panel.GetComponent<Image>().sprite = NeonUi.Body(
                PanelWidth,
                PanelHeight,
                24,
                new Color(0.024f, 0.058f, 0.15f, 0.94f),
                new Color(0.18f, 0.49f, 1f, 0.9f),
                2);
            panel.GetComponent<Image>().raycastTarget = false;
            glow.transform.SetSiblingIndex(panel.GetSiblingIndex() - 1);
            return panel;
        }

        private static InputField CreateField(
            Transform parent,
            string name,
            string placeholder,
            Sprite icon,
            float y,
            bool password = false)
        {
            var go = new GameObject(name, typeof(RectTransform), typeof(Image), typeof(InputField));
            var rect = (RectTransform)go.transform;
            rect.SetParent(parent, false);
            Place(rect, new Vector2(480f, 64f), new Vector2(0f, y));

            var background = go.GetComponent<Image>();
            background.sprite = NeonUi.Body(
                480,
                64,
                10,
                new Color(0.014f, 0.041f, 0.105f, 0.97f),
                new Color(0.22f, 0.53f, 1f, 0.55f),
                1);
            background.type = Image.Type.Simple;
            background.raycastTarget = true;

            var input = go.GetComponent<InputField>();
            input.targetGraphic = background;
            input.lineType = InputField.LineType.SingleLine;
            input.contentType = password
                ? InputField.ContentType.Password
                : InputField.ContentType.Standard;
            input.characterLimit = password ? 128 : 64;
            input.caretColor = new Color(0.55f, 0.82f, 1f);
            input.customCaretColor = true;
            input.selectionColor = new Color(0.22f, 0.53f, 1f, 0.55f);
            input.colors = FieldColors();

            var text = UiKit.CreateText(rect, "Text", string.Empty, 18, Color.white, TextAnchor.MiddleLeft);
            UiKit.Stretch(text.rectTransform);
            text.rectTransform.offsetMin = new Vector2(52f, 0f);
            text.rectTransform.offsetMax = new Vector2(-44f, 0f);
            text.supportRichText = false;
            UiKit.MakeLiteral(text);

            var hint = UiKit.CreateText(
                rect,
                "Placeholder",
                placeholder,
                18,
                new Color(0.55f, 0.63f, 0.78f),
                TextAnchor.MiddleLeft);
            UiKit.Stretch(hint.rectTransform);
            hint.rectTransform.offsetMin = new Vector2(52f, 0f);
            hint.rectTransform.offsetMax = new Vector2(-44f, 0f);
            hint.supportRichText = false;

            input.textComponent = text;
            input.placeholder = hint;

            NeonUi.AddImage(rect, "Icon", icon, new Vector2(22f, 22f), new Vector2(-212f, 0f));
            return input;
        }

        private Image CreatePasswordToggle(Transform parent)
        {
            var go = new GameObject(
                "PasswordToggle",
                typeof(RectTransform),
                typeof(Image),
                typeof(Button));
            var rect = (RectTransform)go.transform;
            rect.SetParent(parent, false);
            Place(rect, new Vector2(32f, 32f), new Vector2(208f, 32f));

            var image = go.GetComponent<Image>();
            image.sprite = EyeIcon();
            image.color = new Color(1f, 1f, 1f, 0.75f);
            image.raycastTarget = true;

            var button = go.GetComponent<Button>();
            button.targetGraphic = image;
            button.transition = Selectable.Transition.ColorTint;
            button.colors = FieldColors();
            button.onClick.AddListener(TogglePassword);

            return image;
        }

        private Button CreateLoginButton(Transform panel, out Text label)
        {
            NeonUi.AddImage(
                panel,
                "LoginButtonGlow",
                NeonUi.Glow(
                    508,
                    100,
                    14,
                    12,
                    new Color(0.25f, 0.6f, 1f, 0.45f)),
                new Vector2(508f, 100f),
                new Vector2(0f, -70f));

            var go = new GameObject(
                "LoginButton",
                typeof(RectTransform),
                typeof(Image),
                typeof(Button));
            var rect = (RectTransform)go.transform;
            rect.SetParent(panel, false);
            Place(rect, new Vector2(480f, 72f), new Vector2(0f, -70f));

            var body = go.GetComponent<Image>();
            body.sprite = NeonUi.Bevel(
                480,
                72,
                14,
                new Color(0.18f, 0.55f, 1f, 1f),
                new Color(0.10f, 0.37f, 0.79f, 1f),
                new Color(0.49f, 0.77f, 1f, 1f),
                2);
            body.type = Image.Type.Simple;
            body.raycastTarget = true;

            var button = go.GetComponent<Button>();
            button.targetGraphic = body;
            button.transition = Selectable.Transition.ColorTint;
            button.colors = new ColorBlock
            {
                normalColor = Color.white,
                highlightedColor = new Color(1.12f, 1.12f, 1.12f, 1f),
                pressedColor = new Color(0.9f, 0.9f, 0.9f, 1f),
                selectedColor = Color.white,
                disabledColor = new Color(0.55f, 0.55f, 0.55f, 0.6f),
                colorMultiplier = 1f,
                fadeDuration = 0.08f,
            };
            button.onClick.AddListener(OnLoginClicked);

            label = UiKit.CreateText(rect, "Label", "Войти", 22, Color.white);
            label.fontStyle = FontStyle.Bold;
            UiKit.Stretch(label.rectTransform);

            return button;
        }

        private static void CreateTagline(Transform root)
        {
            var emblem = NeonUi.AddAnchored(
                root,
                "TaglineEmblem",
                NeonUi.Body(30, 30, 7, new Color(0.24f, 0.58f, 1f, 0.9f), new Color(0.6f, 0.85f, 1f, 0.9f), 1),
                new Vector2(34f, 34f),
                new Vector2(0f, 0f),
                new Vector2(0.5f, 0.5f),
                new Vector2(58f, 66f));
            emblem.localRotation = Quaternion.Euler(0f, 0f, 45f);

            var line1 = UiKit.CreateText(
                root,
                "Tagline1",
                "FIGHT TOGETHER.",
                11,
                new Color(0.59f, 0.76f, 1f, 0.68f),
                TextAnchor.MiddleLeft);
            var rect1 = line1.rectTransform;
            rect1.anchorMin = new Vector2(0f, 0f);
            rect1.anchorMax = new Vector2(0f, 0f);
            rect1.pivot = new Vector2(0f, 0.5f);
            rect1.sizeDelta = new Vector2(360f, 16f);
            rect1.anchoredPosition = new Vector2(88f, 74f);

            var line2 = UiKit.CreateText(
                root,
                "Tagline2",
                "BUILD YOUR FUTURE.",
                11,
                new Color(0.59f, 0.76f, 1f, 0.68f),
                TextAnchor.MiddleLeft);
            var rect2 = line2.rectTransform;
            rect2.anchorMin = new Vector2(0f, 0f);
            rect2.anchorMax = new Vector2(0f, 0f);
            rect2.pivot = new Vector2(0f, 0.5f);
            rect2.sizeDelta = new Vector2(360f, 16f);
            rect2.anchoredPosition = new Vector2(88f, 58f);

            UiKit.MakeLiteral(line1);
            UiKit.MakeLiteral(line2);
        }

        private static void CreateCopyright(Transform root)
        {
            var text = UiKit.CreateText(
                root,
                "Copyright",
                "© Cardfight!! Vanguard Fan Project",
                12,
                new Color(0.51f, 0.65f, 0.84f, 0.5f),
                TextAnchor.MiddleRight);
            var rect = text.rectTransform;
            rect.anchorMin = new Vector2(1f, 0f);
            rect.anchorMax = new Vector2(1f, 0f);
            rect.pivot = new Vector2(1f, 0f);
            rect.sizeDelta = new Vector2(420f, 20f);
            rect.anchoredPosition = new Vector2(-28f, 18f);
            UiKit.MakeLiteral(text);
        }

        // ------------------------------------------------------------ иконки

        private static Sprite UserIcon()
        {
            var head = NeonUi.Circle(10, new Color(0.62f, 0.8f, 1f, 0.85f));
            var body = NeonUi.Body(
                18,
                10,
                5,
                new Color(0.62f, 0.8f, 1f, 0.85f),
                Color.clear,
                0);
            return Compose(22, 22, new[]
            {
                (head, new Vector2(0f, 5f), new Vector2(10f, 10f)),
                (body, new Vector2(0f, -5f), new Vector2(18f, 10f)),
            });
        }

        private static Sprite LockIcon()
        {
            var shackle = NeonUi.Ring(14, 2f, new Color(0.62f, 0.8f, 1f, 0.85f));
            var body = NeonUi.Body(
                18,
                14,
                4,
                new Color(0.62f, 0.8f, 1f, 0.85f),
                Color.clear,
                0);
            return Compose(22, 22, new[]
            {
                (shackle, new Vector2(0f, 4f), new Vector2(14f, 14f)),
                (body, new Vector2(0f, -4f), new Vector2(18f, 14f)),
            });
        }

        private static Sprite EyeIcon()
        {
            var outline = NeonUi.Ring(20, 1.5f, Color.white);
            var pupil = NeonUi.Circle(7, Color.white);
            return Compose(24, 24, new[]
            {
                (outline, Vector2.zero, new Vector2(20f, 20f)),
                (pupil, Vector2.zero, new Vector2(7f, 7f)),
            });
        }

        /// <summary>Собирает несколько спрайтов в один, чтобы не держать лишние Image.</summary>
        private static Sprite Compose(
            int width,
            int height,
            (Sprite sprite, Vector2 offset, Vector2 size)[] parts)
        {
            var pixels = new Color32[width * height];
            foreach (var part in parts)
            {
                if (part.sprite == null)
                    continue;

                var texture = part.sprite.texture;
                var source = texture.GetPixels32();
                var sourceWidth = texture.width;
                var sourceHeight = texture.height;
                var left = Mathf.RoundToInt(width * 0.5f + part.offset.x - part.size.x * 0.5f);
                var bottom = Mathf.RoundToInt(height * 0.5f + part.offset.y - part.size.y * 0.5f);
                var scaleX = sourceWidth / part.size.x;
                var scaleY = sourceHeight / part.size.y;

                for (var y = 0; y < part.size.y; y++)
                {
                    for (var x = 0; x < part.size.x; x++)
                    {
                        var targetX = left + x;
                        var targetY = bottom + y;
                        if (targetX < 0 || targetY < 0 || targetX >= width || targetY >= height)
                            continue;

                        var sx = Mathf.Clamp(Mathf.RoundToInt(x * scaleX), 0, sourceWidth - 1);
                        var sy = Mathf.Clamp(Mathf.RoundToInt(y * scaleY), 0, sourceHeight - 1);
                        var color = source[sy * sourceWidth + sx];
                        if (color.a == 0)
                            continue;

                        var index = targetY * width + targetX;
                        pixels[index] = AlphaBlend(pixels[index], color);
                    }
                }
            }

            var result = new Texture2D(width, height, TextureFormat.RGBA32, false)
            {
                hideFlags = HideFlags.DontSave,
                filterMode = FilterMode.Bilinear,
                wrapMode = TextureWrapMode.Clamp,
            };
            result.SetPixels32(pixels);
            result.Apply(false, false);

            var sprite = Sprite.Create(
                result,
                new Rect(0f, 0f, width, height),
                new Vector2(0.5f, 0.5f),
                100f);
            sprite.hideFlags = HideFlags.DontSave;
            return sprite;
        }

        private static Color32 AlphaBlend(Color32 under, Color32 over)
        {
            var alpha = over.a / 255f;
            return new Color32(
                (byte)(over.r * alpha + under.r * (1f - alpha)),
                (byte)(over.g * alpha + under.g * (1f - alpha)),
                (byte)(over.b * alpha + under.b * (1f - alpha)),
                (byte)Mathf.Clamp(over.a + under.a * (1f - alpha), 0f, 255f));
        }

        // ------------------------------------------------------------ ссылки

        private static Button CreateLink(
            Transform parent,
            string name,
            string label,
            float y,
            TextAnchor alignment,
            Color color,
            UnityAction onClick)
        {
            var go = new GameObject(name, typeof(RectTransform), typeof(Image), typeof(Button));
            var rect = (RectTransform)go.transform;
            rect.SetParent(parent, false);
            Place(rect, new Vector2(480f, 26f), new Vector2(0f, y));

            var image = go.GetComponent<Image>();
            image.color = new Color(0f, 0f, 0f, 0.001f);
            image.raycastTarget = true;

            var button = go.GetComponent<Button>();
            button.targetGraphic = image;
            button.transition = Selectable.Transition.None;
            button.onClick.AddListener(onClick);

            var text = UiKit.CreateText(rect, "Label", label, 15, color, alignment);
            UiKit.Stretch(text.rectTransform);

            return button;
        }

        // ------------------------------------------------------------ логика

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

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

        private void OnForgotClicked()
        {
            SetStatus(
                "Сброс пароля не поддерживается. Обратитесь к администратору.",
                new Color(1f, 0.72f, 0.42f));
        }

        private void TogglePassword()
        {
            _passwordVisible = !_passwordVisible;
            _password.contentType = _passwordVisible
                ? InputField.ContentType.Standard
                : InputField.ContentType.Password;
            _password.ForceLabelUpdate();
            _passwordToggle.color = _passwordVisible
                ? new Color(0.45f, 0.78f, 1f, 1f)
                : new Color(1f, 1f, 1f, 0.75f);
        }

        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 логин и пароль.", new Color(1f, 0.70f, 0.35f));
                return;
            }

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

            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);
                var detail = exception.Message ?? string.Empty;
                if (detail.IndexOf("Insecure connection", StringComparison.OrdinalIgnoreCase) >= 0)
                {
                    SetStatus(
                        "Unity блокирует HTTP. Player Settings → Allow downloads over HTTP = Always, затем перезапусти Unity.",
                        new Color(1f, 0.55f, 0.45f));
                }
                else
                {
                    SetStatus("Не удалось связаться: " + detail, 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;
            _userName.interactable = !busy;
            _password.interactable = !busy;

            if (_loginLabel != null)
                _loginLabel.text = busy ? "Подключение…" : "Войти";

            if (status != null)
                SetStatus(status, StatusColor);
        }

        private void SetStatus(string text, Color color)
        {
            if (_status == null)
                return;

            _status.text = text ?? string.Empty;
            _status.color = color;

            if (string.IsNullOrEmpty(text))
            {
                _ticker.HideAt = 0f;
                return;
            }

            _ticker.HideAt = Time.unscaledTime + 6f;
        }

        // ------------------------------------------------------------ утилиты

        private static readonly Color StatusColor = new Color(0.66f, 0.74f, 0.90f);

        private static void Place(RectTransform rect, Vector2 size, Vector2 position)
        {
            rect.anchorMin = new Vector2(0.5f, 0.5f);
            rect.anchorMax = new Vector2(0.5f, 0.5f);
            rect.pivot = new Vector2(0.5f, 0.5f);
            rect.sizeDelta = size;
            rect.anchoredPosition = position;
        }

        private static ColorBlock FieldColors()
        {
            return new ColorBlock
            {
                normalColor = Color.white,
                highlightedColor = new Color(1.15f, 1.15f, 1.15f, 1f),
                pressedColor = new Color(0.9f, 0.9f, 0.9f, 1f),
                selectedColor = new Color(1.15f, 1.15f, 1.15f, 1f),
                disabledColor = new Color(0.6f, 0.6f, 0.6f, 0.5f),
                colorMultiplier = 1f,
                fadeDuration = 0.08f,
            };
        }

        /// <summary>Скрывает статус через несколько секунд.</summary>
        private sealed class StatusTicker : MonoBehaviour
        {
            public float HideAt;
            public Action Hide;

            private void Update()
            {
                if (HideAt <= 0f || Time.unscaledTime < HideAt)
                    return;

                HideAt = 0f;
                Hide?.Invoke();
            }
        }
    }
}