using System.Linq;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.InputSystem;
using UnityEngine.SceneManagement;

namespace RR.Common.UI
{
    public class LevelSelectModal : MonoBehaviour
    {
        [Header("Управление")]
        [SerializeField] private InputActionReference close;

        [Header("UI")]
        [SerializeField] private CanvasGroup canvasGroup;
        [SerializeField] private Transform content;             // Grid parent
        [SerializeField] private LevelButton levelButtonPrefab;
        [SerializeField] private Button closeButton;
        [SerializeField] private float fadeDuration = 0.15f;

        private readonly List<LevelButton> _levelsPool = new();

        private void Awake()
        {
            if (closeButton) closeButton.onClick.AddListener(Close);
            gameObject.SetActive(false);
        }

        // ==== ПУБЛИЧНЫЙ API ====
        /// <summary>
        /// Метод для открытия модального окна
        /// </summary>
        public void Open()
        {
            BuildIfNeeded();
            gameObject.SetActive(true);
            StopAllCoroutines();
            StartCoroutine(Fade(0f, 1f, fadeDuration));
        }

        /// <summary>
        /// Метод для закрытия модального окна
        /// </summary>
        private void Close()
        {
            StopAllCoroutines();
            StartCoroutine(Fade(1f, 0f, fadeDuration, () => gameObject.SetActive(false)));
        }

        // ==== ВНУТРЕННЕЕ ====
        /// <summary>
        /// Метод для сборки кнопок уровней
        /// </summary>
        private void BuildIfNeeded()
        {
            // Очистим/пересоберём
            foreach (LevelButton b in _levelsPool.Where(b => b))
            {
                Destroy(b.gameObject);
            }

            _levelsPool.Clear();

            List<LevelEntry> levels = EnumerateLevelScenesInBuild()
                        .OrderBy(e => e.world)
                        .ThenBy(e => e.stage)
                        .ToList();

            foreach (LevelButton btn in levels.Select(lv => Instantiate(levelButtonPrefab, content)))
            {
                _levelsPool.Add(btn);
            }

            for (int index = 0; index < _levelsPool.Count; index++)
            {
                LevelButton btn = _levelsPool[index];
                // if (index == 0) btn.Setup(
                //     $"{levels[index].world}-{levels[index].stage}",
                //     levels[index].world,
                //     levels[index].stage,
                //     onDown: closeButton,
                //     onUp: closeButton,
                //     onLeft: closeButton,
                //     onRight: _levelsPool.Count > 1 ? _levelsPool[1].GetComponent<Button>() : closeButton
                //     );
                // else if (index == _levelsPool.Count - 1) btn.Setup(
                //     $"{levels[index].world}-{levels[index].stage}",
                //     levels[index].world,
                //     levels[index].stage,
                //     onDown: closeButton,
                //     onUp: closeButton,
                //     onLeft: _levelsPool.Count > 1 ? _levelsPool[index - 1].GetComponent<Button>() : closeButton,
                //     onRight: closeButton
                //     );
                // else btn.Setup(
                //     $"{levels[index].world}-{levels[index].stage}",
                //     levels[index].world,
                //     levels[index].stage,
                //     onUp: closeButton,
                //     onDown: closeButton,
                //     onLeft: _levelsPool[index - 1].GetComponent<Button>(),
                //     onRight: _levelsPool[index + 1].GetComponent<Button>()
                //     );

                btn.Setup(
                    $"{levels[index].world}-{levels[index].stage}",
                    levels[index].world,
                    levels[index].stage);
                
                switch (levels[index].world)
                {
                    case 1:
                        btn.SetColor(Color.green);
                        break;
                    case 2:
                        btn.SetColor(Color.blue);
                        break;
                }
            }

            if (_levelsPool.Count <= 0) return;
            // Navigation closeNav = closeButton.navigation;
            // closeNav.mode = Navigation.Mode.Explicit;
            // closeNav.selectOnUp = _levelsPool.First().GetComponent<Button>();
            // closeNav.selectOnDown = _levelsPool.First().GetComponent<Button>();
            // closeButton.navigation = closeNav;
        }

        private struct LevelEntry { public string name; public int world; public int stage; }

        /// <summary>
        /// Метод для перебора уровней в игре
        /// </summary>
        /// <returns>LevelEntry - текущий мир при переборе</returns>
        private static IEnumerable<LevelEntry> EnumerateLevelScenesInBuild()
        {
            int n = SceneManager.sceneCountInBuildSettings;
            for (int i = 0; i < n; i++)
            {
                string path = SceneUtility.GetScenePathByBuildIndex(i);
                string buttonName = System.IO.Path.GetFileNameWithoutExtension(path);

                // фильтр "только уровни" по формату имени W-S:
                string[] parts = buttonName.Split('-');
                if (parts.Length != 2) continue;
                if (!int.TryParse(parts[0], out int world)) continue;
                if (!int.TryParse(parts[1], out int stage)) continue;

                // Исключим служебные сцены, даже если вдруг совпадут по формату (на всякий случай)
                if (buttonName.Equals("Level UI", System.StringComparison.OrdinalIgnoreCase)) continue;
                if (buttonName.Equals("MainMenu", System.StringComparison.OrdinalIgnoreCase)) continue;

                yield return new LevelEntry { name = buttonName, world = world, stage = stage };
            }
        }

        /// <summary>
        /// Метод для плавного перехода (затухания)
        /// </summary>
        /// <param name="from">Начальная прозрачность</param>
        /// <param name="to">Конечная прозрачнеость</param>
        /// <param name="time">Время перехода</param>
        /// <param name="onDone">Действие при выполнении перехода</param>
        private IEnumerator Fade(float from, float to, float time, System.Action onDone = null)
        {
            if (!canvasGroup) { onDone?.Invoke(); yield break; }
            float t = 0f;
            canvasGroup.alpha = from;
            canvasGroup.blocksRaycasts = true;
            while (t < time)
            {
                t += Time.unscaledDeltaTime;
                canvasGroup.alpha = Mathf.Lerp(from, to, t / time);
                yield return null;
            }
            canvasGroup.alpha = to;
            canvasGroup.interactable = to > 0.99f;
            canvasGroup.blocksRaycasts = to > 0.99f;
            onDone?.Invoke();
        }

        private void Update()
        {
            // ESC закрыть
            if (gameObject.activeSelf && close.action.WasPressedThisFrame())
                Close();
        }
    }
}