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

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;

    readonly List<LevelButton> levelsPool = new();

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

    // ==== ПУБЛИЧНЫЙ API ====
    public void Open()
    {
        BuildIfNeeded();
        gameObject.SetActive(true);
        StopAllCoroutines();
        StartCoroutine(Fade(0f, 1f, fadeDuration));
    }

    public void Close()
    {
        StopAllCoroutines();
        StartCoroutine(Fade(1f, 0f, fadeDuration, () => gameObject.SetActive(false)));
    }

    // ==== ВНУТРЕННЕЕ ====
    void BuildIfNeeded()
    {
        // Очистим/пересоберём (можно кэшировать, но пересборка надёжнее при изменениях Build Settings)
        foreach (var b in levelsPool) if (b) Destroy(b.gameObject);
        levelsPool.Clear();

        var levels = EnumerateLevelScenesInBuild()
                    .OrderBy(e => e.world)
                    .ThenBy(e => e.stage)
                    .ToList();

        foreach (var lv in levels)
        {
            var btn = Instantiate(levelButtonPrefab, content);
            btn.Setup(lv.name, lv.world, lv.stage);
            btn.SetColor(Color.green);
            levelsPool.Add(btn);
        }
    }

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

    IEnumerable<LevelEntry> EnumerateLevelScenesInBuild()
    {
        int n = SceneManager.sceneCountInBuildSettings;
        for (int i = 0; i < n; i++)
        {
            string path = SceneUtility.GetScenePathByBuildIndex(i);
            string name = System.IO.Path.GetFileNameWithoutExtension(path);

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

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

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

    System.Collections.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.blocksRaycasts = to > 0.99f;
        onDone?.Invoke();
    }

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