using UnityEngine;

namespace BaseGames.Player
{
    /// <summary>
    /// 独立墙壁检测组件（架构 05_PlayerModule §13）。
    /// ⚠️ 不嵌入 PlayerMovement，以保持单一职责。
    /// 每侧发两根射线（Top + Bottom），两根均命中才视为接触墙壁（防卡角误判）。
    /// WallSlideState / WallJumpState 通过 PlayerController.WallDetector 访问。
    /// </summary>
    [RequireComponent(typeof(PlayerMovement))]
    public class PlayerWallDetector : MonoBehaviour
    {
        [SerializeField] private PlayerMovementConfigSO _config;

        [Header("墙壁 Layer（默认使用 \"Wall\" + \"Ground\"）")]
        [SerializeField] private LayerMask _wallLayer;

        /// <summary>当前是否正在触碰墙壁。</summary>
        public bool IsTouchingWall  { get; private set; }

        /// <summary>触碰到的墙壁方向：+1 = 右墙，-1 = 左墙，0 = 无墙。</summary>
        public int  WallDirection   { get; private set; }

        private void Awake()
        {
            Debug.Assert(_config != null, "[PlayerWallDetector] _config 未赋值，请在 Inspector 中指定 PlayerMovementConfigSO。", this);
        }

        private void FixedUpdate()
        {
            bool rightWall = CheckSide(Vector2.right);
            bool leftWall  = CheckSide(Vector2.left);

            IsTouchingWall = rightWall || leftWall;
            WallDirection  = rightWall ? 1 : (leftWall ? -1 : 0);
        }

        /// <summary>
        /// 每侧发两根射线（TopRay + BottomRay），两根均命中才返回 true。
        /// </summary>
        private bool CheckSide(Vector2 dir)
        {
            Vector2 center = transform.position;
            float   len    = _config.WallRayLength;
            float   oy     = _config.WallRayOffsetY;
            int     layer  = _wallLayer != 0 ? (int)_wallLayer : LayerMask.GetMask("Wall", "Ground");

            bool top = Physics2D.Raycast(center + Vector2.up   * oy, dir, len, layer);
            bool bot = Physics2D.Raycast(center + Vector2.down * oy, dir, len, layer);
            return top && bot;
        }

        private void OnDrawGizmosSelected()
        {
            if (_config == null) return;
            float len = _config.WallRayLength;
            float oy  = _config.WallRayOffsetY;
            Vector2 center = transform.position;

            Gizmos.color = IsTouchingWall ? Color.red : Color.cyan;
            // 右侧两根射线
            Gizmos.DrawRay(center + Vector2.up   * oy, Vector2.right * len);
            Gizmos.DrawRay(center + Vector2.down * oy, Vector2.right * len);
            // 左侧两根射线
            Gizmos.DrawRay(center + Vector2.up   * oy, Vector2.left  * len);
            Gizmos.DrawRay(center + Vector2.down * oy, Vector2.left  * len);
        }
    }
}