using UnityEngine;

namespace BaseGames.Player
{
    /// <summary>
    /// 玩家物理移动组件。封装 Rigidbody2D 操作，提供跑动、跳跃、击退等接口。

    /// </summary>
    [RequireComponent(typeof(Rigidbody2D))]
    public class PlayerMovement : MonoBehaviour
    {
        [Header("配置")]
        [SerializeField] private PlayerMovementConfigSO _config;

        [Header("地面检测")]
        [SerializeField] private Transform  _groundCheck;
        [SerializeField] private Vector2    _groundCheckSize  = new Vector2(0.8f, 0.05f);
        [SerializeField] private LayerMask  _groundLayer;

        [Header("朝向")]
        [SerializeField] private SpriteRenderer _spriteRenderer;

        // ── 运行时状态 ────────────────────────────────────────────────────────
        private Rigidbody2D _rb;
        private float       _coyoteTimer;
        private bool        _isGrounded;
        private bool        _isWallLeft;
        private bool        _isWallRight;
        private bool        _onOneWayPlatform;
        private int         _facingDirection = 1;
        private bool        _cancelWindowOpen;
        private SurfaceType _currentSurface = SurfaceType.Ground;
        private readonly Collider2D[] _groundBuffer = new Collider2D[4];

        public bool        IsGrounded      => _isGrounded;
        public bool        HasCoyoteTime   => _coyoteTimer > 0f;
        public bool        IsWallLeft      => _isWallLeft;
        public bool        IsWallRight     => _isWallRight;
        public bool        OnOneWayPlatform => _onOneWayPlatform;
        public int         FacingDirection => _facingDirection;
        public Rigidbody2D Rb              => _rb;
        public bool        CancelWindowOpen => _cancelWindowOpen;
        public SurfaceType CurrentSurface  => _currentSurface;
        /// <summary>垂直速度大于零（处于上升弧段）。供 WallJumpState 判断起跳是否结束。</summary>
        public bool        IsRising        => _rb.velocity.y > 0f;

        private void Awake()
        {
            Debug.Assert(_config != null, "[PlayerMovement] _config 未赋值，请在 Inspector 中指定 PlayerMovementConfigSO。", this);
            _rb = GetComponent<Rigidbody2D>();
            if (_spriteRenderer == null)
                _spriteRenderer = GetComponentInChildren<SpriteRenderer>();
        }

        private void FixedUpdate()
        {
            CheckGrounded();
            CheckWalls();

            if (_isGrounded)
                _coyoteTimer = _config.CoyoteTime;
            else
                _coyoteTimer = Mathf.Max(0f, _coyoteTimer - Time.fixedDeltaTime);
        }

        // ── 移动 ──────────────────────────────────────────────────────────────
        public void Move(float speedX)
        {
            float target = speedX;
            float current = _rb.velocity.x;
            float accel = Mathf.Abs(speedX) > 0.01f ? _config.Acceleration : _config.Deceleration;
            float newX = Mathf.MoveTowards(current, target, accel * Time.fixedDeltaTime);
            _rb.velocity = new Vector2(newX, _rb.velocity.y);
        }

        // ── 跳跃 ──────────────────────────────────────────────────────────────
        public void Jump(bool isVariable = true)
        {
            _rb.velocity = new Vector2(_rb.velocity.x, _config.JumpForce);
            _coyoteTimer = 0f;
        }

        public void CutJump()
        {
            if (_rb.velocity.y > 0f)
                _rb.velocity = new Vector2(_rb.velocity.x, _rb.velocity.y * 0.5f);
        }

        // ── 重力 ──────────────────────────────────────────────────────────────
        public void SetGravityScale(float scale) => _rb.gravityScale = scale;

        // ── 击退 ──────────────────────────────────────────────────────────────
        public void ApplyKnockback(Vector2 direction, float force)
            => _rb.velocity = direction.normalized * force;

        // ── 速度控制 ──────────────────────────────────────────────────────────
        public void ZeroVelocity()           => _rb.velocity = Vector2.zero;
        public void ZeroHorizontalVelocity() => _rb.velocity = new Vector2(0f, _rb.velocity.y);

        // ── 朝向 ──────────────────────────────────────────────────────────────
        public void UpdateFacing()
        {
            float vx = _rb.velocity.x;
            if (Mathf.Abs(vx) < 0.1f) return;
            int dir = vx > 0f ? 1 : -1;
            if (dir == _facingDirection) return;
            _facingDirection = dir;
            if (_spriteRenderer != null)
                _spriteRenderer.flipX = dir < 0;
        }

        // ── 取消窗口 ──────────────────────────────────────────────────────────
        public void SetCancelWindowOpen(bool open) => _cancelWindowOpen = open;

        // ── 冲刺 ──────────────────────────────────────────────────────────────
        /// <summary>
        /// 施加冲刺速度（DashState/AerialDashState 调用）。
        /// direction 应为归一化水平向量（±1, 0）。
        /// 冲刺期间调用 SetGravityScale(0) 可关闭重力；结束后恢复默认重力。
        /// </summary>
        public void Dash(Vector2 direction, float speed)
        {
            _rb.velocity = new Vector2(direction.x * speed, 0f);
        }

        /// <summary>
        /// 壁滑：将垂直速度限制为 -WallSlideSpeed（向下缓慢滑动）。
        /// WallSlideState.OnStateFixedUpdate 每帧调用。
        /// </summary>
        public void ApplyWallSlide()
        {
            float targetY = -_config.WallSlideSpeed;
            if (_rb.velocity.y < targetY)
                _rb.velocity = new Vector2(_rb.velocity.x, targetY);
        }

        /// <summary>
        /// 蹬墙跳：对墙方向施加相反水平力 + 向上力。
        /// wallDir = +1 (右墙) 或 -1 (左墙)，跳跃方向与之相反。
        /// </summary>
        public void WallJump(int wallDir)
        {
            float forceX = -wallDir * _config.WallJumpForceX;
            float forceY = _config.WallJumpForceY;
            _rb.velocity = new Vector2(forceX, forceY);
            _coyoteTimer = 0f;
        }

        /// <summary>单向平台穿透（输入下行 + 跳跃键时触发）。</summary>
        public void DropThroughPlatform() { }

        // ── Physics 检测 ──────────────────────────────────────────────────────
        private void CheckGrounded()
        {
            bool wasGrounded = _isGrounded;
            Vector2 origin = _groundCheck != null
                ? (Vector2)_groundCheck.position
                : (Vector2)transform.position + Vector2.down * 0.5f;

            _isGrounded = Physics2D.OverlapBoxNonAlloc(origin, _groundCheckSize, 0f, _groundBuffer, _groundLayer) > 0;

            if (_isGrounded && !wasGrounded)
                _coyoteTimer = _config.CoyoteTime;
        }

        private void CheckWalls()
        {
            float len = _config.WallRayLength;
            float offY = _config.WallRayOffsetY;
            Vector2 pos = (Vector2)transform.position + Vector2.up * offY;

            _isWallLeft  = Physics2D.Raycast(pos, Vector2.left,  len, _groundLayer);
            _isWallRight = Physics2D.Raycast(pos, Vector2.right, len, _groundLayer);
        }

        private void OnDrawGizmosSelected()
        {
            if (_groundCheck == null) return;
            Gizmos.color = Color.green;
            Gizmos.DrawWireCube(_groundCheck.position, _groundCheckSize);
        }
    }

    /// <summary>当前所在地面类型（用于脚步声等反馈）。</summary>
    public enum SurfaceType
    {
        Ground,
        OneWayPlatform,
        Slope,
        Ice,
    }
}