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>
    // 执行顺序必须早于 PlayerController（-100），确保每帧 FixedUpdate
    // 开头能在状态机写入速度之前先应用"强制清零"标记。
    [DefaultExecutionOrder(-200)]
    [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;
        // Update 中调用 ZeroHorizontalVelocity 后设置此标记；
        // 下一个 FixedUpdate（-200，先于状态机 -100）读取并清零，
        // 防止状态机用旧输入把速度重新写成非零值。
        private bool        _pendingHorizontalZero;
        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];

#if UNITY_EDITOR
        // ── 运行时调试（Inspector 中可见）───────────────────────────────
        [Header("\u2500\u2500 \u8fd0\u884c\u65f6\u8c03\u8bd5 \u2500\u2500")]
        [SerializeField] private string _dbg_Position;
        [SerializeField] private float  _dbg_VelocityX;
        [SerializeField] private float  _dbg_VelocityY;
        [SerializeField] private bool   _dbg_IsGrounded;
        [SerializeField] private bool   _dbg_HasCoyoteTime;
        [SerializeField] private bool   _dbg_IsWallLeft;
        [SerializeField] private bool   _dbg_IsWallRight;
        [SerializeField] private bool   _dbg_CancelWindowOpen;
        [SerializeField] private int    _dbg_FacingDirection;
#endif

        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);
            Debug.Assert(_groundCheck != null,  "[PlayerMovement] GroundCheck 子节点未赋值，地面检测将无法工作，请在 Inspector 中指定 GroundCheck Transform。", this);
            _rb = GetComponent<Rigidbody2D>();
            // 开启位置插值：在物理帧（50Hz）与渲染帧（60Hz+）之间平滑视觉位置，消除跳帧抖动。
            // SpritePixelSnapper（LateUpdate +1000）在插值结果基础上吸附到像素网格，
            // 与 CameraPixelSnapper 同格对齐，消除亚像素模糊；停止时 ≤2 帧像素追赶不可感知。
            _rb.interpolation = RigidbodyInterpolation2D.Interpolate;
            if (_spriteRenderer == null)
                _spriteRenderer = GetComponentInChildren<SpriteRenderer>();
        }

        private void FixedUpdate()
        {
            // 优先处理来自 Update 的强制清零请求（在状态机 OnStateFixedUpdate 之前执行）。
            if (_pendingHorizontalZero)
            {
                _rb.velocity = new Vector2(0f, _rb.velocity.y);
                _pendingHorizontalZero = false;
            }

            CheckGrounded();
            CheckWalls();

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

#if UNITY_EDITOR
            _dbg_VelocityX        = _rb.velocity.x;
            _dbg_VelocityY        = _rb.velocity.y;
            _dbg_IsGrounded       = _isGrounded;
            _dbg_HasCoyoteTime    = _coyoteTimer > 0f;
            _dbg_IsWallLeft       = _isWallLeft;
            _dbg_IsWallRight      = _isWallRight;
            _dbg_CancelWindowOpen = _cancelWindowOpen;
            _dbg_FacingDirection  = _facingDirection;
            _dbg_Position         = $"({transform.position.x:F1}, {transform.position.y:F1})";
#endif
        }

        // ── 移动 ──────────────────────────────────────────────────────────────
        /// <summary>
        /// 直接赋予目标水平速度（按键即全速，松键即停，无加速过渡）。
        /// 地面状态每帧直接到达全速；空中调用时同样即时，但配合 ApplyAirDrag
        /// 在无输入时自然减速，保留跳出时的动量。
        /// </summary>
        public void Move(float speedX)
        {
            _rb.velocity = new Vector2(speedX, _rb.velocity.y);
        }

        /// <summary>
        /// 空中无输入时施加空气阻力：水平速度乘以 <paramref name="factor"/>，
        /// 低于阈值时归零，避免速度无限趋近 0。
        /// 在 FallState / JumpState / WallJumpState 的 OnStateFixedUpdate 中调用。
        /// </summary>
        public void ApplyAirDrag(float factor)
        {
            float newX = _rb.velocity.x * factor;
            if (Mathf.Abs(newX) < 0.05f) newX = 0f;
            _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 * _config.JumpCutMultiplier);
        }

        /// <summary>
        /// 二段跳。覆盖当前垂直速度为 DoubleJumpForce。
        /// FallState / JumpState 在检测到 HasAbility(DoubleJump) && AirJumpsLeft > 0 时调用。
        /// </summary>
        public void DoubleJump()
        {
            _rb.velocity = new Vector2(_rb.velocity.x, _config.DoubleJumpForce);
            _coyoteTimer = 0f;
        }

        // ── 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);
            // 设置标记：下一个 FixedUpdate 开头再次强制清零，
            // 防止因读到旧输入而把速度重新写成非零值。
            _pendingHorizontalZero = true;
        }

        // ── 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（受限抓墙时向下缓慢滑动）。
        /// WallSlideState.OnStateFixedUpdate 在受限模式下每帧调用。
        /// </summary>
        public void ApplyWallSlide()
        {
            float targetY = -_config.WallSlideSpeed;
            if (_rb.velocity.y < targetY)
                _rb.velocity = new Vector2(_rb.velocity.x, targetY);
        }

        /// <summary>
        /// 背墙跳（Jump Away）：远离墙壁斜上方弹出。
        /// wallDir = +1 (右墙) 或 -1 (左墙)，水平方向与之相反。
        /// </summary>
        public void WallJumpAway(int wallDir)
        {
            _rb.velocity = new Vector2(-wallDir * _config.WallJumpAwayForceX, _config.WallJumpAwayForceY);
            _coyoteTimer = 0f;
        }

        /// <summary>
        /// 对墙跳（Jump Toward）：沿墙壁方向偏向正上方弹出，水平分量较小。
        /// wallDir = +1 (右墙) 或 -1 (左墙)，水平方向与之相同。
        /// </summary>
        public void WallJumpToward(int wallDir)
        {
            _rb.velocity = new Vector2(wallDir * _config.WallJumpTowardForceX, _config.WallJumpTowardForceY);
            _coyoteTimer = 0f;
        }

        /// <summary>将垂直速度归零（抓墙悬挂时每帧调用，防止下滑）。</summary>
        public void ZeroVerticalVelocity()
        {
            if (_rb.velocity.y < 0f)
                _rb.velocity = new Vector2(_rb.velocity.x, 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()
        {
            if (_groundCheck == null) return;

            bool wasGrounded = _isGrounded;
            _isGrounded = Physics2D.OverlapBoxNonAlloc(_groundCheck.position, _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 OnDrawGizmos()
        {
#if UNITY_EDITOR
            // ── 1. 角色物理轮廓（浅绿，始终可见）────────────────────────────
            Gizmos.color = new Color(0.4f, 1f, 0.4f, 0.65f);
            foreach (var col in GetComponents<Collider2D>())
            {
                if (col.isTrigger) continue;
                BaseGames.Combat.HitBox.DrawCollider2DWire(col);
            }

            // ── 2. 朝向箭头（金黄）──────────────────────────────────────────
            Vector3 center   = transform.position;
            Vector3 arrowEnd = center + new Vector3(_facingDirection * 0.55f, 0f, 0f);
            DrawArrow2D(center, arrowEnd, new Color(1f, 0.85f, 0.1f, 0.95f));

            // ── 3. 站立检测框（落地亮绿 / 未落地淡绿；未赋值时显示红色警告框）──
            if (_groundCheck == null)
            {
                Gizmos.color = new Color(1f, 0.1f, 0.1f, 0.9f);
                Gizmos.DrawWireSphere(transform.position, 0.25f);
#if UNITY_EDITOR
                UnityEditor.Handles.color = new Color(1f, 0.1f, 0.1f, 1f);
                UnityEditor.Handles.Label(transform.position + Vector3.up * 0.6f, "GroundCheck 未赋值!");
#endif
            }
            else
            {
                bool grounded = Application.isPlaying && _isGrounded;
                Gizmos.color = grounded
                    ? new Color(0.1f, 1f, 0.3f, 0.9f)
                    : new Color(0.4f, 0.85f, 0.4f, 0.35f);
                BaseGames.Combat.HitBox.DrawWireRect2D(_groundCheck.position, _groundCheckSize);
            }

            // ── 4. 靠墙检测射线（碰墙橙色 / 未碰淡黄，带端点圆点）─────────
            if (_config == null) return;
            float wLen  = _config.WallRayLength;
            float wOffY = _config.WallRayOffsetY;
            Vector2 wallPos = (Vector2)transform.position + Vector2.up * wOffY;

            bool lHit = Application.isPlaying && _isWallLeft;
            bool rHit = Application.isPlaying && _isWallRight;

            Gizmos.color = lHit ? new Color(1f, 0.45f, 0f, 1f) : new Color(1f, 0.85f, 0.3f, 0.4f);
            Gizmos.DrawRay(wallPos, Vector2.left * wLen);
            BaseGames.Combat.HitBox.DrawWireCircle2D((Vector3)(wallPos + Vector2.left  * wLen), 0.04f, 8);

            Gizmos.color = rHit ? new Color(1f, 0.45f, 0f, 1f) : new Color(1f, 0.85f, 0.3f, 0.4f);
            Gizmos.DrawRay(wallPos, Vector2.right * wLen);
            BaseGames.Combat.HitBox.DrawWireCircle2D((Vector3)(wallPos + Vector2.right * wLen), 0.04f, 8);
#endif
        }

        private void OnDrawGizmosSelected()
        {
#if UNITY_EDITOR
            // 运行时：用青色箭头显示速度向量（仅选中时，按比例缩放）
            if (!Application.isPlaying || _rb == null) return;
            Vector2 vel = _rb.velocity;
            if (vel.sqrMagnitude < 0.01f) return;
            DrawArrow2D(transform.position, transform.position + (Vector3)(vel * 0.12f),
                        new Color(0.2f, 0.9f, 1f, 0.9f), 0.1f);
#endif
        }

        // 在 Gizmos 空间绘制带箭头的 2D 有向线段
        private static void DrawArrow2D(Vector3 from, Vector3 to, Color color, float headLen = 0.15f)
        {
            Vector3 dir = to - from;
            if (dir.sqrMagnitude < 0.0001f) return;
            dir = dir.normalized;
            Gizmos.color = color;
            Gizmos.DrawLine(from, to);

            // 将 -dir 分别旋转 ±35° 得到箭头两翼
            float cos = 0.8192f; // Mathf.Cos(35° in radians)
            float sin = 0.5736f; // Mathf.Sin(35°)
            float bx = -dir.x, by = -dir.y;
            Vector3 wing1 = new Vector3(bx * cos - by * sin, bx * sin + by * cos, 0f) * headLen;
            Vector3 wing2 = new Vector3(bx * cos + by * sin, -bx * sin + by * cos, 0f) * headLen;
            Gizmos.DrawLine(to, to + wing1);
            Gizmos.DrawLine(to, to + wing2);
        }
    }

    /// <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,
    }
}