using System;
using System.Collections;
using Animancer;
using UnityEngine;

namespace BaseGames.Enemies
{
    /// <summary>
    /// 敌人移动组件（架构 07_EnemyModule §3）。
    /// 实现：水平移动、面向目标、击退，以及导航连接段穿越（<see cref="INavLinkHandler"/>）。
    ///
    /// 作为 <see cref="INavLinkHandler"/> 处理 Jump / Fall 两种 NavLink 类型：
    /// - 跳跃连接（Jump）：调用 <see cref="JumpToTarget"/> 施加物理冲量，等待落地后通知完成
    /// - 下落连接（Fall） ：水平对准目标X，让重力自然下坠，到达目标Y附近通知完成
    /// 没有 EnemyMovement 组件（或 Jump 能力被移除）的敌人将无法通过跳跃连接，
    /// 路径代价保持 TransformBasedMovement 兜底（仍可跳，但无自定义动画/物理）。
    ///
    /// ⚠️ 使用 Rigidbody2D.velocity（Unity 2022 LTS）。
    /// </summary>
    [RequireComponent(typeof(Rigidbody2D))]
    public class EnemyMovement : MonoBehaviour, INavLinkHandler
    {
        [SerializeField] private EnemyStatsSO    _config;
        [SerializeField] private SpriteRenderer  _spriteRenderer;

        [Header("转身动画")]
        [Tooltip("开启后，敌人翻转方向时播放转身动画并暂停水平移动，动画结束后完成翻转")]
        [SerializeField] private bool                   _enableTurnAnimation = false;
        [Tooltip("Animancer 组件引用；留空则在 Awake 时自动从父级查找")]
        [SerializeField] private AnimancerComponent     _animancer;
        [Tooltip("动画配置 SO；留空则在 Awake 时自动从 EnemyBase 读取")]
        [SerializeField] private EnemyAnimationConfigSO _animConfig;

        [Header("导航跳跃能力（INavLinkHandler）")]
        [Tooltip("可处理的最大跳跃垂直高度（超出则让 TBM 兜底）")]
        [SerializeField] private float _navJumpMaxHeight = 6f;
        [Tooltip("可处理的最大跳跃水平距离")]
        [SerializeField] private float _navJumpMaxDist   = 10f;
        [Tooltip("地面检测射线长度（用于判断跳跃是否落地）")]
        [SerializeField] private float _groundCheckDist  = 0.35f;
        [Tooltip("地面层 LayerMask")]
        [SerializeField] private LayerMask _groundMask;

        private Rigidbody2D _rb;
        private int _facingDir = 1;
        private Coroutine _linkCoroutine;

        // ── 转身状态 ────────────────────────────────────────────────────────
        private bool      _isTurning;
        private int       _pendingFacingDir; // 转身目标方向，转身完成后 ApplyFacingFlip 使用
        private Coroutine _turnCoroutine;

        // ── 输入信号（BD 任务在 Update 写入，FixedUpdate 消费后自动清零）──
        public EnemyMoveInput PendingInput;

        public bool IsGrounded { get; private set; }
        /// <summary>当前朝向：1 = 右，-1 = 左。</summary>
        public int FacingDirection => _facingDir;
        /// <summary>当前是否正在播放转身动画（移动输入在此期间被屏蔽）。</summary>
        public bool IsTurning => _isTurning;

#if UNITY_EDITOR
        [Header("── 运行时调试（仅 Editor）──")]
        [SerializeField] private int   _dbg_FacingDirection;
        [SerializeField] private float _dbg_VelocityX;
        [SerializeField] private float _dbg_VelocityY;
        [SerializeField] private bool  _dbg_IsGrounded;
        [SerializeField] private bool  _dbg_IsTurning;
        [Header("── 输入信号（仅 Editor）──")]
        [SerializeField] private float _dbg_Input_MoveDir;
        [SerializeField] private float _dbg_Input_MoveSpeed;
        [SerializeField] private bool  _dbg_Input_WantStop;
        [SerializeField] private bool  _dbg_Input_WantFace;
        [SerializeField] private Vector2 _dbg_Input_FaceTargetPos;
        [SerializeField] private int   _dbg_Input_FaceDir;
#endif

        // ── INavLinkHandler ────────────────────────────────────────────
        private static readonly NavLinkType[] _handledTypes =
            new[] { NavLinkType.Jump, NavLinkType.Fall };

        public NavLinkType[] HandledLinkTypes => _handledTypes;

        public bool CanHandleLink(NavLinkType type, Vector2 linkStart, Vector2 linkEnd)
        {
            if (type == NavLinkType.Jump)
            {
                float dy = Mathf.Abs(linkEnd.y - linkStart.y);
                float dx = Mathf.Abs(linkEnd.x - linkStart.x);
                return dy <= _navJumpMaxHeight && dx <= _navJumpMaxDist;
            }
            return true; // Fall 总是可以处理
        }

        public void BeginLinkTraversal(NavLinkType type, Vector2 linkStart, Vector2 linkEnd, Action onComplete)
        {
            CancelTurn(); // 进入连接段前中止任何进行中的转身
            if (_linkCoroutine != null) StopCoroutine(_linkCoroutine);
            _linkCoroutine = type == NavLinkType.Jump
                ? StartCoroutine(JumpLinkCoroutine(linkStart, linkEnd, onComplete))
                : StartCoroutine(FallLinkCoroutine(linkStart, linkEnd, onComplete));
        }

        public void AbortLinkTraversal()
        {
            if (_linkCoroutine != null) { StopCoroutine(_linkCoroutine); _linkCoroutine = null; }
            CancelTurn();
            StopHorizontal();
        }

        private IEnumerator JumpLinkCoroutine(Vector2 start, Vector2 end, Action onComplete)
        {
            JumpToTarget(end);
            yield return null; // 等一帧让 velocity 生效

            // 等待离地后落地（超时 3s 防死锁）
            float timer = 0f;
            bool  leftGround = false;
            while (timer < 3f)
            {
                timer += Time.fixedDeltaTime;
                yield return new WaitForFixedUpdate();
                if (!leftGround && !IsGroundedCheck()) { leftGround = true; }
                if (leftGround  &&  IsGroundedCheck()) break;
            }
            StopHorizontal();
            _linkCoroutine = null;
            onComplete?.Invoke();
        }

        private IEnumerator FallLinkCoroutine(Vector2 start, Vector2 end, Action onComplete)
        {
            // 水平对准目标
            float dx = end.x - (float)transform.position.x;
            if (Mathf.Abs(dx) > 0.15f) MoveHorizontal(Mathf.Sign(dx));

            // 等待接近目标Y（重力驱动下落）
            float timer = 0f;
            while (timer < 3f)
            {
                timer += Time.fixedDeltaTime;
                yield return new WaitForFixedUpdate();
                if (IsGroundedCheck() && Mathf.Abs(_rb.position.y - end.y) < 0.6f) break;
            }
            StopHorizontal();
            _linkCoroutine = null;
            onComplete?.Invoke();
        }

        private bool IsGroundedCheck() =>
            Physics2D.Raycast(_rb.position, Vector2.down, _groundCheckDist, _groundMask);

        private void Awake()
        {
            Debug.Assert(_config != null, "[EnemyMovement] _config 未赋值，请在 Prefab Inspector 中指定 EnemyStatsSO。", this);
            _rb = GetComponent<Rigidbody2D>();

            // 从 Sprite 或 localScale 的初始状态推断朝向，并统一切换为 localScale 翻转。
            // 这样子对象（含 RaySensor2D）会随 localScale 正确翻转，不再依赖 flipX。
            if (_spriteRenderer != null)
            {
                // 两个信号均可能携带初始朝向信息：flipX 或 localScale.x < 0，
                // XOR 组合：恰好一个翻转 → 面左；两个都翻（互相抵消）→ 面右。
                bool flippedBySprite = _spriteRenderer.flipX;
                bool flippedByScale  = transform.localScale.x < 0f;
                _facingDir = (flippedBySprite ^ flippedByScale) ? -1 : 1;

                _spriteRenderer.flipX = false; // 后续由 localScale 驱动，避免双重镜像
                Vector3 s = transform.localScale;
                transform.localScale = new Vector3(Mathf.Abs(s.x) * _facingDir, s.y, s.z);
            }
            else
            {
                _facingDir = transform.localScale.x >= 0f ? 1 : -1;
            }

            if (_enableTurnAnimation)
            {
                if (_animancer == null) _animancer = GetComponentInParent<AnimancerComponent>(true);
                if (_animConfig  == null)
                {
                    var enemyBase = GetComponentInParent<EnemyBase>(true);
                    if (enemyBase != null) _animConfig = enemyBase.AnimConfig;
                }
            }
        }

        private void OnDisable()
        {
            // 持久信号在对象禁用时必须清零，防止重新启用时继承残留移动状态。
            PendingInput = default;
            StopHorizontal();
        }

        private void FixedUpdate()
        {
            IsGrounded = IsGroundedCheck();
#if UNITY_EDITOR
            _dbg_Input_MoveDir      = PendingInput.MoveDir;
            _dbg_Input_MoveSpeed    = PendingInput.MoveSpeed;
            _dbg_Input_WantStop     = PendingInput.WantStop;
            _dbg_Input_WantFace     = PendingInput.WantFace;
            _dbg_Input_FaceTargetPos = PendingInput.FaceTargetPos;
            _dbg_Input_FaceDir      = PendingInput.FaceDir;
#endif
            ConsumeInput();
#if UNITY_EDITOR
            _dbg_FacingDirection = _facingDir;
            _dbg_VelocityX       = _rb != null ? _rb.velocity.x : 0f;
            _dbg_VelocityY       = _rb != null ? _rb.velocity.y : 0f;
            _dbg_IsGrounded      = IsGrounded;
            _dbg_IsTurning       = _isTurning;
#endif
        }

        private void ConsumeInput()
        {
            // ── 一次性脉冲：消费后清零 ─────────────────────────────────────
            // WantStop / WantFace 只需写一次，消费后自动清除，
            // 避免 BD 任务每帧续写而产生的不必要开销。
            bool wantStop  = PendingInput.WantStop;
            bool wantFace  = PendingInput.WantFace;
            int  faceDir   = PendingInput.FaceDir;
            var  facePosSnapshot = PendingInput.FaceTargetPos;
            PendingInput.WantStop = false;
            PendingInput.WantFace = false;

            // ── 持久字段：MoveDir / MoveSpeed 不清零 ─────────────────────
            // 解决 FixedUpdate 频率 > Update 频率时的空帧问题：
            // 两次 Update 之间如果 FixedUpdate 多执行一次，之前写入的 MoveDir
            // 仍然有效，不会产生意外的 StopHorizontal。
            if (wantStop)
            {
                PendingInput.MoveDir  = 0f;
                PendingInput.MoveSpeed = 0f;
                StopHorizontal();
            }
            else if (PendingInput.MoveDir != 0f)
            {
                if (PendingInput.MoveSpeed > 0f)
                    MoveWithSpeed(PendingInput.MoveDir, PendingInput.MoveSpeed);
                else
                    MoveHorizontal(PendingInput.MoveDir);
            }

            if (wantFace && !_isTurning)
            {
                if (faceDir != 0)
                    UpdateFacing(faceDir > 0 ? 1f : -1f);
                else
                    FaceTarget(facePosSnapshot);
            }
        }

        /// <summary>按 SO 配置速度水平移动。dir: +1 右 / -1 左 / 0 停止。转身动画期间调用无效。</summary>
        public void MoveHorizontal(float dir)
        {
            if (_isTurning) return;
            var vel = _rb.velocity;
            vel.x = dir * _config.WalkSpeed;
            _rb.velocity = vel;
            UpdateFacing(dir);
        }

        /// <summary>显式指定速度（BD 追击任务调用）。转身动画期间调用无效。</summary>
        public void MoveWithSpeed(float dir, float speed)
        {
            if (_isTurning) return;
            var vel = _rb.velocity;
            vel.x = dir * speed;
            _rb.velocity = vel;
            UpdateFacing(dir);
        }

        /// <summary>朝向指定世界坐标（通常传入玩家位置）。</summary>
        public void FaceTarget(Vector2 targetPos)
        {
            float dir = targetPos.x < transform.position.x ? -1f : 1f;
            UpdateFacing(dir);
        }

        /// <summary>
        /// 直接指定朝向方向。dir: +1 = 右，-1 = 左。
        /// 若启用转身动画且方向确实改变，会触发转身流程。
        /// </summary>
        public void FaceDirection(int dir)
        {
            if (dir == 0) return;
            UpdateFacing(dir > 0 ? 1f : -1f);
        }

        /// <summary>朝向右方（+X）。</summary>
        public void FaceRight() => FaceDirection(1);

        /// <summary>朝向左方（-X）。</summary>
        public void FaceLeft()  => FaceDirection(-1);

        public void ApplyKnockback(Vector2 dir, float force)
        {
            _rb.velocity = dir.normalized * force;
        }

        /// <summary>
        /// 击飞冲量：向上 + 沿受击反方向水平。
        /// sourceDir 为伤害来源朝向（通常是 DamageInfo.KnockbackDirection），横向取其反方向。
        /// </summary>
        /// <param name="sourceDir">来袭方向（已归一化）</param>
        /// <param name="horzForce">水平冲量大小</param>
        /// <param name="upForce">纵向冲量大小</param>
        public void LaunchKnockup(Vector2 sourceDir, float horzForce, float upForce)
        {
            if (_rb == null) return;
            float horzSign = sourceDir.x >= 0f ? -1f : 1f; // 反方向弹飞
            _rb.velocity = new Vector2(horzSign * horzForce, upForce);
        }

        public void StopHorizontal()
        {
            var vel = _rb.velocity;
            vel.x = 0f;
            _rb.velocity = vel;
        }

        /// <summary>
        /// 向目标位置抖跃（抛物线累加填充）。
        /// 计算初速使尔子到达目标，用 Impulse 施加力。
        /// </summary>
        public void JumpToTarget(Vector2 target)
        {
            if (_rb == null) return;
            Vector2 delta     = target - (Vector2)transform.position;
            float   gravMag   = Mathf.Abs(Physics2D.gravity.y * _rb.gravityScale);
            float   timeAloft = Mathf.Max(0.1f, delta.x != 0f
                ? Mathf.Abs(delta.x) / _config.RunSpeed
                : 0.5f);

            float vy = (delta.y - 0.5f * (-gravMag) * timeAloft * timeAloft) / timeAloft;
            float vx = delta.x / timeAloft;

            _rb.velocity = new Vector2(vx, vy);
            UpdateFacing(vx);
        }

        private void UpdateFacing(float dir)
        {
            if (Mathf.Approximately(dir, 0f)) return;
            if (_isTurning) return; // 转身进行中，忽略新的朝向请求
            int newDir = dir > 0f ? 1 : -1;
            if (newDir == _facingDir) return;

            if (_enableTurnAnimation && _animancer != null && _animConfig?.Turn != null)
            {
                // 启动转身协程：动画播完后再实际翻转
                _pendingFacingDir = newDir;
                if (_turnCoroutine != null) StopCoroutine(_turnCoroutine);
                _turnCoroutine = StartCoroutine(TurnCoroutine(newDir));
            }
            else
            {
                ApplyFacingFlip(newDir);
            }
        }

        /// <summary>转身动画协程：停止水平移动 → 播放 Turn 动画 → 翻转朝向 → 恢复。</summary>
        private IEnumerator TurnCoroutine(int newDir)
        {
            _isTurning = true;
            StopHorizontal();

            // yield return state：Animancer 的 AnimancerState 是 CustomYieldInstruction，
            // 等待动画自然播完，与 Layer/State 速度缩放无关，比手动计时更可靠。
            var state = _animancer.Play(_animConfig.Turn);
            yield return state;

            ApplyFacingFlip(newDir);
            _isTurning     = false;
            _turnCoroutine = null;
        }

        /// <summary>
        /// 立即中止进行中的转身协程，并将朝向应用到待转方向。
        /// 受击、死亡、NavLink 穿越等外部中断时调用。
        /// </summary>
        public void CancelTurn()
        {
            if (_turnCoroutine == null) return;
            StopCoroutine(_turnCoroutine);
            _turnCoroutine = null;
            if (_isTurning)
            {
                ApplyFacingFlip(_pendingFacingDir);
                _isTurning = false;
            }
        }

        /// <summary>真正执行朝向翻转。始终用 localScale 翻转，子对象（传感器 RaySensor2D）随之正确翻转。</summary>
        private void ApplyFacingFlip(int newDir)
        {
            _facingDir = newDir;
            // 若挂有 SpriteRenderer，重置 flipX = false（localScale 已负责镜像，避免双重翻转）。
            if (_spriteRenderer != null)
                _spriteRenderer.flipX = false;
            Vector3 s = transform.localScale;
            transform.localScale = new Vector3(Mathf.Abs(s.x) * newDir, s.y, s.z);
        }

        private void OnDrawGizmos()
        {
#if UNITY_EDITOR
            // ── 1. 敌人物理轮廓（珊瑚红，区别于玩家绿色）────────────────
            Gizmos.color = new Color(1f, 0.45f, 0.35f, 0.65f);
            foreach (var col in GetComponents<Collider2D>())
            {
                if (col.isTrigger) continue;
                BaseGames.Combat.HitBox.DrawCollider2DWire(col);
            }

            // ── 2. 朝向箭头（橙色）──────────────────────────────────────
            Vector3 center = transform.position;
            DrawArrow2D(center, center + new Vector3(_facingDir * 0.5f, 0f, 0f),
                        new Color(1f, 0.6f, 0.1f, 0.9f));

            // ── 3. 地面检测射线（接地亮绿 / 未接地暗绿）─────────────────
            if (_groundCheckDist > 0f)
            {
                bool grounded = Application.isPlaying && IsGrounded;
                Gizmos.color  = grounded
                    ? new Color(0.2f, 1f, 0.35f, 0.90f)
                    : new Color(0.4f, 0.75f, 0.4f, 0.40f);
                Vector3 origin = transform.position;
                Gizmos.DrawLine(origin, origin + Vector3.down * _groundCheckDist);
                Gizmos.DrawWireSphere(origin + Vector3.down * _groundCheckDist, 0.04f);
            }
#endif
        }

        private void OnDrawGizmosSelected()
        {
#if UNITY_EDITOR
            // 运行时：青色箭头显示速度向量（选中时）
            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);
            float cos = 0.8192f, sin = 0.5736f; // cos/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);
        }
    }
}