using System;
using DragonLi.Frame;
using UnityEngine;

public class SwordProjectile : MonoBehaviour
{
    public enum State
    {
        Idle,
        FlyingOut,
        Grounded,
        Returning
    }

    [Header("飞行参数")]
    public float flySpeed = 15f;
    [Tooltip("落地后停留时间")]
    public float stayDuration = 2f;
    [Tooltip("玩家被击中半径，不使用物理碰撞")]
    private float hitRadius = 3f;
    [Tooltip("落地方向距离的高度偏移(可让剑从空中稍微高出)")]
    public float heightOffset = 0f;

    [Header("伤害")]
    public float damageAmount = 15f;

    private State currentState = State.Idle;
    private Vector3 startPosition;       // BOSS 背部原始位置
    private Vector3 targetPosition;      // 本次飞行的地面目标位置
    private float groundY;               // 地面高度 (scene 中地面 Y 坐标)
    private float stayTimer = 0f;
    private bool hasHitPlayerThisPhase = false;
    private Transform playerTransform;

    // 返回完成时的回调事件（由 BossController 订阅，用于结束投掷动画）
    public event Action OnReturnComplete;

    /// <summary>
    /// 由 BossController 实例化后调用，用来设置飞行目标并开始飞行
    /// </summary>
    /// <param name="player">玩家 Transform</param>
    /// <param name="bossBackPoint">BOSS 背部挂点 Transform</param>
    /// <param name="flySpd">飞行速度</param>
    /// <param name="groundYPos">地面 Y 坐标</param>
    /// <param name="stayTime">落地停留时间</param>
    /// <param name="radius">击中玩家距离阈值</param>
    /// <param name="dmg">伤害值</param>
    public void Initialize(Transform player,
                           Transform bossBackPoint,
                           float flySpd,
                           float groundYPos,
                           float stayTime,
                           float radius,
                           float dmg)
    {
        playerTransform = player;
        flySpeed = flySpd;
        groundY = groundYPos;
        stayDuration = stayTime;
        hitRadius = radius;
        damageAmount = dmg;

        currentState = State.FlyingOut;
        hasHitPlayerThisPhase = false;
        stayTimer = 0f;

        // 记录起始位置（Boss 背部挂点）
        startPosition = bossBackPoint.position;

        // 目标落点：在玩家当前位置正上方，附加 heightOffset
        Vector3 playerPos = playerTransform != null ? playerTransform.position : Vector3.zero;
        targetPosition = new Vector3(playerPos.x, groundY, playerPos.z);

        // 让剑从稍微高于背部位置处起飞（视觉效果可调整）
        transform.position = startPosition + Vector3.up * heightOffset;
    }

    private void Update()
    {
        switch (currentState)
        {
            case State.FlyingOut:
                FlyOut();
                break;
            case State.Grounded:
                HandleGrounded();
                break;
            case State.Returning:
                FlyBack();
                break;
        }
    }

    /// <summary>
    /// 飞出阶段：朝 targetPosition 飞行
    /// </summary>
    private void FlyOut()
    {
        Vector3 dir = (targetPosition - transform.position).normalized;
        transform.position += dir * flySpeed * Time.deltaTime;

        // 飞行途中持续检测与玩家距离，若小于 hitRadius 且本阶段未曾击中，则造成一次伤害
        if (!hasHitPlayerThisPhase && playerTransform != null)
        {
            float sqrDist = (transform.position - playerTransform.position).sqrMagnitude;
            if (sqrDist <= hitRadius * hitRadius)
            {
                HitPlayer();
                hasHitPlayerThisPhase = true;
            }
        }

        // 到达或跌落到 groundY 时，进入 Grounded 阶段
        if (transform.position.y <= groundY)
        {
            // 瞬间把 Y 设为 groundY
            Vector3 pos = transform.position;
            pos.y = groundY;
            transform.position = pos;

            currentState = State.Grounded;
            hasHitPlayerThisPhase = false; // 重置，本阶段可再击中一次
            stayTimer = 0f;
        }
        transform.LookAt(playerTransform.position);
    }

    /// <summary>
    /// 落地停留阶段
    /// </summary>
    private void HandleGrounded()
    {
        stayTimer += Time.deltaTime;

        // 停留阶段再次检测“玩家距离”，若小于阈值且尚未击中本阶段，则造成伤害
        if (!hasHitPlayerThisPhase && playerTransform != null)
        {
            float sqrDist = (transform.position - playerTransform.position).sqrMagnitude;
            if (sqrDist <= hitRadius * hitRadius)
            {
                HitPlayer();
                hasHitPlayerThisPhase = true;
            }
        }

        // 停留时长到，进入返回阶段
        if (stayTimer >= stayDuration)
        {
            currentState = State.Returning;
            hasHitPlayerThisPhase = false;
        }
    }

    /// <summary>
    /// 返回阶段：朝 startPosition 上方飞行 (保留 heightOffset)，
    /// 到达后触发 OnReturnComplete，销毁自身
    /// </summary>
    private void FlyBack()
    {
        // 目标为背部挂点上方相同高度
        Vector3 returnTarget = startPosition + Vector3.up * heightOffset;
        Vector3 dir = (returnTarget - transform.position).normalized;
        transform.position += dir * flySpeed * Time.deltaTime;

        if (!hasHitPlayerThisPhase && playerTransform != null)
        {
            float sqrDist = (transform.position - playerTransform.position).sqrMagnitude;
            if (sqrDist <= hitRadius * hitRadius)
            {
                HitPlayer();
                hasHitPlayerThisPhase = true;
            }
        }

        // 检测是否到达“返回目标”足够近
        if ((transform.position - returnTarget).sqrMagnitude <= 0.01f)
        {
            OnReturnComplete?.Invoke();
            Destroy(gameObject);
        }
    }

    private void HitPlayer()
    {
        var ph = playerTransform.GetComponent<IDamagable>();
        if (ph != null)
            ph.ApplyDamage(damageAmount,null,transform);
    }
}