using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{

    //移动速度
    public float speed = 5f;

    //重力加速度
    public float gravity = -20f;

    //活动范围
    public float range = 500f;

    //兼容旧场景配置，目标搜索不再受此范围限制
    public float detectRange = 200f;

    //攻击范围
    public float attackRange = 5f;

    //完整攻击动作时长，单位为秒；设置为0时使用动画真实时长
    [Min(0f)]
    public float attackDuration = 0f;

    //角色状态
    private State state = State.Alert;

    //攻击目标
    public GameObject target;

    //当前目标点
    private Vector3 targetPos;

    //初始位置坐标
    private Vector3 startPos;

    //动画控制器
    private Animator animator;

    // 角色控制器
    private CharacterController controller;

    //垂直速度
    private float verticalVelocity;

    //状态枚举
    public enum State
    {
        //警戒巡逻
        Alert,

        //追踪状态
        Track, 

        //攻击状态
        Attack
    }






    // Start is called before the first frame update
    void Start()
    {
        //初始化
        animator = GetComponent<Animator>();
        controller = GetComponent<CharacterController>();
        //记录初始坐标
        startPos = transform.position;
        randomTargetPos();
    }



    // Update is called once per frame
    void Update()
    {
        //攻击状态直接返回
        if (state == State.Attack)
        {
            animator.SetInteger("speed", 0);
            applyGravity();
            return;
        }

        //查找场景中距离自己最近的敌对目标
        target = FindNearestOpponent();
        if (target != null)
        {
            state = State.Track;

            //目标在攻击范围外则朝目标移动，否则开始攻击
            if (!IsWithinAttackReach(target))
            {
                move(target.transform.position - transform.position);
            }
            else
            {
                attack(target);
            }

            return;
        }

        //没有目标时回到巡逻
        state = State.Alert;
        move(targetPos - transform.position);

        //到达目标点时候随机目标点，只判断水平距离
        Vector3 patrolOffset = transform.position - targetPos;
        patrolOffset.y = 0;
        if (patrolOffset.sqrMagnitude < 0.01f)
        {
            randomTargetPos();
        }
    }

    //根据自身Tag找到敌对Tag
    private string GetOpponentTag()
    {
        if (CompareTag("Friend"))
        {
            return "Enemy";
        }

        if (CompareTag("Enemy"))
        {
            return "Friend";
        }

        return null;
    }

    //查找距离自己最近的敌对目标
    private GameObject FindNearestOpponent()
    {
        string opponentTag = GetOpponentTag();
        if (string.IsNullOrEmpty(opponentTag))
        {
            return null;
        }

        GameObject nearestOpponent = null;
        float nearestSqrDistance = float.PositiveInfinity;
        GameObject[] opponents = GameObject.FindGameObjectsWithTag(opponentTag);

        foreach (var opponent in opponents)
        {
            //排除自己以及自己所在层级中的对象
            if (opponent == gameObject || opponent.transform.root == transform.root)
            {
                continue;
            }

            float sqrDistance = (opponent.transform.position - transform.position).sqrMagnitude;
            if (sqrDistance < nearestSqrDistance)
            {
                nearestSqrDistance = sqrDistance;
                nearestOpponent = opponent;
            }
        }

        return nearestOpponent;
    }

    //判断是否进入可攻击距离
    private bool IsWithinAttackReach(GameObject opponent)
    {
        if (opponent == null)
        {
            return false;
        }

        // 只保留很小的接触补偿，避免两边半径叠加导致隔空挥剑
        float reachDistance = attackRange + 0.1f;
        return Vector3.Distance(transform.position, opponent.transform.position) <= reachDistance;
    }

    //查找当前Animator中使用的攻击动画时长
    private float GetAttackAnimationDuration()
    {
        if (animator == null || animator.runtimeAnimatorController == null)
        {
            return 0f;
        }

        var overrideController = animator.runtimeAnimatorController as AnimatorOverrideController;
        if (overrideController != null)
        {
            var overrides = new List<KeyValuePair<AnimationClip, AnimationClip>>();
            overrideController.GetOverrides(overrides);

            foreach (var pair in overrides)
            {
                if (IsAttackAnimation(pair.Key))
                {
                    return pair.Value != null ? pair.Value.length : pair.Key.length;
                }
            }
        }

        foreach (var clip in animator.runtimeAnimatorController.animationClips)
        {
            if (IsAttackAnimation(clip))
            {
                return clip.length;
            }
        }

        return 0f;
    }

    //根据动画名称判断是否为攻击动画
    private bool IsAttackAnimation(AnimationClip clip)
    {
        if (clip == null)
        {
            return false;
        }

        string clipName = clip.name.ToLowerInvariant();
        return clipName.Contains("attack")
            || clipName.Contains("攻击")
            || clipName.Contains("挥剑");
    }

    //设置攻击动画播放速度
    private void SetAttackAnimationSpeed()
    {
        float animationDuration = GetAttackAnimationDuration();
        if (animationDuration <= 0f || attackDuration <= 0f)
        {
            animator.speed = 1f;
            return;
        }

        animator.speed = animationDuration / attackDuration;
    }

    //攻击
    private void attack(GameObject friend)
    {
        target = friend;

        //根据目标攻击时长加速或减速完整攻击动画
        SetAttackAnimationSpeed();
        animator.SetInteger("speed", 0);
        animator.SetTrigger("attack");
        state = State.Attack;
    }


    // 在 Animator 的 Attack 动画结束时调用此方法
    public void OnAttackAnimationEnd()
    {
        //攻击动画结束后恢复Animator速度
        animator.speed = 1f;

        //攻击动画结束后，目标仍在攻击范围内则立即进行下一次攻击
        target = FindNearestOpponent();
        if (target != null && IsWithinAttackReach(target))
        {
            attack(target);
            return;
        }

        //目标离开攻击范围，回到追踪或巡逻逻辑
        state = State.Alert;
        randomTargetPos();
    }



    //角色移动,持续到目标点
    void move(Vector3 movement)
    {
        movement.y = 0;
        if (movement == Vector3.zero)
        {
            animator.SetInteger("speed", 0);
            applyGravity();
            return;
        }

        //改变动画控制器的参数
        animator.SetInteger("speed", 1);
        //向目标点移动，同时应用垂直重力
        Vector3 velocity = movement.normalized * speed;
        velocity.y = getVerticalVelocity();
        controller.Move(velocity * Time.deltaTime);
        //改变角色朝向目标点,只改变y轴
        transform.rotation = Quaternion.LookRotation(movement, Vector3.up);
        transform.rotation = Quaternion.Euler(0, transform.rotation.eulerAngles.y, 0);
    }


    private float getVerticalVelocity()
    {
        if (controller.isGrounded && verticalVelocity < 0)
        {
            verticalVelocity = -2f;
        }
        else
        {
            verticalVelocity += gravity * Time.deltaTime;
        }

        return verticalVelocity;
    }

    private void applyGravity()
    {
        controller.Move(Vector3.up * getVerticalVelocity() * Time.deltaTime);
    }

    //随机目标点
    private void randomTargetPos()
    {
        //以startPos为中心，在水平圆形范围内随机一个点
        Vector2 randomOffset = Random.insideUnitCircle * range;
        targetPos = startPos + new Vector3(randomOffset.x, 0, randomOffset.y);
    }
}