using System.Collections.Generic;
using UnityEngine;

public class ArcMove : MonoBehaviour
{
    public float TurnTriggerDistance = 5f;  // 预先转向保留距离
    public float MoveSpeed = 20f;           // 匀速朝向前运动

    private float _angularSpeed = 0f;       // 本次转向的转向速度
    private float _remainingTurnTime = 0f;  // 本次转向的转向时间
    private int _currentNodeIndex = 0;

    private List<Vector3> _route = new()
    {
        new Vector3(10,0,-10),
        new Vector3(-10,0,-10),
        new Vector3(10,0, 0),
        new Vector3(10,0,10),
        new Vector3(-10,0,10),
    };

    private void Start() => ResetState();

    void Update()
    {
        // ECS里的控制系统
        var curPos = transform.position;
        if (_remainingTurnTime <= 0 && _currentNodeIndex == _route.Count - 2)
        {
            var curPoint = _route[_currentNodeIndex];
            var arrivePoint = _route[_currentNodeIndex + 1];
            if (Vector3.Dot(arrivePoint - curPoint, arrivePoint - curPos) < 0)
                ResetState();
        }
        if (_remainingTurnTime > 0)
        {
            _remainingTurnTime -= Time.deltaTime;
            if (_remainingTurnTime <= 0) _angularSpeed = 0;
        }
        else
        {
            var haveNextPoint = _currentNodeIndex + 1 < _route.Count;
            var haveNextNextPoint = _currentNodeIndex + 2 < _route.Count;
            var handled = false;
            if (haveNextNextPoint)
            {
                var curPoint = _route[_currentNodeIndex];
                var nextPoint = _route[_currentNodeIndex + 1];
                var nextNextPoint = _route[_currentNodeIndex + 2];
                var inVector = nextPoint - curPoint;
                var outVector = nextNextPoint - nextPoint;
                var clampTurnTriggerDistance = Mathf.Min(TurnTriggerDistance, Mathf.Min(inVector.magnitude, outVector.magnitude) / 2);
                var nowRemainDist = (curPos - nextPoint).magnitude;
                if (nowRemainDist <= clampTurnTriggerDistance)
                {
                    ++_currentNodeIndex;
                    handled = true;
                    // 脱离
                    var angle = Vector3.SignedAngle(inVector.normalized, outVector.normalized, Vector3.up);
                    var absoluteAngle = Mathf.Abs(angle);
                    if (absoluteAngle < 1f) return; // 角度太小，Tan会很大，安全起见，直接当直线跑
                    var inCircleRadius = nowRemainDist / Mathf.Tan(absoluteAngle * Mathf.Deg2Rad / 2);
                    var arcLength = 2 * Mathf.PI * inCircleRadius * absoluteAngle / 360;
                    _remainingTurnTime = arcLength / MoveSpeed;
                    _angularSpeed = angle / _remainingTurnTime;
                }
            }
            if (haveNextPoint && !handled)
            {
                var curDir = transform.rotation * Vector3.forward;
                var targetDir = _route[_currentNodeIndex + 1] - curPos;
                var diffAngle = Vector3.SignedAngle(curDir.normalized, targetDir.normalized, Vector3.up);
                _angularSpeed = diffAngle * MoveSpeed; // 朝向收敛与速度正相关
            }
        }

        // ECS里的Movement系统
        transform.rotation *= Quaternion.Euler(0, _angularSpeed * Time.deltaTime, 0);
        transform.position = transform.position + MoveSpeed * Time.deltaTime * transform.forward;
    }

    private void ResetState()
    {
        _currentNodeIndex = 0;
        transform.SetPositionAndRotation(_route[_currentNodeIndex], Quaternion.LookRotation(_route[1] - _route[0]));
    }
}

// 原生判断函数是Enum的实例方法，Enum本身是抽象类（引用类型）
public bool HasFlag(Enum flag){
    // ...
}

// 替换 HasFlag 方法，避免装箱，仅适用于Int32枚举
public static bool HasFlagFast<T>(this T flags, T value) where T : struct, Enum
{
    if (Enum.GetUnderlyingType(typeof(T)) != typeof(int))
        throw new ArgumentException($"枚举类型 {typeof(T).Name} 的底层类型不是 Int32，无法使用此方法", nameof(T));
    var f = Unsafe.As<T, int>(ref flags);
    var v = Unsafe.As<T, int>(ref value);
    return (f & v) == v;
}

// 业务层BasicsMain
private Window _winA; // 实例变量
private Window _winB; // 实例变量
private void PlayWindow()
{
    GComponent obj = _demoObjects["Window"];
    obj.GetChild("n0").onClick.Add(() =>
    {
        if (_winA == null)
            _winA = new Window1();
        _winA.Show();
    });

    obj.GetChild("n1").onClick.Add(() =>
    {
        if (_winB == null)
            _winB = new Window2();
        _winB.Show();
    });
}

// FairyGUI.EventListener.cs
public void Add(EventCallback0 callback)
{
    _bridge.Add(callback);
}

// FairyGUI.EventBridge.cs
EventCallback0 _callback0;
public void Add(EventCallback0 callback)
{
    _callback0 -= callback;
    _callback0 += callback;
}