using UnityEngine;

/// <summary>
/// 此代码挂载到相机上，
/// </summary>
public class SmoothUi3DCamera : MonoBehaviour
{
    public static SmoothUi3DCamera instance;
    // 用于旋转的变换
    public Transform pivot;
    // 透视变换的偏移量
    public Vector3 pivotOffset = Vector3.zero;
    // 目标变换
    public Transform target;
    // 与目标的距离
    public float distance = 10.0f;
    // 距离的最小值
    public float minDistance = 5f;
    // 距离的最大值
    public float maxDistance = 15f;
    // 缩放速度
    public float zoomSpeed = 1f;
    // 水平旋转速度
    public float xSpeed = 250.0f;
    // 垂直旋转速度
    public float ySpeed = 250.0f;
    // 触摸旋转速度因子
    [Header("触摸旋转速度因子")]
    public float touchSpeed = 0.05f; // 测试显示0.05f 效果更佳
                                     // 是否允许垂直倾斜
    public bool allowYTilt = true;
    // 垂直倾斜的最小角度限制
    public float yMinLimit = -90f;
    // 垂直倾斜的最大角度限制
    public float yMaxLimit = 90f;
    // 水平旋转角度
    private float x = 0.0f;
    // 垂直旋转角度
    private float y = 0.0f;
    // 目标水平旋转角度
    private float targetX = 0f;
    // 目标垂直旋转角度
    private float targetY = 0f;
    // 目标距离
    public float targetDistance = 0f;
    // 水平旋转速度
    private float xVelocity = 1f;
    // 垂直旋转速度
    private float yVelocity = 1f;
    // 缩放速度
    private float zoomVelocity = 1f;

    // 定义鼠标控制的屏幕范围（左，右，上，下）
    [Header("鼠标控制屏幕范围")]
    public Vector2 screenRangeLeftRight = new Vector2(0f, 1f); // 0f 到 1f 表示整个屏幕宽度
    public Vector2 screenRangeTopBottom = new Vector2(0f, 1f); // 0f 到 1f 表示整个屏幕高度

    private void Awake()
    {
        instance = this;
    }

    private void Start()
    {
        var angles = transform.eulerAngles;
        // 因为是操作的相机，所以我们实际的操作出来是向反的方向
        targetY = x = angles.x;
        targetX = y = ClampAngle(angles.y, yMinLimit, yMaxLimit);
        targetDistance = distance;
    }


    private void LateUpdate()
    {
        if (!pivot) return;

        // 获取鼠标位置
        Vector2 mousePosition = Input.mousePosition;

        // 检查鼠标是否在屏幕范围内
        if (mousePosition.x / Screen.width >= screenRangeLeftRight.x && mousePosition.x / Screen.width <= screenRangeLeftRight.y &&
            mousePosition.y / Screen.height >= screenRangeTopBottom.x && mousePosition.y / Screen.height <= screenRangeTopBottom.y)
        {

            #region 鼠标控制
            // 鼠标中键控制缩放
            var scroll = Input.GetAxis("Mouse ScrollWheel");
            if (scroll > 0.0f) targetDistance -= zoomSpeed;
            else if (scroll < 0.0f)
                targetDistance += zoomSpeed;
            targetDistance = Mathf.Clamp(targetDistance, minDistance, maxDistance);
            // 鼠标左右键操作旋转
            if (Input.GetMouseButton(0) || (Input.GetMouseButton(1) && (Input.GetKey(KeyCode.LeftControl) || Input.GetKey(KeyCode.RightControl))))
            {
                targetX += Input.GetAxis("Mouse X") * xSpeed * 0.02f;
                if (allowYTilt)
                {
                    targetY -= Input.GetAxis("Mouse Y") * ySpeed * 0.02f;
                    targetY = ClampAngle(targetY, yMinLimit, yMaxLimit);
                }
            }
            x = Mathf.SmoothDampAngle(x, targetX, ref xVelocity, 0.3f);
            y = allowYTilt ? Mathf.SmoothDampAngle(y, targetY, ref yVelocity, 0.3f) : targetY;
            Quaternion rotation = Quaternion.Euler(y, x, 0);
            distance = Mathf.SmoothDamp(distance, targetDistance, ref zoomVelocity, 0.5f);
            Vector3 position = rotation * new Vector3(0.0f, 0.0f, -distance) + pivot.position + pivotOffset;
            transform.rotation = rotation;
            transform.position = position;
            #endregion
        }
    }



    private static float ClampAngle(float angle, float min, float max)
    {
        if (angle < -360) angle += 360;
        if (angle > 360) angle -= 360;
        return Mathf.Clamp(angle, min, max);
    }

    [ContextMenu("Load Initialize View")]
    public void LoadInitializeView()
    {

    }

    /// <summary>
    /// 设置相机的初始状态
    /// </summary>
    /// <param name="initialXAngle"></param>
    /// <param name="initialYAngle"></param>
    /// <param name="initialDistance"></param>
    public void InitializeView(float initialXAngle, float initialYAngle, float initialDistance)
    {
        // 设置初始水平旋转角度
        targetX = initialXAngle;
        x = initialXAngle;

        // 设置初始垂直旋转角度，并考虑角度限制
        targetY = ClampAngle(initialYAngle, yMinLimit, yMaxLimit);
        y = targetY;

        // 设置初始距离，并考虑距离限制
        targetDistance = Mathf.Clamp(initialDistance, minDistance, maxDistance);
        distance = targetDistance;

        // 更新相机的位置和旋转
        Quaternion rotation = Quaternion.Euler(y, x, 0);
        Vector3 position = rotation * new Vector3(0.0f, 0.0f, -distance) + pivot.position + pivotOffset;
        transform.rotation = rotation;
        transform.position = position;
    }

}