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

public class PlatformAccountFollower : FollowerBase
{
    [Header("Following Settings")]
    public bool InstantFollowing = false;//是否无延迟跟随
    public bool LinearFollowing;//是否线性移动

    public Vector2 border_x; //x轴边界
    public Vector2 border_y; //y轴边界
    private Transform _slamHead;
    Vector2 initViewPoint;//相机画面的中点，坐标为（0.5f,0.5f）
    Vector3 viewPoint = Vector3.zero;// 面板中心坐标相对于相机画面的坐标。
    private Vector3 velocity = Vector3.zero;
    bool isFollower = false;

    Vector3 originPos = Vector3.zero;
    Vector3 desPos = Vector3.zero;
    float journeyLength = 0f;
    protected override void OnEnable()
    {
        base.OnEnable();

    }

    private void Start()
    {
        InitTrans();
    }

    protected override void LateUpdate()
    {
        if (StopFollower == false)
        {
            if (IsFollower())
            {
                if (LinearFollowing)
                {
                    LinearFollow();
                }
                else
                {
                    Follow();
                }
            }

        }
    }

    void InitTrans()
    {
        if (Camera.main != null)
        {
            _slamHead = Camera.main.transform;
            transform.position = CalculateWindowPosition(Camera.main.transform);
            transform.rotation = CalculateWindowRotation(Camera.main.transform);
            initViewPoint = Camera.main.WorldToViewportPoint(_slamHead.position + (_slamHead.forward * WindowDistance));//相机画面中点坐标
        }
    }


    protected bool IsFollower()
    {
        if ( Camera.main == null)
        {
            return false;
        }
        viewPoint = Camera.main.WorldToViewportPoint(transform.position);// 面板在相机画面上的坐标

        if (viewPoint.x > initViewPoint.x + border_x.x + CalculateWindowOffsetX() || viewPoint.x < initViewPoint.x + border_x.y + CalculateWindowOffsetX() || viewPoint.y < initViewPoint.y + border_y.y + CalculateWindowOffsetY() || viewPoint.y > initViewPoint.y + border_y.x + CalculateWindowOffsetY())//边界判断
        {
            isFollower = true;
        }
        else if (Mathf.Abs(viewPoint.x - initViewPoint.x - CalculateWindowOffsetX()) < 0.03f && Mathf.Abs(viewPoint.y - initViewPoint.y - CalculateWindowOffsetY()) < 0.06f)
        {
            isFollower = false;
        }
        return isFollower;
    }

    //Nonlinear Following by default
    protected override void Follow()
    {
        transform.position = Vector3.Lerp(transform.position, CalculateWindowPosition(Camera.main.transform), WindowFollowSpeed * Time.deltaTime);
        //transform.position = Vector3.SmoothDamp(transform.position, CalculateWindowPosition(Camera.main.transform), ref velocity, WindowFollowSpeed);
        transform.rotation = Quaternion.Slerp(transform.rotation, CalculateWindowRotation(Camera.main.transform), WindowFollowSpeed * Time.deltaTime);
    }



    //For Linear Following, turn down the WindowFollowSpeed to around 0.5 at distance = 1 for best experience
    protected void LinearFollow()
    {
        originPos = transform.position;
        desPos = CalculateWindowPosition(Camera.main.transform);
        journeyLength = Vector3.Distance(originPos, desPos);
        transform.position = Vector3.Lerp(originPos, desPos, (Time.fixedDeltaTime) / journeyLength * WindowFollowSpeed);
        transform.rotation = Quaternion.Slerp(transform.rotation, CalculateWindowRotation(Camera.main.transform), (Time.fixedDeltaTime) / journeyLength * WindowFollowSpeed);
    }

    protected override Vector3 CalculateWindowPosition(Transform cameraTransform)
    {
        Vector3 position = cameraTransform.position + (Vector3.ProjectOnPlane(cameraTransform.forward,Vector3.up).normalized * WindowDistance);
        Vector3 horizontalOffset = cameraTransform.right * windowOffset.x;
        Vector3 verticalOffset = cameraTransform.up * windowOffset.y;

        switch (windowAnchor)
        {
            case TextAnchor.UpperLeft: position += verticalOffset - horizontalOffset; break;
            case TextAnchor.UpperCenter: position += verticalOffset; break;
            case TextAnchor.UpperRight: position += verticalOffset + horizontalOffset; break;
            case TextAnchor.MiddleLeft: position -= horizontalOffset; break;
            case TextAnchor.MiddleRight: position += horizontalOffset; break;

            case TextAnchor.MiddleCenter: position += horizontalOffset + verticalOffset; break;

            case TextAnchor.LowerLeft: position -= verticalOffset + horizontalOffset; break;
            case TextAnchor.LowerCenter: position -= verticalOffset; break;
            case TextAnchor.LowerRight: position -= verticalOffset - horizontalOffset; break;
        }

        return position;
    }


    protected override Quaternion CalculateWindowRotation(Transform cameraTransform)
    {
        Quaternion rotation = Quaternion.Euler(0, cameraTransform.rotation.eulerAngles.y, 0);

        switch (windowAnchor)
        {

            case TextAnchor.UpperLeft: rotation *= windowHorizontalRotationInverse * windowVerticalRotationInverse; break;
            case TextAnchor.UpperCenter: rotation *= windowHorizontalRotationInverse; break;
            case TextAnchor.UpperRight: rotation *= windowHorizontalRotationInverse * windowVerticalRotation; break;
            case TextAnchor.MiddleLeft: rotation *= windowVerticalRotationInverse; break;
            case TextAnchor.MiddleRight: rotation *= windowVerticalRotation; break;
            case TextAnchor.LowerLeft: rotation *= windowHorizontalRotation * windowVerticalRotationInverse; break;
            case TextAnchor.LowerCenter: rotation *= windowHorizontalRotation; break;
            case TextAnchor.LowerRight: rotation *= windowHorizontalRotation * windowVerticalRotation; break;
        }

        return rotation;
    }

}