using BigSpace.XRCore.Base;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class LinerMgr : MonoSingleton<LinerMgr>
{
    public Transform m_target;
    public float height = 0.5f;
    public float arrowLength = 0.5f;
    public float speed = 1f;

    public GameObject arrowPrefab;
    private Vector3 target;

    private List<Transform> arrowList = new List<Transform>();

    private bool start = false;
    // Start is called before the first frame update
    public void SetPositions(Vector3 pos)
    {
        target = pos;
        UpdateArrow();
    }


    public void ShowArrow(bool display, Transform target)
    {
        if (display)
        {
            Vector3 pos = target.position;
            this.target = pos;
        }
        else
            DeActiveArrow();
        start = display;
    }
    public void DeActiveArrow()
    {
        start = false;
        arrowList.ForEach(o => o.gameObject.SetActive(false));
    }
    void Update()
    {
        if (start)
        {
            UpdateArrow();
        }
    }

    void UpdateArrow()
    {
        float distance = Vector3.Distance(transform.position, target);
        float radius = height / 2f + distance * distance / (8f * height);
        float diff = radius - height;
        float angle = 2f * Mathf.Acos(diff / radius);
        float length = angle * radius;
        float segmentAngle = arrowLength / radius * Mathf.Rad2Deg;

        Vector3 center = new Vector3(0, -diff, distance / 2f);

        int segmentsCount = (int)(length / arrowLength) + 1;

        ArrowInit(segmentsCount);

        float offset = Time.time * speed * segmentAngle;
        Vector3 firstSegmentPos =
            Quaternion.Euler(Mathf.Repeat(offset, segmentAngle), 0f, 0f) * (Vector3.zero - center) + center;


        for (int i = 0; i < segmentsCount; i++)
        {
            Vector3 pos = Quaternion.Euler(segmentAngle * i, 0f, 0f) * (firstSegmentPos - center) + center;
            arrowList[i].localPosition = pos;
            arrowList[i].localRotation = Quaternion.FromToRotation(Vector3.up, pos - center);

        }
        transform.LookAt(m_target);
    }

    void ArrowInit(int listCount)
    {
        while (arrowList.Count < listCount)
        {
            GameObject arrow = Instantiate(arrowPrefab, transform);
            arrowList.Add(arrow.transform);
        }

        for (int i = 0; i < arrowList.Count; i++)
        {
            GameObject arrow = arrowList[i].gameObject;
            if (arrow.activeSelf != i < listCount)
                arrow.SetActive(i < listCount);
        }
    }
}