using System.Collections.Generic;
using UnityEngine;

/// <summary>
/// 选关场景循环
/// </summary>
public class LevelSelectLoop : MonoBehaviour
{
    #region 配置参数
    /// <summary>
    /// 地块间隔
    /// </summary>
    [SerializeField]
    private float spacing = 12;
    /// <summary>
    /// 速度
    /// </summary>
    [SerializeField]
    private float speed = 3;
    /// <summary>
    /// 起始位置
    /// </summary>
    [SerializeField]
    private float startPos = -80f;
    /// <summary>
    /// 地块列表根节点
    /// </summary>
    [SerializeField]
    private Transform tsPlotRoot;
    #endregion

    /// <summary>
    /// 当前地图节点
    /// </summary>
    private Transform curTsMap;
    /// <summary>
    /// 地块列表
    /// </summary>
    private readonly List<Transform> listPlot;
    private float curPos = 0f;
    /// <summary>
    /// 上一次地块数量
    /// </summary>
    private int lastCount;

    private void Awake()
    {
        curTsMap = GetComponent<Transform>();
        for (int i = 0; i < tsPlotRoot.childCount; ++i)
        {
            listPlot.Add(tsPlotRoot.GetChild(i));
        }
    }

    private void Start()
    {
        curPos = startPos;
        curTsMap.localPosition = new Vector3(curTsMap.localPosition.x, curTsMap.localPosition.y, curPos);
        lastCount = (int)((startPos - curPos) / spacing) - 1;
    }

    private void Update()
    {
        curPos -= Time.deltaTime * speed;
        int count = (int)((startPos - curPos) / spacing) - 1;
        if (lastCount != count)
        {
            int index = count % listPlot.Count;
            if (index >= 0 && listPlot.Count > index)
            {
                Transform tsPlot = listPlot[index];
                tsPlot.localPosition = new Vector3((listPlot.Count + count) * spacing, tsPlot.localPosition.y, tsPlot.localPosition.z);
            }

            lastCount = count;
        }

        curTsMap.localPosition = new Vector3(curTsMap.localPosition.x, curTsMap.localPosition.y, curPos);
    }
}