using UnityEngine;
using System.Collections.Generic;

[RequireComponent(typeof(Transform))]
public class AdaptiveElectricArc : MonoBehaviour
{
    [Header("Arc Points")]
    public Transform pointA;
    public Transform pointB;

    [Header("Arc Settings")]
    public int arcCount = 3;
    public float segmentSpacing = 0.1f; // 每段长度
    public float arcAmplitude = 0.2f;
    public float noiseSpeed = 10f;
    public float updateInterval = 0.05f;
    public float arcWidth = 0.05f;

    [Header("Flicker Settings")]
    public bool enableFlicker = true;
    public float flickerInterval = 0.1f;

    [Header("Color Gradient")]
    public Gradient arcColorGradient;

    public Material material;

    private List<LineRenderer> arcs = new List<LineRenderer>();
    private float updateTimer = 0f;
    private float flickerTimer = 0f;

    void Start()
    {
        for (int i = 0; i < arcCount; i++)
        {
            GameObject arcObj = new GameObject("Arc_" + i);
            arcObj.transform.parent = transform;

            LineRenderer lr = arcObj.AddComponent<LineRenderer>();
            lr.material = material;
            lr.widthMultiplier = arcWidth;
            lr.colorGradient = arcColorGradient;
            lr.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
            lr.receiveShadows = false;
            lr.useWorldSpace = true;

            arcs.Add(lr);
        }
    }

    void Update()
    {
        updateTimer += Time.deltaTime;
        flickerTimer += Time.deltaTime;

        // 更新电弧形状
        if (updateTimer >= updateInterval)
        {
            foreach (var arc in arcs)
            {
                GenerateArc(arc);
            }
            updateTimer = 0f;
        }

        // 电弧闪烁
        if (enableFlicker && flickerTimer >= flickerInterval)
        {
            foreach (var arc in arcs)
            {
                arc.enabled = Random.value > 0.3f;
            }
            flickerTimer = 0f;
        }
    }

    void GenerateArc(LineRenderer lr)
    {
        if (pointA == null || pointB == null) return;

        Vector3 start = pointA.position;
        Vector3 end = pointB.position;
        Vector3 dir = (end - start).normalized;
        float length = Vector3.Distance(start, end);

        // 自适应段数
        int segmentCount = Mathf.Max(2, Mathf.RoundToInt(length / segmentSpacing));
        lr.positionCount = segmentCount;

        // 正交扰动方向
        Vector3 right = Vector3.Cross(dir, Vector3.up).normalized;
        Vector3 up = Vector3.Cross(right, dir).normalized;

        for (int i = 0; i < segmentCount; i++)
        {
            float t = (float)i / (segmentCount - 1);
            Vector3 point = Vector3.Lerp(start, end, t);

            // 距离越大 → 抖动越大；中段抖动更多
            float noise = Mathf.PerlinNoise(Time.time * noiseSpeed + i, Random.Range(0f, 100f)) * 2f - 1f;
            float localAmplitude = Mathf.Lerp(0.01f, arcAmplitude, length);
            float sinOffset = Mathf.Sin(t * Mathf.PI); // 中间最大
            Vector3 offset = (right + up) * noise * localAmplitude * sinOffset;

            lr.SetPosition(i, point + offset);
        }
    }
}