using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(LineRenderer))]
public class PhysicLineSegment : MonoBehaviour
{
    public float segmentSpacing = 0.1f;
    public int k = 30;

    public Vector3 start;
    public Vector3 end;

    private List<VerletParticle> particles = new List<VerletParticle>();
    private List<VerletStick> sticks = new List<VerletStick>();
    private LineRenderer lineRenderer;
    private int segmentCount;
    public float gravity = -9.8f;

public void Initialize(Vector3 start, Vector3 end)
{
    this.start = start;
    this.end = end;
    //originalLength = Vector3.Distance(start, end);

    // Calculate the number of segments and the spacing between them
    segmentCount = Mathf.RoundToInt(Vector3.Distance(start, end) / segmentSpacing);
    lineRenderer = GetComponent<LineRenderer>();

    // Initialize particles
    for (int i = 0; i < segmentCount; i++)
    {
        // Calculate the position of the segment
        var particle = new VerletParticle(Vector3.Lerp(start, end, i / (float)segmentCount));
        
        particles.Add(particle);
    }

    // Initialize sticks
    for (int i = 0; i < segmentCount - 1; i++)
    {
        sticks.Add(new VerletStick(particles[i], particles[i + 1], segmentSpacing));
    }

    // Lock the first particle
    particles[0].isLocked = true;

    lineRenderer.positionCount = segmentCount;
}


    void FixedUpdate()
    {
        UpdateLine();
        for (int i = 0; i < segmentCount; i++)
        {
            lineRenderer.SetPosition(i, particles[i].position);
        }
    }

    void UpdateLine()
    {
        // Apply gravity to particles
        for (int i = 1; i < particles.Count; i++)
        {
            
            particles[i].ApplyForce(Vector3.up * gravity * Time.deltaTime);
            particles[i].UpdatePosition(Time.deltaTime);
        }

        // Update sticks
        for (int ik = 0; ik < k; ik++)
        {
            foreach (var stick in sticks)
            {
                stick.UpdateStick();
            }
        }
    }
}