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

[Serializable]
public class PolyVector
{
  public float vectorScale = 1f;
  public Mesh meshJoint, meshVector;
  public Material matVector;

  List<Matrix4x4> j4 = new List<Matrix4x4>();
  List<Matrix4x4> v4 = new List<Matrix4x4>();
  int length;
  public void AddVectors(List<Vector3> vectors)
  {
    // vectors.Add(Vector3.zero); // break at end
    length = 0;
    for (int i = 0; i < vectors.Count; i++)
    {
      if (vectors[i] == Vector3.zero)
      {
        length = 0;
      }
      else
      {
        Matrix4x4 newJoint = new Matrix4x4();
        newJoint.SetTRS(vectors[i],
          Quaternion.identity,
          Vector3.one * vectorScale
        );
        j4.Add(newJoint);

        if (length > 0 && vectors[i] != vectors[i - 1]) // *-*-*
        {
          Matrix4x4 m4 = new Matrix4x4();
          m4.SetTRS(vectors[i - 1],
            Quaternion.LookRotation(vectors[i] - vectors[i - 1]),
            new Vector3(vectorScale, vectorScale, Vector3.Distance(vectors[i - 1], vectors[i]))
          );
          v4.Add(m4);
        }
        length++;
      }
    }
  }

  public void Frame()
  {
    // trim before render
    // v4.RemoveRange(vCount - 1, v4.Count - vCount);
    Graphics.DrawMeshInstanced(meshJoint, 0, matVector, j4);
    j4.Clear();
    Graphics.DrawMeshInstanced(meshVector, 0, matVector, v4);
    v4.Clear();
  }

  public Mesh ToMesh(List<Vector3> vectors)
  {
    List<Matrix4x4> js = new List<Matrix4x4>();
    List<Matrix4x4> vs = new List<Matrix4x4>();

    length = 0;
    for (int i = 0; i < vectors.Count; i++)
    {
      if (vectors[i] == Vector3.zero)
      {
        length = 0;
      }
      else
      {
        Matrix4x4 newJoint = new Matrix4x4();
        newJoint.SetTRS(vectors[i],
          Quaternion.identity,
          Vector3.one * vectorScale
        );
        js.Add(newJoint);

        if (length > 0 && vectors[i] != vectors[i - 1]) // *-*-*
        {
          Matrix4x4 newVector = new Matrix4x4();
          newVector.SetTRS(vectors[i - 1],
            Quaternion.LookRotation(vectors[i] - vectors[i - 1]),
            new Vector3(vectorScale, vectorScale, Vector3.Distance(vectors[i - 1], vectors[i]))
          );
          vs.Add(newVector);
        }
        length++;
      }
    }

    CombineInstance[] combI = new CombineInstance[js.Count + vs.Count];
    for (int i = 0; i < js.Count; i++)
    {
      combI[i].mesh = meshJoint;
      combI[i].transform = js[i];
    }

    Debug.Log(vs.Count);
    for (int i = 0; i < vs.Count; i++)
    {
      combI[js.Count + i].mesh = meshVector;
      combI[js.Count + i].transform = vs[i];
    }

    Mesh mesh = new Mesh();
    mesh.CombineMeshes(combI, true, true);
    return mesh;
  }
}