using Microsoft.MixedReality.Toolkit.UI;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Spline : MonoBehaviour
{
    Mesh mesh;

    public int minX;
    public int maxX;

    bool is2D = false;
    bool is3D = false;

    public List<float> factors;
    // Start is called before the first frame update
    void Start()
    {
        mesh = new Mesh
        {
            name = "Spline"
        };
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    public void DrawSpline()
    {
        mesh.Clear();

        Vector3[] vectors = new Vector3[100 * (maxX - minX) + 1];
        int k = 0;
        float step = 0.01f;
        for (float i = minX; i <= maxX; i+=step)
        {
            float y = 0;
            for (int j = factors.Count - 1; j > 0; --j)
            {
                y += factors[j];
                y *= i;
            }
            y += factors[0];
            vectors[k] = new Vector3(i, y, 0);
            k++;
        }

        float ym = 0;
        for (int j = factors.Count - 1; j > 0; --j)
        {
            ym += factors[j];
            ym *= maxX;
        }
        ym += factors[0];
        vectors[100 * (maxX - minX)] = new Vector3(maxX, ym, 0);

        mesh.vertices = vectors;

        int[] triangle = new int[100 * (maxX - minX) * 2];
        for (int i = 0; i < vectors.Length - 1; ++i)
        {
            triangle[2 * i] = i;
            triangle[2 * i + 1] = i + 1;
        }

        mesh.SetIndices(triangle, MeshTopology.Lines, 0);

        GetComponent<MeshFilter>().mesh = mesh;
        is2D = true;
    }

    public void DrawSpline3D()
    {
        mesh.Clear();

        Vector3[] vectors = new Vector3[200 * (maxX - minX) + 2];
        int k = 0;
        float step = 0.01f;
        for (float i = minX; i <= maxX; i += step)
        {
            float y = 0;
            for (int j = factors.Count - 1; j > 0; --j)
            {
                y += factors[j];
                y *= i;
            }
            y += factors[0];
            vectors[k] = new Vector3(i, y, -5);
            k++;
            vectors[k] = new Vector3(i, y, 5);
            k++;
        }

        float ym = 0;
        for (int j = factors.Count - 1; j > 0; --j)
        {
            ym += factors[j];
            ym *= maxX;
        }
        ym += factors[0];
        vectors[200 * (maxX - minX)] = new Vector3(maxX, ym, -5);
        vectors[200 * (maxX - minX) + 1] = new Vector3(maxX, ym, 5);

        mesh.vertices = vectors;
        Vector2[] uvs = new Vector2[vectors.Length];

        for (int i = 0; i < uvs.Length; i++)
        {
            uvs[i] = new Vector2(0, vectors[i].y / 100);
        }
        mesh.uv = uvs;

        int[] triangle = new int[100 * (maxX - minX) * 6];
        for (int i = 0; i < 100 * (maxX - minX); ++i)
        {
            triangle[6 * i] = 2 * i;
            triangle[6 * i + 1] = 2 * i + 1;
            triangle[6 * i + 2] = 2 * i + 2;
            triangle[6 * i + 3] = 2 * i + 1;
            triangle[6 * i + 4] = 2 * i + 3;
            triangle[6 * i + 5] = 2 * i + 2;
        }

        mesh.SetIndices(triangle, MeshTopology.Triangles, 0);

        GetComponent<MeshFilter>().mesh = mesh;
        is3D = true;
    }

    public void MeshClear()
    {
        mesh.Clear();
        GetComponent<MeshFilter>().mesh = mesh;
        is2D = false;
        is3D = false;
    }

    public void OnSliderUpdated(SliderEventData eventData)
    {
        factors[1] = Mathf.Tan((eventData.NewValue - 0.5f) * Mathf.PI);
        if (is2D)
            DrawSpline();
        if (is3D)
            DrawSpline3D();
    }

    public void OnSliderUpdated3(SliderEventData eventData)
    {
        factors[0] = eventData.NewValue * 3;
        if (is2D)
            DrawSpline();
        if (is3D)
            DrawSpline3D();
    }

    public void OnSliderUpdated2(SliderEventData eventData)
    {
        int n = (int)((eventData.NewValue ) * 5);
        factors = new List<float>();
        for(int i = 0; i < n; ++i)
        {
            factors.Add(0);
        }
        factors.Add(1);
        if (is2D)
            DrawSpline();
        if (is3D)
            DrawSpline3D();
    }
}