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

public class UILineRenderer : Graphic
{
	public Vector2Int gridSize;
	public UIGridRenderer grid;

	public List<Vector2> points;

	float width;
	float height;
	float unitWidth;
	float unitHeight;

	public float thickness = 10f;

	public void Redraw()
	{		
		SetVerticesDirty();
	}

	protected override void OnPopulateMesh(VertexHelper vh)
	{		
		vh.Clear();

		width = rectTransform.rect.width;
		height = rectTransform.rect.height;

		unitWidth = width / (float)gridSize.x;
		unitHeight = height / (float)gridSize.y;

		if (points.Count < 2)
		{
			return;
		}

		float angle = 0;

		for (int i = 0; i < points.Count; i++)
		{
			Vector2 point = points[i];

			if (i<points.Count - 1)
			{
				angle = GetAngle(points[i], points[i + 1]) + 45f;
			}
			

			DrawVerticesForPoint(point, vh, angle); 
		}

		for (int i = 0; i < points.Count-1; i++)
		{			
			int index = i * 2;			
			vh.AddTriangle(index + 0, index + 1, index + 3);			
			vh.AddTriangle(index + 3, index + 2, index + 0);  
		}		
	}

	public float GetAngle(Vector2 me, Vector2 target)
	{
		return (float)(Mathf.Atan2(target.y - me.y, target.x - me.x) * (180 / Mathf.PI));
	}

	void DrawVerticesForPoint(Vector2 point, VertexHelper vh, float angle)
	{
		UIVertex vertex = UIVertex.simpleVert;
		vertex.color = color;
		
		vertex.position = Quaternion.Euler(0,0,angle) * new Vector3(-thickness/2,0);
		vertex.position += new Vector3(unitWidth * point.x, unitHeight * point.y);
		vh.AddVert(vertex);

		vertex.position = Quaternion.Euler(0, 0, angle) * new Vector3(thickness / 2, 0);
		vertex.position += new Vector3(unitWidth * point.x, unitHeight * point.y);
		vh.AddVert(vertex);
	}

	private void Update()
	{
		if (grid!=null)
		{
			if (gridSize!=grid.gridSize)
			{
				gridSize = grid.gridSize;
				SetVerticesDirty();
			}
		}
	}

}