package com.gnarly.engine.model;

import static org.lwjgl.opengl.GL11.GL_FLOAT;
import static org.lwjgl.opengl.GL11.GL_TRIANGLES;
import static org.lwjgl.opengl.GL11.GL_UNSIGNED_INT;
import static org.lwjgl.opengl.GL11.glDrawElements;
import static org.lwjgl.opengl.GL15.GL_ARRAY_BUFFER;
import static org.lwjgl.opengl.GL15.GL_ELEMENT_ARRAY_BUFFER;
import static org.lwjgl.opengl.GL15.GL_STATIC_DRAW;
import static org.lwjgl.opengl.GL15.glBindBuffer;
import static org.lwjgl.opengl.GL15.glBufferData;
import static org.lwjgl.opengl.GL15.glDeleteBuffers;
import static org.lwjgl.opengl.GL15.glGenBuffers;
import static org.lwjgl.opengl.GL20.glDisableVertexAttribArray;
import static org.lwjgl.opengl.GL20.glEnableVertexAttribArray;
import static org.lwjgl.opengl.GL20.glVertexAttribPointer;
import static org.lwjgl.opengl.GL30.glBindVertexArray;
import static org.lwjgl.opengl.GL30.glDeleteVertexArrays;
import static org.lwjgl.opengl.GL30.glGenVertexArrays;

import java.util.ArrayList;

public class Vao {

	private int numAttribs = 0;
	
	private int vao, ibo, count;
	
	private ArrayList<Integer> vbos = new ArrayList<>();
	
	public Vao(float[] vertices, int[] indices) {
		vao = glGenVertexArrays();
		glBindVertexArray(vao);
		addAttribute(vertices, 3);
		ibo = glGenBuffers();
		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ibo);
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices, GL_STATIC_DRAW);
		count = indices.length;
	}
	
	public void addAttribute(float[] data, int size) {
		int vbo = glGenBuffers();
		vbos.add(vbo);
		glBindBuffer(GL_ARRAY_BUFFER, vbo);
		glBufferData(GL_ARRAY_BUFFER, data, GL_STATIC_DRAW);
		glVertexAttribPointer(numAttribs, size, GL_FLOAT, false, 0, 0);
		++numAttribs;
	}
	
	public void render() {
		glBindVertexArray(vao);
		
		for (int i = 0; i < numAttribs; ++i)
			glEnableVertexAttribArray(i);
		
		glDrawElements(GL_TRIANGLES, count, GL_UNSIGNED_INT, 0);
		
		for (int i = 0; i < numAttribs; ++i)
			glDisableVertexAttribArray(i);
	}
	
	public void destroy() {
		for(int vbo : vbos)
			glDeleteBuffers(vbo);
		glDeleteBuffers(ibo);
		glDeleteVertexArrays(vao);
	}
}