export const render = (canvas) => {
	let gl = canvas.getContext("webgl");

	const vShaderSrc = `
		attribute vec3 position;

		void main() {
			gl_Position = vec4(position, 1);
		}
	`;

	const fShaderSrc = `
		void main() {
			gl_FragColor = vec4(0.5, 0.5, 0, 1);
		}
	`;

	const compileShader = (src, type) => {
		let shader = gl.createShader(type);
		gl.shaderSource(shader, src);
		gl.compileShader(shader);
		let success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);
		if (!success) {
			throw gl.getShaderInfoLog(vShader);
		}
		return shader;
	}

	let vShader = compileShader(vShaderSrc, gl.VERTEX_SHADER);
	let fShader = compileShader(fShaderSrc, gl.FRAGMENT_SHADER);

	let program = gl.createProgram();
	gl.attachShader(program, vShader);
	gl.attachShader(program, fShader);
	gl.linkProgram(program);
	let success = gl.getProgramParameter(program, gl.LINK_STATUS);
	if (!success) {
		throw gl.getProgramInfoLog(program);
	}
	gl.useProgram(program);

	let vertexBuffer = gl.createBuffer();
	let vertices = new Float32Array([
		0, 0, 0,
		1, 0, 0,
		1, 1, 0,
	]);
	gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
	gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.STATIC_DRAW);
	
	let positionLocation = gl.getAttribLocation(program, "position");
	gl.enableVertexAttribArray(positionLocation);
	gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, 4*3, 0);
	gl.drawArrays(gl.TRIANGLES, 0, 3);
}