import { Renderer } from '../renderer/renderer';

export function loadImage(url: string): Promise<HTMLImageElement> {
	return new Promise((resolve, reject) => {
		const img = new Image();
		img.addEventListener('load', () => { resolve(img); });
		img.addEventListener('error', () => { reject(new Error('failed to load ' + url)); });
		img.src = url;
	});
}

export function mkTexture(
	r: Renderer,
	src: HTMLCanvasElement|HTMLImageElement,
): [WebGLTexture, [number, number]] {
	const gl = r.getContext();
	const texture = gl.createTexture();
	if (!texture)
		throw new Error('unable to create texture');

	gl.bindTexture(gl.TEXTURE_2D, texture);
	gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, src);
	gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
	gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
	gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
	gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);

	const size: [number, number] = [
		src.width / r.coordScale, src.height / r.coordScale,
	];

	return [texture, size];
}