/**
 * Return an endpoint URL that has a protocol, domain and path
 */
function normalizedEndpoint(endpoint) {
	let matches = endpoint.match(/^(https?:\/\/)?([^\/]+)(\/.*)?$/i);
	if (!matches) throw Error("Invalid endpoint URL");

	let protocol = matches[1] || "https://";
	let domain = matches[2];
	let path = matches[3] || "/api/v4";

	return `${protocol}${domain}${path}`;
}

/**
 * Return the endpoint as it should be shown to the user
 */
function humanReadableEndpoint(endpoint) {
	let matches = endpoint.match(/^(https?:\/\/.+)\/api\/v4$/i);
	if (!matches) throw Error("Invalid endpoint URL");

	return matches[1];
}


/**
 * Shorthand for document.getElementById
 */
function byId(id, nullOk=false) {
	const el = document.getElementById(id);
	if (!el && !nullOk) {
		console.error(`No element #${id}`);
	}
	return el;
}


/**
 * Wrap a function so that it receives `this` as first argument
 */
function thisToArg(f) {
	return function(...rest) {
		return f(this, ...rest);
	}
}