/**
 * 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);
	}
}


/**
 * Extend an object in-place with own properties of a second one
 */
function extend(obj1, obj2) {
	for (let key in Object.getOwnPropertyNames(obj1)) {
		obj1[key] = obj2[key];
	}
}


function padLeft(input, width, padding=" ") {
	text = input + "";
	while (text.length < width) {
		text = padding + text;
	}
	return text;
}

function formatDdddMmYy(date) {
	return `${date.getFullYear()}-${padLeft(date.getMonth() + 1, 2, "0")}-${padLeft(date.getDate(), 2, "0")}`;
}

function formatHhMm(date) {
	return `${padLeft(date.getHours(), 2, "0")}:${padLeft(date.getMinutes(), 2, "0")}`;
}


const DATE_SIMILARITY = {
	none:    0,
	year:    1,
	month:   2,
	date:    3,
	hours:   4,
	minutes: 5,
	seconds: 6
}
function dateSimilarity(d1, d2) {
	if (!d1 || !d2) return DATE_SIMILARITY.none;
	if (d1.getFullYear() != d2.getFullYear()) return DATE_SIMILARITY.none;
	if (d1.getMonth() != d2.getMonth())       return DATE_SIMILARITY.year;
	if (d1.getDate() != d2.getDate())         return DATE_SIMILARITY.month;
	if (d1.getHours() != d2.getHours())       return DATE_SIMILARITY.date;
	if (d1.getMinutes() != d2.getMinutes())   return DATE_SIMILARITY.hours;
	if (d1.getSeconds() != d2.getSeconds())   return DATE_SIMILARITY.minutes;
	return DATE_SIMILARITY.seconds;
}


class AssertionError extends Error {}
/**
 * Throw an AssertionError if the first argument is not true
 */
function assert(condition, message) {
	if (!condition) {
		if (message) {
			throw new AssertionError(`Assertion failed: ${message}`);
		} else {
			throw new AssertionError("Assertion failed");
		}
	}
}

const MATTERMOST_ID_REGEXP = /^[a-z0-9]{26}$/;
function assertIsMattermostId(string, name="") {
	assert(MATTERMOST_ID_REGEXP.test(string), `${name} has the form of a Mattermost ID`);
}
function assertIsNullOrMattermostId(string, name="") {
	assert(string === null || MATTERMOST_ID_REGEXP.test(string), `${name} is null or has the form of a Mattermost ID`);
}