const _parse = URL.parse;

// Check for the existence of URL.parse and use that if available, removes the
// performance hit from try..catch blocks.
export const safeUrlParse = _parse
	? (text: string): URL | null => {
			const url = _parse(text);

			if (url !== null && (url.protocol === 'https:' || url.protocol === 'http:')) {
				return url;
			}

			return null;
		}
	: (text: string): URL | null => {
			try {
				const url = new URL(text);

				if (url.protocol === 'https:' || url.protocol === 'http:') {
					return url;
				}
			} catch {}

			return null;
		};

const TRIM_HOST_RE = /^www\./;
const TRIM_URLTEXT_RE = /^\s*(https?:\/\/)?(?:www\.)?/;

export const isLinkValid = (uri: string, text: string) => {
	const url = safeUrlParse(uri);

	if (url === null) {
		return false;
	}

	const expectedHost = buildHostPart(url);
	const length = expectedHost.length;

	const normalized = text.replace(TRIM_URLTEXT_RE, '').toLowerCase();
	const normalizedLength = normalized.length;

	const boundary = normalizedLength >= length ? normalized[length] : undefined;

	return (
		(boundary === undefined || boundary === '/' || boundary === '?' || boundary === '#') &&
		normalized.startsWith(expectedHost)
	);
};

const buildHostPart = (url: URL) => {
	const username = url.username;
	// const password = url.password;

	const hostname = url.hostname.replace(TRIM_HOST_RE, '').toLowerCase();
	const port = url.port;

	// Perhaps might be best if we always warn on authentication being passed.
	// const auth = username ? username + (password ? ':' + password : '') + '@' : '';
	const auth = username ? '\0@@\0' : '';

	const host = hostname + (port ? ':' + port : '');

	return auth + host;
};