thelounge/client/js/libs/handlebars/ircmessageparser/findLinks.js

"use strict";

const URI = require("urijs");

// Known schemes to detect in a text. If a text contains `foo...bar://foo.com`,
// the parsed scheme should be `foo...bar` but if it contains
// `foo...http://foo.com`, we assume the scheme to extract will be `http`.
const commonSchemes = [
	"http", "https",
	"ftp", "sftp",
	"smb", "file",
	"irc", "ircs",
	"svn", "git",
	"steam", "mumble", "ts3server",
	"svn+ssh", "ssh",
];

function findLinks(text) {
	const result = [];

	// URI.withinString() identifies URIs within text, e.g. to translate them to
	// <a>-Tags.
	// See https://medialize.github.io/URI.js/docs.html#static-withinString
	// In our case, we store each URI encountered in a result array.
	try {
		URI.withinString(text, function(url, start, end) {
			let parsedScheme;

			try {
				// Extract the scheme of the URL detected, if there is one
				parsedScheme = URI(url).scheme().toLowerCase();
			} catch (e) {
				// URI may throw an exception for malformed urls,
				// as to why withinString finds these in the first place is a mystery
				return;
			}

			// Check if the scheme of the detected URL matches a common one above.
			// In a URL like `foo..http://example.com`, the scheme would be `foo..http`,
			// so we need to clean up the end of the scheme and filter out the rest.
			const matchedScheme = commonSchemes.find((scheme) => parsedScheme.endsWith(scheme));

			// A known scheme was found, extract the unknown part from the URL
			if (matchedScheme) {
				const prefix = parsedScheme.length - matchedScheme.length;
				start += prefix;
				url = url.slice(prefix);
			}

			// The URL matched but does not start with a scheme (`www.foo.com`), add it
			if (!parsedScheme.length) {
				url = "http://" + url;
			}

			result.push({
				start: start,
				end: end,
				link: url,
			});
		});
	} catch (e) {
		// withinString is wrapped in a try/catch due to https://github.com/medialize/URI.js/issues/359
	}

	return result;
}

module.exports = findLinks;