'use strict';

module.exports = (req, res, strict=false) => {

	//combines a bunch of parts of the post (name, subject, message, filenames+phashes)
	const fileStrings = res.locals.numFiles ? req.files.file.map(f => `${f.name}|${f.phash || ''}`).join('|') : 0;
	const combinedString = [req.body.name, req.body.message, req.body.subject, req.body.email, fileStrings].join('|').toLowerCase();
	let strictCombinedString = combinedString;

	//"strict" filtering adds a bunch of permutations to also compare filters with;
	if (strict === true) {

		//diacritics and "zalgo" removed
		strictCombinedString += combinedString.normalize('NFD').replace(/[\u0300-\u036f]/g, '');

		//zero width spaces removed
		strictCombinedString += combinedString.replace(/[\u200B-\u200D\uFEFF]/g, '');

		//just a-z, 0-9, . and -
		strictCombinedString += combinedString.replace(/[^a-zA-Z0-9.-]+/gm, '');

		//urlendoded characters in URLs replaced (todo: remove this if/when the url regex gets updated to no longer match these)
		strictCombinedString += combinedString.split(/(\%[^\%]+)/).map(part => {
			try {
				return decodeURIComponent(part);
			} catch(e) {
				return '';
			}
		}).join('');

	}

	return [combinedString, strictCombinedString];

};