import type { Request, Response } from 'express';
import type { Twttr } from 'twtxt-lib';

import {
	generateEtag,
	getQueryParameterArray,
	getValueOrFirstEntry,
} from '../../lib/utils.js';
import { QueryParameters } from '../../types.js';
import NodeCache from '@cacheable/node-cache';

/**
 *
 * @param req
 * @param res
 * @param cache
 * @param followingParameter
 */
export default function followingHandler(
	req: Request,
	res: Response,
	following: Twttr[],
	followingParameter: QueryParameters['following']
) {
	const followingsToMatch = getQueryParameterArray(
		req.query[followingParameter]
	);

	const nicksToMatch = getQueryParameterArray(req.query.nick);
	const urlsToMatch = getQueryParameterArray(req.query.url);

	const searchTermsToMatch = [
		...getQueryParameterArray(req.query.search),
		...getQueryParameterArray(req.query.s),
	];

	const wantsJson =
		req.is('json') ||
		getValueOrFirstEntry(getQueryParameterArray(req.query.format)) === 'json';
	if (wantsJson) res.set('content-type', 'application/json');
	else res.set('content-type', 'text/plain');

	const matchedFollowing = following.filter(
		({ nick, url }) =>
			(!followingsToMatch.length ||
				(followingsToMatch.length === 1 && followingsToMatch[0] === '') ||
				followingsToMatch.includes(nick) ||
				followingsToMatch.includes(`@${nick}`) ||
				followingsToMatch.includes(url)) &&
			(!nicksToMatch.length ||
				nicksToMatch.includes(nick) ||
				nicksToMatch.includes(`@${nick}`)) &&
			(!urlsToMatch.length || urlsToMatch.includes(url)) &&
			(!searchTermsToMatch.length ||
				searchTermsToMatch.some(
					(term) => nick.includes(term) || url.includes(term)
				))
	);

	const result = wantsJson
		? JSON.stringify(matchedFollowing)
		: matchedFollowing.map(({ nick, url }) => `@${nick} ${url}`).join('\n');

	res.set('etag', generateEtag(result)).send(result);
}