/**
 * This file is part of Haketilo.
 *
 * Function: Filtering request headers to remove haketilo cookies that might
 *     have slipped through.
 *
 * Copyright (C) 2021 Wojtek Kosior
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * As additional permission under GNU GPL version 3 section 7, you
 * may distribute forms of that code without the copy of the GNU
 * GPL normally required by section 4, provided you include this
 * license notice and, in case of non-source distribution, a URL
 * through which recipients can access the Corresponding Source.
 * If you modify file(s) with this exception, you may extend this
 * exception to your version of the file(s), but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * As a special exception to the GPL, any HTML file which merely
 * makes function calls to this code, and for that purpose
 * includes it by reference shall be deemed a separate work for
 * copyright law purposes. If you modify this code, you may extend
 * this exception to your version of the code, but you are not
 * obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
 * license. Although I request that you do not make use this code in a
 * proprietary program, I am not going to enforce this in court.
 */

/*
 * IMPORTS_START
 * IMPORT extract_signed
 * IMPORTS_END
 */

function is_valid_haketilo_cookie(cookie)
{
    const match = /^haketilo-(\w*)=(.*)$/.exec(cookie);
    if (!match)
	return false;

    return !extract_signed(match.slice(1, 3)).fail;
}

function remove_haketilo_cookies(header)
{
    if (header.name !== "Cookie")
	return header;

    const cookies = header.value.split("; ");
    const value = cookies.filter(c => !is_valid_haketilo_cookie(c)).join("; ");

    return value ? {name: "Cookie", value} : null;
}

function filter_cookie_headers(headers)
{
    return headers.map(remove_haketilo_cookies).filter(h => h);
}

/*
 * EXPORTS_START
 * EXPORT filter_cookie_headers
 * EXPORTS_END
 */