Haketilo

/**

 * This file is part of Haketilo.

 *

 * Function: Operations on page URL patterns.

 *

 * 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.

 */

const MAX = {

    URL_PATH_LEN:   12,

    URL_PATH_CHARS: 255,

    DOMAIN_LEN:     7,

    DOMAIN_CHARS:   100

};

const proto_regex = /^(\w+):\/\/(.*)$/;

const user_re = "[^/?#@]+@"

const domain_re = "[.*a-zA-Z0-9-]+";

const path_re = "[^?#]*";

const query_re = "\\??[^#]*";

const http_regex = new RegExp(`^(${domain_re})(${path_re})(${query_re}).*`);

const file_regex = new RegExp(`^(/${path_re}).*`);

const ftp_regex = new RegExp(`^(${user_re})?(${domain_re})(${path_re}).*`);

function match_or_throw(regex, string, error_msg)

{

    const match = regex.exec(string);

    if (match === null)

	throw error_msg;

    return match;

}

function deconstruct_url(url, use_limits=true)

{

    const max = MAX;

    if (!use_limits) {

	for (key in MAX)

	    max[key] = Infinity;

    }

    const matcher = (re, str) => match_or_throw(re, str, `bad url '${url}'`)

    const proto_match = matcher(proto_regex, url);

    const deco = {proto: proto_match[1]};

    if (deco.proto === "file") {

	deco.path = matcher(file_regex, proto_match[2])[1];

    } else if (deco.proto === "ftp") {

	[deco.domain, deco.path] =

	    matcher(ftp_regex, proto_match[2]).slice(2, 4);

    } else if (deco.proto === "http" || deco.proto === "https") {

	[deco.domain, deco.path, deco.query] =

	    matcher(http_regex, proto_match[2]).slice(1, 4);

	deco.domain = deco.domain.toLowerCase();

    } else {

	throw `unsupported protocol in url '${url}'`;

    }

    deco.trailing_slash = deco.path[deco.path.length - 1] === "/";

    if (deco.domain) {

	if (deco.domain.length > max.DOMAIN_CHARS) {

	    const idx = deco.domain.indexOf(".", deco.domain.length -

					    max.DOMAIN_CHARS);

	    if (idx === -1)

		deco.domain = [];

	    else

		deco.domain = deco.domain.substring(idx + 1);

	    deco.domain_truncated = true;

	}

	if (deco.path.length > max.URL_PATH_CHARS) {

	    deco.path = deco.path.substring(0, deco.path.lastIndexOf("/"));

	    deco.path_truncated = true;

	}

    }

    if (typeof deco.domain === "string") {

	deco.domain = deco.domain.split(".");

	if (deco.domain.splice(0, deco.domain.length - max.DOMAIN_LEN).length

	    > 0)

	    deco.domain_truncated = true;

    }

    deco.path = deco.path.split("/").filter(s => s !== "");

    if (deco.domain && deco.path.splice(max.URL_PATH_LEN).length > 0)

	deco.path_truncated = true;

    return deco;

}

function* each_domain_pattern(deco)

{

    for (let slice = 0; slice < deco.domain.length - 1; slice++) {

	const domain_part = deco.domain.slice(slice).join(".");

	const domain_wildcards = [];

	if (slice === 0 && !deco.domain_truncated)

	    yield domain_part;

	if (slice === 1 && !deco.domain_truncated)

	    yield "*." + domain_part;

	if (slice > 1)

	    yield "**." + domain_part;

	yield "***." + domain_part;

    }

}

function* each_path_pattern(deco)

{

    for (let slice = deco.path.length; slice >= 0; slice--) {

	const path_part = ["", ...deco.path.slice(0, slice)].join("/");

	const path_wildcards = [];

	if (slice === deco.path.length && !deco.path_truncated) {

	    if (deco.trailing_slash)

		yield path_part + "/";

	    if (slice > 0 || deco.proto !== "file")

		yield path_part;

	}

	if (slice === deco.path.length - 1 && !deco.path_truncated &&

	    deco.path[slice] !== "*")

	    yield path_part + "/*";

	if (slice < deco.path.length - 1)

	    yield path_part + "/**";

	if (slice !== deco.path.length - 1 || deco.path_truncated ||

	    deco.path[slice] !== "***")

	    yield path_part + "/***";

    }

}

/* Generate every possible pattern that matches url. */

function* each_url_pattern(url)

{

    const deco = deconstruct_url(url);

    if (deco === undefined) {

	console.error("bad url format", url);

	return false;

    }

    const all_domains = deco.domain ? each_domain_pattern(deco) : [""];

    for (const domain of all_domains) {

	for (const path of each_path_pattern(deco))

	    yield `${deco.proto}://${domain}${path}`;

    }

}

/*

 * EXPORTS_START

 * EXPORT each_url_pattern

 * EXPORT deconstruct_url

 * EXPORTS_END

 */