Haketilo

/**

 * Hachette operations on page url patterns

 *

 * Copyright (C) 2021 Wojtek Kosior

 * Redistribution terms are gathered in the `copyright' file.

 */

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

const domain_re = "[^/?#]+";

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

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

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

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

function deconstruct_url(url)

{

    const proto_match = proto_regex.exec(url);

    if (proto_match === null)

	return undefined;

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

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

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

    } else {

	const http_match = http_regex.exec(proto_match[2]);

	if (!http_match)

	    return undefined;

	[deco.domain, deco.path, deco.query] = http_match.slice(1, 4);

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

    }

    const leading_dash = deco.path[0] === "/";

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

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

    if (leading_dash || deco.path.length === 0)

	deco.path.unshift("");

    return deco;

}

/* Be sane: both arguments should be arrays of length >= 2 */

function domain_matches(url_domain, pattern_domain)

{

    const length_difference = url_domain.length - pattern_domain.length;

    for (let i = 1; i <= url_domain.length; i++) {

	const url_part = url_domain[url_domain.length - i];

	const pattern_part = pattern_domain[pattern_domain.length - i];

	if (pattern_domain.length === i) {

	    if (pattern_part === "*")

		return length_difference === 0;

	    if (pattern_part === "**")

		return length_difference > 0;

	    if (pattern_part === "***")

		return true;

	    return length_difference === 0 && pattern_part === url_part;

	}

	if (pattern_part !== url_part)

	    return false;

    }

    return pattern_domain.length === url_domain.length + 1 &&

	pattern_domain[0] === "***";

}

function path_matches(url_path, url_trailing_dash,

		      pattern_path, pattern_trailing_dash)

{

    const dashes_ok = !(pattern_trailing_dash && !url_trailing_dash);

    if (pattern_path.length === 0)

	return url_path.length === 0 && dashes_ok;

    const length_difference = url_path.length - pattern_path.length;

    for (let i = 0; i < url_path.length; i++) {

	if (pattern_path.length === i + 1) {

	    if (pattern_path[i] === "*")

		return length_difference === 0;

	    if (pattern_path[i] === "**") {

		return length_difference > 0 ||

		    (url_path[i] === "**" && dashes_ok);

	    }

	    if (pattern_path[i] === "***")

		return length_difference >= 0;

	    return length_difference === 0 &&

		pattern_path[i] === url_path[i] && dashes_ok;

	}

	if (pattern_path[i] !== url_path[i])

	    return false;

    }

    return false;

}

function url_matches(url, pattern)

{

    const url_deco = deconstruct_url(url);

    const pattern_deco = deconstruct_url(pattern);

    if (url_deco === undefined || pattern_deco === undefined) {

	console.log(`bad comparison: ${url} and ${pattern}`);

	return false

    }

    return pattern_deco.proto === url_deco.proto &&

	!(pattern_deco.proto === "file" && pattern_deco.trailing_dash) &&

	!!url_deco.domain === !!pattern_deco.domain &&

	(!url_deco.domain ||

	 domain_matches(url_deco.domain, pattern_deco.domain)) &&

	path_matches(url_deco.path, url_deco.trailing_dash,

		     pattern_deco.path, pattern_deco.trailing_dash);

}

function* each_domain_pattern(domain_segments)

{

    for (let slice = 0; slice < domain_segments.length; slice++) {

	const domain_part = domain_segments.slice(slice).join(".");

	const domain_wildcards = [];

	if (slice === 0)

	    yield domain_part;

	if (slice === 1)

	    yield "*." + domain_part;

	if (slice > 1)

	    yield "**." + domain_part;

	yield "***." + domain_part;

    }

}

function* each_path_pattern(path_segments, trailing_dash)

{

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

	const path_part = path_segments.slice(0, slice).join("/");

	const path_wildcards = [];

	if (slice === path_segments.length) {

	    if (trailing_dash)

		yield path_part + "/";

	    yield path_part;

	}

	if (slice === path_segments.length - 1 && path_segments[slice] !== "*")

	    yield path_part + "/*";

	if (slice < path_segments.length - 1)

	    yield path_part + "/**";

	if (slice < path_segments.length - 1 ||

	    path_segments[path_segments.length - 1] !== "***")

	    yield path_part + "/***";

    }

}

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

function* each_url_pattern(url)

{

    const deco = deconstruct_url(url);

    if (deco === undefined) {

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

	return false;

    }

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

    for (const domain of all_domains) {

	for (const path of each_path_pattern(deco.path, deco.trailing_dash))

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

    }

}

/*

 * EXPORTS_START

 * EXPORT url_matches

 * EXPORT each_url_pattern

 * EXPORTS_END

 */