statistics/common.php

<?php
/*
 * Common functions and definitions
 * Copyright (C) 2020  Polyna <https://wandystan.eu/B196>
 *
 * This file is part of LDMW statistical scripts.
 *
 * LDMW statistical scripts are free software: you can redistribute them
 * and/or modify them under the terms of the GNU Affero General Public
 * License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * LDMW statistical scripts are distributed in the hope that they will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public
 * License along with LDMW statistical scripts.  If not, see
 * <https://www.gnu.org/licenses/>.
 */
define('REGEXP_ISO8601_DATE', '\d{4}(-\d{2}|-?(\d{2}-?\d{2}|W\d{2}(-\d)?|\d{3}))');
define('REGEXP_ISO8601_INTERVAL', 'P(\d+Y(\d+M)?(\d+D)?|\d+M(\d+D)?|\d+[DW])');
define('REGEXP_ISO8601_DATE_OR_INTERVAL', '(' . REGEXP_ISO8601_DATE . '|' . REGEXP_ISO8601_INTERVAL . ')');

function exit_error($message) {
	http_response_code(500);
	header('Content-type: text/plain; charset=utf-8');
	print 'ERROR: ' . $message . PHP_EOL;
	exit;
}

function exit_error_handler($exception) {
	exit_error($exception->getMessage());
}
set_exception_handler('exit_error_handler');

function load_remote_dom_document($uri) {
	$content = file_get_contents($uri);
	$document = new DOMDocument;

	if ($content === false)
		throw new Exception("Cannot load remote URI: $uri");

	if (! $document->loadHTML($content, LIBXML_NOWARNING | LIBXML_NOERROR))
		throw new Exception("Cannot parse remote URI as HTML: $uri");

	return $document;
}

function starts_with($haystack, $needle) {
    return substr_compare($haystack, $needle, 0, strlen($needle)) === 0;
}