<?php

/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

declare(strict_types=1);

namespace Elastic\Apm\Impl\Util;

/**
 * Code in this file is part of implementation internals and thus it is not covered by the backward compatibility.
 *
 * @internal
 */
final class ClassNameUtil
{
    use StaticClassTrait;

    /**
     * @param class-string $fqClassName
     *
     * @return string
     */
    public static function fqToShort(string $fqClassName): string
    {
        $namespace = '';
        $shortName = '';
        self::splitFqClassName($fqClassName, /* ref */ $namespace, /* ref */ $shortName);
        return $shortName;
    }

    /**
     * @param class-string $fqClassName
     * @param string       $namespace
     * @param string       $shortName
     *
     * @return void
     */
    public static function splitFqClassName(string $fqClassName, /* out */ string &$namespace, /* out */ string &$shortName): void
    {
        // Check if $fqClassName begin with a back slash(es)
        $firstBackSlashPos = strpos($fqClassName, '\\');
        if ($firstBackSlashPos === false) {
            $namespace = '';
            $shortName = $fqClassName;
            return;
        }
        $firstCanonPos = $firstBackSlashPos === 0 ? 1 : 0;

        $lastBackSlashPos = strrpos($fqClassName, '\\', $firstCanonPos);
        if ($lastBackSlashPos === false) {
            $namespace = '';
            $shortName = substr($fqClassName, $firstCanonPos);
            return;
        }

        $namespace = substr($fqClassName, $firstCanonPos, $lastBackSlashPos - $firstCanonPos);
        $shortName = substr($fqClassName, $lastBackSlashPos + 1);
    }
}