Case insensitive autoload using composer generated classmap

CaseIgnoreAutoloader.php

<?php
/**
 * Case insensitive autoload using composer generated classmap
 *
 * see problem:
 *   - https://github.com/composer/composer/issues/1803
 *   - https://stackoverflow.com/questions/20235922/how-to-add-case-insensitive-autoloading-using-composer-generated-classmap
 *
 * 1. Add this class to project. (you can set any namespace)
 * 2. Add to composer.json section "scripts"
 *    "scripts": {
 *        "post-autoload-dump": ["CaseIgnoreAutoloader::onPostAutoloadDump"]
 *    }
 * 3. run dump-autoload with create classmap
 * 4. view vendor/autoload.php (append registration addition autoloader)
 * - addition classmap ignore VENDOR dir
 * - autoloader not generated when classmap is empty
 * - for temporary disable function you can use key 'map-case-ignore' in 'extra' section (default true)
 *    "extra": {
 *        "map-case-ignore": true
 *    }
 *
 * 5. How to reproduce this as a plugin? Behavioral change is a mystery.
 *
 * update 09 jul 2022
 *   Put an additional autoloader in the beginning.
 *   Now the param "prepend-autoloader" can be used to determine the order in which loaders work.
 *
 * @author https://gist.github.com/AndryG
 * @license MIT
 */

use Composer\Script\Event;

class CaseIgnoreAutoloader {

    /**
     * @param Event $event
     */
    public static function onPostAutoloadDump(Event $event) {
        $isActive = $event->getComposer()->getPackage()->getExtra()['map-case-ignore'] ?? true;
        $vendorDir = $event->getComposer()->getConfig()->get('vendor-dir');
        $camelMapFile = $vendorDir.'/composer/autoload_classmap.php';
        $lowMapFile = $vendorDir.'/composer/autoload_classmap_case_ignore.php';
        $baseDirNameLen = mb_strlen(dirname($vendorDir)) + 1;
        $lowMap = [];

        if ($isActive) { // generate low str map
            foreach (require $camelMapFile as $k => $v) {
                if (0 !== strpos($v, $vendorDir)) { // except vendor
                    $lowMap[mb_strtolower($k)] = mb_substr($v, $baseDirNameLen);
                }
            }
            $isActive = (bool)$lowMap; // disable of empty low str map
        }
        if ($isActive) { // modify autoloader.php and save addition classmap
            file_put_contents($lowMapFile, sprintf('<?'.'php return %s;', var_export($lowMap, true)));

            $anchor = 'require_once __DIR__ . \'/composer/autoload_real.php\';';
            $script = <<<'AUTOLOADER'
                // insert by CaseIgnoreAutoloader
                
                spl_autoload_register(function($class){
                    static $lowMap;
                    $lowMap ??= require(__DIR__.'/composer/autoload_classmap_case_ignore.php');                
                    if($file = $lowMap[mb_strtolower($class)] ?? false){
                        include(__dir__.'/../'.$file);
                        return true;
                    }
                    return null;
                });


                AUTOLOADER;

            // update autoload.php
            $fName = $vendorDir.'/autoload.php';
            $content = file_get_contents($fName);
            $content = str_replace($anchor, $script.$anchor, $content);
            file_put_contents($fName, $content);
        }

        if (!$isActive) {
            unlink($lowMapFile);
        }
    }

}