It fixes php namespaces (only namespaces, not use statements)

namespace-fixer.php

<?php

function usage_error(): void
{
    echo 'Usage: php namespace-fixer.php <path> <prefix>' . PHP_EOL;
    echo 'Example: php namespace-fixer.php src App' . PHP_EOL;
    exit(1);
}

$globalPath = $argv[1] ?? usage_error();
$prefix = $argv[2] ?? usage_error();

echo sprintf(
    'Fixing namespaces, prefixed by "%s", in %s.',
    $prefix,
    $globalPath
 ). PHP_EOL;

function fix_files(string $globalPath, string $path, string $prefix): void
{
    $files = scandir($path);

    foreach ($files as $file) {
        if ($file === '.' || $file === '..') {
            continue;
        }
    
        $filePath = $path . '/' . $file;
        if (is_dir($filePath)) {
            fix_files($globalPath, $filePath, $prefix);
            continue;
        }
    
        if (strpos($file, '.php') === false) {
            continue;
        }
    
        echo 'Fixing ' . $file . PHP_EOL;
    
        $content = file_get_contents($filePath);

        $expectedNamespace = str_replace([
            trim($globalPath, '/'),
            '/',
        ], [
            'App',
            '\\',
        ], $path);

        $content = preg_replace_callback(
            '/(?<!\w)(namespace [^;]+);/',
            function ($matches) use ($expectedNamespace) {
               return 'namespace '.$expectedNamespace.';';
            },
            $content
        );

        file_put_contents($filePath, $content);
    }
}

fix_files($globalPath, $globalPath, $prefix);