Automatically migrates Font Awesome 4 class names to Font Awesome 5 class names

Font-Awesome-4-to-5-Migration.php

<?php

/**
 * Automatically migrates Font Awesome 4 class names to Font Awesome 5 class names.
 *
 * WARNING: THIS WILL REWRITE YOUR FILES.
 * BACK UP YOUR FILES BEFORE RUNNING THIS SCRIPT.
 * YOU HAVE BEEN WARNED.
 *
 * Note: the migration CSV file was parsed from the official migration documentation:
 * https://fontawesome.com/how-to-use/on-the-web/setup/upgrading-from-version-4#name-changes
 */

// Configure whether to perform a dry run
// Only shows the updates that would be performed, but does not modify the files
$dryRun = true;

// Configure project dir
$dir = './src';

// Configure file extensions to process
$extensions = ['php', 'phtml'];

// Let's go!
define('FA_PREFIX', 0);
define('FA_NEWNAME', 1);

// Load migration file
$fp = fopen('Migration.csv', 'rb');

$map = [];

while (! feof($fp)) {
    [$oldName, $newName, $prefix] = fgetcsv($fp);
    $map[$oldName] = [$prefix, $newName];
}

fclose($fp);

// Loop through project files
$files = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir));

foreach($files as $file) {
    /** @var \SplFileInfo $file */
    if (! in_array($file->getExtension(), $extensions)) {
        continue;
    }

    $file = (string) $file;
    $data = file_get_contents($file);

    preg_match_all('/class="([^"]+)"/', $data, $matches, PREG_SET_ORDER);

    $modified = false;

    foreach ($matches as [$attribute, $originalClass]) {
        $classes = explode(' ', $originalClass);

        $prefix = 'fas';

        foreach ($classes as $key => $class) {
            if (substr($class, 0, 3) === 'fa-') {
                $class = substr($class, 3);

                if (isset($map[$class])) {
                    $prefix = $map[$class][FA_PREFIX];
                    $classes[$key] = 'fa-' . $map[$class][FA_NEWNAME];
                }
            }
        }

        foreach ($classes as $key => $class) {
            if ($class === 'fa') {
                $classes[$key] = $prefix;
            }
        }

        $class = implode(' ', $classes);

        if ($class !== $originalClass) {
            echo "$originalClass => $class\n";
            $data = str_replace($attribute, 'class="' . $class . '"', $data);
            $modified = true;
        }
    }

    if ($modified) {
        if ($dryRun) {
            echo "Would write $file\n";
        } else {
            echo "Writing $file\n";
            file_put_contents($file, $data);
        }
    }
}

echo "Done\n";

Migration.csv