Script to read a LESS file, resolve its @imports and generate a new LESS file

less_import_parser.php

<?php
declare(strict_types=1);

class LessImportParser
{
    private $content = '';

    public function load(string $fileName)
    {
        $this->content = $this->resolveImports($fileName);
    }

    public function save(string $fileName)
    {
        file_put_contents($fileName, $this->content);
    }

    private function resolveImports(string $fileName): string
    {
        $fileContent = file_get_contents($fileName);
        $fileDir = dirname($fileName);

        if (!preg_match_all('/@import([^\;]+)/mS', $fileContent, $matches)) {
            return $fileContent;
        }

        foreach ($matches[0] as $matchIndex => $match) {
            $importedFilename = $matches[1][$matchIndex];
            $importedFilename = str_replace('(reference)', '', $importedFilename);
            $importedFilename = str_replace('\'', '', $importedFilename);
            $importedFilename = trim($importedFilename);
            $importedContent = $this->resolveImports($fileDir.'/'.$importedFilename);

            $newContent = "\n // Imported file: ".$importedFilename."\n";
            $newContent .= $importedContent;
            $fileContent = str_replace($match, $newContent, $fileContent);
        }

        return $fileContent;
    }
}

$parser = new LessImportParser;
$parser->load(__DIR__ . '/css/styles-l.less');
$parser->save(__DIR__ . '/css/test-l.less');

$parser->load(__DIR__ . '/css/styles-m.less');
$parser->save(__DIR__ . '/css/test-m.less');