MetaReplacer.php

<?php

/**
 * Class MetaReplacer
 */
class MetaReplacer
{
    /**
     * Path to HEXO source
     *
     * @var string
     */
    private $path = '/home/arie/hexo/source';

    /**
     * Only file with ext .rst in directory _drafts or _posts
     *
     * @var string
     */
    private $pattern = '/^.+_(draft|post)s.+\.rst$/i';

    /**
     * Found files
     *
     * @var array
     */
    private $files = [];

    /**
     * Initialize
     */
    public function __construct()
    {
        $this->rstFinder();
    }

    /**
     * Run replacer
     */
    public function run()
    {
        foreach ($this->files as $file) {
            $this->updateHeader($file);
        }
    }

    /**
     * Update file header
     *
     * @param string $file
     */
    private function updateHeader($file)
    {
        $original_content = file_get_contents($file);

        if (preg_match('!^(?<fl>-{2,})$\n(?<c>.*)\n^(?<sl>-{2,})$!sim', $original_content, $match)) {
            $match     = array_only($match, ['fl', 'c', 'sl']);
            $separator = $match['fl'];
            $original  = join("\n", $match);

            $this->createDescriptionFrom($match['c']);
            $this->fixOverLineLength($match['c'], $separator);

            $new_meta  = join("\n", [$separator, $match['c'], $separator]);
            $content   = str_replace($original, $new_meta, $original_content);

            file_put_contents($file, $content);
        }
    }

    /**
     * Create default description (copied from title)
     *
     * @param string $header
     */
    private function createDescriptionFrom(& $header)
    {
        /*
         * if only doesn't have description
         */
        if (! preg_match('!^description:!mi', $header)) {
            if (preg_match("!^(title: (?<title>.+))$!mi", $header, $match)) {
                $header .= "\ndescription: {$match['title']}";
            }
        }
    }

    private function fixOverLineLength($content, & $overLine)
    {
        $array = explode("\n", $content);

        /**
         * Find max length
         *
         * @param $line
         * @param $line_length
         */
        $separator_check_length = function($line, & $line_length) {
            $current_length = strlen($line);
            if ($current_length > $line_length) {
                $line_length = $current_length;
            }
        };

        $length = 0;
        foreach ($array as $line) $separator_check_length($line, $length);

        $overLine = str_repeat('-', $length);
    }

    /**
     * Find all .rst file
     */
    private function rstFinder()
    {
        $directory = new \RecursiveDirectoryIterator($this->path);
        $iterator  = new \RecursiveIteratorIterator($directory);
        $regex     = new \RegexIterator($iterator, $this->pattern, \RecursiveRegexIterator::GET_MATCH);

        foreach ($regex as $r) $this->addFile($r[0]);
    }

    /**
     * Add file to the list
     *
     * @param string $file
     */
    private function addFile($file)
    {
        $this->files[$file];
    }
}