<?php

namespace dokuwiki\plugin\luxtools;

/**
 * Cache invalidation helpers for luxtools.
 *
 * Provides a full DokuWiki cache purge (all rendered pages, instructions,
 * CSS/JS bundles) as well as luxtools-specific cache cleanup (thumbnails,
 * pagelink mapping).
 */
class CacheInvalidation
{
    /**
     * Purge the DokuWiki cache directory, preserving the luxtools subfolder.
     *
     * Removes all files and subdirectories inside $conf['cachedir'] except
     * the `luxtools/` subdirectory, which contains plugin-specific caches
     * (thumbnails, pagelink mapping) that are expensive to rebuild and are
     * managed separately via {@see purgePagelinks()} and {@see purgeThumbs()}.
     *
     * @return int Number of removed entries.
     */
    public static function purgeAll(): int
    {
        global $conf;

        $cacheDir = rtrim((string)($conf['cachedir'] ?? ''), '/');
        if ($cacheDir === '' || !is_dir($cacheDir)) {
            return 0;
        }

        return self::removeDirectoryEntries($cacheDir, ['luxtools']);
    }

    /**
     * Purge the luxtools pagelink cache file.
     *
     * Deletes {@see PageLink::CACHE_FILE} from the luxtools cache sub-directory
     * ($conf['cachedir']/luxtools/pagelink_cache.json). The file is rebuilt
     * automatically on the next page request that needs it.
     *
     * @return int 1 if the file was removed, 0 otherwise.
     */
    public static function purgePagelinks(): int
    {
        global $conf;

        $cacheDir = rtrim((string)($conf['cachedir'] ?? ''), '/');
        if ($cacheDir === '') {
            return 0;
        }

        $file = $cacheDir . '/luxtools/pagelink_cache.json';
        if (!file_exists($file)) {
            return 0;
        }

        return @unlink($file) ? 1 : 0;
    }

    /**
     * Purge the luxtools thumbnail cache directory.
     *
     * Removes all files and sub-directories inside
     * $conf['cachedir']/luxtools/thumbs. Thumbnails are regenerated
     * on demand by file.php.
     *
     * @return int Number of removed entries.
     */
    public static function purgeThumbs(): int
    {
        global $conf;

        $cacheDir = rtrim((string)($conf['cachedir'] ?? ''), '/');
        if ($cacheDir === '') {
            return 0;
        }

        $thumbsDir = $cacheDir . '/luxtools/thumbs';
        if (!is_dir($thumbsDir)) {
            return 0;
        }

        return self::removeDirectoryEntries($thumbsDir);
    }

    /**
     * Execute a selective cache purge.
     *
     * Always purges the DokuWiki cache (skipping the luxtools subfolder).
     * Optionally also purges the pagelinks cache and/or the thumbnail cache.
     *
     * @param bool $pagelinks Whether to also purge the pagelink cache.
     * @param bool $thumbs    Whether to also purge the thumbnail cache.
     * @return array{dokuwiki: int, pagelinks: int|null, thumbs: int|null}
     *   Removed-entry counts per component; pagelinks/thumbs are null when not purged.
     */
    public static function purgeSelected(bool $pagelinks, bool $thumbs): array
    {
        return [
            'dokuwiki'  => self::purgeAll(),
            'pagelinks' => $pagelinks ? self::purgePagelinks() : null,
            'thumbs'    => $thumbs    ? self::purgeThumbs()    : null,
        ];
    }

    /**
     * Remove all files and subdirectories inside a directory
     * without removing the directory itself.
     *
     * @param string   $directory
     * @param string[] $skip      Entry names (not paths) to leave untouched.
     * @return int Number of removed files/directories.
     */
    public static function removeDirectoryEntries(string $directory, array $skip = []): int
    {
        if ($directory === '' || !is_dir($directory) || !is_readable($directory)) {
            return 0;
        }

        $entries = @scandir($directory);
        if (!is_array($entries)) return 0;

        $removed = 0;
        foreach ($entries as $entry) {
            if ($entry === '.' || $entry === '..') continue;
            if ($skip !== [] && in_array($entry, $skip, true)) continue;

            $path = $directory . '/' . $entry;
            if (is_dir($path) && !is_link($path)) {
                $removed += self::removeDirectoryEntries($path);
                if (@rmdir($path)) {
                    $removed++;
                }
                continue;
            }

            if ((is_file($path) || is_link($path)) && @unlink($path)) {
                $removed++;
            }
        }

        return $removed;
    }
}