<?php

namespace dokuwiki\plugin\luxtools;

/**
 * Shared utility for thumbnail cache management and display logic.
 *
 * Used by both the image syntax and the gallery rendering to avoid code duplication.
 */
class ThumbnailHelper
{
    /**
     * Get thumbnail URL and metadata for rendering.
     *
     * This is the main entry point for getting thumbnails. The helper handles
     * all URL construction, cache checking, and provides ready-to-use URLs.
     *
     * @param string $rootPath Root filesystem path (e.g., '/data/images/')
     * @param string $localPath Local path relative to root (e.g., 'photo.jpg')
     * @param string $pageId Page ID for ACL check
     * @param int $width Desired width
     * @param int $height Desired height
     * @param int $quality JPEG quality (0-100)
     * @param string|null $placeholderId Optional MediaManager ID for custom placeholder
     * @return array [
     *   'url' => string,      // Always usable URL (thumbnail or placeholder)
     *   'isFinal' => bool,    // true if thumbnail ready, false if placeholder
     *   'thumbUrl' => string  // Real thumbnail URL (for lazy loading)
     * ]
     */
    public static function getThumbnail(
        string $rootPath,
        string $localPath,
        string $pageId,
        int $width,
        int $height,
        int $quality = 80,
        ?string $placeholderId = null
    ): array {
        $fullPath = $rootPath . $localPath;
        $thumbUrl = self::buildThumbnailUrl($rootPath, $localPath, $pageId, $width, $height, $quality);
        
        // Check if cached
        $cachePath = self::getCachePath($fullPath, $width, $height, $quality);
        $isCached = $cachePath !== null && @is_file($cachePath);
        
        if ($isCached) {
            return [
                'url' => $thumbUrl,
                'isFinal' => true,
                'thumbUrl' => $thumbUrl,
            ];
        }
        
        // Not cached: return placeholder
        return [
            'url' => self::getPlaceholderUrl($width, $height, $placeholderId),
            'isFinal' => false,
            'thumbUrl' => $thumbUrl,
        ];
    }

    /**
     * Build the file.php URL for a thumbnail.
     *
     * @param string $rootPath Root filesystem path
     * @param string $localPath Local path relative to root
     * @param string $pageId Page ID for ACL check
     * @param int $width Width
     * @param int $height Height
     * @param int $quality JPEG quality
     * @return string Complete URL to file.php with thumbnail parameters
     */
    protected static function buildThumbnailUrl(
        string $rootPath,
        string $localPath,
        string $pageId,
        int $width,
        int $height,
        int $quality
    ): string {
        $params = [
            'root' => $rootPath,
            'file' => $localPath,
            'id' => $pageId,
            'thumb' => 1,
            'w' => $width,
            'h' => $height,
            'q' => $quality,
        ];
        return DOKU_BASE . 'lib/plugins/luxtools/file.php?' . http_build_query($params, '', '&');
    }

    /**
     * Compute the expected thumbnail cache path.
     *
     * Mirrors the hashing scheme in file.php so we can detect whether a thumb
     * already exists and can be used immediately.
     *
     * @param string $path Full filesystem path to the image
     * @param int $w Width
     * @param int $h Height
     * @param int $q Quality (JPEG)
     * @return string|null Path to cached thumbnail, or null if unavailable
     */
    public static function getCachePath(string $path, int $w, int $h, int $q = 80): ?string
    {
        if ($path === '' || !is_file($path)) return null;

        $mtime = @filemtime($path);
        if ($mtime === false) return null;

        // Decide output format the same way file.php does
        try {
            [, $mime,] = mimetype($path, false);
        } catch (\Throwable $e) {
            return null;
        }
        if (!is_string($mime) || !str_starts_with($mime, 'image/')) return null;
        $dstFormat = ($mime === 'image/png' || $mime === 'image/gif') ? 'png' : 'jpg';

        global $conf;
        if (!isset($conf['cachedir']) || !is_string($conf['cachedir']) || trim($conf['cachedir']) === '') return null;

        $hash = sha1($path . '|' . $mtime . '|w=' . $w . '|h=' . $h . '|q=' . $q . '|f=' . $dstFormat);
        $sub = substr($hash, 0, 2);
        $cacheDir = rtrim($conf['cachedir'], '/');
        return $cacheDir . '/luxtools/thumbs/' . $sub . '/' . $hash . '.' . $dstFormat;
    }

    /**
     * Get placeholder image URL.
     *
     * @param int $width Desired width
     * @param int $height Desired height
     * @param string|null $placeholderId Optional MediaManager ID for custom placeholder
     * @return string Placeholder URL
     */
    public static function getPlaceholderUrl(int $width, int $height, ?string $placeholderId = null): string
    {
        $placeholderUrl = DOKU_BASE . 'lib/images/blank.gif';
        
        if ($placeholderId !== null && $placeholderId !== '' && function_exists('ml')) {
            $placeholderUrl = ml($placeholderId, ['w' => $width, 'h' => $height], true, '&');
        }
        
        return $placeholderUrl;
    }

    /**
     * Determine the initial image source and data attributes for lazy thumbnail loading.
     *
     * Returns placeholder info if thumbnail needs to be loaded, or the actual
     * thumbnail URL if it's already cached.
     *
     * @param string $imagePath Full filesystem path to the image
     * @param string $thumbUrl URL to the thumbnail
     * @param int $width Width
     * @param int $height Height
     * @param int $quality Quality (JPEG)
     * @param string|null $placeholderId Optional MediaManager ID for custom placeholder
     * @return array ['src' => string, 'dataThumbAttr' => string]
     */
    public static function getDisplayInfo(
        string $imagePath,
        string $thumbUrl,
        int $width,
        int $height,
        int $quality = 80,
        ?string $placeholderId = null
    ): array {
        $thumbCachePath = self::getCachePath($imagePath, $width, $height, $quality);
        
        if ($thumbCachePath !== null && @is_file($thumbCachePath)) {
            // Thumbnail exists: display it immediately
            return [
                'src' => $thumbUrl,
                'dataThumbAttr' => '',
            ];
        }
        
        // Thumbnail doesn't exist: show placeholder and lazy-load
        $placeholderUrl = self::getPlaceholderUrl($width, $height, $placeholderId);
        return [
            'src' => $placeholderUrl,
            'dataThumbAttr' => ' data-thumb-src="' . hsc($thumbUrl) . '"',
        ];
    }
}