<?php
namespace App\Services;

use Illuminate\Support\Facades\Storage;

class ThumbnailService
{
    protected const CDN_HOST = 'http://files.skinbase.org';

    protected const VALID_SIZES = ['sm','md','lg','xl'];

    protected const THUMB_SIZES = [
        'sm' => ['height' => 240, 'quality' => 78, 'dir' => 'sm'],
        'md' => ['height' => 360, 'quality' => 82, 'dir' => 'md'],
        'lg' => ['height' => 1200, 'quality' => 85, 'dir' => 'lg'],
        'xl' => ['height' => 2400, 'quality' => 90, 'dir' => 'xl'],
    ];

    /**
     * Build a thumbnail URL from a filePath/hash/id and ext.
     * Accepts either a direct hash string in $filePath, or an $id + $ext pair.
     * Legacy size codes (4 -> sm, others -> md) are supported.
     */
    public static function url(?string $filePath, ?int $id = null, ?string $ext = null, $size = 6): string
    {
        // If $filePath seems to be a content hash and $ext is provided, build directly
        if (!empty($filePath) && !empty($ext) && preg_match('/^[0-9a-f]{16,128}$/i', $filePath)) {
            $sizeKey = is_string($size) ? $size : (($size === 4) ? 'sm' : 'md');
            return self::fromHash($filePath, $ext, $sizeKey) ?: '';
        }

        // Resolve by id when provided
        if ($id !== null) {
            try {
                $artClass = '\\App\\Models\\Artwork';
                if (class_exists($artClass)) {
                    $art = $artClass::where('id', $id)->orWhere('legacy_id', $id)->first();
                    if ($art) {
                        $hash = $art->hash ?? null;
                        $extToUse = $ext ?? ($art->thumb_ext ?? null);
                        $sizeKey = is_string($size) ? $size : (($size === 4) ? 'sm' : 'md');
                        if (!empty($hash) && !empty($extToUse)) {
                            return self::fromHash($hash, $extToUse, $sizeKey) ?: '';
                        }
                    }
                }
            } catch (\Throwable $e) {
                // fallthrough to storage/filePath fallback
            }
        }

        // Fallback to Storage::url or return provided path
        if (!empty($filePath)) {
            try {
                return Storage::url($filePath);
            } catch (\Throwable $e) {
                return $filePath;
            }
        }

        return '';
    }

    /**
     * Build CDN URL from hash and extension.
     */
    public static function fromHash(?string $hash, ?string $ext, string $sizeKey = 'md'): ?string
    {
        if (empty($hash) || empty($ext)) return null;
        $sizeKey = in_array($sizeKey, self::VALID_SIZES) ? $sizeKey : 'md';
        $h = $hash;
        $h1 = substr($h, 0, 2);
        $h2 = substr($h, 2, 2);
        return sprintf('%s/%s/%s/%s/%s.%s', rtrim(self::CDN_HOST, '/'), $sizeKey, $h1, $h2, $h, $ext);
    }

    /**
     * Build srcset using sm and md sizes for legacy layouts.
     */
    public static function srcsetFromHash(?string $hash, ?string $ext): ?string
    {
        $a = self::fromHash($hash, $ext, 'sm');
        $b = self::fromHash($hash, $ext, 'md');
        if (!$a || !$b) return null;
        return $a . ' 320w, ' . $b . ' 600w';
    }
}