<?php

namespace App\Support;

use App\Models\Video;
use App\Services\NasSyncService;

/**
 * Resolves a video's thumbnail to a local absolute file path so it can be
 * embedded inline (CID) in transactional emails.
 *
 * Remote mail clients (notably Gmail's image proxy) cannot reliably fetch the
 * dynamic /media/thumbnails route — it sits behind Cloudflare and PHP, so the
 * proxy may be challenged or time out, leaving a broken image. Embedding the
 * bytes directly in the message removes that external dependency entirely.
 */
class EmailThumbnail
{
    public static function localPath(?Video $video): ?string
    {
        if (! $video || ! $video->thumbnail) {
            return null;
        }

        $thumb = $video->thumbnail;
        $nas   = app(NasSyncService::class);

        // NAS-mirrored path format: "users/{slug}/videos/{song}/…"
        if (str_starts_with($thumb, 'users/')) {
            $local = storage_path('app/' . $thumb);
            if (file_exists($local)) {
                return $local;
            }

            @mkdir(dirname($local), 0755, true);

            // The DB path mirrors the NAS path exactly — try it directly first.
            if ($nas->ensureLocalAsset($local, $thumb)) {
                return $local;
            }

            // Extension may differ on NAS (e.g. canonical thumb.webp).
            $dir = $nas->resolveVideoDir($video);
            $ext = pathinfo($thumb, PATHINFO_EXTENSION) ?: 'jpg';
            foreach (["thumb.webp", "thumb.{$ext}"] as $nasFile) {
                if ($nas->ensureLocalAsset($local, "{$dir}/{$nasFile}")) {
                    return $local;
                }
            }

            return file_exists($local) ? $local : null;
        }

        // Legacy flat filename format.
        $local = storage_path('app/public/thumbnails/' . $thumb);

        return file_exists($local) ? $local : null;
    }
}