<?php

namespace App\Services;

use App\Models\Setting;
use App\Models\User;
use App\Models\Video;
use Illuminate\Support\Facades\Log;

class NasSyncService
{
    // ── Enable check ──────────────────────────────────────────────────────────

    public function isEnabled(): bool
    {
        return Setting::get('nas_sync_enabled', 'false') === 'true'
            && ! empty($this->cfg()['host']);
    }

    // ── Slug helpers ──────────────────────────────────────────────────────────

    public function userSlug(User $user): string
    {
        return $user->username ?: (string) $user->id;
    }

    public function titleSlug(string $title): string
    {
        $slug = mb_strtolower($title);
        $slug = preg_replace('/[^a-z0-9]+/u', '-', $slug);
        $slug = trim($slug, '-');
        return $slug ?: 'video';
    }

    /**
     * Return the NAS directory for a video.
     *
     * On first sync  → pick a conflict-free slug and create the folder.
     * On subsequent  → find the existing folder by matching video ID in meta.json
     *                  so renames of the title never lose the folder.
     */
    public function resolveVideoDir(Video $video): string
    {
        $video->loadMissing('user');
        $userSlug  = $this->userSlug($video->user);
        $base      = "users/{$userSlug}/videos";
        $titleSlug = $this->titleSlug($video->title);

        // 1. Try the current title slug and numbered variants (-2, -3 …)
        //    If any of them already hold meta.json with our video ID → reuse it.
        for ($serial = 1; $serial <= 50; $serial++) {
            $candidate = $serial === 1 ? $titleSlug : "{$titleSlug}-{$serial}";
            $meta      = $this->readMeta("{$base}/{$candidate}");

            if ($meta === null) {
                // Folder is free — this is where we'll write
                return "{$base}/{$candidate}";
            }

            if (($meta['id'] ?? null) === $video->id) {
                // This folder already belongs to our video
                return "{$base}/{$candidate}";
            }
        }

        // 2. Fallback: scan all folders in the user's videos directory
        $found = $this->scanForVideoDir($base, $video->id);
        if ($found) return $found;

        // 3. Last resort: use title slug + video ID suffix (guaranteed unique)
        return "{$base}/{$titleSlug}-{$video->id}";
    }

    /**
     * Read meta.json from a NAS directory. Returns decoded array or null.
     */
    private function readMeta(string $dir): ?array
    {
        $content = $this->getContent("{$dir}/meta.json");
        if ($content === null) return null;
        $decoded = json_decode($content, true);
        return is_array($decoded) ? $decoded : null;
    }

    /**
     * List all subdirectories under $base and find the one whose
     * meta.json carries the given video ID.
     */
    private function scanForVideoDir(string $base, int $videoId): ?string
    {
        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));

        $smbPath = str_replace('/', '\\', $base) . '\\*';
        exec('smbclient ' . $target . ' -U ' . $cred . ' -c ' . escapeshellarg("ls \"{$smbPath}\"") . ' 2>&1', $output);

        foreach ($output as $line) {
            if (! preg_match('/^  (.+?)\s{2,}D\s/', $line, $m)) continue;
            $name = trim($m[1]);
            if ($name === '.' || $name === '..') continue;

            $meta = $this->readMeta("{$base}/{$name}");
            if (($meta['id'] ?? null) === $videoId) {
                return "{$base}/{$name}";
            }
        }

        return null;
    }

    // ── Local-cache helpers (used when NAS is the primary storage) ───────────

    /**
     * Absolute path where a NAS video is cached locally for HTTP streaming.
     * Separate from public storage so it's never accidentally served statically.
     */
    public function localCachePath(Video $video): string
    {
        return storage_path('app/nas_cache/videos/' . $video->filename);
    }

    /**
     * Ensure the video file is available at a local path for streaming.
     *
     * Priority:
     *   1. Regular local storage  (video uploaded while NAS was off, or not yet cleaned)
     *   2. NAS stream cache       (previously downloaded copy)
     *   3. Download from NAS      (first-time stream after NAS-primary upload)
     *
     * Returns the local absolute path, or null if unavailable.
     */
    public function ensureLocalCopy(Video $video): ?string
    {
        // 1. Regular local storage
        $regularPath = storage_path('app/' . $video->path);
        if (file_exists($regularPath)) return $regularPath;

        // 2. Existing stream cache
        $cachePath = $this->localCachePath($video);
        if (file_exists($cachePath)) return $cachePath;

        // 3. Download from NAS
        if (! $this->isEnabled()) return null;

        $cacheDir = dirname($cachePath);
        if (! is_dir($cacheDir)) mkdir($cacheDir, 0755, true);

        $nasDir   = $this->resolveVideoDir($video);
        $ext      = pathinfo($video->filename, PATHINFO_EXTENSION) ?: 'mp4';
        $fileSlug = $this->titleSlug($video->title);
        $nasFile  = "{$nasDir}/{$fileSlug}.{$ext}";

        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));

        exec('smbclient ' . $target . ' -U ' . $cred
            . ' -c ' . escapeshellarg('get "' . $nasFile . '" "' . $cachePath . '"')
            . ' 2>&1', $out, $code);

        if ($code !== 0 || ! file_exists($cachePath)) {
            @unlink($cachePath);
            Log::warning('NAS: failed to cache video for streaming', [
                'video_id' => $video->id,
                'nas_path' => $nasFile,
                'output'   => implode(' ', $out),
            ]);
            return null;
        }

        Log::info('NAS: video cached locally for streaming', ['video_id' => $video->id]);
        return $cachePath;
    }

    /**
     * Delete the local video file after it has been successfully pushed to NAS.
     */
    public function deleteLocalVideo(Video $video): void
    {
        $path = storage_path('app/' . $video->path);
        if (file_exists($path)) {
            @unlink($path);
            Log::info('NAS: local video removed after NAS push', ['video_id' => $video->id]);
        }
    }

    // ── High-level sync methods ───────────────────────────────────────────────

    public function syncVideo(Video $video): void
    {
        $video->loadMissing('user');
        $dir       = $this->resolveVideoDir($video);
        $fileSlug  = $this->titleSlug($video->title);
        $this->mkdirp($dir);

        // {title-slug}.{ext}
        $localVideo = storage_path('app/' . $video->path);
        if (file_exists($localVideo)) {
            $ext = pathinfo($video->filename, PATHINFO_EXTENSION) ?: 'mp4';
            $this->putFile($localVideo, "{$dir}/{$fileSlug}.{$ext}");
        }

        // thumb.webp
        if ($video->thumbnail) {
            $localThumb = storage_path('app/public/thumbnails/' . $video->thumbnail);
            if (file_exists($localThumb)) {
                $this->putFile($localThumb, "{$dir}/thumb.webp");
            }
        }

        // meta.json  (always written last so readMeta can find the folder)
        $this->putContent(json_encode([
            'id'          => $video->id,
            'user_id'     => $video->user_id,
            'title'       => $video->title,
            'description' => $video->description,
            'type'        => $video->type,
            'visibility'  => $video->visibility,
            'status'      => $video->status,
            'duration'    => $video->duration,
            'width'       => $video->width,
            'height'      => $video->height,
            'orientation' => $video->orientation,
            'mime_type'   => $video->mime_type,
            'size'        => $video->size,
            'created_at'  => $video->created_at?->toIso8601String(),
        ], JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE), "{$dir}/meta.json");
    }

    public function syncVideoMeta(Video $video): void
    {
        $video->loadMissing('user');
        $dir = $this->resolveVideoDir($video);
        $this->mkdirp($dir);

        $this->putContent(json_encode([
            'id'          => $video->id,
            'user_id'     => $video->user_id,
            'title'       => $video->title,
            'description' => $video->description,
            'type'        => $video->type,
            'visibility'  => $video->visibility,
            'status'      => $video->status,
            'duration'    => $video->duration,
            'width'       => $video->width,
            'height'      => $video->height,
            'orientation' => $video->orientation,
            'mime_type'   => $video->mime_type,
            'size'        => $video->size,
            'updated_at'  => $video->updated_at?->toIso8601String(),
        ], JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE), "{$dir}/meta.json");
    }

    public function deleteVideo(Video $video): void
    {
        $video->loadMissing('user');
        $dir = $this->resolveVideoDir($video);
        $ext = pathinfo($video->filename, PATHINFO_EXTENSION) ?: 'mp4';

        $this->deleteFile("{$dir}/" . $this->titleSlug($video->title) . ".{$ext}");
        $this->deleteFile("{$dir}/thumb.webp");
        $this->deleteFile("{$dir}/meta.json");
        $this->deleteFile("{$dir}/view-log.json");
        $this->deleteFile("{$dir}/edit-log.json");
        $this->deleteFolder($dir);
    }

    public function syncAvatar(User $user, string $localAbsPath): void
    {
        $dir = "users/{$this->userSlug($user)}/profile";
        $this->mkdirp($dir);
        $this->putFile($localAbsPath, "{$dir}/avatar.webp");
    }

    public function syncCover(User $user, string $localAbsPath): void
    {
        $dir = "users/{$this->userSlug($user)}/profile";
        $this->mkdirp($dir);
        $this->putFile($localAbsPath, "{$dir}/cover.webp");
    }

    // ── SMB primitives ────────────────────────────────────────────────────────

    public function mkdirp(string $path): void
    {
        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));

        $parts = array_values(array_filter(explode('/', str_replace('\\', '/', $path))));
        $cmds  = [];
        $built = '';
        foreach ($parts as $part) {
            $built  = $built ? "{$built}/{$part}" : $part;
            $cmds[] = 'mkdir "' . $built . '"';
        }

        exec('smbclient ' . $target . ' -U ' . $cred . ' -c ' . escapeshellarg(implode('; ', $cmds)) . ' 2>&1');
        // Intentionally ignore exit code — NT_STATUS_OBJECT_NAME_COLLISION means dir exists
    }

    public function putFile(string $localAbsPath, string $nasRelPath): bool
    {
        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));
        $cmd    = 'put "' . $localAbsPath . '" "' . $nasRelPath . '"';

        exec('smbclient ' . $target . ' -U ' . $cred . ' -c ' . escapeshellarg($cmd) . ' 2>&1', $output, $code);

        if ($code !== 0) {
            Log::warning('NAS putFile failed [' . $nasRelPath . ']: ' . implode(' ', $output));
        }

        return $code === 0;
    }

    public function putContent(string $content, string $nasRelPath): bool
    {
        $tmp = tempnam(sys_get_temp_dir(), 'nassync_');
        file_put_contents($tmp, $content);
        $ok = $this->putFile($tmp, $nasRelPath);
        @unlink($tmp);
        return $ok;
    }

    public function getContent(string $nasRelPath): ?string
    {
        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));
        $tmp    = tempnam(sys_get_temp_dir(), 'nasget_');
        $cmd    = 'get "' . $nasRelPath . '" "' . $tmp . '"';

        exec('smbclient ' . $target . ' -U ' . $cred . ' -c ' . escapeshellarg($cmd) . ' 2>&1', $output, $code);

        if ($code !== 0 || ! file_exists($tmp)) {
            @unlink($tmp);
            return null;
        }

        $content = file_get_contents($tmp);
        @unlink($tmp);
        return $content !== false ? $content : null;
    }

    public function deleteFile(string $nasRelPath): void
    {
        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));
        exec('smbclient ' . $target . ' -U ' . $cred . ' -c ' . escapeshellarg('rm "' . $nasRelPath . '"') . ' 2>&1');
    }

    public function deleteFolder(string $nasRelPath): void
    {
        $cfg    = $this->cfg();
        $target = escapeshellarg($this->smbTarget($cfg));
        $cred   = escapeshellarg($this->smbCredential($cfg));
        exec('smbclient ' . $target . ' -U ' . $cred . ' -c ' . escapeshellarg('rmdir "' . $nasRelPath . '"') . ' 2>&1');
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    private function cfg(): array
    {
        return config('nas-file-manager.connection', []);
    }

    private function smbTarget(array $cfg): string
    {
        return '//' . $cfg['host'] . '/' . trim($cfg['smb_share'] ?? '', '/');
    }

    private function smbCredential(array $cfg): string
    {
        $domain = ! empty($cfg['smb_domain']) ? $cfg['smb_domain'] . '/' : '';
        return $domain . ($cfg['username'] ?? '') . '%' . ($cfg['password'] ?? '');
    }
}