<?php

namespace App\Services;

use App\Models\Commons\File;
use App\Models\FileShareLink;
use App\Models\Folder;
use App\Models\Tenants\Tenant;
use Illuminate\Http\UploadedFile;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Storage;

/**
 * New file storage system service (Phase 2 implementation)
 * Uses: files table, folders table, Storage Facade, tenant disk
 */
class FileStorageService extends Service
{
    /**
     * Generate 64-bit random filename
     */
    public static function generateStoredName(string $extension): string
    {
        return bin2hex(random_bytes(32)).'.'.$extension;
    }

    /**
     * Upload file to temp folder
     */
    public function upload(UploadedFile $file, ?string $description = null): File
    {
        $tenantId = $this->tenantId();
        $userId = $this->apiUserId();

        // Check storage quota
        $tenant = Tenant::findOrFail($tenantId);
        $quotaCheck = $tenant->canUpload($file->getSize());

        if (! $quotaCheck['allowed']) {
            throw new \Exception($quotaCheck['message']);
        }

        // Generate stored name
        $extension = $file->getClientOriginalExtension();
        $storedName = self::generateStoredName($extension);

        // Build temp path: /tenants/{tenant_id}/temp/{year}/{month}/{stored_name}
        $date = now();
        $tempPath = sprintf(
            '%d/temp/%s/%s/%s',
            $tenantId,
            $date->format('Y'),
            $date->format('m'),
            $storedName
        );

        // Store file
        Storage::disk('tenant')->putFileAs(
            dirname($tempPath),
            $file,
            basename($tempPath)
        );

        // Determine file type
        $mimeType = $file->getMimeType();
        $fileType = $this->determineFileType($mimeType);

        // Create DB record
        $fileRecord = File::create([
            'tenant_id' => $tenantId,
            'display_name' => $file->getClientOriginalName(),
            'stored_name' => $storedName,
            'file_path' => $tempPath,
            'file_size' => $file->getSize(),
            'mime_type' => $mimeType,
            'file_type' => $fileType,
            'is_temp' => true,
            'folder_id' => null,
            'description' => $description,
            'uploaded_by' => $userId,
            'created_by' => $userId,
        ]);

        // Increment tenant storage
        $tenant->incrementStorage($file->getSize());

        return $fileRecord;
    }

    /**
     * Move files from temp to folder
     */
    public function moveToFolder(array $fileIds, int $folderId, ?int $documentId = null, ?string $documentType = null): array
    {
        $tenantId = $this->tenantId();
        $folder = Folder::where('tenant_id', $tenantId)->findOrFail($folderId);

        $movedFiles = [];

        DB::transaction(function () use ($fileIds, $folder, $documentId, $documentType, &$movedFiles) {
            foreach ($fileIds as $fileId) {
                $file = File::where('tenant_id', $this->tenantId())
                    ->where('is_temp', true)
                    ->findOrFail($fileId);

                // Move file
                $file->moveToFolder($folder);

                // Update document reference
                if ($documentId && $documentType) {
                    $file->update([
                        'document_id' => $documentId,
                        'document_type' => $documentType,
                    ]);
                }

                $movedFiles[] = $file->fresh();
            }
        });

        return $movedFiles;
    }

    /**
     * Get file by ID
     */
    public function getFile(int $fileId): File
    {
        return File::where('tenant_id', $this->tenantId())->findOrFail($fileId);
    }

    /**
     * List files with filters
     */
    public function listFiles(array $filters = []): \Illuminate\Pagination\LengthAwarePaginator
    {
        $query = File::where('tenant_id', $this->tenantId())
            ->with(['folder', 'uploader']);

        // Filter by folder
        if (isset($filters['folder_id'])) {
            $query->where('folder_id', $filters['folder_id']);
        }

        // Filter by temp
        if (isset($filters['is_temp'])) {
            $query->where('is_temp', $filters['is_temp']);
        }

        // Filter by document
        if (isset($filters['document_id']) && isset($filters['document_type'])) {
            $query->forDocument($filters['document_id'], $filters['document_type']);
        }

        // Exclude soft deleted by default
        if (! isset($filters['with_trashed']) || ! $filters['with_trashed']) {
            $query->whereNull('deleted_at');
        }

        return $query->orderBy('created_at', 'desc')
            ->paginate($filters['per_page'] ?? 20);
    }

    /**
     * Get trash files
     */
    public function getTrash(): \Illuminate\Pagination\LengthAwarePaginator
    {
        return File::where('tenant_id', $this->tenantId())
            ->onlyTrashed()  // SoftDeletes: deleted_at IS NOT NULL인 항목만
            ->with(['folder', 'uploader'])
            ->orderBy('deleted_at', 'desc')
            ->paginate(20);
    }

    /**
     * Soft delete file
     */
    public function deleteFile(int $fileId): File
    {
        $userId = $this->apiUserId();
        $file = $this->getFile($fileId);

        DB::transaction(function () use ($file, $userId) {
            // Soft delete
            $file->softDeleteFile($userId);

            // Log deletion
            DB::table('file_deletion_logs')->insert([
                'tenant_id' => $file->tenant_id,
                'file_id' => $file->id,
                'file_name' => $file->display_name,
                'file_path' => $file->file_path,
                'file_size' => $file->file_size,
                'folder_id' => $file->folder_id,
                'document_id' => $file->document_id,
                'document_type' => $file->document_type,
                'deleted_by' => $userId,
                'deleted_at' => now(),
                'deletion_type' => 'soft',
            ]);
        });

        return $file->fresh();
    }

    /**
     * Restore file from trash
     */
    public function restoreFile(int $fileId): File
    {
        $file = File::where('tenant_id', $this->tenantId())
            ->onlyTrashed()  // SoftDeletes: 삭제된 항목만 조회
            ->findOrFail($fileId);

        $file->restore();
        $file->update(['deleted_by' => null]);

        return $file;
    }

    /**
     * Permanently delete file
     */
    public function permanentDelete(int $fileId): void
    {
        $file = File::where('tenant_id', $this->tenantId())
            ->onlyTrashed()  // SoftDeletes: 삭제된 항목만 조회
            ->findOrFail($fileId);

        DB::transaction(function () use ($file) {
            // Update deletion log
            DB::table('file_deletion_logs')
                ->where('file_id', $file->id)
                ->where('deletion_type', 'soft')
                ->update(['deletion_type' => 'permanent']);

            // Permanently delete
            $file->permanentDelete();
        });
    }

    /**
     * Create share link
     */
    public function createShareLink(int $fileId, ?int $expiryHours = 24): FileShareLink
    {
        $file = $this->getFile($fileId);
        $userId = $this->apiUserId();

        return FileShareLink::create([
            'file_id' => $file->id,
            'tenant_id' => $file->tenant_id,
            'expires_at' => now()->addHours($expiryHours),
            'created_by' => $userId,
        ]);
    }

    /**
     * Get file by share token (no tenant context required)
     */
    public static function getFileByShareToken(string $token): File
    {
        $link = FileShareLink::where('token', $token)
            ->valid()
            ->firstOrFail();

        // Increment download count
        $link->incrementDownloadCount(request()->ip());

        return $link->file;
    }

    /**
     * Get storage usage
     */
    public function getStorageUsage(): array
    {
        $tenant = Tenant::findOrFail($this->tenantId());

        // Folder usage
        $folderUsage = DB::table('files')
            ->where('tenant_id', $this->tenantId())
            ->whereNull('deleted_at')
            ->whereNotNull('folder_id')
            ->selectRaw('folder_id, COUNT(*) as file_count, SUM(file_size) as total_size')
            ->groupBy('folder_id')
            ->get()
            ->map(function ($item) {
                $folder = Folder::find($item->folder_id);

                return [
                    'folder_id' => $item->folder_id,
                    'folder_name' => $folder->folder_name ?? 'Unknown',
                    'file_count' => $item->file_count,
                    'total_size' => $item->total_size,
                    'formatted_size' => $this->formatBytes($item->total_size),
                ];
            });

        return [
            'storage_used' => $tenant->storage_used,
            'storage_limit' => $tenant->storage_limit,
            'storage_used_formatted' => $tenant->getStorageUsedFormatted(),
            'storage_limit_formatted' => $tenant->getStorageLimitFormatted(),
            'usage_percentage' => $tenant->getStorageUsagePercentage(),
            'is_near_limit' => $tenant->isStorageNearLimit(),
            'is_exceeded' => $tenant->isStorageExceeded(),
            'grace_period_until' => $tenant->storage_grace_period_until,
            'folder_usage' => $folderUsage,
        ];
    }

    /**
     * Determine file type from MIME type
     */
    private function determineFileType(string $mimeType): string
    {
        if (str_starts_with($mimeType, 'image/')) {
            return 'image';
        }

        if (in_array($mimeType, [
            'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
            'application/vnd.ms-excel',
            'text/csv',
        ])) {
            return 'excel';
        }

        if (in_array($mimeType, ['application/zip', 'application/x-rar-compressed'])) {
            return 'archive';
        }

        return 'document';
    }

    /**
     * Format bytes to human-readable
     */
    private function formatBytes(int $bytes): string
    {
        $units = ['B', 'KB', 'MB', 'GB', 'TB'];
        $bytes = max($bytes, 0);
        $pow = floor(($bytes ? log($bytes) : 0) / log(1024));
        $pow = min($pow, count($units) - 1);
        $bytes /= (1 << (10 * $pow));

        return round($bytes, 2).' '.$units[$pow];
    }
}