torrent-gateway/internal/storage/backend.go

package storage

import (
	"crypto/sha256"
	"database/sql"
	"encoding/hex"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
	"strings"
	"time"

	"torrentGateway/internal/config"
	_ "github.com/mattn/go-sqlite3"
)

// Backend provides unified storage for chunks, blobs, and metadata
type Backend struct {
	db           *sql.DB
	chunkDir     string
	blobDir      string
	chunkSize    int64
	config       *config.Config
}

// FileMetadata represents metadata about stored files
type FileMetadata struct {
	Hash         string
	OriginalName string
	Size         int64
	ChunkCount   int
	ContentType  string
	StorageType  string
	OwnerPubkey  string
	AccessLevel  string
	InfoHash     string
	CreatedAt    time.Time
	AccessCount  int64
	LastAccess   time.Time
}

// ChunkInfo represents information about a file chunk
type ChunkInfo struct {
	FileHash   string
	ChunkIndex int
	ChunkHash  string
	Size       int64
	Offset     int64
}

// BlobInfo represents information about a Blossom blob
type BlobInfo struct {
	Hash      string
	Size      int64
	CreatedAt time.Time
	MimeType  string
}

// NewBackend creates a new unified storage backend
func NewBackend(dbPath, chunkDir, blobDir string, chunkSize int64, cfg *config.Config) (*Backend, error) {
	// Create directories
	if err := os.MkdirAll(chunkDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create chunk directory: %w", err)
	}
	if err := os.MkdirAll(blobDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create blob directory: %w", err)
	}

	// Ensure database directory exists
	dbDir := filepath.Dir(dbPath)
	if err := os.MkdirAll(dbDir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create database directory: %w", err)
	}

	// Open database
	db, err := sql.Open("sqlite3", dbPath+"?cache=shared&mode=rwc")
	if err != nil {
		return nil, fmt.Errorf("failed to open database: %w", err)
	}

	backend := &Backend{
		db:        db,
		chunkDir:  chunkDir,
		blobDir:   blobDir,
		chunkSize: chunkSize,
		config:    cfg,
	}

	if err := backend.initializeSchema(); err != nil {
		return nil, fmt.Errorf("failed to initialize database schema: %w", err)
	}

	// Run migrations
	if err := backend.runMigrations(); err != nil {
		return nil, fmt.Errorf("failed to run migrations: %w", err)
	}

	return backend, nil
}

// initializeSchema creates the database tables
func (b *Backend) initializeSchema() error {
	queries := []string{
		`CREATE TABLE IF NOT EXISTS files (
			hash TEXT PRIMARY KEY,
			original_name TEXT NOT NULL,
			size INTEGER NOT NULL,
			chunk_count INTEGER NOT NULL,
			content_type TEXT,
			storage_type TEXT DEFAULT 'torrent',
			owner_pubkey TEXT,
			access_level TEXT DEFAULT 'public',
			info_hash TEXT,
			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			access_count INTEGER DEFAULT 0,
			last_access DATETIME DEFAULT CURRENT_TIMESTAMP,
			FOREIGN KEY (owner_pubkey) REFERENCES users(pubkey)
		)`,
		`CREATE TABLE IF NOT EXISTS chunks (
			file_hash TEXT NOT NULL,
			chunk_index INTEGER NOT NULL,
			chunk_hash TEXT NOT NULL,
			size INTEGER NOT NULL,
			offset INTEGER NOT NULL,
			PRIMARY KEY (file_hash, chunk_index),
			FOREIGN KEY (file_hash) REFERENCES files(hash)
		)`,
		`CREATE TABLE IF NOT EXISTS blobs (
			hash TEXT PRIMARY KEY,
			size INTEGER NOT NULL,
			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			mime_type TEXT,
			access_count INTEGER DEFAULT 0,
			last_access DATETIME DEFAULT CURRENT_TIMESTAMP
		)`,
		`CREATE TABLE IF NOT EXISTS users (
			pubkey TEXT PRIMARY KEY,
			display_name TEXT,
			profile_image TEXT,
			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			last_login DATETIME DEFAULT CURRENT_TIMESTAMP,
			storage_used INTEGER DEFAULT 0,
			file_count INTEGER DEFAULT 0
		)`,
		`CREATE TABLE IF NOT EXISTS sessions (
			token TEXT PRIMARY KEY,
			pubkey TEXT NOT NULL,
			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			expires_at DATETIME NOT NULL,
			FOREIGN KEY (pubkey) REFERENCES users(pubkey)
		)`,
		`CREATE TABLE IF NOT EXISTS admin_actions (
			id INTEGER PRIMARY KEY,
			admin_pubkey TEXT NOT NULL,
			action_type TEXT NOT NULL,
			target_id TEXT,
			reason TEXT,
			timestamp DATETIME DEFAULT CURRENT_TIMESTAMP
		)`,
		`CREATE TABLE IF NOT EXISTS banned_users (
			pubkey TEXT PRIMARY KEY,
			banned_by TEXT NOT NULL,
			reason TEXT,
			banned_at DATETIME DEFAULT CURRENT_TIMESTAMP
		)`,
		`CREATE TABLE IF NOT EXISTS content_reports (
			id INTEGER PRIMARY KEY,
			file_hash TEXT NOT NULL,
			reporter_pubkey TEXT,
			reason TEXT,
			status TEXT DEFAULT 'pending',
			created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
			FOREIGN KEY (file_hash) REFERENCES files(hash)
		)`,
		`CREATE INDEX IF NOT EXISTS idx_files_created_at ON files(created_at)`,
		`CREATE INDEX IF NOT EXISTS idx_files_owner_pubkey ON files(owner_pubkey)`,
		`CREATE INDEX IF NOT EXISTS idx_files_storage_type ON files(storage_type)`,
		`CREATE INDEX IF NOT EXISTS idx_files_access_level ON files(access_level)`,
		`CREATE INDEX IF NOT EXISTS idx_files_size ON files(size)`,
		`CREATE INDEX IF NOT EXISTS idx_files_last_access ON files(last_access)`,
		`CREATE INDEX IF NOT EXISTS idx_files_owner_created ON files(owner_pubkey, created_at)`,
		`CREATE INDEX IF NOT EXISTS idx_blobs_created_at ON blobs(created_at)`,
		`CREATE INDEX IF NOT EXISTS idx_blobs_size ON blobs(size)`,
		`CREATE INDEX IF NOT EXISTS idx_blobs_mime_type ON blobs(mime_type)`,
		`CREATE INDEX IF NOT EXISTS idx_chunks_file_hash ON chunks(file_hash)`,
		`CREATE INDEX IF NOT EXISTS idx_chunks_chunk_hash ON chunks(chunk_hash)`,
		`CREATE INDEX IF NOT EXISTS idx_sessions_pubkey ON sessions(pubkey)`,
		`CREATE INDEX IF NOT EXISTS idx_sessions_expires_at ON sessions(expires_at)`,
		`CREATE INDEX IF NOT EXISTS idx_sessions_created_at ON sessions(created_at)`,
		`CREATE INDEX IF NOT EXISTS idx_users_created_at ON users(created_at)`,
		`CREATE INDEX IF NOT EXISTS idx_users_last_login ON users(last_login)`,
		`CREATE INDEX IF NOT EXISTS idx_admin_actions_timestamp ON admin_actions(timestamp)`,
		`CREATE INDEX IF NOT EXISTS idx_admin_actions_admin_pubkey ON admin_actions(admin_pubkey)`,
		`CREATE INDEX IF NOT EXISTS idx_admin_actions_action_type ON admin_actions(action_type)`,
		`CREATE INDEX IF NOT EXISTS idx_banned_users_banned_at ON banned_users(banned_at)`,
		`CREATE INDEX IF NOT EXISTS idx_banned_users_banned_by ON banned_users(banned_by)`,
		`CREATE INDEX IF NOT EXISTS idx_content_reports_status ON content_reports(status)`,
		`CREATE INDEX IF NOT EXISTS idx_content_reports_file_hash ON content_reports(file_hash)`,
		`CREATE INDEX IF NOT EXISTS idx_content_reports_created_at ON content_reports(created_at)`,
	}

	for _, query := range queries {
		if _, err := b.db.Exec(query); err != nil {
			return fmt.Errorf("failed to execute schema query: %w", err)
		}
	}

	// Migration: Add storage_type column if it doesn't exist
	_, err := b.db.Exec(`ALTER TABLE files ADD COLUMN storage_type TEXT DEFAULT 'torrent'`)
	if err != nil && !isColumnExistsError(err) {
		return fmt.Errorf("failed to add storage_type column: %w", err)
	}

	// Migration: Add owner_pubkey column if it doesn't exist
	_, err = b.db.Exec(`ALTER TABLE files ADD COLUMN owner_pubkey TEXT`)
	if err != nil && !isColumnExistsError(err) {
		return fmt.Errorf("failed to add owner_pubkey column: %w", err)
	}

	// Migration: Add access_level column if it doesn't exist
	_, err = b.db.Exec(`ALTER TABLE files ADD COLUMN access_level TEXT DEFAULT 'public'`)
	if err != nil && !isColumnExistsError(err) {
		return fmt.Errorf("failed to add access_level column: %w", err)
	}

	// Migration: Add storage limit fields to users table
	defaultStorageLimit, _ := b.config.GetDefaultUserStorageLimitBytes()
	_, err = b.db.Exec(fmt.Sprintf(`ALTER TABLE users ADD COLUMN storage_limit INTEGER DEFAULT %d`, defaultStorageLimit))
	if err != nil && !isColumnExistsError(err) {
		return fmt.Errorf("failed to add storage_limit column: %w", err)
	}

	_, err = b.db.Exec(`ALTER TABLE users ADD COLUMN account_tier TEXT DEFAULT 'free'`)
	if err != nil && !isColumnExistsError(err) {
		return fmt.Errorf("failed to add account_tier column: %w", err)
	}

	_, err = b.db.Exec(`ALTER TABLE users ADD COLUMN subscription_expires DATETIME`)
	if err != nil && !isColumnExistsError(err) {
		return fmt.Errorf("failed to add subscription_expires column: %w", err)
	}

	// Create indexes for new columns after they've been added
	additionalIndexes := []string{
		`CREATE INDEX IF NOT EXISTS idx_users_storage_used ON users(storage_used)`,
		`CREATE INDEX IF NOT EXISTS idx_users_account_tier ON users(account_tier)`,
	}

	for _, query := range additionalIndexes {
		if _, err := b.db.Exec(query); err != nil {
			// Log but don't fail if index creation fails
			log.Printf("Warning: failed to create index: %v", err)
		}
	}

	return nil
}

// isColumnExistsError checks if the error is due to column already existing
func isColumnExistsError(err error) bool {
	return err != nil && (
		strings.Contains(err.Error(), "duplicate column name") ||
		strings.Contains(err.Error(), "column already exists"))
}

// StoreFile stores a file by splitting it into chunks
func (b *Backend) StoreFile(reader io.Reader, originalName, contentType string) (*FileMetadata, error) {
	return b.StoreFileWithOwner(reader, originalName, contentType, "", "public")
}

// StoreFileWithOwner stores a file with ownership information
func (b *Backend) StoreFileWithOwner(reader io.Reader, originalName, contentType, ownerPubkey, accessLevel string) (*FileMetadata, error) {
	// Create temporary file to calculate hash and size
	tempFile, err := os.CreateTemp("", "upload_*")
	if err != nil {
		return nil, fmt.Errorf("failed to create temp file: %w", err)
	}
	defer os.Remove(tempFile.Name())
	defer tempFile.Close()

	// Copy and hash the entire file
	hasher := sha256.New()
	size, err := io.Copy(io.MultiWriter(tempFile, hasher), reader)
	if err != nil {
		return nil, fmt.Errorf("failed to copy file: %w", err)
	}

	fileHash := hex.EncodeToString(hasher.Sum(nil))

	// Check if file already exists
	if existing, _ := b.GetFileMetadata(fileHash); existing != nil {
		return existing, nil
	}

	// Seek back to beginning for chunking
	if _, err := tempFile.Seek(0, io.SeekStart); err != nil {
		return nil, fmt.Errorf("failed to seek temp file: %w", err)
	}

	// Store chunks
	chunkCount := int((size + b.chunkSize - 1) / b.chunkSize)
	chunks := make([]ChunkInfo, 0, chunkCount)

	for i := 0; i < chunkCount; i++ {
		chunkData := make([]byte, b.chunkSize)
		chunkSize, err := io.ReadFull(tempFile, chunkData)
		if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
			return nil, fmt.Errorf("failed to read chunk %d: %w", i, err)
		}

		// Trim to actual size
		chunkData = chunkData[:chunkSize]

		// Calculate chunk hash
		chunkHasher := sha256.New()
		chunkHasher.Write(chunkData)
		chunkHash := hex.EncodeToString(chunkHasher.Sum(nil))

		// Store chunk to disk
		chunkPath := filepath.Join(b.chunkDir, chunkHash)
		if err := os.WriteFile(chunkPath, chunkData, 0644); err != nil {
			return nil, fmt.Errorf("failed to write chunk %s: %w", chunkHash, err)
		}

		chunk := ChunkInfo{
			FileHash:   fileHash,
			ChunkIndex: i,
			ChunkHash:  chunkHash,
			Size:       int64(chunkSize),
			Offset:     int64(i) * b.chunkSize,
		}
		chunks = append(chunks, chunk)
	}

	// Store metadata in database
	tx, err := b.db.Begin()
	if err != nil {
		return nil, fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	// Insert file metadata
	_, err = tx.Exec(`
		INSERT INTO files (hash, original_name, size, chunk_count, content_type, storage_type, owner_pubkey, access_level)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?)
	`, fileHash, originalName, size, chunkCount, contentType, "torrent", ownerPubkey, accessLevel)
	if err != nil {
		return nil, fmt.Errorf("failed to insert file metadata: %w", err)
	}

	// Insert chunk metadata
	for _, chunk := range chunks {
		_, err = tx.Exec(`
			INSERT INTO chunks (file_hash, chunk_index, chunk_hash, size, offset)
			VALUES (?, ?, ?, ?, ?)
		`, chunk.FileHash, chunk.ChunkIndex, chunk.ChunkHash, chunk.Size, chunk.Offset)
		if err != nil {
			return nil, fmt.Errorf("failed to insert chunk metadata: %w", err)
		}
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("failed to commit transaction: %w", err)
	}

	metadata := &FileMetadata{
		Hash:         fileHash,
		OriginalName: originalName,
		Size:         size,
		ChunkCount:   chunkCount,
		ContentType:  contentType,
		StorageType:  "torrent",
		OwnerPubkey:  ownerPubkey,
		AccessLevel:  accessLevel,
		CreatedAt:    time.Now(),
		AccessCount:  0,
		LastAccess:   time.Now(),
	}

	return metadata, nil
}

// StoreBlobAsFile stores a blob and also records it in files table for unified access
func (b *Backend) StoreBlobAsFile(reader io.Reader, originalName, contentType string) (*FileMetadata, error) {
	return b.StoreBlobAsFileWithOwner(reader, originalName, contentType, "", "public")
}

// StoreBlobAsFileWithOwner stores a blob with ownership information
func (b *Backend) StoreBlobAsFileWithOwner(reader io.Reader, originalName, contentType, ownerPubkey, accessLevel string) (*FileMetadata, error) {
	// Read and hash the blob
	hasher := sha256.New()
	tempFile, err := os.CreateTemp("", "blob_*")
	if err != nil {
		return nil, fmt.Errorf("failed to create temp file: %w", err)
	}
	defer os.Remove(tempFile.Name())
	defer tempFile.Close()

	// Copy and hash the entire file
	size, err := io.Copy(io.MultiWriter(tempFile, hasher), reader)
	if err != nil {
		return nil, fmt.Errorf("failed to copy blob: %w", err)
	}

	blobHash := hex.EncodeToString(hasher.Sum(nil))

	// Check if file already exists
	if existing, _ := b.GetFileMetadata(blobHash); existing != nil {
		return existing, nil
	}

	// Seek back to beginning for storage
	if _, err := tempFile.Seek(0, io.SeekStart); err != nil {
		return nil, fmt.Errorf("failed to seek temp file: %w", err)
	}

	// Store blob to disk
	blobPath := filepath.Join(b.blobDir, blobHash)
	blobFile, err := os.Create(blobPath)
	if err != nil {
		return nil, fmt.Errorf("failed to create blob file: %w", err)
	}
	defer blobFile.Close()

	if _, err := io.Copy(blobFile, tempFile); err != nil {
		os.Remove(blobPath)
		return nil, fmt.Errorf("failed to write blob file: %w", err)
	}

	// Start transaction
	tx, err := b.db.Begin()
	if err != nil {
		return nil, fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	// Insert blob metadata
	_, err = tx.Exec(`
		INSERT INTO blobs (hash, size, mime_type)
		VALUES (?, ?, ?)
	`, blobHash, size, contentType)
	if err != nil {
		return nil, fmt.Errorf("failed to insert blob metadata: %w", err)
	}

	// Insert file metadata for unified access
	_, err = tx.Exec(`
		INSERT INTO files (hash, original_name, size, chunk_count, content_type, storage_type, owner_pubkey, access_level)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?)
	`, blobHash, originalName, size, 1, contentType, "blob", ownerPubkey, accessLevel)
	if err != nil {
		return nil, fmt.Errorf("failed to insert file metadata: %w", err)
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("failed to commit transaction: %w", err)
	}

	metadata := &FileMetadata{
		Hash:         blobHash,
		OriginalName: originalName,
		Size:         size,
		ChunkCount:   1,
		ContentType:  contentType,
		StorageType:  "blob",
		OwnerPubkey:  ownerPubkey,
		AccessLevel:  accessLevel,
		CreatedAt:    time.Now(),
		AccessCount:  0,
		LastAccess:   time.Now(),
	}

	return metadata, nil
}

// GetFileMetadata retrieves metadata for a file
func (b *Backend) GetFileMetadata(hash string) (*FileMetadata, error) {
	var metadata FileMetadata
	err := b.db.QueryRow(`
		SELECT hash, original_name, size, chunk_count, content_type, 
		       COALESCE(storage_type, 'torrent'), COALESCE(owner_pubkey, ''), 
		       COALESCE(access_level, 'public'), created_at, access_count, last_access
		FROM files WHERE hash = ?
	`, hash).Scan(
		&metadata.Hash, &metadata.OriginalName, &metadata.Size,
		&metadata.ChunkCount, &metadata.ContentType, &metadata.StorageType,
		&metadata.OwnerPubkey, &metadata.AccessLevel, &metadata.CreatedAt, 
		&metadata.AccessCount, &metadata.LastAccess,
	)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, nil
		}
		return nil, fmt.Errorf("failed to get file metadata: %w", err)
	}

	return &metadata, nil
}

// GetFileChunks retrieves all chunks for a file
func (b *Backend) GetFileChunks(fileHash string) ([]ChunkInfo, error) {
	rows, err := b.db.Query(`
		SELECT file_hash, chunk_index, chunk_hash, size, offset
		FROM chunks WHERE file_hash = ? ORDER BY chunk_index
	`, fileHash)
	if err != nil {
		return nil, fmt.Errorf("failed to query chunks: %w", err)
	}
	defer rows.Close()

	var chunks []ChunkInfo
	for rows.Next() {
		var chunk ChunkInfo
		if err := rows.Scan(&chunk.FileHash, &chunk.ChunkIndex, &chunk.ChunkHash, &chunk.Size, &chunk.Offset); err != nil {
			return nil, fmt.Errorf("failed to scan chunk: %w", err)
		}
		chunks = append(chunks, chunk)
	}

	return chunks, nil
}

// GetChunkData retrieves raw data for a specific chunk
func (b *Backend) GetChunkData(chunkHash string) ([]byte, error) {
	chunkPath := filepath.Join(b.chunkDir, chunkHash)
	data, err := os.ReadFile(chunkPath)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil
		}
		return nil, fmt.Errorf("failed to read chunk %s: %w", chunkHash, err)
	}
	return data, nil
}

// AssembleFile reassembles a complete file from its chunks
func (b *Backend) AssembleFile(fileHash string, writer io.Writer) error {
	chunks, err := b.GetFileChunks(fileHash)
	if err != nil {
		return fmt.Errorf("failed to get chunks: %w", err)
	}

	for _, chunk := range chunks {
		chunkData, err := b.GetChunkData(chunk.ChunkHash)
		if err != nil {
			return fmt.Errorf("failed to get chunk data: %w", err)
		}
		if chunkData == nil {
			return fmt.Errorf("chunk %s not found", chunk.ChunkHash)
		}

		if _, err := writer.Write(chunkData); err != nil {
			return fmt.Errorf("failed to write chunk: %w", err)
		}
	}

	// Update access statistics
	_, err = b.db.Exec(`
		UPDATE files SET access_count = access_count + 1, last_access = CURRENT_TIMESTAMP
		WHERE hash = ?
	`, fileHash)
	if err != nil {
		// Log but don't fail on stats update
		fmt.Printf("Warning: failed to update access stats for %s: %v\n", fileHash, err)
	}

	return nil
}

// StoreBlob stores a Blossom blob
func (b *Backend) StoreBlob(reader io.Reader, mimeType string) (string, error) {
	// Read and hash the blob
	hasher := sha256.New()
	tempFile, err := os.CreateTemp("", "blob_*")
	if err != nil {
		return "", fmt.Errorf("failed to create temp file: %w", err)
	}
	defer os.Remove(tempFile.Name())
	defer tempFile.Close()

	size, err := io.Copy(io.MultiWriter(tempFile, hasher), reader)
	if err != nil {
		return "", fmt.Errorf("failed to copy blob: %w", err)
	}

	blobHash := hex.EncodeToString(hasher.Sum(nil))
	blobPath := filepath.Join(b.blobDir, blobHash)

	// Check if blob already exists
	if _, err := os.Stat(blobPath); err == nil {
		return blobHash, nil
	}

	// Move temp file to blob location
	if _, err := tempFile.Seek(0, io.SeekStart); err != nil {
		return "", fmt.Errorf("failed to seek temp file: %w", err)
	}

	blobFile, err := os.Create(blobPath)
	if err != nil {
		return "", fmt.Errorf("failed to create blob file: %w", err)
	}
	defer blobFile.Close()

	if _, err := io.Copy(blobFile, tempFile); err != nil {
		os.Remove(blobPath)
		return "", fmt.Errorf("failed to copy to blob file: %w", err)
	}

	// Store blob metadata
	_, err = b.db.Exec(`
		INSERT OR REPLACE INTO blobs (hash, size, mime_type)
		VALUES (?, ?, ?)
	`, blobHash, size, mimeType)
	if err != nil {
		os.Remove(blobPath)
		return "", fmt.Errorf("failed to store blob metadata: %w", err)
	}

	return blobHash, nil
}

// GetBlobData retrieves blob data
func (b *Backend) GetBlobData(blobHash string) (io.ReadCloser, *BlobInfo, error) {
	// Get blob metadata
	var info BlobInfo
	err := b.db.QueryRow(`
		SELECT hash, size, created_at, mime_type
		FROM blobs WHERE hash = ?
	`, blobHash).Scan(&info.Hash, &info.Size, &info.CreatedAt, &info.MimeType)
	if err != nil {
		if err == sql.ErrNoRows {
			return nil, nil, nil
		}
		return nil, nil, fmt.Errorf("failed to get blob metadata: %w", err)
	}

	// Open blob file
	blobPath := filepath.Join(b.blobDir, blobHash)
	file, err := os.Open(blobPath)
	if err != nil {
		if os.IsNotExist(err) {
			return nil, nil, nil
		}
		return nil, nil, fmt.Errorf("failed to open blob file: %w", err)
	}

	// Update access statistics
	_, err = b.db.Exec(`
		UPDATE blobs SET access_count = access_count + 1, last_access = CURRENT_TIMESTAMP
		WHERE hash = ?
	`, blobHash)
	if err != nil {
		// Log but don't fail on stats update
		fmt.Printf("Warning: failed to update blob access stats for %s: %v\n", blobHash, err)
	}

	return file, &info, nil
}

// GetChunkHashes retrieves all chunk hashes for a file in order
func (b *Backend) GetChunkHashes(fileHash string) ([]string, error) {
	rows, err := b.db.Query(`
		SELECT chunk_hash 
		FROM chunks 
		WHERE file_hash = ? 
		ORDER BY chunk_index
	`, fileHash)
	if err != nil {
		return nil, fmt.Errorf("failed to query chunks: %w", err)
	}
	defer rows.Close()

	var chunkHashes []string
	for rows.Next() {
		var chunkHash string
		if err := rows.Scan(&chunkHash); err != nil {
			return nil, fmt.Errorf("failed to scan chunk hash: %w", err)
		}
		chunkHashes = append(chunkHashes, chunkHash)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating chunks: %w", err)
	}

	return chunkHashes, nil
}

// GetUserFiles retrieves all files owned by a user
func (b *Backend) GetUserFiles(pubkey string) ([]*FileMetadata, error) {
	rows, err := b.db.Query(`
		SELECT hash, original_name, size, chunk_count, content_type, 
		       COALESCE(storage_type, 'torrent'), COALESCE(owner_pubkey, ''), 
		       COALESCE(access_level, 'public'), created_at, access_count, last_access
		FROM files 
		WHERE owner_pubkey = ?
		ORDER BY created_at DESC
	`, pubkey)
	if err != nil {
		return nil, fmt.Errorf("failed to query user files: %w", err)
	}
	defer rows.Close()

	var files []*FileMetadata
	for rows.Next() {
		var metadata FileMetadata
		err := rows.Scan(
			&metadata.Hash, &metadata.OriginalName, &metadata.Size,
			&metadata.ChunkCount, &metadata.ContentType, &metadata.StorageType,
			&metadata.OwnerPubkey, &metadata.AccessLevel, &metadata.CreatedAt,
			&metadata.AccessCount, &metadata.LastAccess,
		)
		if err != nil {
			return nil, fmt.Errorf("failed to scan file metadata: %w", err)
		}
		files = append(files, &metadata)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating files: %w", err)
	}

	return files, nil
}

// GetPublicFiles returns all public files in the system
func (b *Backend) GetPublicFiles() ([]*FileMetadata, error) {
	rows, err := b.db.Query(`
		SELECT hash, original_name, size, chunk_count, content_type, 
		       COALESCE(storage_type, 'torrent'), COALESCE(owner_pubkey, ''), 
		       COALESCE(access_level, 'public'), COALESCE(info_hash, ''),
		       created_at, access_count, last_access
		FROM files 
		WHERE access_level = 'public'
		ORDER BY created_at DESC
	`)
	if err != nil {
		return nil, fmt.Errorf("failed to query public files: %w", err)
	}
	defer rows.Close()

	var files []*FileMetadata
	for rows.Next() {
		var metadata FileMetadata
		err := rows.Scan(
			&metadata.Hash, &metadata.OriginalName, &metadata.Size,
			&metadata.ChunkCount, &metadata.ContentType, &metadata.StorageType,
			&metadata.OwnerPubkey, &metadata.AccessLevel, &metadata.InfoHash,
			&metadata.CreatedAt, &metadata.AccessCount, &metadata.LastAccess,
		)
		if err != nil {
			return nil, fmt.Errorf("failed to scan file metadata: %w", err)
		}
		files = append(files, &metadata)
	}

	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("error iterating over public files: %w", err)
	}

	return files, nil
}

// GetUserStats calculates storage statistics for a user
func (b *Backend) GetUserStats(pubkey string) (int64, int, error) {
	var storageUsed int64
	var fileCount int

	err := b.db.QueryRow(`
		SELECT COALESCE(SUM(size), 0), COUNT(*)
		FROM files 
		WHERE owner_pubkey = ?
	`, pubkey).Scan(&storageUsed, &fileCount)
	if err != nil {
		return 0, 0, fmt.Errorf("failed to get user stats: %w", err)
	}

	return storageUsed, fileCount, nil
}

// DeleteUserFile deletes a file owned by a user
func (b *Backend) DeleteUserFile(hash, ownerPubkey string) error {
	// Verify ownership
	metadata, err := b.GetFileMetadata(hash)
	if err != nil {
		return fmt.Errorf("failed to get file metadata: %w", err)
	}
	if metadata == nil {
		return fmt.Errorf("file not found")
	}
	if metadata.OwnerPubkey != ownerPubkey {
		return fmt.Errorf("permission denied: not file owner")
	}

	// Start transaction
	tx, err := b.db.Begin()
	if err != nil {
		return fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	// Delete chunks if it's a torrent file
	if metadata.StorageType == "torrent" {
		// Get chunk hashes for deletion
		chunkHashes, err := b.GetChunkHashes(hash)
		if err != nil {
			return fmt.Errorf("failed to get chunk hashes: %w", err)
		}

		// Delete chunk files
		for _, chunkHash := range chunkHashes {
			chunkPath := filepath.Join(b.chunkDir, chunkHash)
			if err := os.Remove(chunkPath); err != nil && !os.IsNotExist(err) {
				log.Printf("Warning: failed to delete chunk file %s: %v", chunkHash, err)
			}
		}

		// Delete chunk metadata
		_, err = tx.Exec(`DELETE FROM chunks WHERE file_hash = ?`, hash)
		if err != nil {
			return fmt.Errorf("failed to delete chunk metadata: %w", err)
		}
	}

	// Delete blob file if it's a blob
	if metadata.StorageType == "blob" {
		blobPath := filepath.Join(b.blobDir, hash)
		if err := os.Remove(blobPath); err != nil && !os.IsNotExist(err) {
			log.Printf("Warning: failed to delete blob file %s: %v", hash, err)
		}

		// Delete blob metadata
		_, err = tx.Exec(`DELETE FROM blobs WHERE hash = ?`, hash)
		if err != nil {
			return fmt.Errorf("failed to delete blob metadata: %w", err)
		}
	}

	// Delete file metadata
	_, err = tx.Exec(`DELETE FROM files WHERE hash = ?`, hash)
	if err != nil {
		return fmt.Errorf("failed to delete file metadata: %w", err)
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}

	return nil
}

// AdminDeleteFile allows admin to delete any file without ownership check
func (b *Backend) AdminDeleteFile(hash string) error {
	// Get file metadata
	metadata, err := b.GetFileMetadata(hash)
	if err != nil {
		return fmt.Errorf("failed to get file metadata: %w", err)
	}
	if metadata == nil {
		return fmt.Errorf("file not found")
	}

	// Start transaction
	tx, err := b.db.Begin()
	if err != nil {
		return fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	// Delete chunks if it's a torrent file
	if metadata.StorageType == "torrent" {
		// Get chunk hashes for deletion
		chunkHashes, err := b.GetChunkHashes(hash)
		if err != nil {
			return fmt.Errorf("failed to get chunk hashes: %w", err)
		}

		// Delete chunk files
		for _, chunkHash := range chunkHashes {
			chunkPath := filepath.Join(b.chunkDir, chunkHash)
			if err := os.Remove(chunkPath); err != nil && !os.IsNotExist(err) {
				log.Printf("Warning: failed to delete chunk file %s: %v", chunkHash, err)
			}
		}

		// Delete chunk metadata
		_, err = tx.Exec(`DELETE FROM chunks WHERE file_hash = ?`, hash)
		if err != nil {
			return fmt.Errorf("failed to delete chunk metadata: %w", err)
		}
	} else if metadata.StorageType == "blob" {
		// Delete blob file
		blobPath := filepath.Join(b.blobDir, hash)
		if err := os.Remove(blobPath); err != nil && !os.IsNotExist(err) {
			log.Printf("Warning: failed to delete blob file %s: %v", hash, err)
		}

		// Delete blob metadata
		_, err = tx.Exec(`DELETE FROM blobs WHERE hash = ?`, hash)
		if err != nil {
			return fmt.Errorf("failed to delete blob metadata: %w", err)
		}
	}

	// Delete content reports
	_, err = tx.Exec(`DELETE FROM content_reports WHERE file_hash = ?`, hash)
	if err != nil {
		return fmt.Errorf("failed to delete content reports: %w", err)
	}

	// Delete file metadata
	_, err = tx.Exec(`DELETE FROM files WHERE hash = ?`, hash)
	if err != nil {
		return fmt.Errorf("failed to delete file metadata: %w", err)
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}

	return nil
}

// UpdateFileAccess updates the access level of a file
func (b *Backend) UpdateFileAccess(hash, ownerPubkey, accessLevel string) error {
	// Verify ownership
	metadata, err := b.GetFileMetadata(hash)
	if err != nil {
		return fmt.Errorf("failed to get file metadata: %w", err)
	}
	if metadata == nil {
		return fmt.Errorf("file not found")
	}
	if metadata.OwnerPubkey != ownerPubkey {
		return fmt.Errorf("permission denied: not file owner")
	}

	// Update access level
	_, err = b.db.Exec(`UPDATE files SET access_level = ? WHERE hash = ?`, accessLevel, hash)
	if err != nil {
		return fmt.Errorf("failed to update file access level: %w", err)
	}

	return nil
}

// CheckFileAccess checks if a user can access a file based on access level
func (b *Backend) CheckFileAccess(hash, requestorPubkey string) (bool, error) {
	metadata, err := b.GetFileMetadata(hash)
	if err != nil {
		return false, fmt.Errorf("failed to get file metadata: %w", err)
	}
	if metadata == nil {
		return false, nil
	}

	switch metadata.AccessLevel {
	case "public":
		return true, nil
	case "private":
		return metadata.OwnerPubkey == requestorPubkey, nil
	case "followers":
		// TODO: Implement follower checking via Nostr social graph
		// For now, treat as private
		return metadata.OwnerPubkey == requestorPubkey, nil
	default:
		return false, nil
	}
}

// GetDB returns the database connection for auth module
func (b *Backend) GetDB() *sql.DB {
	return b.db
}

// Close closes the storage backend
func (b *Backend) Close() error {
	if b.db != nil {
		return b.db.Close()
	}
	return nil
}

// FileExistsByInfoHash checks if a file exists by its BitTorrent info hash
func (b *Backend) FileExistsByInfoHash(infoHash string) (bool, error) {
	var count int
	err := b.db.QueryRow(`
		SELECT COUNT(*) FROM files WHERE info_hash = ?
	`, infoHash).Scan(&count)
	
	if err != nil {
		return false, err
	}
	
	return count > 0, nil
}

// GetFileHashByInfoHash returns the file hash for a given info hash
func (b *Backend) GetFileHashByInfoHash(infoHash string) (string, error) {
	var fileHash string
	err := b.db.QueryRow(`
		SELECT hash FROM files WHERE info_hash = ?
	`, infoHash).Scan(&fileHash)
	
	if err != nil {
		return "", err
	}
	
	return fileHash, nil
}

// UpdateFileInfoHash updates the info_hash for a file
func (b *Backend) UpdateFileInfoHash(fileHash, infoHash string) error {
	_, err := b.db.Exec(`
		UPDATE files SET info_hash = ? WHERE hash = ?
	`, infoHash, fileHash)
	
	if err != nil {
		return fmt.Errorf("failed to update info_hash: %w", err)
	}
	
	return nil
}

// StoreNostrEvents stores Nostr event IDs for a file
func (b *Backend) StoreNostrEvents(fileHash, nip71EventID, nip35EventID string) error {
	_, err := b.db.Exec(`
		UPDATE files SET nip71_event_id = ?, nip35_event_id = ? WHERE hash = ?
	`, nip71EventID, nip35EventID, fileHash)
	
	if err != nil {
		return fmt.Errorf("failed to store nostr event IDs: %w", err)
	}
	
	return nil
}

// GetNostrEvents retrieves Nostr event IDs for a file
func (b *Backend) GetNostrEvents(fileHash string) (nip71EventID, nip35EventID string, err error) {
	err = b.db.QueryRow(`
		SELECT COALESCE(nip71_event_id, ''), COALESCE(nip35_event_id, '') FROM files WHERE hash = ?
	`, fileHash).Scan(&nip71EventID, &nip35EventID)
	
	if err != nil {
		return "", "", fmt.Errorf("failed to get nostr event IDs: %w", err)
	}
	
	return nip71EventID, nip35EventID, nil
}

// runMigrations applies database schema migrations
func (b *Backend) runMigrations() error {
	// Check if info_hash column exists
	var columnExists bool
	err := b.db.QueryRow(`
		SELECT COUNT(*) > 0 FROM pragma_table_info('files') WHERE name = 'info_hash'
	`).Scan(&columnExists)
	
	if err != nil {
		return fmt.Errorf("failed to check info_hash column: %w", err)
	}
	
	// Add info_hash column if it doesn't exist
	if !columnExists {
		_, err = b.db.Exec(`ALTER TABLE files ADD COLUMN info_hash TEXT`)
		if err != nil {
			return fmt.Errorf("failed to add info_hash column: %w", err)
		}
		log.Printf("Added info_hash column to files table")
	}

	// Check if nostr event ID columns exist
	var nip71ColumnExists, nip35ColumnExists bool
	err = b.db.QueryRow(`
		SELECT COUNT(*) > 0 FROM pragma_table_info('files') WHERE name = 'nip71_event_id'
	`).Scan(&nip71ColumnExists)
	if err != nil {
		return fmt.Errorf("failed to check nip71_event_id column: %w", err)
	}

	err = b.db.QueryRow(`
		SELECT COUNT(*) > 0 FROM pragma_table_info('files') WHERE name = 'nip35_event_id'
	`).Scan(&nip35ColumnExists)
	if err != nil {
		return fmt.Errorf("failed to check nip35_event_id column: %w", err)
	}

	// Add nostr event ID columns if they don't exist
	if !nip71ColumnExists {
		_, err = b.db.Exec(`ALTER TABLE files ADD COLUMN nip71_event_id TEXT`)
		if err != nil {
			return fmt.Errorf("failed to add nip71_event_id column: %w", err)
		}
		log.Printf("Added nip71_event_id column to files table")
	}

	if !nip35ColumnExists {
		_, err = b.db.Exec(`ALTER TABLE files ADD COLUMN nip35_event_id TEXT`)
		if err != nil {
			return fmt.Errorf("failed to add nip35_event_id column: %w", err)
		}
		log.Printf("Added nip35_event_id column to files table")
	}
	
	return nil
}