package storage

import (
	"database/sql"
	"fmt"
	"strings"
)

// SnapshotTo writes a consistent point-in-time copy of the database to destPath
// using SQLite's VACUUM INTO (never touching/locking the live file). When
// includeBlobs is false, the image_data blobs are stripped from the copy,
// leaving only metadata — which is ~99% smaller.
//
// destPath must not already exist (VACUUM INTO requires this).
func (s *Store) SnapshotTo(destPath string, includeBlobs bool) error {
	if _, err := s.db.Exec(`VACUUM INTO '` + escapeSQLiteString(destPath) + `'`); err != nil {
		return fmt.Errorf("vacuum into snapshot: %w", err)
	}
	if includeBlobs {
		return nil
	}

	// Strip blobs from the copy only. image_data is NOT NULL, so use an empty blob.
	// Both receipts and their attachments carry blobs.
	snap, err := sql.Open("sqlite", destPath)
	if err != nil {
		return fmt.Errorf("open snapshot: %w", err)
	}
	defer snap.Close()
	for _, table := range []string{"receipts", "attachments"} {
		if _, err := snap.Exec(`UPDATE ` + table + ` SET image_data = X''`); err != nil {
			return fmt.Errorf("strip %s blobs: %w", table, err)
		}
	}
	if _, err := snap.Exec(`VACUUM`); err != nil {
		return fmt.Errorf("vacuum stripped snapshot: %w", err)
	}
	return nil
}

// escapeSQLiteString escapes a string for use inside single quotes in SQL.
func escapeSQLiteString(s string) string {
	return strings.ReplaceAll(s, "'", "''")
}