chapter-organizer/WebApp/Services/DatabaseBackupService.cs

using Data;
using Microsoft.EntityFrameworkCore;

namespace WebApp.Services;

/// <summary>
/// Creates SQLite database backups via VACUUM INTO.
/// </summary>
public class DatabaseBackupService : IDatabaseBackupService
{
    private readonly AppDbContext _context;
    private readonly IWebHostEnvironment _environment;
    private readonly ILogger<DatabaseBackupService> _logger;

    public DatabaseBackupService(
        AppDbContext context,
        IWebHostEnvironment environment,
        ILogger<DatabaseBackupService> logger)
    {
        _context = context;
        _environment = environment;
        _logger = logger;
    }

    public async Task<string> CreatePreRolloverBackupAsync(CancellationToken cancellationToken = default)
    {
        var backupsDir = Path.Combine(_environment.ContentRootPath, "Data", "backups");
        Directory.CreateDirectory(backupsDir);

        var fileName = $"pre-rollover-{DateTime.Now:yyyyMMdd-HHmmss}.db";
        var backupPath = Path.Combine(backupsDir, fileName);

        // Path is server-generated (never user input); escape single quotes for SQLite string literal.
        var escapedPath = backupPath.Replace("'", "''", StringComparison.Ordinal);
#pragma warning disable EF1002 // Path is fully server-controlled; VACUUM INTO cannot use parameters.
        await _context.Database.ExecuteSqlRawAsync($"VACUUM INTO '{escapedPath}'", cancellationToken);
#pragma warning restore EF1002

        if (!File.Exists(backupPath))
        {
            throw new InvalidOperationException(
                $"Database backup was requested but the file was not created at '{backupPath}'.");
        }

        _logger.LogInformation("Created pre-rollover database backup at {BackupPath}", backupPath);
        return backupPath;
    }
}