{ config, lib, ... }: {

  options = {

    backup.s3 = {
      endpoint = lib.mkOption {
        type = lib.types.nullOr lib.types.str;
        description = "S3 endpoint for backups";
        default = null;
      };
      bucket = lib.mkOption {
        type = lib.types.nullOr lib.types.str;
        description = "S3 bucket for backups";
        default = null;
      };
      accessKeyId = lib.mkOption {
        type = lib.types.nullOr lib.types.str;
        description = "S3 access key ID for backups";
        default = null;
      };
    };

  };

  config = lib.mkIf (config.backup.s3.endpoint != null) {

    users.groups.backup = { };

    secrets.backup = {
      source = ../../private/backup.age;
      dest = "${config.secretsDirectory}/backup";
      group = "backup";
      permissions = "0440";
    };

    users.users.litestream.extraGroups = [ "backup" ];

    services.litestream = {
      enable = true;
      environmentFile = config.secrets.backup.dest;
    };

    # Wait for secret to exist
    systemd.services.litestream = {
      after = [ "backup-secret.service" ];
      requires = [ "backup-secret.service" ];
      environment.AWS_ACCESS_KEY_ID = config.backup.s3.accessKeyId;
    };

    # # Backup library to object storage
    # services.restic.backups.calibre = {
    #   user = "calibre-web";
    #   repository =
    #     "s3://${config.backup.s3.endpoint}/${config.backup.s3.bucket}/calibre";
    #   paths = [
    #     "/var/books"
    #     "/var/lib/calibre-web/app.db"
    #     "/var/lib/calibre-web/gdrive.db"
    #   ];
    #   initialize = true;
    #   timerConfig = { OnCalendar = "00:05:00"; };
    #   environmentFile = backup.s3File;
    # };

  };

}