import { Prisma } from '../../generated/prisma';
import { PrismaService } from './prisma.service';

/**
 * The root client or the client of an interactive transaction, for helpers
 * that work on either (e.g. notifyWorker). A helper that must run inside the
 * caller's business transaction takes Prisma.TransactionClient instead and
 * checks it with assertTransactionClient.
 */
export type DbClient = PrismaService | Prisma.TransactionClient;

/**
 * Throws if `db` is the root client: a write through it would commit on its
 * own, even if the caller's business transaction rolls back. `$connect` is
 * withheld from transaction clients; `$transaction` does not tell the two
 * apart, because a Prisma 7 transaction client can open nested transactions.
 * `caller` names the method in the error, e.g. "DomainEventsService.recordAll".
 */
export function assertTransactionClient(db: DbClient, caller: string): void {
  if ('$connect' in db) {
    throw new Error(`${caller} needs the transaction client`);
  }
}