class MailDeliverError extends Error {
  constructor(
    message: string,
    options: ErrorOptions,
    public readonly rawMail: string,
  ) {
    super(message, options);
  }
}

export class MailDeliverContext {
  constructor(public rawMail: string) {}
}

type MailDeliverHook<Context> = (context: Context) => Promise<void>;

export abstract class MailDeliverer<out TContext extends MailDeliverContext = MailDeliverContext> {
  preHooks: MailDeliverHook<MailDeliverContext>[] = [];
  postHooks: MailDeliverHook<MailDeliverContext>[] = [];

  constructor(public readonly destination: string) {}

  protected abstract doPrepare(rawMail: string): Promise<TContext>;
  protected abstract doDeliver(context: TContext): Promise<void>;

  async deliver(rawMail: string): Promise<void> {
    const context = await this.doPrepare(rawMail);

    for (const hook of this.preHooks) {
      await hook(context);
    }

    await this.doDeliver(context);

    for (const hook of this.postHooks) {
      await hook(context);
    }
  }

  protected throwError(
    reason: string,
    rawMail: string,
    cause?: unknown,
  ): never {
    throw new MailDeliverError(
      `Failed to deliver mail to ${this.destination}: ${reason}`,
      { cause },
      rawMail,
    );
  }
}