// Web Streams API types are now available globally via DOM types in tsconfig

class TypeTransformer<I, O> implements Transformer<I, O> {
  private buffer?: O[];
  private doneCallback?: (args0: readonly O[]) => Promise<void>;
  private transformFn: (arg0: I) => O;

  constructor(
    transformFn: (arg0: I) => O,
    doneCallback?: (args0: readonly O[]) => Promise<void>
  ) {
    this.transformFn = transformFn;
    this.doneCallback = doneCallback;
    this.buffer = doneCallback ? [] : undefined;
  }

  async transform(obj: I, controller: TransformStreamDefaultController<O>) {
    const val = this.transformFn(obj);
    if (val) {
      controller.enqueue(val);
      this.buffer?.push(val);
    }
  }

  async flush(controller: TransformStreamDefaultController<O>) {
    await this.doneCallback?.(this.buffer ?? []);
    controller.terminate();
  }
}

export class RespTransformStream<I, O> extends TransformStream<I, O> {
  constructor(
    transformFn: (arg0: I) => O,
    doneCallback?: (args0: readonly O[]) => Promise<void>
  ) {
    super(new TypeTransformer<I, O>(transformFn, doneCallback));
  }
}