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

export interface TextDecoderCommon {
  readonly encoding: string;
  readonly fatal: boolean;
  readonly ignoreBOM: boolean;
}

class TextDecodeTransformer
  implements Transformer<ArrayBuffer | Uint8Array, string>
{
  private decoder;

  constructor() {
    this.decoder = new TextDecoder();
  }

  transform(
    chunk: ArrayBuffer | Uint8Array,
    controller: TransformStreamDefaultController<string>
  ) {
    if (!(chunk instanceof ArrayBuffer || ArrayBuffer.isView(chunk))) {
      throw new TypeError('Input data must be a BufferSource');
    }
    const text = this.decoder.decode(chunk, { stream: true });
    if (text.length !== 0) {
      controller.enqueue(text);
    }
  }

  flush(controller: TransformStreamDefaultController<string>) {
    const text = this.decoder.decode();
    if (text.length !== 0) {
      controller.enqueue(text);
    }
  }
}

export class TextDecoderStreamPolyfill extends TransformStream<
  ArrayBuffer | Uint8Array,
  string
> {
  constructor() {
    super(new TextDecodeTransformer());
  }
}