WTF am I doing

MaybeUnzipGzipTransformer.ts

type U8Arr = Uint8Array<ArrayBuffer>

class MaybeUnzipGzipTransformer implements Transformer<U8Arr, U8Arr> {
  nbytes = 0
  isGzip: boolean | null = null
  static expectedHeader = new Uint8Array([0x1f, 0x8b, 0x08])
  sink: WritableStreamDefaultWriter<U8Arr> | undefined

  transform(chunk: U8Arr, controller: TransformStreamDefaultController<U8Arr>) {
    if (this.isGzip == null) {
      let i = 0
      while (this.nbytes < 3 && i < chunk.length) {
        if (MaybeUnzipGzipTransformer.expectedHeader[this.nbytes] != chunk[i]) {
          this.isGzip = false
          break
        }
        this.nbytes++
        i++
      }

      if (this.nbytes >= 3) {
        this.isGzip = true
        const ds = new DecompressionStream('gzip')
        this.sink = ds.writable.getWriter()
        this.sink.write(MaybeUnzipGzipTransformer.expectedHeader)
        this.sink.write(chunk.subarray(i))
        ;(async () => {
          const reader = ds.readable.getReader()
          while (true) {
            const data = await reader.read()
            if (data.done) break
            controller.enqueue(data.value)
          }
        })
      } else if (this.isGzip === false) {
        controller.enqueue(MaybeUnzipGzipTransformer.expectedHeader.subarray(0, this.nbytes))
        controller.enqueue(chunk.subarray(i))
      }
    } else if (this.isGzip) {
      this.sink!.write(chunk)
    } else {
      controller.enqueue(chunk)
    }
  }
}