import std/sequtils

import pkg/chronos

import pkg/codex/chunker
import pkg/codex/rng

export chunker

type
  RandomChunker* = Chunker

proc new*(
    T: type RandomChunker,
    rng: Rng,
    chunkSize: int | NBytes,
    size: int | NBytes,
    pad = false
): RandomChunker =
  ## Create a chunker that produces random data
  ##

  let
    size = size.int
    chunkSize = chunkSize.NBytes
  
  var consumed = 0
  proc reader(data: ChunkBuffer, len: int): Future[int]
    {.async, gcsafe, raises: [Defect].} =
    var alpha = toSeq(byte('A')..byte('z'))

    if consumed >= size:
      return 0

    var read = 0
    while read < len:
      rng.shuffle(alpha)
      for a in alpha:
        if read >= len:
          break

        data[read] = a
        read.inc

    consumed += read
    return read

  Chunker.new(
    reader = reader,
    pad = pad,
    chunkSize = chunkSize)