package ixee.cryptopals.utils

import ixee.cryptopals.utils.crypto._
import ixee.cryptopals.utils.StreamUtils._
import ixee.cryptopals.utils.FunctionUtils._
import javax.crypto.Cipher
import javax.crypto.spec.SecretKeySpec

object CryptoUtils {

  def pkcs7pad(s: Seq[Byte], blockSize: Int): Seq[Byte] = {
    val padLength = blockSize - (s.length % blockSize)
    s ++ Stream.continually(padLength.toByte).take(padLength)
  }

  def stripPkcs7Pad(s: Seq[Byte]): Seq[Byte] =
    s.dropRight(s.last)

  def cbcEncrypt(builder: CbcBuilder)(data: Seq[Byte]) =
    builder.encrypt.end(data)

  def cbcDecrypt(builder: CbcBuilder)(data: Seq[Byte]) =
    stripPkcs7Pad(builder.decrypt.end(data))

  def ecbEncrypt(builder: EcbBuilder)(data: Seq[Byte]) =
    builder.encrypt.end(data)

  def ecbDecrypt(builder: EcbBuilder)(data: Seq[Byte]) =
    stripPkcs7Pad(builder.decrypt.end(data))

  def detectMode(xs: Seq[Byte]): String = {
    def dupBlocks(xs: Seq[Seq[Byte]]) =
      pairsOf(xs).map(tup(_ == _)).count(_ == true)

    def countDupBlocks(xs: Seq[Byte]): Int =
      dupBlocks(xs.grouped(16).toSeq.init.toStream)

                              //.... well very probably.
    if (countDupBlocks(xs) > 0) "ECB"
    else "CBC"

  }

}