import scala.util.Random

object Vinger {
  def main(args: Array[String]) {
    println(Cipher.encrypt("TO JEST BARDZO TAJNY TEKST"))
  }
  object Cipher {
    val EMPTY = "";
    val LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    private def encryptWithFullKey(text: String, key: String): String =
      if(key.length < text.length) throw new Error("Key is too short") else{
      def encryptAcc(acc: String): String = if (acc.length() < text.length()) {
        val offset = acc.length
        if (LETTERS contains (text(offset))) {
          val keyOffset = LETTERS indexOf key(offset)
          val letterOffset = LETTERS indexOf text(offset)
          val finalOffset = (letterOffset + keyOffset) % LETTERS.size
          encryptAcc(acc + LETTERS(finalOffset))
        } else encryptAcc(acc + text(offset))
      } else acc;
      encryptAcc(EMPTY)
    }

    def encrypt(text: String, key: String): String = if(key.length < text.length) {
      var finalKey = key;
      val times = (text.length.toDouble / key.length).toInt + 1
      for(a <- 0 to times) {finalKey = finalKey + key}
      encryptWithFullKey(text, finalKey.substring(0, text.length))
    }else encryptWithFullKey(text, key)

    def encrypt(text: String): (String, String) = {
      val key = text.map(_ => LETTERS.charAt(Random.nextInt(LETTERS.length)))
      return (encryptWithFullKey(text, key), key)
    }

  }

}