use Carp;
use Compress::Zlib;
use constant SHORT_TEXT => 50;

# This takes text that might or might not be encrypted and
# returns it decrypted.  Assumes that the text was produced
# by a human or get_encrypted_code, and that decrypt will
# reverse encrypt.
sub get_decrypted_code {
  my ($text, @pass_through) = @_;
  (length($text) < SHORT_TEXT or text_is_normal($text))
    ? $text
    : decrypt($text, @pass_through);
}

# This takes text that might or might not be encrypted and
# returns it encrypted.  Assumes that encrypt() does
# not compress text and the text was produced by
# get_encrypted_code if it is encrypted.
sub get_encrypted_code {
  my ($text, @pass_through) = @_;
  if (length($text) < SHORT_TEXT) {
    # Need to encrypt equivalent but longer text to be
    # sure our test works later.
    return encrypt(("#\n" x SHORT_TEXT) . $text, @pass_through);
  }
  elsif (text_is_normal($text)) {
    return encrypt($text, @pass_through);
  }
  else {
    return $text;
  }
}

# Here is the test function.  It takes a string and returns
# whether or not it looks like it probably is
# human-generated text.  It is a fatal error if the text
# is too short to tell.
sub text_is_normal {
  my $text = shift;
  length($text) < SHORT_TEXT
    ? confess("Too little text for a reliable test")
    : (length(compress($text)) < 0.8*length($text));
}