package Crypto;

use strict;
use warnings;
use POSIX qw(fmod ceil);

sub new {
    my ($class, $plaintext) = @_;
    return bless { plaintext => $plaintext } => $class;
}

sub normalize_plaintext {
    my $self = shift;
    my $normalized = lc $self->{plaintext}; 
    $normalized =~ s/[^0-9a-zA-Z]//g;

    return $normalized;
}

sub size {
    my $self = shift;
    my $size = @_ > 0 ? sqrt(length $_[0]) : sqrt(length $self->normalize_plaintext);

    return  int($size) if fmod($size, 1) == 0;
    return ceil($size);
}

sub normalize_ciphertext {
    my $self = shift;
    join ' ', $self->_columns;
}

sub ciphertext {
    my $self = shift;
    join '', $self->_columns;
}

sub plaintext_segments {
    my $self = shift;
    return $self->_segmentize($self->normalize_plaintext, $self->size);           
}

sub _segmentize {
    my ($self, $to_segment, $size) = @_;
    [grep {$_} split /(.{$size})/, $to_segment];
}

sub _columns {
    my $self = shift;
    my $plaintext_segments = $self->plaintext_segments;
    my @columns;
    
    foreach my $index (0 .. @$plaintext_segments) {
        my $column;
        foreach my $seg ( @$plaintext_segments ) {
            $column .= substr $seg, $index, 1 if $index < length $seg;
        }
        push @columns, $column if $column;
    }
    @columns;
}

__PACKAGE__;