#!/usr/bin/perl
use strict;
use warnings;
# credit: http://www.caveofprogramming.com/perl/perl-base64/
use MIME::Base64;
use Getopt::Std;
sub usage {
my $usage = q{
Encodes or decodes base64 files to or from binary files.
usage:
    code64.pl [-d|-e] <input file> [-o]
    
examples:
    decoding:
    code64.pl -d temp.txt -o out.txt
    
    encoding:
    code64.pl -e temp.txt -o out.txt
};
    return $usage;
}
sub main {
    my %opts;
    
    # Get command-line options. We want the user
    # to specify an input file (either for encoding
    # or decoding) and an output file.
    getopts('e:d:o:', \%opts);
    
    # User must enter either -e  or
    # -d
    unless($opts{e} or $opts{d}) {
        print "\nNo input file specified\n";
        die usage();
    }
    
    # User must specify -o  and hasn't.
    unless($opts{o}) {
        die "\nNo output file specified\n";
    }
    
    # Now we've got an output file name.
    my $output = $opts{o};
    
    # The input file name is after -e or -d.
    my $input = $opts{e} || $opts{d};
    
    # Open the input file.
    unless(open INPUT, $input) {
        die "\nUnable to open input file '$input'\n";
    }
    
    unless(open OUTPUT, '>'.$output) {
        die "\nUnable to create output file '$output'\n";
    }
    
    # Stop text mode mangling our files.
    binmode INPUT;
    binmode OUTPUT;
    
    # Undef the file record separator so we can read the
    # whole thing in one go.
    undef $/;
    
    # Read the input file.
    my $contents = <INPUT>;
    
    # Create the output file, encoding or decoding as
    # specified by the user.
    if($opts{e}) {
        print OUTPUT encode_base64($contents);
        print "Encoded '$input'; results in '$output'\n";
    }
    elsif($opts{d}) {
        print OUTPUT decode_base64($contents);
        print "Decoded '$input'; results in '$output'\n";
    }
    
    close INPUT;
    close OUTPUT;
}
main();