#! /usr/bin/perl -w

use strict; 
use GnuPG; 
use Getopt::Long; 

use IO::File;
use POSIX qw(tmpnam);
use Data::Dumper; 

use vars qw[ $temp_name $passphrase $gpg %tan_array $round ]; 

use vars qw[ $number $debug $multiple $free $keep $help ]; 

my $opt_result = GetOptions( 
            'n=i' => \$number,
            'd'   => \$debug,
            'k'   => \$keep,
            'f'   => \$free,
            'm'   => \$multiple,
            'h'   => \$help ); 

&help() unless( $opt_result ); 
&help() if( defined( $help )); 

my $temp_fh; 

# open temporary file to store decrypted TANs
do { $temp_name = tmpnam() }
    until $temp_fh = IO::File->new($temp_name, O_RDWR|O_CREAT|O_EXCL);

### Initialise $gpg
$gpg = new GnuPG();

# Delete temporary file automatically at the end
END { 
    
    if( defined( $temp_name )){

        unlink($temp_name) or die "Couldn't unlink $temp_name : $!" 
        
    }

}

## check for argument
my $arg_check = &check_args(); 

if( $arg_check ne 'true' ){ die "Error: ${arg_check}!\n"; }


## Get passphrase
$passphrase = &password(); 

%tan_array = &decrypt(); 

if( defined( $free )){

    # Calculate number of items in hash
    my $items = &num_tan( %tan_array );
    print "\n$items iTANs in list!\n\n";
    exit; 

}

while( my @testarray = each( %tan_array )){

    print "Index $testarray[0] has value $testarray[1]\n" if( defined( $debug )); 

}


while(){


$number = &ask_number() unless( defined( $number )); 
last if( $number !~ /^\d+$/ ); 


    if( defined( $tan_array{$number} )){

        print "iTAN #$number is:   $tan_array{$number}\n"; 
        delete( $tan_array{$number} ) unless( defined( $keep )); 

    }else{

        print "No iTAN #$number\n"; 

    }


## Break if multiple was not defined
last unless( defined( $multiple )); 
undef( $number ); 

}

## After that loop, we need to write the unused iTANs back to the file
## if saving was not disabled ($keep is set).

&write_tan( %tan_array ) unless( defined( $keep )); 


# Calculate number of items in hash
my $items = &num_tan( %tan_array );
print "\n$items iTANs remaining!\n\n"; 





sub num_tan {

my( %tans ) = @_; 

# Calculate number of items in hash
my @items = values( %tans );
my $items = @items;

return $items; 

}



sub write_tan {

my ( %tans ) = @_; 
die "No argument given! Expect hash of iTANs!\n" unless( defined( $_[0] )); 

open( WRITE, "> $temp_name" ) || die "Can't save unused iTANs to temporary file: $!\n";

    while( my @testarray = each( %tan_array )){

        print WRITE $testarray[0] . ',' . $testarray[1] . "\n"; 

    }

close( WRITE ); 

&encrypt_file(); 

}

sub encrypt_file {

    $gpg->encrypt( plaintext  => $temp_name, 
                   output     => $ARGV[0], 
                   passphrase => $passphrase,
                   recipient  => 'to.c@gmx.net' ); 

return 1;

}


sub decrypt(){

my %temp_tan_array; 

$gpg->decrypt( ciphertext   => $ARGV[0],  
               output       => $temp_name, 
               passphrase   => $passphrase );

open( READ, "< $temp_name" ) || die "Can't open decrypted file!\n"; 

while(<READ>){

    chop; 

    my ( $id, $tan ) = split/[-,\-\s]+/; 
    $temp_tan_array{$id} = $tan; 
    print "ID: $id - TAN $tan\n" if( defined( $debug )); 

}

close( READ ); 

return %temp_tan_array; 

}

sub password(){
my $password;

## Turn printing characters off
qx(/bin/stty -echo);

print "\nGnuPG Passphrase: ";

$password = <STDIN>;

chop ( $password );


## turn it on again
qx(/bin/stty echo);

print "\n\n";

return $password;


}

sub ask_number(){

    my $number; 
    print "Which iTAN do you want to see: ";

    $number = <STDIN>; 
    chop( $number ); 

    return $number; 

}






sub check_args(){

    return "No argument to decrypt" unless( defined( $ARGV[0] )); 
    return "No such file: $ARGV[0]" unless( -f $ARGV[0] ); 
    return "File not readable" unless( -r $ARGV[0] ); 

    return "true"; 

}

sub help {

    print <<EOF; 

    Reads a GPG encrypted file with iTANs and returns the iTAN with the number that 
    was either defined by the -n switch or provided upon question. 

          -n INT   Show iTAN with number INT
          -d       Show debugging information
          -k       Don't delete shown iTANS from list, and don't override encrypted file
          -m       Go for multiple iTANs. 
          -h       Show this help

EOF

exit; 

}