use Tie::Hash;
use DBI;

my $dbh = DBI->connect("DBI:mysql:book","book","addison")
          or die "Error: $DBI::errstr\n";
my @KEYS;

package ShopCart;

@ISA = qw(Tie::StdHash);

sub STORE {
    my ($self, $key, $val) = @_;
    my $modified = time();
    my $session = main::Session();
    my $existed = $self->EXISTS($key); # Already exist?
    my $action = main::param('action'); 
    my $new_qty;

    unless($val){
        $self->DELETE($key);
        return;
    }

    if($existed) {
        if($action eq "update"){
            $new_qty = $val;
        }
        else{
            $new_qty = $existed + $val;
        }

        my $sth = $dbh->prepare( qq{ UPDATE cart
                                     SET qty = '$new_qty'
                                     WHERE session = ?
                                     AND sku = ? });

        $sth->execute($session, $key);
    }
    else{
        my $sth = $dbh->prepare( qq{ INSERT INTO cart
                                     VALUES (?,?,?,?) });

         $sth->execute($key, $val, $modified, $session);
    } # End of if..else
} # End of STORE

sub EXISTS{
    my($self, $key) = @_;
    my $session     = main::Session();
    my $sth = $dbh->prepare( qq{ SELECT qty FROM cart
                                 WHERE session = ?
                                 AND sku = ? });

    $sth->execute($session, $key);

    my $temp = $sth->fetch;
    return $temp->[0] ? $temp->[0] : 0;
} # End of EXISTS

sub DELETE{
    my ($self, $key) = @_;
    my $session = main::Session();
    my $sth = $dbh->prepare( qq{ DELETE FROM cart
                                 WHERE session = ?
                                 AND sku = ? });

    $sth->execute($session, $key);
} # End of DELETE

sub FETCH{
    my ($self, $key) = @_;
    my $session = main::Session();
    my $sth = $dbh->prepare( qq{ SELECT qty FROM cart
                                 WHERE session = ?
                                 AND sku = ? });

    $sth->execute($session, $key);

    my $temp = $sth->fetch;
    return $temp->[0];
} # End of FETCH

sub FIRSTKEY{
    my $self = shift;
    my $session = main::Session();
    my $sth = $dbh->prepare( qq{ SELECT qty, sku
                                 FROM cart
                                 WHERE session = ? });

    $sth->execute($session);
    $self->{DATA}  = $sth->fetchall_arrayref;
    $self->{INDEX} = 0;

    my $val = $self->{DATA}->[0][0];
    my $key = $self->{DATA}->[0][1];

    return if !@{$self->{DATA}}; # No data, return.

    foreach(@{$self->{DATA}}){
        my $key = $_->[1];
        my $val = $_->[0];
        $self->{LIST}{$key} = $val;
    }

    @KEYS = keys ( %{$self->{LIST}} );
    $self->{FIRSTKEY} = $key;

    return ($val, $key);
} # End of FIRSTKEY

sub NEXTKEY{
    my $self    = shift;
    my $lastkey = shift;

    $key = $KEYS[$self->{INDEX}++];
    next if($key eq $self->{FIRSTKEY});

    return($key);
} # End of NEXTKEY

sub DESTROY {
    $dbh->disconnect();
} # End of DESTROY

package Colors;

use Tie::Scalar;

sub TIESCALAR{
    my ($class, @values) = @_;
    return bless \@values, $class;
}

sub FETCH {
    my $self = shift;
    push(@$self, shift(@$self));

    return $self->[-1];
}
1;