use strict;
use warnings;
use LWP::Simple;
use HTML::TableExtract;
use Sort::Versions;
use MIME::Lite;

# A few configuration variables...
my $datafile = 'gpsdata.dat';
my $website = 'http://www.garmin.com/support/download.jsp';
my $mailfrom = 'your@return.address';
my $email_notify = 'Yes';
my $mailto = 'notification@email.address';
my $mailhost = 'smtp.host.net';
my @devices = ( 'GPSMAP 76', 'MapSource' );

my %found_device;
{
    # Pull in the webpage...
    my $raw_html = get( $website );

    # For testing, save the webpage as 'garmin.htm', comment out the
    # preceeding line, and uncomment the following six lines.  This
    # will test against the saved version rather than hitting 
    # the remote site.

#    my $raw_html = do {
#        open my $in, '<', 'garmin.htm'
#            or die "Can't open infile: $!\n";
#        local $/ = undef;
#        <$in>;
#    };

    # Define which tables to search.
    my $te = new HTML::TableExtract( headers => 
        [ 'Product\s+Name',
          'Software\s+Version',
          'Compatible\s+with\s+Versions',
          'Date' ] );
    $te->parse($raw_html);

    # Find and keep track of the applicable entries.
    my $find_devices = join '|', @devices;
    my $re_devices = qr/$find_devices/;
    foreach my $ts ( $te->table_states ) {
        foreach my $row ( $ts->rows ) {
            s/^\s+// foreach @{$row};
            s/\s+$// foreach @{$row};
            $found_device{ $row->[0] } = [ @$row ]
                if $row->[0] =~ /^(?:$re_devices)$/i;
        }
    }
}

# Check for and pull in previous-run data.
my %prev_device = ();
if ( -e $datafile ) {
    open my $dat, '<', $datafile 
        or die "Couldn't open input file: $!\n";
    while ( my $line = <$dat> ) {
        chomp $line;
        my @row = split /\s*\|\s*/, $line;
        $prev_device{ $row[0] } = [ @row ];
    }
    close $dat;
}


# Compare site data with stored data.
my @changed;
foreach my $key ( keys %found_device ) {
    push @changed, $key if ( 
        ( not defined $prev_device{$key} )
        or  versioncmp( $prev_device{$key}[1], 
                        $found_device{$key}[1] ) == -1 );
}

# We're done if there are no updates available.
unless ( @changed ) {
    print "No updates available at $website.\n";
    exit;
}


# If updates, print results and, send an email message.
my $out_text = "Download from $website:\n";
foreach ( @changed ) {
    $out_text   .= "Upgrade available for $_: "
                .  "    version $found_device{$_}[1], "
                .  "$found_device{$_}[3]\n";
}

print $out_text;

# Email stuff.
if ( $email_notify =~ /^y/i ) {
    my $msg = MIME::Lite->new( 
        'From'      =>  $mailfrom,
        'To'        =>  $mailto,
        'Subject'   =>  "[Upgrade] Updates available for " 
                        . do { local $" = ', '; "@changed"; }
                        . ".", 
        'Data'      =>  $out_text );
    # This line is for us Windows folks.
    MIME::Lite->send( 'smtp', $mailhost, 'Timeout' => 60 );
    $msg->send();
}

# Save updates to data file.
open my $fh, '>', $datafile
    or die "Can't write update to $datafile: $!\n";
foreach my $key ( keys %found_device ) {
    local $" = '|';
    print $fh "@{$found_device{$key}}\n";
}
close $fh or die "Can't close $datafile after update: $!\n";