# Vanya A. Sergeev <vsergeev@san.rr.com>
# 08/01/2006
# Checks a POP3 account and displays the number of new messages on a
# 7-segment LED display, interfaced through the PC parallel port.
#
# Note: set_byte()/set_data() function of Device::ParallelPort was not 
# working for me, so I had to manually set/check bits on the parallel port.

use strict;
use Device::ParallelPort;
use Mail::POP3Client;

############### CHANGE THESE ###############

my $username = '';
my $password = '';

my $hostname = '';
my $hostport = '';

############################################


# Digits coded in binary for the hardware output to the LED display
# Consists of characters 0 through 9, and 'E'
my @hwdigits = (0b00111111, 0b00110000, 0b01011011, 0b01001111, 0b01110010, 0b01101101, 0b01111101, 0b00000111, 0b01111111, 0b01101111, 0b01111001);

# Make parallel port driver object
my $pport = Device::ParallelPort->new();

# Set nInitialize bit to 0, this lets the switch pull down the nAck bit of
# the parallel port when pressed.
$pport->set_bit(18, 0);

# Main program execution loop
while (1) {
	# Clear screen, set busy to show email is being checked, get number of new messages
	clear_display();
	set_busy();
	my $newmessages = check_mail();
	# If there are more than 9 new messages, display the 9 digit and the dot,
	# otherwise display how many messages there are, and clear the dot.
	# If an error occured ($newmessages is -1), display an 'E' character with the dot.
	print STDERR "$newmessages new messages.\n";
	if ($newmessages > 9) {
		set_digit(9);
	} elsif ($newmessages == -1) {
		set_digit(10);
	} else {
		set_digit($newmessages);
		clear_busy();
	}
	# Wait until button to check email is depressed again...
	while ($pport->get_bit(14) == 1) { }
	# Sleep to prevent button bouncing
	sleep 1;
}


# Connect to the POP3 server with login details, and return the number of new messages.
sub check_mail {
	# Make new pop3client object and connect
	my $pop3client = new Mail::POP3Client(HOST => $hostname, PORT => $hostport);
	$pop3client->User($username);
	$pop3client->Pass($password);
	$pop3client->Connect() >= 0 || die $pop3client->Message();
	# Get number of new messages
	my $newmessages = $pop3client->Count();
	# Close pop3client object
	$pop3client->Close();
	# Return number of new messages
	$_ = $newmessages;
}

# Clear the data bits of the parallel port (clears LED display)
sub clear_display {
	# For some reason $pport->set_byte(0,0); leaves D4 and D5 on, but
	# manual set_bit() calls work fine.
	for (my $i = 0; $i < 8; $i++) {
		$pport->set_bit($i, 0);
	}
}

# Set the dot of the LED Display
sub set_busy {
	$pport->set_bit(7, 1);
}

# Clear the dot of the LED Display
sub clear_busy {
	$pport->set_bit(7, 0);
}

# Sets a certain digit on the LED Display
sub set_digit {
	# Grab digit argument
	my($digit) = @_;
	# Go bit by bit through the digit encoded in binary for the hardware LEDs
	# Toggle bit on parallel port when necessary.
	for (my $i = 0; $i < 7; $i++) {
		if (($hwdigits[$digit] & (1 << $i)) == 0) {
			$pport->set_bit($i, 0);
		} else {
			$pport->set_bit($i, 1);
		}
	}
}