#!/usr/bin/perl -w

package SCX::Reader;

use Time::HiRes qw(gettimeofday tv_interval);
use FileHandle;
use SCX::CRC;

our $PACKET_SIZE = 9; # 9 bytes + 0x05
our $LOG_ROTATE  = 600;

sub new {
	my ($class, $args) = @_;

	my $callback = $args->{callback}
		or die "callback arg not defined";

	my $portname = $args->{portname}
		or die "portname not specified";
	
	system 'stty', '-F', $portname, '115200', 'raw';
	if ($?) {
		die "stty died with code $? (no permissions?)";
	}

	open my $tty, '<:raw', $portname
		or die "Can't open $portname: $!";

	my $logfile = $args->{logfile};
	my $log_gen = 0;

	open my $logfh, '>', "$logfile.$log_gen"
	or die "Can't open $logfile.$log_gen: $!";

	my $now = gettimeofday;

	my $self = {
		portname  => $portname,
		fh        => $tty,
		logfile   => $logfile,
		logfh     => $logfh,
		log_gen   => $log_gen,
		log_start => $now,
		starttime => $now,
		callback  => $callback,
		bytes     => [],
	};

	bless $self, $class;

	return $self;
}

sub fh { return shift->{fh}; }

sub read {
	my ($self) = @_;

	my $data;
	my $bytes_read = sysread $self->fh, $data, $PACKET_SIZE;
	die "Read error on $self->{portname}: $!"
		if !$bytes_read;

	my @bytes = unpack("C*", $data);

	push @{ $self->{bytes} }, @bytes;
	@bytes = @{ $self->{bytes} };

	my @bad_bytes;

	while (@bytes > $PACKET_SIZE) {
		if ($bytes[0] != 0x55) {
			push @bad_bytes, shift @bytes;
			next;
		}
		my $cmd = $bytes[1];

		if ($bytes[$PACKET_SIZE] != 0x05
			|| SCX::CRC::digest(@bytes[0..$PACKET_SIZE-2])
				!= $bytes[$PACKET_SIZE-1]) {
			push @bad_bytes, shift @bytes;
			next;
		}
		
		if (@bad_bytes) { # Report previous bad bytes first
			$self->log_bytes(\@bad_bytes, "Cannot parse packet");
			@bad_bytes = ();
		}

		my @packet = splice @bytes, 0, $PACKET_SIZE+1;
		my $rv = &{ $self->{callback} }(@packet[1..$PACKET_SIZE]);
		$self->log_bytes(@packet, $rv);
	}
	$self->log_bad_bytes(\@bad_bytes, "Cannot parse packet");

	@{ $self->{bytes} } = @bytes;
}

sub log_bytes {
	my ($self, $bytes, $msg) = @_;

	return if !@$bytes;

	$msg = defined $msg ? ' # ' . $msg : '';

	my $now = gettimeofday;

	if ($now - $self->{log_start} >= $LOG_ROTATE) {
		close $self->{logfh};
		$self->{log_gen} = $self->{log_gen} ? 0 : 1;
		open my $fh, '>', $logfile . '.' . $self->{log_gen}
			or die "Can't open $logfile.$self->{log_gen}: $!";
		$self->{logfh} = $fh;
		$self->{log_start} = $now;
	}

	$self->{logfh}->print(sprintf('% 10.3f', $now - $self->{starttime}),
		(map { sprintf(" %02x", $_) } @bytes),
		$msg, "\n");
}

1;