#!/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,
		track     => $track,
		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);
		$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");
}

our %COMMANDS = (
	0xAA => \&bus_free_time_packet,
	0xCC => \&car_programming_packet,
	0xD0 => \&reset_packet,
	0xD3 => \&standings_packet,
	0xD4 => \&lap_time_packet,
	0xD5 => \&race_setup_packet,
	0xD6 => \&fuel_level_packet,
	0xD7 => \&brake_set_packet,
	0xDB => \&qualification_packet,
	0xDC => \&end_of_race_packet,
	0xDD => \&race_start_packet,
	0xDE => \&display_change_packet,
	0xEE => \&finish_line_packet,
	0xFF => \&controller_status_packet,
);

sub handle_packet {
	my ($self, @data) = @_;

	my $cmd = $data[1];
	my @args = $data[2..7];

	my $sub = $COMMANDS{$cmd};
	return "Unknown packet"
		if !defined $sub;

	return &$sub($self, @args);
}

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

	my $msg = 'Strange bus free time packet'
		if $bytes[2] != 0xF0
		|| $bytes[3] != 0xF0
		|| $bytes[4] != 0xF0
		|| $bytes[5] != 0xF0;

	return $msg; # No need to handle this, I think
}

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

	my $msg = 'Strange car programming packet'
		if $bytes[0] & 0xF8 != 0 || $bytes[0] & 0x07 > 5
		|| $bytes[1] != 0xFE
		|| $bytes[2] != 0xFF
		|| $bytes[3] != 0xFF
		|| $bytes[4] != 0xFF
		|| $bytes[5] != 0xFF;

	return $msg;
}

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

	my $msg = 'Strange reset packet'
		if $bytes[0] != 0xFF
		|| $bytes[3] != 0xAA
		|| $bytes[4] != 0xAA
		|| $bytes[5] != 0xAA;

	return $msg; # FIXME - to be implemented
}

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

	my $msg = 'Strange standings packet'
		if $bytes[0] & 0x07 > 5
		|| $bytes[1] & 0x07 > 5
		|| $bytes[2] & 0x07 > 5
		|| $bytes[3] & 0x07 > 5
		|| $bytes[4] & 0x07 > 5
		|| $bytes[5] & 0x07 > 5;

	return $msg; # FIXME - to be implemented
}

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

	my $msg = 'Strange lap time packet'
		if $bytes[0] > 5
		|| $bytes[1] & 0x01
		|| $bytes[2] & 0x01
		|| $bytes[3] & 0xF8 != 0
		|| $bytes[4] & 0x01
		|| $bytes[5] & 0x01;

	return $msg; # FIXME - to be implemented
}


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

	my $msg = 'Strange race setup packet'
		if ($bytes[0] != 0x00 && $bytes[0] != 0xFF)
		|| $bytes[1] & 0xF0
		|| $bytes[2] & 0xF0
		|| $bytes[3] & 0xF0
		|| $bytes[4] != 0xFF
		|| $bytes[5] != 0xFF;

	return $msg; # FIXME - to be implemented
}


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

	my $msg = 'Strange fuel_level packet'
		if ($bytes[0] >> 4) > 8
		|| $bytes[0] & 0x0F > 8
		|| ($bytes[1] >> 4) > 8
		|| $bytes[1] & 0x0F > 8
		|| ($bytes[2] >> 4) > 8
		|| $bytes[2] & 0x0F > 8
		|| ($bytes[5] != 0xAA && $bytes[5] != 0xFF);

	my @fuel = (
		$bytes[1] >> 4, $bytes[1] & 0x0f,
		$bytes[2] >> 4, $bytes[2] & 0x0f,
		$bytes[3] >> 4, $bytes[3] & 0x0f,
	);

	for my $car (0..5) {
		$track->car($car)->set_fuel($fuel[$car]);
	}

	return $msg;
}


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

	return 'Unexpected brake_set packet (should be in the pit lane only)';
}


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

	my $msg = 'Strange qualification packet'
		if $bytes[0] & 0xF0
		|| $bytes[1] & 0xF0
		|| $bytes[2] & 0xF0
		|| $bytes[3] > 5
		|| $bytes[4] != 0xFF
		|| $bytes[5] != 0xFF;

	return $msg; # FIXME - to be implemented
}


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

	my $msg = 'Strange end_of_race packet'
		if $bytes[0] != 0xFF
		|| $bytes[1] != 0xFF
		|| $bytes[2] != 0xFF
		|| $bytes[3] != 0xFF
		|| $bytes[4] != 0xFF
		|| $bytes[5] != 0xFF;

	return $msg; # FIXME - to be implemented
}


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

	my $msg = 'Strange race_start packet'
		if $bytes[0] != 0x00
		|| $bytes[1] != 0xAA
		|| $bytes[2] != 0xAA
		|| $bytes[3] != 0xAA
		|| $bytes[4] != 0xAA
		|| $bytes[5] != 0xAA;

	return $msg; # FIXME - to be implemented
}


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

	my $msg = 'Strange display_change packet'
		if $bytes[0] & 0xFE
		|| $bytes[1] != 0xFF
		|| $bytes[2] != 0xFF
		|| $bytes[3] != 0xFF
		|| $bytes[4] != 0xFF
		|| $bytes[5] != 0xFF;

	return $msg; # FIXME - to be implemented
}


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

	my $fail;
	for my $byte (@bytes) {
		$fail = 1
			if $byte != 0xAA
			&& $byte != 0xE7
			&& $byte != 0xF0
			&& $byte != 0xFE
	}

	my $msg = 'Strange finish_line packet'
		if $fail;

	return $msg; # FIXME - to be implemented
}


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

	my $fail;
	for my $byte (@bytes) {
		$fail = 1
			if $byte & 0xC0 != 0xC0
			|| $byte & 0x0F > 12
	}

	my $msg = 'Strange controller_status packet'
		if $fail;

	my @fuel = (
		$bytes[1] >> 4, $bytes[1] & 0x0f,
		$bytes[2] >> 4, $bytes[2] & 0x0f,
		$bytes[3] >> 4, $bytes[3] & 0x0f,
	);

	for my $car (0..5) {
		my $byte = $bytes[$car];

		if ($byte == 0xAA) {
			$track->car($car)->set_throttle(undef);
			next;
		}

		my $light = !($byte & 0x20);
		my $backbutton = !($byte & 0x10);
		my $throttle = $byte & 0x0f;

		$track->car($car)->set_throttle($throttle);
		$track->car($car)->set_light($light);
		$track->car($car)->set_backbutton($backbutton);
	}

	return $msg;
}

1;