#!/usr/bin/perl
# Emulate -c option of gpsdrive to jump to the waypoint

@NEW_ARGS = ("-G", "1200x580", "-p", "-B", "");	# Set defaults here.
	# -B '' to stop launching gpsd

$RC_DIR = "$ENV{HOME}/.gpsdrive";
$RC_PATH = "$RC_DIR/gpsdriverc";
$WP_PATH = "$RC_DIR/way.txt";

sub coord_from_waypoint
{
    my($wp_name) = @_;

    open(IN, $WP_PATH) or die "$WP_PATH: $!";
    while (<IN>) {
	my($n, $lat, $lon) = split;
	$n eq $wp_name and return ($lat, $lon);
    }
    close(IN);
    ();	# not found
}

sub embed_coord
{
    my($lat, $lon) = @_;

    rename($RC_PATH, "$RC_PATH~") or die "Renaming $RC_PATH: $!";
    open(IN, "$RC_PATH~") or die "$RC_PATH~: $!";
    open(OUT, ">$RC_PATH") or die "$RC_PATH: $!";
    while (<IN>) {
	s/^lastlong = ([0-9.])*/lastlong = $lon/;
	s/^lastlat = ([0-9.])*/lastlat = $lat/;
	print OUT;
    }
    close(OUT);
    close(IN);
}

sub main
{
    while (my $arg = shift(@ARGV)) {
	if ($arg eq "-c") {
	    my $wp_name = shift(@ARGV);
	    my($lat, $lon) = coord_from_waypoint($wp_name) or
		die "$wp_name not found in $WP_PATH";
	    embed_coord($lat, $lon);
	} else {
	    push(@NEW_ARGS, $arg);
	}
    }
    chdir($RC_DIR);	# to see way.txt
    exec("/usr/bin/gpsdrive", @NEW_ARGS);
}

main;