#!/usr/bin/perl
#
#
# Great Circle Distance Batch script
# Written by A. Gray 22 September 2001
#
# Input file format:
# location,locationid,deg min [N/S], deg min [E/W]
#                        ^SP ^SP        ^SP ^SP
# location is a string which will be used when outputting the matrix
# locationid is a arbitary number, not currently used
# deg  are the degrees of latitude or longitude
# deg  are the minutes of latitude or longitude
#
use POSIX;
use Math::Trig;
#
$EARTH_RADIUS = 6371.0;    # radius of earth in kilometres
$KM_TO_MILES  = 0.621;
#
$infile = "sample.csv";
#
&read_datafile;
#
# &output_human_readable;
&output_matrix;
exit 0;
#

sub output_matrix
{

    printf(" ,");
    foreach $country ( sort keys %country_code )
    {
	printf("%s,",$country);
    }
    print "\n";

    foreach $country ( sort keys %country_code )
    {
	print $country,",";
	if ( $error{$country} == 1 ) 
	{
	    print "    *** Input data parse error \r\n";
	    print "---------------------------------------\r\n";
	    next;
	}
	
	foreach $country2 ( sort keys %country_code )
	{
	    if ( $country eq $country2 ) 
	    {
		print "0,";
	    } else
	    {
	    
		if ( $error{$country2} == 1 ) 
		{
		    printf("ERROR,");
		    
		} else {
		    $distance = &calc_distance($latitude{$country}  ,$longitude{$country},
					       $latitude{$country2} ,$longitude{$country2}),
#		    $miles = $distance * $KM_TO_MILES;
		    printf("%7.1f,",$distance);
		}
	    }
	}
	print "\r\n";
    }
}

sub output_human_readable
{

    foreach $country ( sort keys %country_code )
    {
	print $country,"\r\n";
	if ( $error{$country} == 1 ) 
	{
	    print "    *** Input data parse error \r\n";
	    print "---------------------------------------\r\n";
	    next;
	}
	
	foreach $country2 ( sort keys %country_code )
	{
	    if ( $country eq $country2 ) 
	    {
		next;
	    }
	    
	    if ( $error{$country2} == 1 ) 
	    {
		printf("     %s *** Input data parse error\r\n",$country2);
		
	    } else {
		$distance = &calc_distance($latitude{$country}  ,$longitude{$country},
					   $latitude{$country2} ,$longitude{$country2}),
		$miles = $distance * $KM_TO_MILES;
		printf("     %-30s,  %7.1f, %7.1f\r\n",$country2,$distance,$miles);
	    }
	}
	print "---------------------------------------\r\n";
    }
}
#
sub read_datafile 
{
    open(DATA,$infile) || die "unable to open $infile $! \n";
    while( <DATA> )
    {
	chomp;
	$_ =~  s/\s+$//;   # Need this to handle DOS format txt files
	@vals = split(/,/);
	$country = $vals[0];
	$code    = $vals[1];
	$lat     = $vals[2];
	$long    = $vals[3];
	$y = $#vals + 1;
#
#	printf(STDERR ">>%s:%s:%s:%s<<\n",$country,$code,$lat,$long);
	if ( $y eq 4 )
	{
	    $country =~ s/^\s+//;
	    $code =~ s/^\s+//;
	    $lat=&parse_lat_long($lat);
	    $long=&parse_lat_long($long);
#	    printf("%4d,%s:%s:%7.2f:%7.2f\n",$y,$country,$code,$lat,$long);
	    $latitude{$country} = $lat;
	    $longitude{$country} = $long;
	    $country_code{$country} = $code;
	    $country_name{$code} = $country;
	    if ( ( $lat eq "ERROR" ) || ( $long eq "ERROR" )  )
	    {
		$error{$country} = 1;
	    } else {
		$error{$country} = 0;
	    }
	} else {
	    print STDERR "y = ",$y;
	    printf(STDERR "*** Parse error at line %d  ;\n",$.);
	    printf(STDERR "     %s\n",$_);
	}
    }
    close DATA;
}
#
sub calc_distance()
{
    my($lat1,$lon1,$lat2,$lon2) = @_;
    my($distance);

    $p1 = cos($lat1) * cos($lon1) * cos($lat2) * cos($lon2);
    $p2 = cos($lat1) * sin($lon1) * cos($lat2) * sin($lon2);
    $p3 = sin($lat1) * sin($lat2);

    $distance = acos($p1+$p2+$p3)*$EARTH_RADIUS;
    return($distance);
}
#
sub parse_lat_long
{
    local $y;
    $x=join(" ",@_);
    $x =~ s/^\s+//;

    $y=0;
    $y = split(/ /,$x);
#    printf(STDERR "x = >>>%s    y = %s ***\n",$x,$y);
    if ( $y == 3 )
    {
	($degrees,$minutes,$compass) = split(/ /,$x);
	
	$compass = uc($compass);
	$d = $degrees + ( $minutes / 60.0 );
	
	if ( ( $compass eq "S" ) || ( $compass eq "W" )) {
	    $d = $d * (-1);
	}
	$d = deg2rad($d);
	
#    printf("%s,%s-%s ... %6.4f\n",$degrees,$minutes,$compass,$d);
    } else {
	printf(STDERR "*** Lat/Long parse error at line %d  ;\n",$.);
	printf(STDERR "***     >>>%s<<<",$x);
	$d = "ERROR";
    }
    return($d);
}