#!/usr/bin/perl -w
#
#
# This program converts the lat/long on the clipboard, which 
# is assumed to be in NAD27 datum to the WGS84 datum, or at 
# least the NAD83 datum.  The lat/long on the clipboard can 
# be in any format recognized by Geo::ExtractDD.  The longitudes
# in this program are all kept in the positive sign (no negative numbers).
#
# This program uses the simple grid-based shift method, with bilinear 
# interpolation between 0.25 degree grid points.  The program NADCON 
# 
#
#

use strict;
use warnings;
use Text::CSV;
use Win32::Clipboard;
use Geo::ExtractDD;
use Geo::WebService::Elevation::USGS;
use Geo::Coordinates::Converter;

$| = 1; #Autoflush STDOUT

my $infile1 = 'conus-lat.txt';
my $infile2 = 'conus-long.txt';

chdir 'C:/Perl64/DB/NAD27 to WGS84';

my ($latlow, $longlow, $latdifflow1, $latdifflow2, $latdiffhi1, $latdiffhi2, $longdifflow1, $longdifflow2, $longdiffhi1, $longdiffhi2);
my (@fields1, @fields2);


#my $latd = '38.898748';
#my $longd = '-77.037684';

my $clip = Win32::Clipboard();
my $latlong = $clip->GetText();


my ($latd, $longd) = extractdd($latlong);

die "\nLat/long given is outside the continental US.\nThe program only works within the continental US.\n\n" if ($latd < 20 or $latd > 50 or $longd < 64 or $longd > 132);

if ($latd) {

	# $longd = 0 - $longd;
	
	# die "\$latd = $latd\n\$longd = $longd\n\n";
	
	
	my $intlatd = int $latd;
	
	if ($latd - $intlatd < 0.25) {
		$latlow = $intlatd;
	}
	elsif ($latd - $intlatd < 0.5 and $latd - $intlatd >= 0.25) {
		$latlow = $intlatd + 0.25;
	}
	elsif ($latd - $intlatd < 0.75 and $latd - $intlatd >= 0.5) {
		$latlow = $intlatd + 0.5;
	}
	elsif ($latd - $intlatd < 0.999999999999 and $latd - $intlatd >= 0.75) {
		$latlow = $intlatd + 0.75;
	}
	
	
	my $lathi = $latlow + 0.25;
	$latlow = sprintf("%.2f", $latlow);
	$lathi = sprintf("%.2f", $lathi);
	
	
	
	my $intlongd = int $longd;
	
	if ($longd - $intlongd < 0.25) {
		$longlow = $intlongd;
	}
	elsif ($longd - $intlongd < 0.5 and $longd - $intlongd >= 0.25) {
		$longlow = $intlongd + 0.25;
	}
	elsif ($longd - $intlongd < 0.75 and $longd - $intlongd >= 0.5) {
		$longlow = $intlongd + 0.5;
	}
	elsif ($longd - $intlongd < 0.999999999999 and $longd - $intlongd >= 0.75) {
		$longlow = $intlongd + 0.75;
	}
	
	my $longhi = $longlow + 0.25;
	$longlow = sprintf("%.2f", $longlow);
	$longhi = sprintf("%.2f", $longhi);
	
	
	
	my $csv1 = Text::CSV->new({ sep_char => "\t" });

	open(INLAT, '<', $infile1) or die "Can't open '$infile1': $!";
	
	
	while (my $line = <INLAT>) {
		chomp $line;
		if ($csv1->parse($line)) {
			@fields1 = $csv1->fields();
			
			if ($fields1[0] =~ /$latlow/ and $fields1[1] =~ /$longlow/) {
				$latdifflow1 = $fields1[2];
				$latdifflow2 = $fields1[3];
				
				$latdifflow1 = $latdifflow1 * 1 / 60 / 60;
				$latdifflow2 = $latdifflow2 * 1 / 60 / 60;
				
			}
			if ($fields1[0] =~ /$lathi/ and $fields1[1] =~ /$longlow/) {
				$latdiffhi1 = $fields1[2];
				$latdiffhi2 = $fields1[3];
				
				$latdiffhi1 = $latdiffhi1 * 1 / 60 / 60;
				$latdiffhi2 = $latdiffhi2 * 1 / 60 / 60;
				
			}
		}
	}
	
	close INLAT;
	
	
	
	
	my $csv2 = Text::CSV->new({ sep_char => "\t" });

	open(INLONG, '<', $infile2) or die "Can't open '$infile2': $!";
	
	
	while (my $line = <INLONG>) {
		chomp $line;
		if ($csv2->parse($line)) {
			@fields2 = $csv2->fields();
			
			if ($fields2[0] =~ /$latlow/ and $fields2[1] =~ /$longlow/) {
				$longdifflow1 = $fields2[2];
				$longdifflow2 = $fields2[3];
				
				$longdifflow1 = $longdifflow1 * 1 / 60 / 60;
				$longdifflow2 = $longdifflow2 * 1 / 60 / 60;

			}
			if ($fields2[0] =~ /$latlow/ and $fields2[1] =~ /$longhi/) {
				$longdiffhi1 = $fields2[2];
				$longdiffhi2 = $fields2[3];
				
				$longdiffhi1 = $longdiffhi1 * 1 / 60 / 60;
				$longdiffhi2 = $longdiffhi2 * 1 / 60 / 60;
				
			}
		}
	}
	
	close INLONG;
	
	
	
#	print "$latlow, $lathi, $longlow, $longhi, $latd, $longd\n";
	
#	print "\n$latdiffhi2 - $latdiffhi1\n$latdifflow2 - $latdifflow1\n$longdiffhi2 - $longdiffhi1\n$longdifflow2 - $longdifflow1\n\n";
	
	my $latinterp = ($latd - $latlow) / ($lathi - $latlow);
	my $longinterp = ($longd - $longlow) / ($longhi - $longlow);
	
	
	my $latcalc1 = $latinterp * ($latdiffhi2 - $latdifflow2) + $latdifflow2;
	my $latcalc2 = $latinterp * ($latdiffhi1 - $latdifflow1) + $latdifflow1;
	my $latdiff = $longinterp * ($latcalc1 - $latcalc2) + $latcalc2;
	
	my $longcalc1 = $longinterp * ($longdifflow2 - $longdifflow1) + $longdifflow1;
	my $longcalc2 = $longinterp * ($longdiffhi2 - $longdiffhi1) + $longdiffhi1;
	my $longdiff = $latinterp * ($longcalc2 - $longcalc1) + $longcalc1;
	
	
#	print "\n\n$latdiff - $longdiff\n\n";
	
	my $wgslat = $latd + $latdiff;
	my $wgslong = $longd + $longdiff;
	
	
	$wgslat = sprintf("%.7f", $wgslat);
	$wgslong = sprintf("%.7f", $wgslong);
	
	print "\n\nWGS84 = $wgslat, $wgslong\n\n";
	
	$clip->Empty();
	$clip->Set("$wgslat, $wgslong");
	
	
	print "\nAll done.   \n\n";
}

else {
	print "Did not match on lat/long $latlong\n\n";
}


__END__