<?php
/**
This file has two parts:

* a heavily stripped-down version of the "gPoint.php class"
  written by Brenor Brophy  http://www.brenorbrophy.com
  (original found at http://www.phpclasses.org)

* a program to connect to www.emaps.bg, converting geographic coordinates
  to UTM coordinates, made for the purposes of bg.wikipedia.org
  written by Petko Yotov http://5ko.free.fr/


This file may be copied and modified under the terms of the
*** GNU Ceneral Public License version 2 or newer ***

*/





/*------------------------------------------------------------------------------
** PHP class to convert Latitude & Longitude coordinates into
**				UTM & Lambert Conic Conformal Northing/Easting coordinates.
** Version:		1.0
** Author:		Brenor Brophy
** Email & URL:	brenor@sbcglobal.net www.brenorbrophy.com
**
** Code for datum and UTM conversion was converted from C++ code written by
** Chuck Gantz (chuck.gantz@globalstar.com) from  http://www.gpsy.com/gpsinfo/geotoutm/
** This URL has many other references to useful information concerning conversion
** of coordinates.
*/
define ("meter2nm", (1/1852));
define ("nm2meter", 1852);

/*------------------------------------------------------------------------------
** class gPoint		... for Geographic Point
**
** This class encapsulates the methods for representing a geographic point on the
** earth in three different coordinate systema. Lat/Long, UTM and Lambert Conic
** Conformal.
*/
class gPoint
{
/* Reference ellipsoids derived from Peter H. Dana's website-
** http://www.utexas.edu/depts/grg/gcraft/notes/datum/elist.html
** Department of Geography, University of Texas at Austin
** Internet: pdana@mail.utexas.edu 3/22/95
**
** Source:
** Defense Mapping Agency. 1987b. DMA Technical Report: Supplement to Department
** of Defense World Geodetic System 1984 Technical Report. Part I and II.
** Washington, DC: Defense Mapping Agency
*/
	var $ellipsoid = array(//Ellipsoid name, Equatorial Radius, square of eccentricity
	"Airy"					=>array (6377563, 0.00667054),
	"Australian National"	=>array	(6378160, 0.006694542),
	"Bessel 1841"			=>array	(6377397, 0.006674372),
	"Bessel 1841 Nambia"	=>array	(6377484, 0.006674372),
	"Clarke 1866"			=>array	(6378206, 0.006768658),
	"Clarke 1880"			=>array	(6378249, 0.006803511),
	"Everest"				=>array	(6377276, 0.006637847),
	"Fischer 1960 Mercury"	=>array (6378166, 0.006693422),
	"Fischer 1968"			=>array (6378150, 0.006693422),
	"GRS 1967"				=>array	(6378160, 0.006694605),
	"GRS 1980"				=>array	(6378137, 0.00669438),
	"Helmert 1906"			=>array	(6378200, 0.006693422),
	"Hough"					=>array	(6378270, 0.00672267),
	"International"			=>array	(6378388, 0.00672267),
	"Krassovsky"			=>array	(6378245, 0.006693422),
	"Modified Airy"			=>array	(6377340, 0.00667054),
	"Modified Everest"		=>array	(6377304, 0.006637847),
	"Modified Fischer 1960"	=>array	(6378155, 0.006693422),
	"South American 1969"	=>array	(6378160, 0.006694542),
	"WGS 60"				=>array (6378165, 0.006693422),
	"WGS 66"				=>array (6378145, 0.006694542),
	"WGS 72"				=>array (6378135, 0.006694318),
	"WGS 84"				=>array (6378137, 0.00669438));

	// Properties
	var $a;										// Equatorial Radius
	var	$e2;									// Square of eccentricity
	var	$datum;									// Selected datum
	var	$Xp, $Yp;								// X,Y pixel location
	var $lat, $long;							// Latitude & Longitude of the point
	var $utmNorthing, $utmEasting, $utmZone;	// UTM Coordinates of the point
	var	$lccNorthing, $lccEasting;				// Lambert coordinates of the point
	var $falseNorthing, $falseEasting;			// Origin coordinates for Lambert Projection
	var $latOfOrigin;							// For Lambert Projection
	var $longOfOrigin;							// For Lambert Projection
	var $firstStdParallel;						// For lambert Projection
	var $secondStdParallel;						// For lambert Projection

	// constructor
	function gPoint($datum='WGS 84')			// Default datum is WGS 84
	{
		$this->a = $this->ellipsoid[$datum][0];		// Set datum Equatorial Radius
		$this->e2 = $this->ellipsoid[$datum][1];	// Set datum Square of eccentricity
		$this->datum = $datum;						// Save the datum
	}

	//
	// Set/Get/Output Longitude & Latitude of the point
	//
	function setLongLat($long, $lat)
	{
		$this->long = $long; $this->lat = $lat;
	}
	function convertLLtoTM($LongOrigin='')
	{
		$k0 = 0.9996;
		$falseEasting = 500000.0;

		//Make sure the longitude is between -180.00 .. 179.9
		$LongTemp = ($this->long+180)-(integer)(($this->long+180)/360)*360-180; // -180.00 .. 179.9;
		$LatRad = deg2rad($this->lat);
		$LongRad = deg2rad($LongTemp);

		$ZoneNumber=35; // Added by Petko Yotov
		$LongOrigin = ($ZoneNumber - 1)*6 - 180 + 3;  //+3 puts origin in middle of zone

		$LongOriginRad = deg2rad($LongOrigin);

		$eccPrimeSquared = ($this->e2)/(1-$this->e2);

		$N = $this->a/sqrt(1-$this->e2*sin($LatRad)*sin($LatRad));
		$T = tan($LatRad)*tan($LatRad);
		$C = $eccPrimeSquared*cos($LatRad)*cos($LatRad);
		$A = cos($LatRad)*($LongRad-$LongOriginRad);

		$M = $this->a*((1	- $this->e2/4		- 3*$this->e2*$this->e2/64	- 5*$this->e2*$this->e2*$this->e2/256)*$LatRad
							- (3*$this->e2/8	+ 3*$this->e2*$this->e2/32	+ 45*$this->e2*$this->e2*$this->e2/1024)*sin(2*$LatRad)
												+ (15*$this->e2*$this->e2/256 + 45*$this->e2*$this->e2*$this->e2/1024)*sin(4*$LatRad)
												- (35*$this->e2*$this->e2*$this->e2/3072)*sin(6*$LatRad));

		$this->utmEasting = ($k0*$N*($A+(1-$T+$C)*$A*$A*$A/6
						+ (5-18*$T+$T*$T+72*$C-58*$eccPrimeSquared)*$A*$A*$A*$A*$A/120)
						+ $falseEasting);

		$this->utmNorthing = ($k0*($M+$N*tan($LatRad)*($A*$A/2+(5-$T+9*$C+4*$C*$C)*$A*$A*$A*$A/24
					 + (61-58*$T+$T*$T+600*$C-330*$eccPrimeSquared)*$A*$A*$A*$A*$A*$A/720)));
		if($this->lat < 0)
			$this->utmNorthing += 10000000.0; //10000000 meter offset for southern hemisphere
	}
} // end of class gPoint




// Next code by Petko Yotov
function create_link($lat, $lon, $ell)
{
	$gpoint =& new gPoint($ell);
	$gpoint->setLongLat($lon, $lat);
	$gpoint->convertLLtoTM('');
	$mapX = round($gpoint->utmEasting);
	$mapY = round($gpoint->utmNorthing);
	$minx = $mapX-14425;
	$maxx = $mapX+14425;
	$miny = $mapY-10000;
	$maxy = $mapY+10000;

	$base_url = "http://www.emaps.bg/emaps/content.asp?mapSize=1&cboMaps=0";

	$url = "$base_url&minx=$minx&maxx=$maxx&miny=$miny&maxy=$maxy";
	return $url;
}

function message($en, $bg)
{
	header("Content-type: text/html; charset=UTF-8");

	echo <<<EOF
<html><title>Error... Грешка...</title><body>
<h1>Error... Грешка...</h1>

<strong><big>$en</big></strong><br/>

You can:
<ul>
<li><a href='javascript:history.go(-1);'>Go back</a>.</li>
<li>Go to <a href='http://www.emaps.bg/'>www.emaps.bg</a>.</li>
<li>Go to <a href='http://bg.wikipedia.org/'>bg.wikipedia.org</a>.</li>
<li>View the <a href='{$_SERVER["PHP_SELF"]}?q=source'>source code of this script</a>.</li>
</ul>
<br/>
<br/>
<strong><big>$bg</big></strong><br/>

Можете:
<ul>
<li><a href='javascript:history.go(-1);'>Да се върнете</a>.</li>
<li>Да посетите <a href='http://www.emaps.bg/'>www.emaps.bg</a>.</li>
<li>Да посетите <a href='http://bg.wikipedia.org/'>bg.wikipedia.org</a>.</li>
<li>Да прегледате <a href='{$_SERVER["PHP_SELF"]}?q=source'>изходния код на този скрипт</a>.</li>
</ul>
<br/>
<br/>
<hr/>
<address>
<small>Script by <a href="http://5ko.free.fr/">Petko Yotov</a>.</small>
</address>
</body></html>

EOF;
	exit;


}


if(strtolower($_GET['q']) == "source")
{
	header("Content-type: text/html; charset=UTF-8");
	highlight_file(__FILE__);
	exit;
}

if(!isset($_GET['q']) || preg_match("/[^0-9,\.]/", trim($_GET['q']) ) )
{
	message("No coordinates requested or illegal character", "Не са посочени координати или е въведен неразрешен символ");
}





list($lat, $lon) = explode(",", $_GET['q'], 2);

$lat = floatval($lat); // 41..45
$lon = floatval($lon); // 22..29

if($lat<41 || $lat>45 || $lon<22 || $lon>29 )
{
	message("Coordinates are out of range. Lattitude '$lat' (must be 41..45), Longitude '$lon' (must be 22..29)", "Координатите са извън картата. Ширина: '$lat' (трябва да е 41..45), дължина: '$lon' (трябва да е 22..29)");
}


$url = create_link($lat, $lon, "WGS 84");
header("Location: $url");
exit;
?>