<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Qra {

	/*
	*	Class Description: QRA handles manipulation of the Gridsquares used within amateur radio
	*
	*	Units of measurement are the following
	*
	*	Info: Distance Function
	*
	*	M = Miles
	*	K = Kilometers
	*	N = Nautical Miles
	*/

	// Name: qra2latlong
	// Task: convert qra to lat/long
	function qra2latlong($strQRA)
	{
		return qra2latlong($strQRA);
	}

	// calculate  the bearing between two squares
	function bearing($tx, $rx, $unit = 'M') {
		$my = qra2latlong($tx);
		$stn = qra2latlong($rx);

		if ($my !== false && $stn !== false ) {
			$bearing = bearing($my[0], $my[1], $stn[0], $stn[1], $unit);
			return $bearing;
		} else {
			return false;
		}
	}

	/*
	* Function: calculate the distance between two gridsqaures
	*
	*	Inputs are QRA's TX and TX and the unit
	*
	*/
	function distance($tx, $rx, $unit = 'M') {
      // Calc LatLongs
      $my = qra2latlong($tx);
      $stn = qra2latlong($rx);
  
      // Check if qra2latlong returned valid values
      if ($my && $stn) {
         // Feed in Lat Longs plus the unit type
         try
		   {
            $total_distance = distance($my[0], $my[1], $stn[0], $stn[1], $unit);
         } 
          catch (Exception $e)
		   {
            $total_distance = 0;
         }
  
          // Return the distance
          return $total_distance;
      } else {
          // Handle the case where qra2latlong did not return valid values
          return 0;
      }
   }

	/*
	* Function returns just the bearing
	*  Input locator1 and locator2
	*/
	function get_bearing($tx, $rx) {
		$my = qra2latlong($tx);
		$stn = qra2latlong($rx);
		return get_bearing($my[0], $my[1], $stn[0], $stn[1]);
	}

	/*
	Find the Midpoint between two gridsquares using lat / long

	Needs following passed

	$coords[]=array('lat' => '53.344104','lng'=>'-6.2674937');
	$coords[]=array('lat' => '51.5081289','lng'=>'-0.128005');    

*/

function get_midpoint($coords)
{
    $count_coords = count($coords);
    $xcos=0.0;
    $ycos=0.0;
    $zsin=0.0;
    
        foreach ($coords as $lnglat)
        {
            $lat = $lnglat['lat'] * pi() / 180;
            $lon = $lnglat['lng'] * pi() / 180;
            
            $acos = cos($lat) * cos($lon);
            $bcos = cos($lat) * sin($lon);
            $csin = sin($lat);
            $xcos += $acos;
            $ycos += $bcos;
            $zsin += $csin;
        }
    
    $xcos /= $count_coords;
    $ycos /= $count_coords;
    $zsin /= $count_coords;
    $lon = atan2($ycos, $xcos);
    $sqrt = sqrt($xcos * $xcos + $ycos * $ycos);
    $lat = atan2($zsin, $sqrt);
    
    return array($lat * 180 / pi(), $lon * 180 / pi());
}
}

function distance($lat1, $lon1, $lat2, $lon2, $unit = 'M') {
  $theta = $lon1 - $lon2;
  $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
  $dist = acos($dist);
  $dist = rad2deg($dist);
  $dist = $dist * 60 * 1.1515;

  if ($unit == "K") {
	$dist *= 1.609344;
  } else if ($unit == "N") {
	$dist *= 0.8684;
  }

  return round($dist, 1);
}

function bearing($lat1, $lon1, $lat2, $lon2, $unit = 'M') {
  $dist = distance($lat1, $lon1, $lat2, $lon2, $unit);
  $dist = round($dist, 0);

  $bearing = get_bearing($lat1, $lon1, $lat2, $lon2);

  $dirs = array("N","E","S","W");

  $rounded = round($bearing / 22.5) % 16;
  if (($rounded % 4) == 0) {
	$dir = $dirs[$rounded / 4];
  } else {
	$dir = $dirs[2 * floor(((floor($rounded / 4) + 1) % 4) / 2)];
	$dir .= $dirs[1 + 2 * floor($rounded / 8)];
	#if ($rounded % 2 == 1)
	#  $dir = $dirs[round_to_int($rounded/4) % 4] . "-" . $dir;
  }
  $var_dist = "";
  #return $dir;
  if (isset($dist)) {
	$var_dist = $dist;
	switch ($unit) {
		case 'M':
			$var_dist .= " miles";
			break;
		case 'N':
			$var_dist .= " nautic miles";
			break;
		case 'K':
			$var_dist .= " kilometers";
			break;
	}
  }
  return round($bearing, 0)."&#186; ".$dir." ".$var_dist;
}

function get_bearing($lat1, $lon1, $lat2, $lon2) {
	return (int)(rad2deg(atan2(sin(deg2rad($lon2) - deg2rad($lon1)) * cos(deg2rad($lat2)), cos(deg2rad($lat1)) * sin(deg2rad($lat2)) - sin(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($lon2) - deg2rad($lon1)))) + 360) % 360;
}

function qra2latlong($strQRA) {
	$strQRA=preg_replace('/\s+/', '', $strQRA);
	if (substr_count($strQRA, ',') > 0) {
		if (substr_count($strQRA, ',') == 3) {
			// Handle grid corners
			$grids = explode(',', $strQRA);
			$gridlengths = array(strlen($grids[0]), strlen($grids[1]), strlen($grids[2]), strlen($grids[3]));
			$same = array_count_values($gridlengths);
			if (count($same) != 1) {
				return false;
			}
			$coords = array(0, 0);
			for($i=0; $i<4; $i++) {
				$cornercoords[$i] = qra2latlong($grids[$i]);
				$coords[0] += $cornercoords[$i][0];
				$coords[1] += $cornercoords[$i][1];
			}
			return array (round($coords[0]/4), round($coords[1]/4));
		} else if (substr_count($strQRA, ',') == 1) {
			// Handle grid lines
			$grids = explode(',', $strQRA);
			if (strlen($grids[0]) != strlen($grids[1])) {
				return false;
			}
			$coords = array(0, 0);
			for($i=0; $i<2; $i++) {
				$linecoords[$i] = qra2latlong($grids[$i]);
			}
			if ($linecoords[0][0] != $linecoords[1][0]) {
				$coords[0] = round((($linecoords[0][0] + $linecoords[1][0]) / 2),1);
			} else {
				$coords[0] = round($linecoords[0][0],1);
			}
			if ($linecoords[0][1] != $linecoords[1][1]) {
				$coords[1] = round(($linecoords[0][1] + $linecoords[1][1]) / 2);
			} else {
				$coords[1] = round($linecoords[0][1]);
			}
			return $coords;
		} else {
			return false;
		}
	}

	if ((strlen($strQRA) % 2 == 0) && (strlen($strQRA) <= 10)) {	// Check if QRA is EVEN (the % 2 does that) and smaller/equal 8
		$strQRA = strtoupper($strQRA);
		if (strlen($strQRA) == 4)  $strQRA .= "LL";	// Only 4 Chars? Fill with center "LL" as only A-R allowed
		if (strlen($strQRA) == 6)  $strQRA .= "55";	// Only 6 Chars? Fill with center "55"
		if (strlen($strQRA) == 8)  $strQRA .= "LL";	// Only 8 Chars? Fill with center "LL" as only A-R allowed

		if (!preg_match('/^[A-R]{2}[0-9]{2}[A-X]{2}[0-9]{2}[A-X]{2}$/', $strQRA)) {
			return false;
		}

		list($a, $b, $c, $d, $e, $f, $g, $h, $i, $j) = str_split($strQRA, 1);	// Maidenhead is always alternating. e.g. "AA00AA00AA00" - doesn't matter how deep. 2 chars, 2 numbers, etc.
		$a = ord($a) - ord('A');
		$b = ord($b) - ord('A');
		$c = ord($c) - ord('0');
		$d = ord($d) - ord('0');
		$e = ord($e) - ord('A');
		$f = ord($f) - ord('A');
		$g = ord($g) - ord('0');
		$h = ord($h) - ord('0');
		$i = ord($i) - ord('A');
		$j = ord($j) - ord('A');

		$nLong = ($a*20) + ($c*2) + ($e/12) + ($g/120) + ($i/2880) - 180;
		$nLat = ($b*10) + $d + ($f/24) + ($h/240) + ($j/5760) - 90;

		$arLatLong = array($nLat, $nLong);
		return $arLatLong;
	} else {
		return array(0, 0);
	}
}


/* End of file Qra.php */