<?php

$debug = false;

$buttonid = 0;	// low boundary for button IDs and ReqIs, change in case of overlap
$buttonx = 100;	// midpoint between buttons, span 15+5 left and right
$buttony = 175;	// top buttons' vertical position

$ip = '127.0.0.1'; // your local IP
$port = 29999; // your InSim IP
$admin = 'mypass'; // your admin password (set from MP host menu)

$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_connect($socket, $ip, $port);
socket_write($socket, pack('CCCCSSCCSa16a16', 44, 1, 0, 0, NULL, 20, 0, NULL, 0, $admin, 'gapmon'));

// request all players for initial datas
socket_write($socket, pack('CCCC', 4, 3, 254, 14));

$race = array();
$follow = null;

while(true) {
	if(socket_select($r = array($socket), $w = null, $e = null, 0, 200) > 0) {
		$header = unpack('Csize/Ctype/Creqi/Cdata', socket_read($socket, 4, PHP_BINARY_READ));
		if(!$header) die();
		$data = socket_read($socket, $header['size'] - 4, PHP_BINARY_READ);
		
		switch($header['type']) {				
			case 3: // TINY, keep-alive
				if($header['reqi'] === 0 && $header['data'] === 0) {
					socket_write($socket, pack('CCCC', 4, 3, 0, 0));
				}
				break;
				
			case 21: // NPL
				$race[$header['data']] = 	array('position' => 0,
									'lap' => 0,
									'etime' => 0,
									'gapahead' => 0,
									'gapbehind' => 0,
									'REMOTE' => 1);
			
				$data = unpack('Cptype', substr($data, 1, 1));
				if(!($data['ptype'] & 6)) {
					$follow = $header['data'];	// PLID to time for
					$race[$follow]['remote'] = 0;
					
					// init buttons
					socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+1, 0, $buttonid+0, 0, 16, 0, $buttonx-20, $buttony, 15, 5, str_pad('0.00', 8, "\0")));	// top left
					socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+2, 0, $buttonid+1, 0, 20, 0, $buttonx-20, $buttony+5, 15, 5, str_pad('0.00', 8, "\0")));	// bottom left
					socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+3, 0, $buttonid+2, 0, 16, 0, $buttonx+5, $buttony, 15, 5, str_pad('0.00', 8, "\0")));	// top right
					socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+4, 0, $buttonid+3, 0, 20, 0, $buttonx+5, $buttony+5, 15, 5, str_pad('0.00', 8, "\0")));	// bottom right
				}
				break;
				
			case 23: // PLL
				unset($race[$header['data']]);
				if(isset($follow)) {
					if($header['data'] == $follow) {
						unset($follow);
						// clear buttons
						socket_write($socket, pack('CCCCCCCC', 8, 42, 0 , 1, 0, 0, 0, 0));
					}
				}
				break;
				
			case 24: // LAP
				$etime = unpack('Ival', substr($data, 4, 4));
				$race[$header['data']]['etime'] = $etime['val'];
				socket_write($socket, pack('CCCC', 4, 3, $header['data'], 16));
				break;
				
			case 25: // SPX
				$etime = unpack('Ival', substr($data, 4, 4));
				$race[$header['data']]['etime'] = $etime['val'];
				socket_write($socket, pack('CCCC', 4, 3, $header['data'], 16));
				break;
				
			case 37: // NLP
				while(strlen($data) >= 6) {
					$nlp = unpack('Snode/Slap/Cplid/Cposition', substr($data, 0, 6));
					$race[$nlp['plid']]['position'] = $nlp['position'];
					$race[$nlp['plid']]['lap'] = $nlp['lap'];
					$data = substr($data, 6, strlen($data)-6);
				}
				if(isset($follow)) {
					if(($header['reqi'] == $follow) && ($race[$follow]['position'] >= 2)) {
						// gap ahead
						foreach($race as $racer) {
							if($racer['position'] == $race[$follow]['position'] -1) {
								$gap = $race[$follow]['etime'] - $racer['etime'];
								socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+1, 0, $buttonid+0, 0, 16, 0, $buttonx-20, $buttony, 15, 5, str_pad('+'.number_format($gap / 1000, 2), 8, "\0")));	// top left
								$diff = $gap - $race[$follow]['gapahead'];
								if($diff <= 0) socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+2, 0, $buttonid+1, 0, 20, 0, $buttonx-20, $buttony+5, 15, 5, str_pad(number_format($diff / 1000, 2), 8, "\0")));	// bottom left
								if($diff > 0) socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+2, 0, $buttonid+1, 0, 21, 0, $buttonx-20, $buttony+5, 15, 5, str_pad('+'.number_format($diff / 1000, 2), 8, "\0")));	// bottom left
								$race[$follow]['gapahead'] = $gap;
							}
						}
					}
					
					if($race[$header['reqi']]['position'] == $race[$follow]['position'] +1) {
						// gap behind
						$gap = $race[$header['reqi']]['etime'] - $race[$follow]['etime'];
						socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+3, 0, $buttonid+2, 0, 16, 0, $buttonx+5, $buttony, 15, 5, str_pad('+'.number_format($gap / 1000, 2), 8, "\0")));	// top right
						$diff = $gap - $race[$follow]['gapbehind'];
						if($diff <= 0) socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+4, 0, $buttonid+3, 0, 20, 0, $buttonx+5, $buttony+5, 15, 5, str_pad(number_format($diff / 1000, 2), 8, "\0")));	// bottom right
						if($diff > 0) socket_write($socket, pack('CCCCCCCCCCCCa8', 20, 45, $buttonid+4, 0, $buttonid+3, 0, 21, 0, $buttonx+5, $buttony+5, 15, 5, str_pad('+'.number_format($diff / 1000, 2), 8, "\0")));	// bottom right
						$race[$follow]['gapbehind'] = $gap;
					}
				}				
				break;
				
			case 17: // RST
				$race = array();
				socket_write($socket, pack('CCCCCCCC', 8, 42, 0 , 1, 0, 0, 0, 0));
				socket_write($socket, pack('CCCC', 4, 3, 254, 14));
				break;
				
			default: if($debug) {
					print_r($header);
				}
				break;
		}
	}
}

socket_close($socket);

?>