A Tropo SMS/IM app that provides transit route and stop locations.

transit-location-finder.php

<?php

/* 
 * Copyright 2010 Mark J. Headd
 * 
 * This application is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This application is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

require_once 'path/to/tropo.class.php';

// Constants used to geocode an address.
define("MAPS_LOOKUP_BASE_URL", "http://maps.google.com/maps/geo");
define("MAPS_LOOKUP_FORMAT", "xml");
define("MAPS_API_KEY", "your-api-key-goes-here");

// Configurable items.
define("DEFAULT_ERROR_MESSAGE", "An error occured. Try again later. :-(");
define("DEFAULT_NO_INFORMATION_MESSAGE", "No information was available to respond to your request. Try again...");
define("DEFAULT_NUMBER_DEPARTURES", 3);
define("DEFAULT_ROUNDING_PRECISION", 2);
define("DEFAULT_STOP_DISTANCE", 5);
define("DEFAULT_NUMBER_STOPS", 3);

// Exception classes.
class DatabaseException extends Exception {}
class GeoCodeException extends Exception {}

/*********************************************************************
 *  Display methods. 
 *********************************************************************/

// Get the latest departure times for a specific stop, identified by stopID.
function getDepartureTimes(&$tropo, $stopID) {
	
	$sql = "CALL GetDepartureTimesAndRoutesByStopID($stopID, ".DEFAULT_NUMBER_DEPARTURES.", DAYOFWEEK(CURDATE()))";
	$result = runQuery($sql);
	while ($row = $result->fetch_assoc()) {
		$tropo->say("Route ". $row["route_id"]."/".$row["route_long_name"].", Departs in: ".$row["min_leaving"]);
	}
	
}

// Get the closest transit stop given a specific address.
function getClosestStop(&$tropo, $address) {
	
	$geoXML = new SimpleXmlElement(geoCodeAddress($address));
	$coordinates = $geoXML->Response->Placemark->Point->coordinates;
	$coordinatesArray = explode(",", $coordinates);
	$sql = "CALL GetClosestStopsByLocation($coordinatesArray[1], $coordinatesArray[0], ".DEFAULT_ROUNDING_PRECISION.", ".DEFAULT_STOP_DISTANCE.", ".DEFAULT_NUMBER_STOPS.")";
	$result = runQuery($sql);
	
	while ($row = $result->fetch_assoc()) {
		$tropo->say($row["stop_id"]."/". $row["stop_name"].", Distance: ".$row["DISTANCE"]." miles");
	}

}

/*********************************************************************
 *  Helper methods. 
 *********************************************************************/

// Geocode an address.
function geoCodeAddress($address) {
	
	// Format address and URL.
	$address = str_replace(" ", "+", $address);
	$url = MAPS_LOOKUP_BASE_URL."?q=".$address."&output=".MAPS_LOOKUP_FORMAT."&sensor=".false."&key=".MAPS_API_KEY;	
	
	// Set up cURL call.
	$ch = curl_init($url);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	
	// Execute.
	$output = curl_exec($ch);
	$info = curl_getinfo($ch);
	
	// Return results.
	if($info['http_code'] != '200') {
		throw new GeoCodeException(DEFAULT_ERROR_MESSAGE);
	}
	else {
		return $output;
	}
}

// Run an SQL query.
function runQuery($query) {
	
	try {
		
	$mysqli = new mysqli($_SERVER["TRANSIT_DB_HOST"], $_SERVER["TRANSIT_DB_USER"], $_SERVER["TRANSIT_DB_USER"], $_SERVER["TRANSIT_DB_USER"], $_SERVER["TRANSIT_DB_USER"]);
		if (mysqli_connect_errno()) {
		    throw new Exception(DEFAULT_ERROR_MESSAGE);
		}
		
		$result = $mysqli->query($query);
		if($result->num_rows > 0) {
			return $result;
		}
		else {
			throw new Exception(DEFAULT_NO_INFORMATION_MESSAGE);
		}
		
	}
	catch (Exception $ex) {
		throw new DatabaseException($ex->getMessage());
	}
	
}

// Instantiate a new Tropo object.
$tropo = new Tropo();

// Get the incoming session information from Tropo
$session = new Session();

// Access the initial text sent with the session.
$message = $session->getInitialText();

try {
	// If the user sent a stop number.
	if(is_numeric($message)) {
		getDepartureTimes($tropo, $message);
	}
	// If the user sent an address.
	else {		
		getClosestStop($tropo, $message);
	}

	$tropo->renderJSON();
}

// Handler for various database exceptions.
catch (DatabaseException $ex) {
	$tropo->say($ex->getMessage());
	$tropo->renderJSON();
}

// Handler for geocoding exceptions.
catch (GeoCodeException $ex) {
	$tropo->say($ex->getMessage());
	$tropo->renderJSON();
}

?>