A Tropo scripting application that finds library locations in Philadelphia.

philly-locater.php

<?php

/**
 * Find My Library - an IM and SMS application that finds library locations in Philadelphia. 
 *
 * @copyright 2011 Mark J. Headd (http://www.voiceingov.org)
 * @author Mark Headd
 * 
 * Deploy this application on http://www.tropo.com
 */

// Constants used to geocode an address.
define("MAPS_LOOKUP_BASE_URL", "http://maps.googleapis.com/maps/api/geocode/json");
define("MAPS_API_KEY", "your-api-key");

// CouchDB Details.
define("GEO_COUCH_URL", "http://libraries.phillyapi.com:5984/v1/locations?bbox=");

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

// Get the lat / lon for an address.
function geoCodeAddress($address) {

	// Format address and URL.
	$address = str_replace(" ", "+", $address);
	$url = MAPS_LOOKUP_BASE_URL."?address=".$address."&sensor=false&key=".MAPS_API_KEY;

	return makeCurlCall($url, GeoCodeException, "Could not Geocode that address.");
}

// Mak call to GeoCouch and get locations.
function getLocations($bb_array) {

	// Format URL to GeoCouch instance.
	$url = GEO_COUCH_URL;
	$url .= implode(",", $bb_array);

	return makeCurlCall($url, GeoCouchException, "Could not connect to GeoCouch instance.");

}

// Heler method to make an HTTP request.
function makeCurlCall($url, $exceptionType, $exceptionMessage) {
		
	// Set up cURL call.
	$ch = curl_init($url);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

	// Execute.
	$output = curl_exec($ch);
	$code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
	
	// Return results.
	if($code != '200') {
		throw new $exceptionType($exceptionMessage);
	}
	else {
		return $output;
	}

}

// Make a bounding box from a lat / lon pair
function makeBoundingBox($lon, $lat, $factor=.015) {
	$bb_array = Array($lon-$factor, $lat-$factor, $lon+$factor, $lat+$factor);
	return $bb_array;
}

// Calculate the distance between 2 points.
function calculateDistance($lat1, $lon1, $lat2, $lon2) {
	return 3958*3.1415926*sqrt(($lat2-$lat1)*($lat2-$lat1) + cos($lat2/57.29578)*cos($lat1/57.29578)*($lon2-$lon1)*($lon2-$lon1))/180;
}

try {

	// Get the address submited by the user.
	$result = ask("", array("choices" => "[ANY]"));

	// Geocode address and get lat / lon.
	$geocoded_address = json_decode(geoCodeAddress($result->value));
	$lat = $geocoded_address->results[0]->geometry->location->lat;
	$lon = $geocoded_address->results[0]->geometry->location->lng;

	// Create a bound box from the lat / lon pair.
	$bb_array = makeBoundingBox($lon, $lat);

	// Get the locations from geocouch.
	$locations = json_decode(getLocations($bb_array));
	
	// If locations are found,iterate over JSON and render to user.
	if($locations->rows) {

		foreach($locations->rows as $location) {
			
			$property = $location->value->properties;
			$geometry = $location->value->geometry->coordinates;
			
			$library =  'Library Name: '.strtoupper($property->BRANCH_NAM);
			$library .= '. Library Address: '.$property->HOUSENUM.' '.strtoupper($property->ADDRESS);
			
			$distance = round(calculateDistance($lat, $lon, $geometry[1], $geometry[0]), 2);
			
			$library .= ' Distance: '.$distance.' miles.';
			
			say($library);
		}

	}
	
	// Otherwise, tell user no locations found.
	else {		
		say("No locations found.");
	}

}

// If address can not be Geocoded.
catch (GeoCodeException $ex) {
	say("An error occured. ". $ex->getMessage());
	hangup();
}

// If call can not be made to GeoCoud
catch (GeoCouchException $ex) {
	say("An error occured. ". $ex->getMessage());
	hangup();
}


// Last ditch exception handler.
catch (Exception $ex) {
	say("Sorry. Something really bad happened.");
	_log("*** ". $ex->getMessage() . " ***");
	hangup();
}


?>