	<?php
	
	/**
	 * PhindItForMe - an IM, SMS, Twitter and Phone application that finds locations in Philadelphia.
	 *
	 * @copyright 2011 Mark J. Headd (http://www.voiceingov.org)
	 * @author Mark Headd
	 */
	
	// Constants used to geocode an address.
	define("MAPS_LOOKUP_BASE_URL", "http://maps.googleapis.com/maps/api/geocode/json");
	define("MAPS_API_KEY", "");
	
	// CouchDB Details.
	define("COUCH_BASE_URL", "http://phlapi.com/");
	define("COUCH_DESIGN_DOC_PATH", "_design/geojson/_spatial/points");
	
	define("LOCATION_NUMBER_LIMIT", 3);
	
	// Exception classes.
	class GeoCodeException extends Exception {}
	class CouchException extends Exception {}
	
	// An array to hold locations returned from CouchDB instances.
	$phl_locations = array();
	
	// Get list of DB's in CouchDB instance.
	function getDatabaseNames() {
		$url = COUCH_BASE_URL."_all_dbs";
		return makeCurlCall($url, CouchException, "Could not connect to PHLAPI instance. :-(");
	}
	
	// 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. Try again.");
	}
	
	// Mak call to Couch and get locations.
	function getLocations($bb_array, $db_name) {
	
		// Format URL to Couch instance.
		$url = COUCH_BASE_URL."/$db_name/".COUCH_DESIGN_DOC_PATH."?bbox=";
		$url .= implode(",", $bb_array);
	
		return makeCurlCall($url, CouchException, "Could not connect to PHLAPI 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;
	}
	
	// Helper method to parse the properties of a specific location.
	function makeLocation($location_type, $properties) {
		
		$location = "";
		
		switch($location_type) {
			
			case "libraries":
				$location = $properties->BRANCH_NAM . " " . $properties->ADDRESS;
				break;
	
			case "schools":
				$location = $properties->LOCNAMESHO . " " . $properties->LOCTYPE . " " . $properties->LOCADDRESS;
				break;
				
			case "police":
				$location = $properties->LOCATION . " " . $properties->PHONE__;
				break;
	
			case "fire":
				$location = $properties->LOCATION;
				break;
		}	
		
		return $location;
	}
	
	try {
	
		// Get the address submited by the user.
		$result = ask("", array("choices" => "[ANY]"));
	
		if(strstr($result->value, " #")) {
	
			$message = explode(" #", $result->value);
			$address = trim($message[0]);
			$location_type = trim($message[1]);
			
			// Get all of the CouchDB DB names that hold locational data. 
			$all_db_names = json_decode(getDatabaseNames(), true);
			$db_names = array();
			foreach($all_db_names as $key => $value) {
				if(substr($value, 0, 1) == "_") {
					continue;
				}
				array_push($db_names, $value);
			}
	
			// If the user sent in a valid DB name, get the locations.
			if(in_array($location_type, $db_names)) {
					
				// Geocode address and get lat / lon.
				$geocoded_address = json_decode(geoCodeAddress($address));
				$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, $location_type));
	
				// If locations are found,iterate over JSON and render to user.
				if($locations->rows) {
	
					foreach($locations->rows as $location) {
							
						$properties = $location->value->properties;
						$geometry = $location->value->geometry->coordinates;					
						$place = "Location: " . makeLocation($location_type, $properties);
						$distance = round(calculateDistance($lat, $lon, $geometry[1], $geometry[0]), 2);
						$place .= " Distance: $distance miles.";						
						array_push($phl_locations, array("distance" => $distance, "place" => $place));
					}
					
					// Use the LOCATION_NUMBER_LIMIT constant to throttle numbr of messages sent to user.
					$limit = LOCATION_NUMBER_LIMIT < count($phl_locations) ? LOCATION_NUMBER_LIMIT : count($phl_locations);
					for($i = 0; $i<$limit; $i++) {
						say($phl_locations[$i]["place"]);	
					}				
	
				}
	
				// Otherwise, tell user no locations found.
				else {
					say("No locations found.");
				}
					
			}
			
			// Otherwise, tell them to only send valid resource names.
			else {
				say("Send address followed by #".implode(", #", $db_names));					
			}
		}
		
		// No location type sent.
		else {
			say("You must sent a location type to use this service.");
		}
	
	}
	
	// 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 (CouchException $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();
	}
	
	
	?>