Update getData and httpRequest to modern TypeScript

routes/weather.ts

@@ -14,16 +14,19 @@ var http		= require( "http" ),
 
 // If location does not match GPS or PWS/ICAO, then attempt to resolve
 // location using Weather Underground autocomplete API
-function resolveCoordinates( location, callback ) {
+async function resolveCoordinates( location, callback ) {
 
 	// Generate URL for autocomplete request
 	var url = "http://autocomplete.wunderground.com/aq?h=0&query=" +
 		encodeURIComponent( location );
 
-	httpRequest( url, function( data ) {
-
-		// Parse the reply for JSON data
-		data = JSON.parse( data );
+	let data;
+	try {
+		data = await getData( url );
+	} catch (err) {
+		// If the request fails, indicate no data was found.
+		callback( false );
+	}
 
 	// Check if the data is valid
 	if ( typeof data.RESULTS === "object" && data.RESULTS.length && data.RESULTS[ 0 ].tz !== "MISSING" ) {
@@ -35,21 +38,22 @@ function resolveCoordinates( location, callback ) {
 		// Otherwise, indicate no data was found
 		callback( false );
 	}
-	} );
 }
 
-function getData( url, callback ) {
-
-	httpRequest( url, function( data ) {
+/**
+ * Makes an HTTP GET request to the specified URL and parses the JSON response body.
+ * @param url The URL to fetch.
+ * @return A Promise that will be resolved the with parsed response body if the request succeeds, or will be rejected
+ * with an Error if the request or JSON parsing fails.
+ */
+async function getData( url: string ): Promise< any > {
 	try {
-			data = JSON.parse( data );
+		const data: string = await httpRequest(url);
+		return JSON.parse(data);
 	} catch (err) {
-			callback( {} );
-			return;
+		// Reject the promise if there was an error making the request or parsing the JSON.
+		throw err;
 	}
-		callback( data );
-		return;
-	} );
 }
 
 // Retrieve data from Open Weather Map for water level calculations
@@ -57,11 +61,19 @@ function getOWMWateringData( location, callback ) {
 	var OWM_API_KEY = process.env.OWM_API_KEY,
 		forecastUrl = "http://api.openweathermap.org/data/2.5/forecast?appid=" + OWM_API_KEY + "&units=imperial&lat=" + location[ 0 ] + "&lon=" + location[ 1 ];
 
-	getTimeData( location, function( weather ) {
+	getTimeData( location, async function( weather ) {
 
 		// Perform the HTTP request to retrieve the weather data
-		getData( forecastUrl, function( forecast ) {
+		let forecast;
+		try {
+			forecast = await getData( forecastUrl );
+		} catch (err) {
+			// Return just the time data if retrieving the forecast fails.
+			callback( weather );
+			return;
+		}
 
+		// Return just the time data if the forecast data is incomplete.
 		if ( !forecast || !forecast.list ) {
 			callback( weather );
 			return;
@@ -85,7 +97,6 @@ function getOWMWateringData( location, callback ) {
 
 		callback( weather );
 	} );
-	} );
 }
 
 // Retrieve weather data from Open Weather Map for App
@@ -94,12 +105,19 @@ function getOWMWeatherData( location, callback ) {
 		currentUrl = "http://api.openweathermap.org/data/2.5/weather?appid=" + OWM_API_KEY + "&units=imperial&lat=" + location[ 0 ] + "&lon=" + location[ 1 ],
 		forecastDailyUrl = "http://api.openweathermap.org/data/2.5/forecast/daily?appid=" + OWM_API_KEY + "&units=imperial&lat=" + location[ 0 ] + "&lon=" + location[ 1 ];
 
-	getTimeData( location, function( weather ) {
+	getTimeData( location, async function( weather ) {
 
-		getData( currentUrl, function( current ) {
-
-			getData( forecastDailyUrl, function( forecast ) {
+		let current, forecast;
+		try {
+			current = await getData( currentUrl );
+			forecast = await getData( forecastDailyUrl );
+		} catch (err) {
+			// Return just the time data if retrieving weather data fails.
+			callback( weather );
+			return;
+		}
 
+		// Return just the time data if the weather data is incomplete.
 		if ( !current || !current.main || !current.wind || !current.weather || !forecast || !forecast.list ) {
 			callback( weather );
 			return;
@@ -130,8 +148,6 @@ function getOWMWeatherData( location, callback ) {
 
 		callback( weather );
 	} );
-		} );
-	} );
 }
 
 // Calculate timezone and sun rise/set information
@@ -386,33 +402,40 @@ exports.getWateringData = function( req, res ) {
     }
 };
 
-// Generic HTTP request handler that parses the URL and uses the
-// native Node.js http module to perform the request
-function httpRequest( url, callback ) {
-	url = url.match( filters.url );
+/**
+ * Makes an HTTP GET request to the specified URL and returns the response body.
+ * @param url The URL to fetch.
+ * @return A Promise that will be resolved the with response body if the request succeeds, or will be rejected with an
+ * Error if the request fails.
+ */
+async function httpRequest( url: string ): Promise< string > {
+	return new Promise< any >( ( resolve, reject ) => {
 
-	var options = {
-		host: url[ 1 ],
-		port: url[ 2 ] || 80,
-		path: url[ 3 ]
+		const splitUrl: string[] = url.match( filters.url );
+
+		const options = {
+			host: splitUrl[ 1 ],
+			port: splitUrl[ 2 ] || 80,
+			path: splitUrl[ 3 ]
 		};
 
-	http.get( options, function( response ) {
-        var data = "";
+		http.get( options, ( response ) => {
+			let data = "";
 
 			// Reassemble the data as it comes in
-        response.on( "data", function( chunk ) {
+			response.on( "data", ( chunk ) => {
 				data += chunk;
 			} );
 
-        // Once the data is completely received, return it to the callback
-        response.on( "end", function() {
-            callback( data );
+			// Once the data is completely received, resolve the promise
+			response.on( "end", () => {
+				resolve( data );
 			} );
-	} ).on( "error", function() {
+		} ).on( "error", ( err ) => {
 
-		// If the HTTP request fails, return false
-		callback( false );
+			// If the HTTP request fails, reject the promise
+			reject( err );
+		} );
 	} );
 }