Add the heat index as well as some error handling.

lib/helpers/http.dart

@@ -10,26 +10,30 @@ import 'dart:convert';
 Future<String> hitAPI(String url) async {
   if (debug) debugPrint("DEBUG: URL is '$url'.");
 
-  http.Response response = await http.get(Uri.parse(url));
+  try {
+    http.Response response = await http.get(Uri.parse(url));
 
-  String data = "";
-  if (response.statusCode == 200) {
-    data = response.body;
-    var decodedData = jsonDecode(data);
-    //data = decodedData.toString();
-    //data = jsonEncode(decodedData);
-    if (debugVerbose) {
-      debugPrint("DEBUG-VERBOSE: Response data: \n\n$data\n");
-    }
-  } else {
-    if (debug) {
-      debugPrint(
-        "DEBUG: Response failed with code '${response.statusCode.toString()}'",
-      );
+    String data = "";
+    if (response.statusCode == 200) {
+      data = response.body;
+      var decodedData = jsonDecode(data);
+      //data = decodedData.toString();
+      //data = jsonEncode(decodedData);
+      if (debugVerbose) {
+        debugPrint("DEBUG-VERBOSE: Response data: \n\n$data\n");
+      }
+    } else {
+      if (debug) {
+        debugPrint(
+          "DEBUG: Response failed with code '${response.statusCode.toString()}'",
+        );
+      }
     }
+
+    return data;
+  } catch (e) {
+    return "Sorry! It seems we have an issue: '${e.toString()}'.";
   }
-
-  return data;
 }
 
 // How to guide: https://openweathermap.org/current#zip

lib/helpers/json.dart

@@ -11,7 +11,8 @@ String formatOpenWeatherData(var data) {
       windSpeed = pullOpenWeatherWind(data),
       humidity = pullOpenWeatherHumidity(data);
 
-  String windChill = getWindChill(temp, windSpeed), heatIndex = "";
+  String windChill = getWindChill(temp, windSpeed),
+      heatIndex = getHeatIndex(temp, humidity);
 
   String comfort = "";
 
@@ -19,7 +20,8 @@ String formatOpenWeatherData(var data) {
       "$location is $temp$tempUnits and $conditions"
       " with a wind speed of $windSpeed$windUnits"
       " and humidity of $humidity$humidityUnits."
-      " $windChill$heatIndex"
+      " $windChill"
+      " $heatIndex"
       " $comfort";
 
   final String doubleSpace = "  ", singleSpace = " ";
@@ -89,10 +91,54 @@ String getWindChill(String temp, String windSpeed) {
   double temperature = double.parse(temp);
   double wind = double.parse(windSpeed);
 
-  if (temperature < 50 && wind > 5) {
+  if ((temperature < 50 && wind > 5) || debug) {
     double windChill = calcWindChill((temperature), (wind));
-    return "My guess is that's a wind chill of $windChill$tempUnits";
+    return "My guess is that's a wind chill of $windChill$tempUnits.";
+  }
+  return "";
+}
+
+double calcHeatIndex(double temp, double humidity) {
+  // ## Heat Index ##
+  // # Official formula: https://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml
+  double heatIndex =
+      -42.379 +
+      2.04901523 * temp +
+      10.14333127 * humidity -
+      0.22475541 * temp * humidity -
+      0.00683783 * temp * temp -
+      0.05481717 * humidity * humidity +
+      0.00122874 * temp * temp * humidity +
+      0.00085282 * temp * humidity * humidity -
+      0.00000199 * temp * temp * humidity * humidity;
+
+  if (humidity < 13 && temp >= 80 && temp <= 112) {
+    heatIndex -= ((13 - humidity) / 4) * sqrt((17 - (temp - 95.0).abs()) / 17);
+  }
+
+  if (humidity > 85 && temp >= 80 && temp <= 87) {
+    heatIndex += ((humidity - 85) / 10) * ((87 - temp) / 5);
+  }
+
+  if (heatIndex < 80) {
+    heatIndex =
+        0.5 * (temp + 61.0 + ((temp - 68.0) * 1.2) + (humidity * 0.094));
+    heatIndex = (heatIndex + temp) / 2;
+  }
+
+  if (debug) {
+    debugPrint("DEBUG: heatIndex = '$heatIndex'");
+  }
+  return heatIndex;
+}
+
+String getHeatIndex(String temp, String humidity) {
+  double temperature = double.parse(temp);
+  double humid = double.parse(humidity);
+
+  if (temperature > 80 || debug) {
+    double heatIndex = calcHeatIndex((temperature), (humid));
+    return "My guess is that's a heat index of $heatIndex$tempUnits.";
   }
-
   return "";
 }

lib/main.dart

@@ -97,6 +97,10 @@ class _MainAppState extends State<MainApp> {
       weather = "Please enter a location.";
     }
 
+    if (weather.toString().contains("Sorry!")) {
+      return weather;
+    }
+
     if (weather != loadText) {
       if (debug) {
         debugPrint("DEBUG: Formatting text.");