Testcases passes

CodeChallengeV2/Services/GeocodeService.cs

@@ -1,16 +1,20 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
+using System.Net.Http;
 using System.Threading.Tasks;
 using CodeChallengeV2.Models;
+using Newtonsoft.Json.Linq;
 
 namespace CodeChallengeV2.Services
 {
     public class GeocodeService : IGeocodeService
     {
-        public Task<string> FindCountryCode(GeocodePayload payload)
+        static readonly HttpClient client = new HttpClient();
+        public async Task<string> FindCountryCode(GeocodePayload payload)
         {
-            return Task.FromResult("DK");
+            var requestStr = $"http://api.geonames.org/findNearbyPlaceNameJSON?lat={payload.Lat}&lng={payload.Long}&username=kk9440";
+
+            HttpResponseMessage response = (await client.GetAsync(requestStr)).EnsureSuccessStatusCode();
+            var parsedContent = JObject.Parse(await response.Content.ReadAsStringAsync());
+            return (string) parsedContent["geonames"][0]["countryCode"];
         }
     }
 }

CodeChallengeV2/Services/NetworkSimulatorService.cs

@@ -15,7 +15,20 @@ public class NetworkSimulatorService : INetworkSimulatorService
         /// <returns></returns>
         public Task<List<Node>> FindCritialGateways(NetworkGraph graph)
         {
-            return Task.FromResult(Enumerable.Empty<Node>().ToList());
+            var devDict = new Dictionary<String, List<String>>();
+            List <Node> criticalGatewayNodes = new List<Node>();
+
+            graph.Graphs.ToList().ForEach(g => {
+                List<String> devices = g.Nodes.Where(x => x.Type == "Device").Select(x => x.Id).ToList();
+
+                devices.ForEach(dev => devDict[dev] = new List<string>());
+                g.Edges.Where(x => x.Relation == "is_connected_to").ToList().ForEach(y => devDict[y.Source].Add(y.Target));
+
+                List<String> criticalGateways = devDict.Where( x => x.Value.Count == 1).Select( y => y.Value.First()).ToList(); 
+                criticalGatewayNodes.AddRange(g.Nodes.Where(x => x.Type == "Gateway" && criticalGateways.Contains(x.Id)).ToList());
+            });
+
+            return Task.FromResult(criticalGatewayNodes);
         }
     }
 }

CodeChallengeV2/Services/SensorService.cs

@@ -1,22 +1,67 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using CodeChallengeV2.Models;
 
 namespace CodeChallengeV2.Services
 {
     public class SensorService : ISensorService
     {
+        private static byte[] StringToByteArray(string hex) {
+            byte[] bytes = new byte[(hex.Length >> 1)];
+            for (int idx = 0; idx < hex.Length; idx += 2) bytes[(idx >> 1)] = Convert.ToByte(hex.Substring(idx, 2), 16);
+            return bytes;
+        }
+
+        private static T GetData<T>(byte[] bytes, int offset, int dataSize) {
+            T result = default(T);
+            for (int i = 0; i < Marshal.SizeOf(default(T)); i++) {
+                result = (result * (dynamic)256) | bytes[0];
+            }
+
+            return result;
+        }
+
         public Task<SensorPayloadDecoded> DecodePayload(SensorPayload payload)
         {
-            //TODO: implement decoding
+            byte[] bytes = StringToByteArray(payload.FPort.ToString("X2") + payload.Data);
+            int arrayIdx = 0;
             var res = new SensorPayloadDecoded()
             {
                 DevEUI = payload.DevEUI,
-                Time = payload.Time
+                Time = payload.Time            
             };
 
+            while (arrayIdx < bytes.Length) {
+                double data = (double)((Int16)(bytes[arrayIdx+2] << 8 | bytes[arrayIdx+1]));
+                switch(bytes[arrayIdx]) {
+                    case 20:
+                        arrayIdx += 3;                     
+                        break;
+                    case 40:
+                        res.TempInternal = data / 100.0;
+                        arrayIdx += 3;                     
+                        break;
+                    case 41:
+                        res.TempRed = data / 100.0;
+                        arrayIdx += 3;                     
+                        break;
+                    case 42:
+                        res.TempBlue = data / 100.0;                
+                        arrayIdx += 3;                     
+                        break;
+                    case 43:
+                        res.TempHumidity = data / 100.0;
+                        res.Humidity = (double)((SByte)(bytes[arrayIdx+3])) / 2.0;
+                        arrayIdx += 4;                     
+                        break;
+                    default:
+                        break;
+                }
+            }
+
             return Task.FromResult(res);
         }
     }