NUC-27: Implement Firebase firestore telemetry publisher

.gitignore

@@ -2,4 +2,5 @@ bin/
 obj/
 /packages/
 .idea/
-.vs
+.vs
+NucuCar.Sensors/firebaseConfig.json

NucuCar.Domain/NucuCar.Domain.csproj

@@ -16,6 +16,7 @@
     </ItemGroup>
     
     <ItemGroup>
+      <PackageReference Include="Google.Cloud.Firestore" Version="1.1.0" />
       <PackageReference Include="Google.Protobuf" Version="3.10.1" />
       <PackageReference Include="Grpc" Version="2.25.0" />
       <PackageReference Include="Grpc.Tools" Version="2.25.0" />

NucuCar.Domain/Telemetry/TelemetryPublisher.cs

@@ -115,7 +115,7 @@ namespace NucuCar.Domain.Telemetry
             var metadata = new Dictionary<string, object>
             {
                 ["source"] = TelemetrySource ?? nameof(TelemetryPublisher),
-                ["timestamp"] = DateTime.Now,
+                ["timestamp"] = DateTime.UtcNow,
                 ["data"] = data.ToArray()
             };
             return metadata;

NucuCar.Domain/Telemetry/TelemetryPublisherAzure.cs

@@ -8,6 +8,13 @@ using Newtonsoft.Json;
 
 namespace NucuCar.Domain.Telemetry
 {
+    /// <summary>
+    /// Constructs an instance of <see cref="TelemetryPublisherAzure"/>. It is used to publish telemetry to Microsoft
+    /// Azure IotHub
+    /// <remarks>
+    ///    The connection string can be found in your Azure IotHub.
+    /// </remarks>
+    /// </summary>
     public class TelemetryPublisherAzure : TelemetryPublisher
     {
         protected readonly DeviceClient DeviceClient;

NucuCar.Domain/Telemetry/TelemetryPublisherDisk.cs

@@ -11,7 +11,7 @@ using NucuCar.Domain.Utilities;
 namespace NucuCar.Domain.Telemetry
 {
     /// <summary>
-    /// The TelemetryPublisherDisk is used to publish telemetry data to a file residing on the disk.
+    /// The TelemetryPublisherDisk is used to publish telemetry data to a file on the disk.
     /// </summary>
     public class TelemetryPublisherDisk : TelemetryPublisher
     {
@@ -22,7 +22,7 @@ namespace NucuCar.Domain.Telemetry
         /// Constructs an instance of <see cref="TelemetryPublisherDisk"/>.
         /// <remarks>
         ///    The connection string must contain the following options:
-        ///     Filename (required) - The path of the filename in which to log telemetry data.
+        ///     Filename (optional) - The path of the filename in which to log telemetry data.
         ///     FileExtension (optional) - The extension of the filename. Default csv
         ///     Separator (optional) - The separator of the messages. Default ,
         ///     BufferSize (optional) - The buffer size for the async writer. Default: 4096
@@ -32,7 +32,7 @@ namespace NucuCar.Domain.Telemetry
         public TelemetryPublisherDisk(TelemetryPublisherBuilderOptions opts) : base(opts)
         {
             var connectionStringParams = ConnectionStringParser.Parse(opts.ConnectionString);
-            var fileName = connectionStringParams.GetValueOrDefault("FileName");
+            var fileName = connectionStringParams.GetValueOrDefault("FileName", "telemetry");
             var fileExtension = connectionStringParams.GetValueOrDefault("FileExtension", "csv");
             var bufferSize = connectionStringParams.GetValueOrDefault("BufferSize", "4096");
             _separator = connectionStringParams.GetValueOrDefault("Separator", ",");

NucuCar.Domain/Telemetry/TelemetryPublisherFactory.cs

@@ -47,6 +47,7 @@ namespace NucuCar.Domain.Telemetry
             {
                 TelemetryPublisherType.Azure => (TelemetryPublisher) new TelemetryPublisherAzure(opts),
                 TelemetryPublisherType.Disk => new TelemetryPublisherDisk(opts),
+                TelemetryPublisherType.Firestore => new TelemetryPublisherFirestore(opts),
                 _ => throw new ArgumentException($"Invalid TelemetryPublisher type: {type}.")
             };
         }

NucuCar.Domain/Telemetry/TelemetryPublisherFirestore.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Google.Cloud.Firestore;
+using Microsoft.Extensions.Logging;
+using NucuCar.Domain.Utilities;
+
+namespace NucuCar.Domain.Telemetry
+{
+    /// <summary>
+    /// This class is used to publish the telemetry data to Google's Cloud Firestore.
+    /// Requires the environment variable: GOOGLE_APPLICATION_CREDENTIALS to be set.
+    /// See: https://cloud.google.com/docs/authentication/getting-started
+    /// or Firebase > Project Settings > Service Accounts
+    /// <remarks>
+    ///    The connection string has the following parameters:
+    ///    ProjectId (required) — The string for the Firestore project id.
+    ///    CollectionName (required) — The string for the Firestore collection name.
+    ///    Timeout (optional) — The number in milliseconds in which to timeout if publishing fails. Default: 10000
+    /// </remarks>
+    /// </summary>
+    public class TelemetryPublisherFirestore : TelemetryPublisher
+    {
+        private readonly FirestoreDb _database;
+        private readonly string _firestoreCollection;
+        private readonly int _timeout;
+
+        public TelemetryPublisherFirestore(TelemetryPublisherBuilderOptions opts) : base(opts)
+        {
+            var options = ConnectionStringParser.Parse(opts.ConnectionString);
+            if (!options.TryGetValue("ProjectId", out var firestoreProjectId))
+            {
+                Logger?.LogCritical(
+                    $"Can't start {nameof(TelemetryPublisherFirestore)}! Malformed connection string! " +
+                    $"Missing ProjectId!");
+            }
+
+            if (!options.TryGetValue("CollectionName", out _firestoreCollection))
+            {
+                Logger?.LogCritical(
+                    $"Can't start {nameof(TelemetryPublisherFirestore)}! Malformed connection string! " +
+                    $"Missing CollectionName!");
+            }
+            _timeout = int.Parse(options.GetValueOrDefault("Timeout", "10000"));
+
+
+            _database = FirestoreDb.Create(firestoreProjectId);
+            Logger?.LogInformation($"Initialized {nameof(TelemetryPublisherFirestore)}");
+        }
+
+        public override async Task PublishAsync(CancellationToken cancellationToken)
+        {
+            if (cancellationToken.IsCancellationRequested)
+            {
+                return;
+            }
+
+            var docRef = _database.Collection(_firestoreCollection).Document();
+            var data = GetTelemetry();
+            var cts = new CancellationTokenSource();
+            cts.CancelAfter(_timeout);
+            try
+            {
+                await docRef.SetAsync(data, cancellationToken: cts.Token);
+                Logger?.LogInformation("Published data to Firestore!");
+            }
+            catch (Exception e)
+            {
+                Logger?.LogError($"Failed to publish telemetry data!\n{e.GetType().FullName}: {e.Message}");
+                throw;
+            }
+        }
+
+        public override void Dispose()
+        {
+        }
+    }
+}

NucuCar.Domain/Telemetry/TelemetryPublisherType.cs

@@ -8,5 +8,6 @@ namespace NucuCar.Domain.Telemetry
     {
         public const string Azure = "Azure";
         public const string Disk = "Disk";
+        public const string Firestore = "Firestore";
     }
 }