Initial version.

TINKLib/Services/Geolocation/GeolocationService.cs

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+using Serilog;
+using System;
+using System.Threading.Tasks;
+using TINK.Model.Device;
+using Xamarin.Essentials;
+
+namespace TINK.Model.Services.Geolocation
+{
+    public class GeolocationService : IGeolocation
+    {
+        /// <summary> Timeout for geolocation request operations.</summary>
+        private const int GEOLOCATIONREQUEST_TIMEOUT_MS = 5000;
+
+        private IGeolodationDependent Dependent { get; }
+        
+        public GeolocationService(IGeolodationDependent dependent)
+        {
+            Dependent = dependent;
+        }
+
+        public bool IsSimulation => false;
+
+        public bool IsGeolcationEnabled => Dependent.IsGeolcationEnabled;
+
+        /// <param name="timeStamp">Time when geolocation is of interest. Is used to determine whether cached geoloation can be used or not.</param>
+        public async Task<Location> GetAsync(DateTime? timeStamp = null)
+        {
+            try
+            {
+                var request = new GeolocationRequest(GeolocationAccuracy.Medium, TimeSpan.FromMilliseconds(GEOLOCATIONREQUEST_TIMEOUT_MS));
+                return await Xamarin.Essentials.Geolocation.GetLocationAsync(request);
+            }
+            catch (FeatureNotSupportedException fnsEx)
+            {
+                // Handle not supported on device exception
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation not supported on device. {Exception}", fnsEx);
+                throw new Exception("Abfrage Standort nicht möglich auf Gerät.", fnsEx);
+            }
+            catch (FeatureNotEnabledException fneEx)
+            {
+                // Handle not enabled on device exception
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation not enabled on device. {Exception}", fneEx);
+                throw new Exception("Abfrage Standort nicht aktiviert auf Gerät.", fneEx);
+            }
+            catch (PermissionException pEx)
+            {
+                // Handle permission exception
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation not permitted on device. {Exception}", pEx);
+                throw new Exception("Berechtiung für Abfrage Standort nicht erteilt für App.", pEx);
+            }
+            catch (Exception ex)
+            {
+                // Unable to get location
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation failed. {Exception}", ex);
+                throw new Exception("Abfrage Standort fehlgeschlagen.", ex);
+            }
+        }
+    }
+}

TINKLib/Services/Geolocation/IGeolocation.cs

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+using System;
+using System.Threading.Tasks;
+using TINK.Model.Device;
+using Xamarin.Essentials;
+
+namespace TINK.Model.Services.Geolocation
+{
+    /// <summary> Query geolocation. </summary>
+    public interface IGeolocation : IGeolodationDependent
+    {
+        /// <summary> Gets the current location.</summary>
+        /// <param name="timeStamp">Time when geolocation is of interest. Is used to determine for some implementations whether cached geoloation can be used or not.</param>
+        /// <returns></returns>
+        Task<Location> GetAsync(DateTime? timeStamp = null);
+
+        /// <summary> If true location data returned is simulated.</summary>
+        bool IsSimulation { get; }
+    }
+}

TINKLib/Services/Geolocation/LastKnownGeolocationService.cs

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+using Serilog;
+using System;
+using System.Threading.Tasks;
+using TINK.Model.Device;
+using Xamarin.Essentials;
+
+namespace TINK.Model.Services.Geolocation
+{
+    public class LastKnownGeolocationService : IGeolocation
+    {
+        /// <summary> Timeout for geolocation request operations.</summary>
+        private const int GEOLOCATIONREQUEST_TIMEOUT_MS = 5000;
+
+        private IGeolodationDependent Dependent { get; }
+
+        public LastKnownGeolocationService(IGeolodationDependent dependent)
+        {
+            Dependent = dependent;
+        }
+        
+        /// <param name="timeStamp">Time when geolocation is of interest. Is used to determine whether cached geoloation can be used or not.</param>
+        public async Task<Location> GetAsync(DateTime? timeStamp = null)
+        {
+            Location location;
+            try
+            {
+                var request = new GeolocationRequest(GeolocationAccuracy.Medium, TimeSpan.FromMilliseconds(GEOLOCATIONREQUEST_TIMEOUT_MS));
+                location = await Xamarin.Essentials.Geolocation.GetLocationAsync(request);
+            }
+            catch (FeatureNotSupportedException fnsEx)
+            {
+                // Handle not supported on device exception
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation not supported on device. {Exception}", fnsEx);
+                throw new Exception("Abfrage Standort nicht möglich auf Gerät.", fnsEx);
+            }
+            catch (FeatureNotEnabledException fneEx)
+            {
+                // Handle not enabled on device exception
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation not enabled on device. {Exception}", fneEx);
+                throw new Exception("Abfrage Standort nicht aktiviert auf Gerät.", fneEx);
+            }
+            catch (PermissionException pEx)
+            {
+                // Handle permission exception
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation not permitted on device. {Exception}", pEx);
+                throw new Exception("Berechtiung für Abfrage Standort nicht erteilt für App.", pEx);
+            }
+            catch (Exception ex)
+            {
+                // Unable to get location
+                Log.ForContext<LastKnownGeolocationService>().Error("Retrieving Geolocation failed. {Exception}", ex);
+                throw new Exception("Abfrage Standort fehlgeschlagen.", ex);
+            }
+
+            if (location != null // Cached location is available.
+                && (timeStamp == null || timeStamp.Value.Subtract(location.Timestamp.DateTime) < MaxAge))
+            {   
+                // No time stamp available or location not too old.
+                return location;
+            }
+
+            return await Xamarin.Essentials.Geolocation.GetLocationAsync();
+        }
+
+        /// <summary> If true location data returned is simulated.</summary>
+        public bool IsSimulation { get => false; }
+
+        public TimeSpan MaxAge => new TimeSpan(0, 3, 0);
+
+        public bool IsGeolcationEnabled => Dependent.IsGeolcationEnabled;
+    }
+}

TINKLib/Services/Geolocation/SimulatedGeolocationService.cs

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+using System;
+using System.Threading.Tasks;
+using TINK.Model.Device;
+using Xamarin.Essentials;
+
+namespace TINK.Model.Services.Geolocation
+{
+    public class SimulatedGeolocationService : IGeolocation
+    {
+        private IGeolodationDependent Dependent { get; }
+
+        public SimulatedGeolocationService(IGeolodationDependent dependent)
+        {
+            Dependent = dependent;
+        }
+
+        public async Task<Location> GetAsync(DateTime? timeStamp = null)
+        {
+            return await Task.FromResult(new Location(47.976634, 7.825490) { Accuracy = 0, Timestamp = timeStamp ?? DateTime.Now }); ;
+        }
+
+        /// <summary> If true location data returned is simulated.</summary>
+        public bool IsSimulation { get => true; }
+
+        public bool IsGeolcationEnabled => Dependent.IsGeolcationEnabled;
+    }
+}