using System;
using System.Threading;
using System.Threading.Tasks;
using Serilog;
using TINK.Model.Device;
using Xamarin.Essentials;

namespace TINK.Services.Geolocation
{
	public abstract class GeolocationService : IGeolocationService
	{
		/// <summary> Timeout for geolocation request operations.</summary>
		private const int GEOLOCATIONREQUEST_TIMEOUT_MS = 5000;

		private IGeolodationDependent Dependent { get; }

		private GeolocationAccuracy Accuracy { get; }

		public GeolocationService(
			IGeolodationDependent dependent,
			GeolocationAccuracy accuracy = GeolocationAccuracy.Default)
		{
			Dependent = dependent;
			Accuracy = accuracy;
		}

		public bool IsSimulation => false;

		public bool IsGeolcationEnabled => Dependent.IsGeolcationEnabled;

		/// <summary> Gets the current location.</summary>
		/// <param name="cancellationToken">Token to cancel request for geolocation.</param>
		/// <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<IGeolocation> GetAsync(CancellationToken? cancellationToken = null, DateTime? timeStamp = null)
		{
			try
			{
				var request = new GeolocationRequest(Accuracy, TimeSpan.FromMilliseconds(GEOLOCATIONREQUEST_TIMEOUT_MS));
				return cancellationToken.HasValue
					? (await Xamarin.Essentials.Geolocation.GetLocationAsync(request, cancellationToken.Value)).ToGeolocation()
					: (await Xamarin.Essentials.Geolocation.GetLocationAsync(request)).ToGeolocation();
			}
			catch (FeatureNotSupportedException fnsEx)
			{
				// Handle not supported on device exception
				Log.ForContext<GeolocationService>().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<GeolocationService>().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<GeolocationService>().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<GeolocationService>().Error("Retrieving Geolocation failed. {Exception}", ex);
				throw new Exception("Abfrage Standort fehlgeschlagen.", ex);
			}
		}
	}
}