using System.Threading.Tasks;
using Xamarin.Essentials;

namespace TINK.Services.Permissions.Essentials
{
	using XamPermission = Xamarin.Essentials.Permissions;
	using XamPermissionStatus = PermissionStatus;

	public class Permissions : ILocationPermission
	{
		/// <summary> Checks the permission status.</summary>
		/// <returns>Current permission status.</returns>
		public async Task<Status> CheckStatusAsync()
		{
			var status = await XamPermission.CheckStatusAsync<XamPermission.LocationWhenInUse>();
			if (status == XamPermissionStatus.Granted)
			{
				return Status.Granted;
			}

			if (status == XamPermissionStatus.Denied
				&& DeviceInfo.Platform == DevicePlatform.iOS)
			{
				// Prompt the user to turn on in settings
				// On iOS once a permission has been denied it may not be requested again from the application
				return Status.DeniedRequiresSettingsUI;
			}

			if (XamPermission.ShouldShowRationale<XamPermission.LocationWhenInUse>())
			{
				// Prompt the user with additional information as to why the permission is needed
				return Status.Denied;
			}

			switch (status)
			{
				case XamPermissionStatus.Unknown:
				case XamPermissionStatus.Denied: // Map Denied to unknown because "denied means user did not allow access to location".
					return Status.Unknown;

				default:
					// Comprises: 
					// - XamPermissionStatus.Restricted:
					// - XamPermissionStatus.Disabled
					// Perission XamPermissionStatus.Granted is handled above.
					return Status.DeniedRequiresSettingsUI;
			}
		}

		/// <summary> Requests location permission.</summary>
		/// <returns>Permission status after request.</returns>
		public async Task<Status> RequestAsync()
		{
			switch (await XamPermission.RequestAsync<XamPermission.LocationWhenInUse>())
			{
				case XamPermissionStatus.Unknown:
					return Status.Unknown;

				case XamPermissionStatus.Denied:
					return Status.Denied;

				case XamPermissionStatus.Granted:
					return Status.Granted;

				default:
					// Comprises: 
					// - XamPermissionStatus.Restricted:
					// - XamPermissionStatus.Disabled
					return Status.DeniedRequiresSettingsUI;
			}
		}

		/// <summary> Opens app settings dialog.</summary>
		public bool OpenAppSettings()
		{
			AppInfo.ShowSettingsUI();
			return true;
		}
	}
}