using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Serilog;
using TINK.Model.Connector;
using TINK.Repository.Exception;
using TINK.Repository.Request;
using TINK.Services.BluetoothLock;
using TINK.Services.BluetoothLock.Exception;
using TINK.Services.BluetoothLock.Tdo;
using TINK.Services.Geolocation;

namespace TINK.Model.Bikes.BikeInfoNS.BluetoothLock.Command
{
	public static class CloseCommand
	{
		/// <summary>
		/// Possible steps of closing a lock.
		/// </summary>
		public enum Step
		{
			StartStopingPolling,
			StartingQueryingLocation,
			ClosingLock,
			WaitStopPollingQueryLocation,
			/// <summary>
			/// Notifies back end about modified lock state.
			/// </summary>
			UpdateLockingState,
			QueryLocationTerminated
		}

		/// <summary>
		/// Possible steps of closing a lock.
		/// </summary>
		public enum State
		{
			OutOfReachError,
			CouldntCloseMovingError,
			CouldntCloseBoltBlockedError,
			GeneralCloseError,
			StartGeolocationException,
			WaitGeolocationException,
			WebConnectFailed,
			ResponseIsInvalid,
			BackendUpdateFailed
		}

		/// <summary>
		/// Interface to notify view model about steps/ state changes of closing process.
		/// </summary>
		public interface ICloseCommandListener
		{
			/// <summary>
			/// Reports current step.
			/// </summary>
			/// <param name="currentStep">Current step to report.</param>
			void ReportStep(Step currentStep);

			/// <summary>
			/// Reports current state.
			/// </summary>
			/// <param name="currentState">Current state to report.</param>
			/// <param name="message">Message describing the current state.</param>
			/// <returns></returns>
			Task ReportStateAsync(State currentState, string message);
		}

		/// <summary>
		/// Closes the lock and updates copri.
		/// </summary>
		/// <param name="listener">Interface to notify view model about steps/ state changes of closing process.</param>
		/// <param name="stopPolling">Task which stops polling.</param>
		public static async Task InvokeAsync<T>(
			IBikeInfoMutable bike,
			IGeolocationService geolocation,
			ILocksService lockService,
			Func<bool> isConnectedDelegate,
			Func<bool, IConnector> connectorFactor,
			ICloseCommandListener listener,
			Task stopPollingTask)
		{
			// Invokes member to notify about step being started.
			void InvokeCurrentStep(Step step)
			{
				if (listener == null)
					return;

				try
				{
					listener.ReportStep(step);
				}
				catch (Exception ex)
				{
					Log.ForContext<T>().Error("An exception {exception} was thrown invoking step- action for set {step} ", ex, step);
				}
			}

			// Invokes member to notify about state change.
			async Task InvokeCurrentStateAsync(State state, string message)
			{
				if (listener == null)
					return;

				try
				{
					await listener.ReportStateAsync(state, message);
				}
				catch (Exception ex)
				{
					Log.ForContext<T>().Error("An exception {exception} was thrown invoking state- action for set {state} ", ex, state);
				}
			}

			// Wait for geolocation and polling task to stop (on finished or on canceled).
			async Task<IGeolocation> WaitForPendingTasks(Task<IGeolocation> locationTask)
			{
				// Step: Wait until getting geolocation has completed.
				InvokeCurrentStep(Step.WaitStopPollingQueryLocation);
				Log.ForContext<T>().Debug($"Waiting on steps {Step.StartingQueryingLocation} and {Step.StartStopingPolling} to finish...");
				try
				{
					await Task.WhenAll(new List<Task> { locationTask, stopPollingTask ?? Task.CompletedTask });
				}
				catch (Exception ex)
				{
					// No location information available.
					Log.ForContext<T>().Information("Canceling query location/ wait for polling task to finish failed. {Exception}", ex);
					await InvokeCurrentStateAsync(State.WaitGeolocationException, ex.Message);
					InvokeCurrentStep(Step.QueryLocationTerminated);
					return null;
				}

				Log.ForContext<T>().Debug($"Steps {Step.StartingQueryingLocation} and {Step.StartStopingPolling} finished.");
				InvokeCurrentStep(Step.QueryLocationTerminated);
				return locationTask.Result;
			}

			// Updates locking state
			async Task UpdateLockingState(IGeolocation location, DateTime timeStamp)
			{
				// Step: Update backend.
				InvokeCurrentStep(Step.UpdateLockingState);
				try
				{
					await connectorFactor(true).Command.UpdateLockingStateAsync(
						bike,
						location != null
							? new LocationDto.Builder
							{
								Latitude = location.Latitude,
								Longitude = location.Longitude,
								Accuracy = location.Accuracy ?? double.NaN,
								Age = timeStamp.Subtract(location.Timestamp.DateTime),
							}.Build()
							: null);
				}
				catch (Exception exception)
				{
					//BikesViewModel.RentalProcess.Result = CurrentStepStatus.Failed;
					if (exception is WebConnectFailureException)
					{
						// Copri server is not reachable.
						Log.ForContext<T>().Information("User locked bike {bike} in order to pause ride but updating failed (Copri server not reachable).", bike);
						await InvokeCurrentStateAsync(State.WebConnectFailed, exception.Message);
						return;
					}
					else if (exception is ResponseException copriException)
					{
						// Copri server is not reachable.
						Log.ForContext<T>().Information("User locked bike {bike} in order to pause ride but updating failed. Message: {Message} Details: {Details}", bike, copriException.Message, copriException.Response);
						await InvokeCurrentStateAsync(State.ResponseIsInvalid, exception.Message);
						return;
					}
					else
					{
						Log.ForContext<T>().Error("User locked bike {bike} in order to pause ride but updating failed. {@l_oException}", bike.Id, exception);
						await InvokeCurrentStateAsync(State.BackendUpdateFailed, exception.Message);
						return;
					}
				}
			}

			// Start query geolocation data.
			Log.ForContext<T>().Debug($"Starting step {Step.StartingQueryingLocation}...");
			InvokeCurrentStep(Step.StartingQueryingLocation);
			var ctsLocation = new CancellationTokenSource();
			Task<IGeolocation> currentLocationTask = Task.FromResult<IGeolocation>(null);
			var timeStampNow = DateTime.Now;
			try
			{
				currentLocationTask = geolocation.GetAsync(ctsLocation.Token, timeStampNow);
			}
			catch (Exception ex)
			{
				// No location information available.
				Log.ForContext<T>().Information("Starting query location failed. {Exception}", bike, ex);
				await InvokeCurrentStateAsync(State.StartGeolocationException, ex.Message);
			}

			// Close lock.
			IGeolocation currentLocation;
			Log.ForContext<T>().Debug($"Starting step {Step.ClosingLock}...");
			InvokeCurrentStep(Step.ClosingLock);
			LockitLockingState? lockingState;
			try
			{
				lockingState = await lockService[bike.LockInfo.Id].CloseAsync();
			}
			catch (Exception exception)
			{
				if (exception is OutOfReachException)
				{
					Log.ForContext<T>().Debug("Lock can not be closed. {Exception}", exception);
					await InvokeCurrentStateAsync(State.OutOfReachError, exception.Message);
				}
				else if (exception is CouldntCloseMovingException)
				{
					Log.ForContext<T>().Debug("Lock can not be closed. Lock is out of reach. {Exception}", exception);
					await InvokeCurrentStateAsync(State.CouldntCloseMovingError, exception.Message);
				}
				else if (exception is CouldntCloseBoltBlockedException)
				{
					Log.ForContext<T>().Debug("Lock can not be closed. Lock is out of reach. {Exception}", exception);
					await InvokeCurrentStateAsync(State.CouldntCloseBoltBlockedError, exception.Message);
				}
				else
				{
					Log.ForContext<T>().Debug("Lock can not be closed. Lock is out of reach. {Exception}", exception);
					await InvokeCurrentStateAsync(State.GeneralCloseError, exception.Message);
				}

				Log.ForContext<T>().Error("Lock can not be closed. {Exception}", exception);

				// Signal cts to  cancel getting geolocation.
				ctsLocation.Cancel();

				//// Step: Wait until getting geolocation and stop polling has completed.
				currentLocation = await WaitForPendingTasks(currentLocationTask);

				// Update current state from exception
				bike.LockInfo.State = exception is StateAwareException stateAwareException
					? stateAwareException.State
					: LockingState.UnknownDisconnected;

				if (!isConnectedDelegate())
				{
					// Lock state can not be updated because there is no connected.
					throw;
				}

				if (exception is OutOfReachException)
				{
					// Locking state can not be updated because lock is not connected.
					throw;
				}

				// Step: Update backend.
				// Do this even if current lock state is open (lock state must not necessarily be open before try to open, i.e. something undefined between open and closed).
				await UpdateLockingState(currentLocation, timeStampNow);

				throw;
			}

			//// Step: Wait until getting geolocation and stop polling has completed.
			currentLocation = await WaitForPendingTasks(currentLocationTask);

			bike.LockInfo.State = lockingState?.GetLockingState() ?? LockingState.UnknownDisconnected;

			// Keep geolocation where closing action occurred.
			bike.LockInfo.Location = currentLocation;

			if (!isConnectedDelegate())
			{
				return;
			}

			//// Step: Update backend.
			await UpdateLockingState(currentLocation, timeStampNow);
		}
	}
}