using System;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Serilog;
using TINK.Model;
using TINK.Model.Bikes.BikeInfoNS.CopriLock;
using TINK.Model.Connector;
using TINK.Model.Connector.Updater;
using TINK.Model.Device;
using TINK.Model.Services.CopriApi;
using TINK.Repository;
using TINK.Repository.Response;
using TINK.Services.CopriApi.Exception;

namespace TINK.Services.CopriApi
{
	public static class Polling
	{
		/// <summary> Timeout for open/ close operations.</summary>
		private const int OPEN_CLOSE_TIMEOUT_MS = 50000;

		/// <summary> Opens lock.</summary>
		/// <param name="copriServer"> Instance to communicate with backend.</param>
		/// <param name="bike">Bike object holding id of bike to open. Lock state of object is updated after open request.</param>
		public static async Task OpenAync(
			this ICopriServerBase copriServer,
			IBikeInfoMutable bike)
		{
			if (!(copriServer is ICachedCopriServer cachedServer))
				throw new ArgumentNullException(nameof(copriServer));

			await cachedServer.OpenAync(bike);
		}

		/// <summary> Opens lock.</summary>
		/// <param name="cachedServer"> Instance to communicate with backend.</param>
		/// <param name="bike">Bike object holding id of bike to open. Lock state of object is updated after open request.</param>
		public static async Task OpenAync(
			this ICachedCopriServer cachedServer,
			IBikeInfoMutable bike)
		{
			// Send command to close lock
			await cachedServer.UpdateLockingStateAsync(
				bike.Id,
				Repository.Request.lock_state.unlocking,
				bike.OperatorUri);

			var lockingState = await cachedServer.GetLockStateAsync(bike.Id);

			var watch = new Stopwatch();
			watch.Start();

			while (lockingState != LockingState.Open
				&& lockingState != LockingState.UnknownDisconnected
				&& watch.Elapsed < TimeSpan.FromMilliseconds(OPEN_CLOSE_TIMEOUT_MS))
			{
				// Delay a litte to reduce load on backend.
				await Task.Delay(3000);

				lockingState = await cachedServer.GetLockStateAsync(bike.Id);
				Log.Information($"Current lock state is {lockingState}.");
			}

			// Update locking state.
			bike.LockInfo.State = lockingState;
		}


		/// <summary>
		/// Books a bike and opens the lock.
		/// </summary>
		/// <param name="copriServer"> Instance to communicate with backend.</param>
		/// <param name="bike">Bike to book and open.</param>
		/// <param name="mailAddress">Mail address of user which books bike.</param>
		public static async Task BookAndOpenAync(
			this ICopriServerBase copriServer,
			IBikeInfoMutable bike,
			string mailAddress)
		{
			if (bike == null)
			{
				throw new ArgumentNullException(nameof(bike), "Can not book bike and open lock. No bike object available.");
			}

			if (!(copriServer is ICachedCopriServer cachedServer))
				throw new ArgumentNullException(nameof(copriServer));

			// Send command to open lock
			var response = bike.State.Value == Model.State.InUseStateEnum.Disposable
				? (await copriServer.BookAvailableAndStartOpeningAsync(bike.Id, bike.OperatorUri)).GetIsBookingResponseOk(bike.Id)
				: (await copriServer.BookReservedAndStartOpeningAsync(bike.Id, bike.OperatorUri)).GetIsBookingResponseOk(bike.Id);

			// Upated locking state.
			var lockingState = await cachedServer.GetOccupiedBikeLockStateAsync(bike.Id);

			var watch = new Stopwatch();
			watch.Start();

			while (lockingState.HasValue /* if null bike is no more occupied*/ &&
				lockingState.Value != LockingState.Open
				&& watch.Elapsed < TimeSpan.FromMilliseconds(OPEN_CLOSE_TIMEOUT_MS))
			{
				// Delay a litte to reduce load on backend.
				await Task.Delay(3000);

				lockingState = await cachedServer.GetOccupiedBikeLockStateAsync(bike.Id);
				Log.Debug($"Current lock state of bike {bike.Id} is {(lockingState.HasValue ? lockingState.Value.ToString() : "-")}.");
			}

			// Check if bike is still occupied.
			if (lockingState == null)
			{
				// User did not take bike out of the station
				throw new BikeStillInStationException("Booking was canceled because bike is still in station.");
			}

			// Upate booking state.
			bike.Load(
				response,
				mailAddress,
				Model.Bikes.BikeInfoNS.BC.NotifyPropertyChangedLevel.None);

			// Update locking state.
			bike.LockInfo.State = lockingState.Value;
		}

		/// <summary>
		/// Returns a bike and closes the lock.
		/// </summary>
		/// <param name="copriServer"> Instance to communicate with backend.</param>
		/// <param name="bike">Bike to close.</param>
		public static async Task CloseAync(
			this ICopriServerBase copriServer,
			IBikeInfoMutable bike)
		{
			if (!(copriServer is ICachedCopriServer cachedServer))
				throw new ArgumentNullException(nameof(copriServer));

			// Send command to close lock
			await copriServer.UpdateLockingStateAsync(
				bike.Id,
				Repository.Request.lock_state.locking,
				bike.OperatorUri);

			var lockingState = await cachedServer.GetLockStateAsync(bike.Id);

			var watch = new Stopwatch();
			watch.Start();

			while (lockingState != LockingState.Closed
				&& lockingState != LockingState.UnknownDisconnected
				&& watch.Elapsed < TimeSpan.FromMilliseconds(OPEN_CLOSE_TIMEOUT_MS))
			{
				// Delay a litte to reduce load on backend.
				await Task.Delay(3000);

				lockingState = await cachedServer.GetLockStateAsync(bike.Id);
				Log.Information($"Current lock state is {lockingState}.");
			}

			// Update locking state.
			bike.LockInfo.State = lockingState;
		}

		/// <summary>
		/// Returns a bike and closes the lock.
		/// </summary>
		/// <param name="copriServer"> Instance to communicate with backend.</param>
		/// <param name="smartDevice">Smart device on which app runs on.</param>
		/// <param name="mailAddress">Mail address of user which books bike.</param>
		public static async Task<BookingFinishedModel> ReturnAndCloseAync(
			this ICopriServerBase copriServer,
			ISmartDevice smartDevice,
			IBikeInfoMutable bike)
		{
			if (!(copriServer is ICachedCopriServer cachedServer))
				throw new ArgumentNullException(nameof(copriServer));

			// Send command to open lock
			DoReturnResponse response =
				await copriServer.ReturnAndStartClosingAsync(bike.Id, bike.OperatorUri);

			// Upate booking state
			bike.Load(Model.Bikes.BikeInfoNS.BC.NotifyPropertyChangedLevel.None);

			var lockingState = await cachedServer.GetLockStateAsync(bike.Id);

			var watch = new Stopwatch();
			watch.Start();

			while (lockingState != LockingState.Closed
				&& lockingState != LockingState.UnknownDisconnected
				&& watch.Elapsed < TimeSpan.FromMilliseconds(OPEN_CLOSE_TIMEOUT_MS))
			{
				// Delay a litte to reduce load on backend.
				await Task.Delay(3000);

				lockingState = await cachedServer.GetLockStateAsync(bike.Id);
				Log.Information($"Current lock state is {lockingState}.");
			}

			// Update locking state.
			bike.LockInfo.State = lockingState;

			return response?.Create() ?? new BookingFinishedModel();
		}

		/// <summary>
		/// Queries the locking state from copri.
		/// </summary>
		/// <param name="copriServer">Service to use.</param>
		/// <param name="bikeId">Bike id to query lock state for.</param>
		/// <returns>Locking state</returns>
		private static async Task<LockingState> GetLockStateAsync(
			this ICachedCopriServer copriServer,
			string bikeId)
		{
			// Querry reserved or booked bikes first for performance reasons.
			var bikeReservedOrBooked = (await copriServer.GetBikesOccupied(false))?.Response.bikes_occupied?.Values?.FirstOrDefault(x => x.bike == bikeId);
			if (bikeReservedOrBooked != null)
			{
				return bikeReservedOrBooked.GetCopriLockingState();
			}

			var bikeAvailable = (await copriServer.GetBikesAvailable(false))?.Response.bikes?.Values?.FirstOrDefault(x => x.bike == bikeId);
			if (bikeAvailable != null)
			{
				return bikeAvailable.GetCopriLockingState();
			}

			return LockingState.UnknownDisconnected;
		}

		/// <summary>
		/// Queries the locking state of a occupied bike from copri.
		/// </summary>
		/// <param name="copriServer">Service to use.</param>
		/// <param name="bikeId">Bike id to query lock state for.</param>
		/// <returns>Locking state if bike is still occupied, null otherwise.</returns>
		private static async Task<LockingState?> GetOccupiedBikeLockStateAsync(
			this ICachedCopriServer copriServer,
			string bikeId)
		{
			var bikeReservedOrBooked = (await copriServer.GetBikesOccupied(false))?.Response.bikes_occupied?.Values?.FirstOrDefault(x => x.bike == bikeId);
			if (bikeReservedOrBooked != null)
			{
				return bikeReservedOrBooked.GetCopriLockingState();
			}

			return null;
		}
	}
}