using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Serilog;
using ShareeBike.Model.Bikes.BikeInfoNS.BluetoothLock;
using ShareeBike.Model.Connector;
using ShareeBike.Model.Device;
using ShareeBike.Services.BluetoothLock.Tdo;
using Xamarin.Essentials;

namespace ShareeBike.Services.BluetoothLock.BLE
{
	public abstract class LockItServiceBase
	{
		/// <summary>Constructs base object.</summary>
		/// <param name="cipher">Encrpyting/ decrypting object.</param>        /// <param name="connectTimeout">Timeout to apply when connecting to bluetooth lock.</param>
		public LockItServiceBase(ICipher cipher)
		{
			Cipher = cipher;
		}

		/// <summary> Holds timeout values for series of connecting attempts to a lock or multiple locks. </summary>
		public ITimeOutProvider TimeOut { get; set; }

		protected ICipher Cipher { get; }

		/// <summary> List of available or connected bluetooth devices. </summary>
		protected List<ILockService> DeviceList = new List<ILockService>();


		/// <summary> Reconnect locks of interest if required. </summary>
		/// <remarks> Consists of a bluetooth connect plus invocation of an authentication sequence for each lock to be reconnected. </remarks>
		/// <param name="locksInfo">Locks to reconnect.</param>
		/// <param name="connectTimeout">Timeout for connect operation.</param>
		public static async Task CheckReconnect(
			IEnumerable<ILockService> deviceList,
			IEnumerable<LockInfoAuthTdo> locksInfo,
			TimeSpan connectTimeout)
		{
			// Get list of target locks without invalid entries.
			var validLocksInfo = locksInfo
				.Where(x => x.IsIdValid || x.IsGuidValid)
				.Where(x => x.K_seed.Length > 0 && x.K_u.Length > 0)
				.ToList();

			foreach (var device in deviceList)
			{
				if (device.GetDeviceState() == DeviceState.Connected)
				{
					// No need to reconnect device because device is already connected.
					continue;
				}

				var lockInfo = validLocksInfo.FirstOrDefault(x => x.Id == device.Name.GetBluetoothLockId() || x.Guid == device.Guid);

				if (lockInfo == null)
				{
					// Current lock from deviceList is not of interest detected, no need to reconnect.
					continue;
				}

				try
				{
					await device.ReconnectAsync(lockInfo, connectTimeout);
				}
				catch (System.Exception exception)
				{
					// Member is called for background update of missing devices. 
					// Do not display any error messages.
					Log.ForContext<LockItServiceBase>().Error($"Reconnect failed. {exception.Message}");
					continue;
				}
			}
		}

		/// <summary> Gets the state for locks of interest.</summary>
		/// <remarks>
		/// Might require a
		/// - connect to lock 
		/// - reconnect to lock
		/// </remarks>
		/// <param name="locksInfo">Locks toget info for.</param>
		/// <param name="connectTimeout">Timeout for connect operation of a single lock.</param>
		public async Task<IEnumerable<LockInfoTdo>> GetLocksStateAsync(
			IEnumerable<LockInfoAuthTdo> locksInfo,
			TimeSpan connectTimeout)
		{
			if (locksInfo.Count() == 0)
			{
				// Nothing to do.
				return new List<LockInfoTdo>();
			}

			// Reconnect locks.
			await CheckReconnect(DeviceList, locksInfo, connectTimeout);

			// Connect to locks which were not yet discovered.
			DeviceList.AddRange(await CheckConnectMissing(locksInfo, connectTimeout));

			// Get devices for which to update state.            
			var locksInfoState = new List<LockInfoTdo>();

			foreach (var device in DeviceList)
			{
				var lockInfoAuth = locksInfo.FirstOrDefault(x => x.Guid == device.Guid || x.Id == device.Id);
				if (lockInfoAuth == null)
				{
					// Device is not of interest.
					continue;
				}

				var state = await device.GetLockStateAsync();
				locksInfoState.Add(new LockInfoTdo.Builder
				{
					Id = lockInfoAuth.Id,
					Guid = lockInfoAuth.IsGuidValid ? lockInfoAuth.Guid : device.Guid,
					State = state?.State
				}.Build());
			}

			return locksInfoState;
		}

		/// <remarks> Consists of a bluetooth connect plus invocation of an authentication sequence. </remarks>
		/// <param name="locksInfo">Locks to reconnect.</param>
		/// <param name="connectTimeout">Timeout for connect operation of a single lock.</param>
		protected abstract Task<IEnumerable<ILockService>> CheckConnectMissing(
			IEnumerable<LockInfoAuthTdo> locksInfo,
			TimeSpan connectTimeout);

		/// <summary>Gets a lock by bike Id.</summary>
		/// <param name="bikeId"></param>
		/// <returns>Lock object</returns>
		public ILockService this[int bikeId]
		{
			get
			{
				var device = DeviceList.FirstOrDefault(x => x.Name.GetBluetoothLockId() == bikeId);
				if (device == null)
				{
					return new NullLock(bikeId);
				}

				return device;
			}
		}

		/// <summary> Connects to lock.</summary>
		/// <remarks> Consists of a bluetooth connect plus invocation of an authentication sequence. </remarks>
		/// <param name="authInfo"> Info required to connect to lock.</param>
		/// <param name="connectTimeout">Timeout for connect operation.</param>
		public async Task<LockingState> DisconnectAsync(int bikeId, Guid bikeGuid)
		{
			if (DeviceInfo.Platform != DevicePlatform.Unknown && MainThread.IsMainThread == false)
			{
				throw new System.Exception("Can not disconnect from lock. Platform must not be unknown and bluetooth code must be run on main thread.");
			}

			Log.ForContext<LockItByScanServiceBase>().Debug($"Request to disconnect from device {bikeId}/ {bikeGuid}.");

			var lockIt = DeviceList.FirstOrDefault(x => x.Name.GetBluetoothLockId() == bikeId || x.Guid == bikeGuid);

			if (lockIt == null)
			{
				// Nothing to do
				return LockingState.UnknownDisconnected;
			}

			DeviceList.Remove(lockIt);

			if (lockIt.GetDeviceState() == DeviceState.Disconnected)
			{
				// Nothing to do
				return LockingState.UnknownDisconnected;
			}

			await lockIt.Disconnect();
			return LockingState.UnknownDisconnected;
		}
	}
}