using ModelTools.BusinessLogics;
using SecurityBusinessLogic.BindingModels;
using SecurityBusinessLogic.ViewModels;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace SecurityBusinessLogic.BusinessLogics
{
	/// <summary>
	/// Менеджер по работе с пользователем системы
	/// </summary>
	public class UserManager
	{
		private readonly int _countDayToBanned = 3;

		private readonly int _countMaxAttempt = 3;

		private readonly RoleBusinessLogic _roleBusinessLogic;

		private readonly UserBusinessLogic _userBusinessLogic;

		private static UserManager _userManager;

		private static readonly object _lockObject = new();

		private UserManager()
		{
			_roleBusinessLogic = UnityContainerConfigurator.Resolve<RoleBusinessLogic>();
			_userBusinessLogic = UnityContainerConfigurator.Resolve<UserBusinessLogic>();
		}

		public static UserManager GetInstance
		{
			get
			{
				if (_userManager == null)
				{
					lock (_lockObject)
					{
						_userManager = new UserManager();
					}
				}

				return _userManager;
			}
		}

		/// <summary>
		/// Аутентифицированный пользователь
		/// </summary>
		public UserViewModel User { get; private set; }

		/// <summary>
		/// Список ролей аутентифицированного пользователь
		/// </summary>
		public List<Guid> Roles { get; private set; }

		/// <summary>
		/// Сообщение об ошибке
		/// </summary>
		public string ErrorMessage { get; private set; }

		/// <summary>
		/// Идентификатор аутентифицированного пользователь
		/// </summary>
		public Guid? UserId => User?.Id;

		/// <summary>
		/// Выполнена ли аутентификация
		/// </summary>
		public bool IsAuth => User != null;

		/// <summary>
		/// Аутентификация пользователя
		/// </summary>
		/// <param name="login"></param>
		/// <param name="password"></param>
		/// <returns></returns>
		public async Task LoginAsync(string login, string password)
		{
			await Task.Run(() =>
			{
				UserSetBindingModel model;
				var passwordHash = GetPasswordHash(password);
				var user = _userBusinessLogic.GetElement(new UserGetBindingModel
				{
					Login = login,
					Password = passwordHash,
					SkipCheck = true
				});

				if (user == null)
				{
					if(_userBusinessLogic.Errors.Count > 0)
					{
						throw new Exception(_userBusinessLogic.Errors[0].Message);
					}

					user = _userBusinessLogic.GetElement(new UserGetBindingModel
					{
						Login = login,
						IsBanned = true,
						SkipCheck = true
					});
					if (user != null)
					{
						user.CountAttempt++;
						if (user.CountAttempt > _countMaxAttempt)
						{
							user.IsBanned = true;
							user.DateBanned = DateTime.Now;
						}

						model = GetSetBindingModel(user);
						model.Password = passwordHash;
						_userBusinessLogic.Update(model);
					}

					if (_userBusinessLogic.Errors.Count > 0)
					{
						throw new Exception(_userBusinessLogic.Errors[0].Message);
					}

					throw new Exception("Введен неверный логин/пароль");
				}
				if (user.IsBanned)
				{
					if (user.DateBanned.Value.AddDays(_countDayToBanned) > DateTime.Now)
					{
						user.IsBanned = false;
					}
					else
					{
						throw new Exception("Пользователь заблокирован");
					}
				}

				user.DateLastVisit = DateTime.Now;
				user.CountAttempt = 0;

				model = GetSetBindingModel(user);
				model.Password = passwordHash;
				_userBusinessLogic.Update(model);

				User = user;
				Roles = _roleBusinessLogic.GetList(new RoleGetBindingModel { UserId = User.Id }).List.Select(x => x.Id).ToList();
			});
		}

		/// <summary>
		/// Выход из системы
		/// </summary>
		/// <returns></returns>
		public async Task LogoutAsync()
		{
			await Task.Run(() =>
			{
				User = null;
				Roles = null;
			});
		}

		/// <summary>
		/// Смена пароля
		/// </summary>
		/// <param name="login"></param>
		/// <param name="oldPassword"></param>
		/// <param name="newPassword"></param>
		public void ChangePassword(string login, string oldPassword, string newPassword)
		{
			var user = _userBusinessLogic.GetElement(new UserGetBindingModel
			{
				Login = login,
				Password = GetPasswordHash(oldPassword),
				SkipCheck = true
			});
			if (user == null)
			{
				throw new Exception("Введен неверный логин/пароль");
			}
			if (user.IsBanned)
			{
				throw new Exception("Пользователь забаннен");
			}
			var model = GetSetBindingModel(user);
			model.Password = GetPasswordHash(newPassword);
			_userBusinessLogic.Update(model);
		}

		/// <summary>
		/// Получение хеша пароля
		/// </summary>
		/// <param name="password"></param>
		/// <returns></returns>
		public static string GetPasswordHash(string password) => Encoding.ASCII.GetString((new MD5CryptoServiceProvider()).ComputeHash(Encoding.ASCII.GetBytes(password)));

		/// <summary>
		/// Получение модели для сохранения из представления
		/// </summary>
		/// <param name="model"></param>
		/// <returns></returns>
		private static UserSetBindingModel GetSetBindingModel(UserViewModel model)
		{
			return new UserSetBindingModel
			{
				Id = model.Id,
				Login = model.Login,
				LecturerId = model.LecturerId,
				StudentId = model.StudentId,
				EmployeeId = model.EmployeeId,
				Avatar = model.Avatar,
				IsBanned = model.IsBanned,
				DateBanned = model.DateBanned,
				CountAttempt = model.CountAttempt,
				DateLastVisit = model.DateLastVisit
			};
		}
	}
}