using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using TINK.Model.User.Account;

namespace TINK.Model.User
{
	public delegate void LoginStateChangedDelegate(object p_oSender, EventArgs p_oEventArgs);


	/// <summary>
	/// Manages user of the app.
	/// </summary>
	public class User : IUser
	{
		/// <summary> Holds account data. </summary>
		private AccountMutable Account { get; }

		/// <summary>
		/// Provides storing functionality.
		/// </summary>
		private IStore Store { get; }

		/// <summary> Holds the id of the device. </summary>
		public string DeviceId { get; }

		/// Loads user name and passwort from account store.
		/// </summary>
		/// <param name="p_oAccountStore"> Object to use for loading and saving user data.</param>
		public User(
			IStore accountStore,
			IAccount account,
			string deviceId)
		{
			Store = accountStore
				?? throw new ArgumentException("Can not instantiate user- object. No store functionality available.");
			DeviceId = deviceId;
			Account = new AccountMutable(account);
		}

		/// <summary> Is fired wheneverlogin state changes. </summary>
		public event LoginStateChangedDelegate StateChanged;

		/// <summary>
		/// Holds a value indicating whether user is logged in or not.
		/// </summary>
		public bool IsLoggedIn => Account.GetIsLoggedIn();

		/// <summary>
		/// Holds the mail address.
		/// </summary>
		public string Mail
		{
			get { return Account.Mail; }
		}

		/// <summary>
		/// Gets the sessiong cookie.
		/// </summary>
		public string SessionCookie
		{
			get { return Account.SessionCookie; }
		}
		/// <summary>
		/// Holds the password.
		/// </summary>
		public string Password
		{
			get { return Account.Pwd; }
		}

		/// <summary>Holds the debug level.</summary>
		public Permissions DebugLevel
		{
			get { return Account.DebugLevel; }
		}

		/// <summary> Holds the group of the bike (TINK, Konrad, ...).</summary>
		public IEnumerable<string> Group { get { return Account.Group; } }

		/// <summary> Logs in user. </summary>
		/// <param name="p_oAccount">Account to use for login.</param>
		/// <param name="p_str_DeviceId">Holds the Id to identify the device.</param>
		/// <param name="isConnected">True if connector has access to copri server, false if cached values are used.</param>
		public void CheckIsPasswordValid(string mail, string password)
		{
			if (IsLoggedIn)
			{
				throw new Exception($"Can not log in user {mail} because user {Account} is already logged in.");
			}

			// Check if password might be valid before connecting to copri.
			var l_oResult = Validator.ValidateMailAndPasswordDelegate(mail, password);

			if (!l_oResult.IsValid)
			{
				// Password is not valid.
				throw new ArgumentException(l_oResult.Description[Elements.Account]);
			}
		}

		/// <summary> Logs in user. </summary>
		/// <param name="p_oAccount">Account to use for login.</param>
		/// <param name="p_str_DeviceId">Holds the Id to identify the device.</param>
		/// <param name="isConnected">True if connector has access to copri server, false if cached values are used.</param>
		public async Task Login(IAccount account)
		{
			// Update account instance from copri data.
			Account.Copy(account);

			// Save data to store.
			await Store.Save(Account);

			// Nothing to do because state did not change.
			StateChanged?.Invoke(this, new EventArgs());
		}

		/// <summary> Logs in user</summary>
		/// <returns></returns>
		public void Logout()
		{
			var l_oPreviousState = IsLoggedIn;

			Account.Copy(Store.Delete(Account));

			if (IsLoggedIn == l_oPreviousState)
			{
				// Nothing to do because state did not change.
				return;
			}

			StateChanged?.Invoke(this, new EventArgs());
		}

		/// <summary> 
		/// Filters bike groups depending on whether user has access to all groups of bikes.
		/// Some user may be "TINK"- user only, some "Konrad" and some may be "TINK" and "Konrad" users.
		/// </summary>
		/// <param name="p_oAccount">Account to filter with.</param>
		/// <param name="source">Groups to filter..</param>
		/// <returns>Filtered bike groups.</returns>
		public IEnumerable<string> DoFilter(IEnumerable<string> source = null)
		{
			return Account.DoFilter(source);
		}
	}
}