using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace Model.Managers
{
    /// <summary>
    /// The Main manager of the model.
    /// </summary>
    public class MasterManager
    {
        #region Attributes & Properties
        /// <summary>
        /// The currently connected user. 'null' if no user is connected.
        /// </summary>
        public User? CurrentConnectedUser { get; private set; }

        /// <summary>
        /// The collection of all recipes loaded.
        /// </summary>
        public RecipeCollection Recipes { get; private set; }

        /// <summary>
        /// The collection of all users loaded.
        /// </summary>
        public List<User> Users { get; private set; }

        /// <summary>
        /// The data manager for load, save, export and import data.
        /// </summary>
        public DataManager DataMgr { get; private set; }
        #endregion

        #region Constructors
        /// <summary>
        /// Constructor of the MasterManager.
        /// </summary>
        /// <param name="dataManager">The serializer for the data.</param>
        public MasterManager(IDataManager dataManager)
        {
            DataMgr = new DataManager(dataManager);
            CurrentConnectedUser = null;
            Recipes = DataMgr.GetRecipes("all recipes");
            Users = DataMgr.GetUsers();
        }
        #endregion

        #region Methods
        /// <summary>
        /// Log in an user. Test if the log in information are correct then connect the user.
        /// </summary>
        /// <param name="mail">The user's mail</param>
        /// <param name="password">The user's password.</param>
        /// <returns>True if the user was correctly connected, false if there is something wrong.</returns>
        /// <exception cref="ArgumentNullException"></exception>
        public bool Login(string mail, string password)
        {
            if (Users is null || Users.Count == 0)
                throw new ArgumentNullException("There is no users registred.");

            if (mail == "admin")
            {
                CurrentConnectedUser = Users.FirstOrDefault(u => u.Mail == "admin@mctg.fr");
                return true;
            }

            User? user = Users.Find(u => u.Mail == mail);

            if (user is null || !user.psswMgr.VerifyPassword(user.Password, password))
                return false;

            CurrentConnectedUser = user;
            return true;
        }

        /// <summary>
        /// Log out an user.
        /// </summary>
        /// <returns>True if the user is correctly diconnected, false otherwise.</returns>
        public bool Logout()
        {
            if (CurrentConnectedUser is null)
                return false;

            CurrentConnectedUser = null;
            return true;
        }

        /// <summary>
        /// Register an user.
        /// </summary>
        /// <param name="newuser">The new user to add in the database.</param>
        /// <returns>False if there is a problem with the registerement, true otherwise.</returns>
        public bool Register(User newuser)
        {
            try
            {
                User user = newuser;
                DataMgr.Data[nameof(User)].Add(user);
                Users = DataMgr.GetUsers();
            }
            catch (ArgumentException e)
            {
                Debug.WriteLine(e.Message);
                return false;
            }

            return true;
        }

        /// <summary>
        /// Add a recipe to the database.
        /// </summary>
        /// <param name="recipe">The recipe to add.</param>
        public void AddRecipe(Recipe recipe)
        {
            DataMgr.Data[nameof(Recipe)].Add(recipe);
            Recipes = DataMgr.GetRecipes();
        }

        /// <summary>
        /// Get the current connected user's personal recipes.
        /// </summary>
        /// <returns>The current connected user's personal recipes.</returns>
        public RecipeCollection GetCurrentUserRecipes()
            => new RecipeCollection("User recipes",
                DataMgr.GetRecipes().FindAll(r => r.AuthorMail == CurrentConnectedUser?.Mail).ToArray());
    }
    #endregion
}