using System;

using System.Collections.Generic;

using System.Linq;

​

namespace SSI_Interview

{

    class Program

    {

        /// Support Ticket #1:

        ///

        /// PROBLEM: The user (UserID: 1001) attempts to add a new Ticket to the system without any requirements. A fatal error occurs with no feedback. 

        ///

        /// ACCEPTANCE CRITERIA: There must be at least one requirement per Ticket. If there is not a requirement, an exception should be raised stating: "You must have at least one requirement".

        ///

        /// ############

        ///

        /// Support Ticket #2:

        ///

        /// PROBLEM: The user (UserID: 1001) attempts to mark a ticket's Status as "Closed". A fatal error occurs with no feedback.

        ///

        /// ACCEPTANCE CRITERIA: The user should be able to mark a ticket as closed.

        ///

        /// ############

        ///

        /// STEPS PER SUPPORT TICKET:

        /// #1 - Reproduce the PROBLEM stated above by adding code to the Main function. Use the TicketStore to Add or Update a Ticket.

        /// #2 - Add your implementation to meet the ACCEPTANCE CRITERIA

        static void Main(string[] args)

        {

            var ticket = new Ticket();

            TicketStore.Add(ticket);

        }

​

        static readonly TicketStore TicketStore = new TicketStore();

    }

​

    public class Ticket : IModel

    {

        public int ID { get; set; }

        public int UserID { get; set; }

        public string Status { get; set; }

        public List<Requirement> Requirements { get; set; }

​

        public class Requirement

        {

            public int? ID { get; set; }

            public string Description { get; set; }

        }

    }

​

    public class User : IModel

    {

        public int ID { get; set; }

        public string Email { get; set; }

    }

​

    public class TicketStore

    {

        private readonly Repository<Ticket, MockTicketDatabase> _repository;

        private readonly TicketPreSaver _preSaver;

        private readonly TicketPostSaver _postSaver;

​

        public TicketStore()

        {

            _repository = new Repository<Ticket, MockTicketDatabase>();

            _preSaver = new TicketPreSaver();

            _postSaver = new TicketPostSaver();

        }

​

        public Ticket Add(Ticket ticket)

        {

            _preSaver.Execute(ticket);

            _repository.Add(ticket);

            _postSaver.Execute(ticket);

            return ticket;

        }

​

        public Ticket Update(Ticket ticket)

        {

            _preSaver.Execute(ticket);

            _repository.Update(ticket);

            _postSaver.Execute(ticket);

            return ticket;

        }

    }

​

    public class TicketPreSaver

    {

        private readonly UserStore _userStore;

​

        public TicketPreSaver()

        {

            _userStore = new UserStore();

        }

​

        public void Execute(Ticket ticket)

        {

            if (ticket.Requirements.Count > 10)

            {

                throw new Exception("A ticket cannot have more than 10 requirements");

            }

​

            if (!_userStore.Exists(ticket.UserID))

            {

                throw new Exception("User does not exist");

            }

​

            if (ticket.ID == 0)

            {

                ticket.Status = "New";

            }

        }

    }

​

    public class TicketPostSaver

    {

        private readonly EmailService _emailService;

        private readonly UserStore _userStore;

​

        public TicketPostSaver()

        {

            _emailService = new EmailService();

            _userStore = new UserStore();

        }

​

        public void Execute(Ticket ticket)

        {

            if (ticket.Status == "New")

            {

                _emailService.SendEmail("admin@streetsolutions.com", $"Ticket #{ticket.ID} has been created.");

            }

​

            if (ticket.Status == "Closed")

            {

                var user = _userStore.Get(ticket.UserID);

                _emailService.SendEmail(user?.Email, $"Your ticket #{ticket.ID} has been closed.");

            }

        }

    }

​

    public class Repository<T, TDataStore> where T : IModel, new() where TDataStore : IDataStore<T>, new()

    {

        private readonly IDataStore<T> _database;

​

        public Repository()

        {

            _database = new TDataStore();

        }

​

        public T Get(int ID)

        {

            return _database.Items.SingleOrDefault(x => x.ID == ID);

        }

​

        public void Add(T item)

        {

            item.ID = !_database.Items.Any() ? 1 : _database.Items.Select(x => x.ID).Max() + 1;

            _database.Items.Add(item);

        }

​

        public void Update(T item)

        {

            var existingItem = _database.Items.SingleOrDefault(x => x.ID == item.ID);

            if (existingItem == null)

            {

                throw new Exception("Item not found");

            }

            var index = _database.Items.FindIndex(x => x.ID == item.ID);

            _database.Items[index] = item;

        }

    }

​

    public class UserStore

    {

        private readonly Repository<User, MockUserDatabase> _repository;

​

        public UserStore()

        {

            _repository = new Repository<User, MockUserDatabase>();

        }

​

        public bool Exists(int userID)

        {

            return _repository.Get(userID) != null;

        }

​

        public User Get(int userID)

        {

            return _repository.Get(userID);

        }

    }

​

    public class EmailService

    {

        public void SendEmail(string to, string message)

        {

            if (string.IsNullOrEmpty(to))

            {

                throw new Exception();

            }

​

            Console.WriteLine($"Email sent to {to} with message: {message}");

        }

    }

​

    public class MockUserDatabase : IDataStore<User>

    {

        public List<User> Items { get; set; }

​

        public MockUserDatabase()

        {

            Items = new List<User>()

            {

                new User(){ ID = 1000, Email = "admin@streetsolutions.com" },

                new User(){ ID = 1001},

                new User(){ ID = 1002, Email = "john@streetsolutions.com" },

                new User(){ ID = 1003, Email = "jane@streetsolutions.com" }

            };

        }

    }

​

    public class MockTicketDatabase : IDataStore<Ticket>

    {

        public List<Ticket> Items { get; set; }

​

        public MockTicketDatabase()

        {

            Items = new List<Ticket>();

        }

    }

​

    public interface IModel

    {

        int ID { get; set; }

    }

​

    public interface IDataStore<T> where T : IModel, new()

    {

        public List<T> Items { get; set; }

    }

}