Final Exam - 07 December 2019 Group 1 - Inbox Manager

03.Inbox Manager
Create a program that manages users and Emails sent by users. You need to keep information about their username and their sent Emails. The Emails are represented as strings. You will be receiving lines with commands separated by "->" until you receive the "Statistics" command.  There are three possible commands:
• "Add->{username}":
o   Check if the username exists and if it does print:
"{username} is already registered"
 If it doesn’t exist, then add the user to the collection of users.
• "Send->{username}->{Email}"
o   Add the {Email} to the {username}'s collection of sent Emails.
• "Delete->{username}":
o   Delete the given user, if he exists. If the user doesn’t exist, print:
"{username} not found!"
In the end, you have to print the count of users, each user with his/her Emails. Users need to be sorted in descending order by the count of sent Emails and then by their username in ascending order in the following format:
Users count: {count}
{username}
 - {Email1}
 - {Email2}
 - {Emailn}
Input
• You will be receiving lines until you receive the "Statistics" command.
• The commands will be in the format described above.
Output
• Print the collection in the format described above after the "Statistics" command.

Examples
Input                                                       Output
Add->Mike                                                   Users count: 2
Add->George                                                 George
Send->George->Hello World                                    - Hello World
Send->George->Some random test mail                          - Some random test mail
Send->Mike->Hello, do you want to meet up tomorrow?          - It would be a pleasure
Send->George->It would be a pleasure                        Mike
Send->Mike->Another random test mail                         - Hello, do you want to meet up tomorrow?
Statistics                                                   - Another random test mail

Comments
First we receive our users. Since they are not already in our collection, we add them. Then they start sending emails and in the end we print the output in the described format.

Add->Mike
Add->George
Send->George->Hello World
Send->George->Your loan is overdue
Add->Mike                                                    Mike is already registered
Send->Mike->Hello, do you want to meet up tomorrow?
Delete->Peter                                                Peter not found!
Send->George->I'm busy                                       Users count: 1
Send->Mike->Another random test mail                         Mike
Delete->George                                                - Hello, do you want to meet up tomorrow?
Statistics                                                    - Another random test mail

using System;
using System.Collections.Generic;
using System.Linq;

public class Program
{
    public static void Main()
    {
          var listEmails = new Dictionary<string, List<string>>();
            var input = "";
            while ((input = Console.ReadLine()) != "Statistics")
            {
                var command = input.Split("->");
                var userName = command[1];

                switch (command[0])
                {
                    case "Add":
                        if (!listEmails.ContainsKey(userName))
                        {
                            listEmails.Add(userName, new List<string>());
                        }
                        else
                        {
                            Console.WriteLine($"{userName} is already registered");
                        }
                        break;
                    case "Send":
                      //var email = $" - {command[2]}";
                        var email = command[2];
                            listEmails[userName].Add(email);
                        break;
                    case "Delete":
                        if (listEmails.ContainsKey(userName))
                        {
                            listEmails.Remove(userName);
                        }
                        else
                        {
                            Console.WriteLine($"{userName} not found!");
                        }
                        break;
                }
            }
            Console.WriteLine($"Users count: {listEmails.Count}");
            if (listEmails.Count == 0)
            {
                return;
            }
            listEmails = listEmails.OrderByDescending(x => x.Value.Count).ThenBy(x => x.Key).ToDictionary(x => x.Key, y => y.Value);
            foreach (var infoData in listEmails/*.OrderByDescending(x => x.Value.Count).ThenBy(x => x.Key)*/)
            {
                Console.WriteLine(infoData.Key);
                foreach(var email in infoData.Value)
                {
                    Console.WriteLine($" - {email}");
                }
              //Console.WriteLine(string.Join("\n", infoData.Value));
            }
    }
}