using System; using System.IO; using System.Collections.Generic; class VisageTome { #region Main private static Dictionary users = new Dictionary(); static void Main() { Console.WriteLine("Welcome to VisageTome!"); Console.WriteLine("Executing from file..."); foreach (string line in File.ReadAllLines("commands.txt")) { Console.WriteLine(" > {0}", line); ProcessCommand(line); } Console.WriteLine(" Executing from user..."); bool continue_user_input = true; while (continue_user_input) { Console.Write(" > "); string command = Console.ReadLine(); continue_user_input = ProcessCommand(command); } } static bool ProcessCommand(string command) { string[] command_split = command.Split(' '); if (command_split.Length >= 1) { if (command_split[0] == "user") { if (command_split.Length >= 2) { string new_user = command_split[1]; if (users.ContainsKey(new_user)) { Console.WriteLine("User {0} already exists.", new_user); } else { users.Add(new_user, new User(new_user)); Console.WriteLine("User {0} added.", new_user); } } else { Console.WriteLine("Usage: user "); } } else if (command_split[0] == "list") { Console.WriteLine("Users:"); foreach (User user in users.Values) { Console.WriteLine("\t{0}: {1}", user.Name, user.Status); } } else if (command_split[0] == "status") { if (command_split.Length >= 3) { string user = command_split[1]; if (users.ContainsKey(user)) { string status = command.Replace("status " + user + " ", ""); Console.WriteLine("User {0} status changing to \"{1}\".", user, status); users[user].Status = status; } else { Console.WriteLine("User {0} does not exist.", user); } } else { Console.WriteLine("Usage: status "); } } else if (command_split[0] == "follow") { if (command_split.Length >= 3) { string follower = command_split[1]; string target = command_split[2]; if (users.ContainsKey(follower) && users.ContainsKey(target)) { users[follower].FollowUser(users[target]); Console.WriteLine("User {0} now following user {1}.", follower, target); } else { Console.WriteLine("User {0} and/or user {1} not found.", follower, target); } } else { Console.WriteLine("Usage: follow "); } } else if (command_split[0] == "unfollow") { if (command_split.Length >= 3) { string follower = command_split[1]; string target = command_split[2]; if (users.ContainsKey(follower) && users.ContainsKey(target)) { users[follower].UnfollowUser(users[target]); Console.WriteLine("User {0} no longer following user {1}.", follower, target); } else { Console.WriteLine("User {0} and/or user {1} not found.", follower, target); } } else { Console.WriteLine("Usage: unfollow "); } } else if (command_split[0] == "quit") { return false; } else { Console.WriteLine("Usage: [command_args]"); Console.WriteLine("Valid commands: user list status follow unfollow quit"); } } else { Console.WriteLine("Usage: [command_args]"); Console.WriteLine("Valid commands: user status follow unfollow quit"); } return true; } #endregion #region User Class class User { private string name; public string Name { get { return name; } } private string status; public string Status { get { return status; } set { if (value != status) { status = value; //TODO: Invoke an event that notifies subscribers that this user's status has changed } } } //TODO: Declare an EventHandler delegate to handle subscribers public User(string name) { this.name = name; status = "(No status yet)"; } public void FollowUser(User other) { //TODO: Let this user subscribe to the status changed event of the other user; // be sure to keep the subscriber from subscribing multiple times } public void UnfollowUser(User other) { //TODO: Let this user unsubscribe from the status changed event of the other user } private void ReceiveStatusChanged(object sender, StatusChangedEventArgs e) { //In a full application, this might involve sending an email or a pop-up to this user Console.WriteLine("\t{0} has been notified that {1}'s status has just changed to \"{2}\".", Name, e.Name, e.NewStatus); } //TODO: Properly finish the StatusChangedEventArgs class (see ReceiveStatusChanged for a use example) public class StatusChangedEventArgs : EventArgs { public string Name; public string NewStatus; } } #endregion }

Fill in the "TODO"