add new Command pattern example

Serb17 · Serb17 · commit c99cac3b2606 · 2024-10-18T18:48:04.000+04:00
diff --git a/.vscode/settings.json b/.vscode/settings.json
@@ -0,0 +1,12 @@
+{
+    "files.exclude": {
+        "**/.git": true,
+        "**/.svn": true,
+        "**/.hg": true,
+        "**/CVS": true,
+        "**/.DS_Store": true,
+        "**/Thumbs.db": true,
+        "**/bin": true,
+        "**/obj": true
+    }
+}
diff --git a/CommandPattern3/CommandPattern3.csproj b/CommandPattern3/CommandPattern3.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>NET8</TargetFramework>
   </PropertyGroup>
 
 </Project>
diff --git a/CommandPattern3/Program.cs b/CommandPattern3/Program.cs
@@ -23,8 +23,6 @@ static void Main(string[] args)
                 string input = Console.ReadLine();
                 Command command = CommandFactory.CreateCommand(input.ToLower(), Session);
 
-                if (command == null) continue;                
-                
                 Session.ExecuteCommand(command);
 
                 name = command.Name;
diff --git a/CommandPattern3/Session.cs b/CommandPattern3/Session.cs
@@ -9,7 +9,7 @@ namespace CommandPattern3
     /// </summary>
     public class Session
     {
-        protected readonly List<string> history = new List<string>();
+        protected readonly List<string> history = new();
 
         public Session(Terminal terminal)
         {
diff --git a/CommandPattern3/Terminal.cs b/CommandPattern3/Terminal.cs
@@ -6,20 +6,20 @@
 namespace CommandPattern3
 {
     /// <summary>
-    /// Reciever, who recive commands and do some job
+    /// Receiver, who receives commands and do some job
     /// </summary>
     public class Terminal : IDisposable
     {
-        private readonly Stack<Command> stack;        
+        private readonly Stack<Command> stack;
 
-        public readonly Stopwatch Uptime;        
+        public readonly Stopwatch Uptime;
 
         public Terminal()
         {
             Uptime = new Stopwatch();
             Uptime.Start();
-            
-            stack = new Stack<Command>();            
+
+            stack = new Stack<Command>();
         }
 
         public Command PopCommand()
@@ -33,7 +33,7 @@ public Command PopCommand()
             {
                 Console.WriteLine(e.Message);
                 return null;
-            }                        
+            }
         }
 
         public void PushCommand(Command cmd)
@@ -49,7 +49,7 @@ public string GetCommands()
 
         public void Dispose()
         {
-            Uptime.Stop();                        
+            Uptime.Stop();
         }
     }
 }
diff --git a/CommandPattern4/CommandPattern4.csproj b/CommandPattern4/CommandPattern4.csproj
@@ -0,0 +1,10 @@
+﻿<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>
diff --git a/CommandPattern4/Commands/AddUserCommand.cs b/CommandPattern4/Commands/AddUserCommand.cs
@@ -0,0 +1,20 @@
+namespace CommandPattern4.Commands;
+
+using CommandPattern4.DataStore;
+
+internal class AddUserCommand : Command
+{
+    private readonly IUserStore _userStore;
+    private readonly User _user;
+
+    public AddUserCommand(User user, CommandContext context)
+    {
+        _userStore = context.DataStore ?? throw new ArgumentNullException(nameof(context.DataStore));
+        _user = user ?? throw new ArgumentNullException(nameof(user));
+    }
+
+    public override void Execute()
+    {
+        _userStore.AddUser(_user);
+    }
+}
diff --git a/CommandPattern4/Commands/Command.cs b/CommandPattern4/Commands/Command.cs
@@ -0,0 +1,16 @@
+using CommandPattern4.DataStore;
+
+internal abstract class Command
+{
+    public abstract void Execute();
+}
+
+internal class CommandContext
+{
+    public IUserStore DataStore { get; }
+
+    public CommandContext(IUserStore dataStore)
+    {
+        DataStore = dataStore;
+    }
+}
diff --git a/CommandPattern4/Commands/DispalyUsersCommand.cs b/CommandPattern4/Commands/DispalyUsersCommand.cs
@@ -0,0 +1,19 @@
+namespace CommandPattern4.Commands;
+
+using CommandPattern4.DataStore;
+
+internal class DisplayUsersCommand : Command
+{
+    private readonly IUserStore _userStore;
+
+    public DisplayUsersCommand(CommandContext context)
+    {
+        _userStore = context.DataStore ?? throw new ArgumentNullException(nameof(context.DataStore));
+    }
+
+    public override void Execute()
+    {
+        var users = _userStore.GetUsers();
+        users.ToList().ForEach(u => Console.WriteLine(u.Username));
+    }
+}
diff --git a/CommandPattern4/Commands/RemoveUserCommand.cs b/CommandPattern4/Commands/RemoveUserCommand.cs
@@ -0,0 +1,21 @@
+namespace CommandPattern4.Commands;
+
+using CommandPattern4.DataStore;
+
+internal class RemoveUserCommand : Command
+{
+    private readonly IUserStore _userStore;
+    private readonly string _username;
+
+    public RemoveUserCommand(string username, CommandContext context)
+    {
+        ArgumentNullException.ThrowIfNull(username, nameof(username));
+        _userStore = context.DataStore;
+        _username = username;
+    }
+
+    public override void Execute()
+    {
+        _userStore.RemoveUser(_username);
+    }
+}
diff --git a/CommandPattern4/Commands/UnknownUserCommand.cs b/CommandPattern4/Commands/UnknownUserCommand.cs
@@ -0,0 +1,17 @@
+namespace CommandPattern4.Commands;
+
+using CommandPattern4.DataStore;
+
+internal class UnknownUserCommand : Command
+{
+    private readonly IUserStore _userStore;
+    public UnknownUserCommand(CommandContext context)
+    {
+        _userStore = context.DataStore;
+    }
+
+    public override void Execute()
+    {
+        Console.WriteLine("Unknown command");
+    }
+}
diff --git a/CommandPattern4/DataStore/InMemoryUserStore.cs b/CommandPattern4/DataStore/InMemoryUserStore.cs
@@ -0,0 +1,51 @@
+namespace CommandPattern4.DataStore;
+
+/// <summary>
+/// User data model
+/// </summary>
+/// <param name="Username">fixed string represents user name</param>
+/// <param name="Password">fixed string represents clear text user password</param> <summary> 
+/// </summary>
+internal record User(string Username, string Password);
+
+internal interface IUserStore
+{
+    void AddUser(User user);
+    void RemoveUser(string username);
+    User GetUser(string username);
+    User? FindUser(string username);
+    IEnumerable<User> GetUsers();
+}
+
+/// <summary>
+/// Receiver
+/// </summary>
+internal class InMemoryUserStore : IUserStore
+{
+    private readonly List<User> users = new();
+
+    public void AddUser(User user)
+    {
+        users.Add(user);
+    }
+
+    public void RemoveUser(string username)
+    {
+        users.Remove(users.First(u => u.Username == username));
+    }
+
+    public User GetUser(string username)
+    {
+        return users.First(u => u.Username == username);
+    }
+
+    public User? FindUser(string username)
+    {
+        return users.FirstOrDefault(u => u.Username == username);
+    }
+
+    public IEnumerable<User> GetUsers()
+    {
+        return users;
+    }
+}
diff --git a/CommandPattern4/Management/UserManager.cs b/CommandPattern4/Management/UserManager.cs
@@ -0,0 +1,14 @@
+namespace CommandPattern4.Management;
+
+/// <summary>
+/// Class "Invoker" to effectively invoke commands
+/// Can store commands or implement Undo/Redo logic
+/// </summary>
+internal class UserManager
+{
+    public void Invoke(Command command)
+    {
+        command.Execute();
+    }
+}
+0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
diff --git a/CommandPattern4/Program.cs b/CommandPattern4/Program.cs
@@ -0,0 +1,67 @@
+﻿using CommandPattern4.DataStore;
+using CommandPattern4.Commands;
+using CommandPattern4.Management;
+
+namespace CommandPattern4;
+
+public class Program
+{
+    public static void Main(string[] args)
+    {
+        // Invoker
+        var userManager = new UserManager();
+
+        // Receiver
+        var userStore = new InMemoryUserStore();
+
+        CommandFactory.Usage();
+
+        do
+        {
+            var input = Console.ReadLine();
+
+            if (input is null || input == "exit")
+            {
+                break;
+            }
+
+            var cmd = CommandFactory.CreateCommand(input, userStore);
+
+            if (cmd is UnknownUserCommand)
+            {
+                CommandFactory.Usage();
+            }
+
+            userManager.Invoke(cmd);
+
+        } while (true);
+    }
+}
+
+internal static class CommandFactory
+{
+    public static Command CreateCommand(string input, IUserStore store)
+    {
+        var parts = input.Split(' ');
+        var cmd = parts[0].ToLower();
+        var context = new CommandContext(store);
+
+        return cmd switch
+        {
+            "add" => new AddUserCommand(new User(parts[1], parts[2]), context),
+            "remove" => new RemoveUserCommand(parts[1], context),
+            "display" => new DisplayUsersCommand(context),
+            _ => new UnknownUserCommand(context),
+        };
+    }
+
+    public static void Usage()
+    {
+        Console.WriteLine("┌──────────────────────────────┐");
+        Console.WriteLine("│Usage: add <username> <passwd>│");
+        Console.WriteLine("│Usage: remove <username>      │");
+        Console.WriteLine("│Usage: display                │");
+        Console.WriteLine("│Usage: exit                   │");
+        Console.WriteLine("└──────────────────────────────┘");
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -9,7 +9,7 @@ namespace CommandPattern3`
`9`	`9`	`/// </summary>`
`10`	`10`	`public class Session`
`11`	`11`	`{`
`12`		`- protected readonly List<string> history = new List<string>();`
	`12`	`+ protected readonly List<string> history = new();`
`13`	`13`
`14`	`14`	`public Session(Terminal terminal)`
`15`	`15`	`{`
Original file line number	Diff line number	Diff line change
`@@ -6,20 +6,20 @@`
`6`	`6`	`namespace CommandPattern3`
`7`	`7`	`{`
`8`	`8`	`/// <summary>`
`9`		`- /// Reciever, who recive commands and do some job`
	`9`	`+ /// Receiver, who receives commands and do some job`
`10`	`10`	`/// </summary>`
`11`	`11`	`public class Terminal : IDisposable`
`12`	`12`	`{`
`13`		`- private readonly Stack<Command> stack;`
	`13`	`+ private readonly Stack<Command> stack;`
`14`	`14`
`15`		`- public readonly Stopwatch Uptime;`
	`15`	`+ public readonly Stopwatch Uptime;`
`16`	`16`
`17`	`17`	`public Terminal()`
`18`	`18`	`{`
`19`	`19`	`Uptime = new Stopwatch();`
`20`	`20`	`Uptime.Start();`
`21`		`-`
`22`		`- stack = new Stack<Command>();`
	`21`	`+`
	`22`	`+ stack = new Stack<Command>();`
`23`	`23`	`}`
`24`	`24`
`25`	`25`	`public Command PopCommand()`
`@@ -33,7 +33,7 @@ public Command PopCommand()`
`33`	`33`	`{`
`34`	`34`	`Console.WriteLine(e.Message);`
`35`	`35`	`return null;`
`36`		`- }`
	`36`	`+ }`
`37`	`37`	`}`
`38`	`38`
`39`	`39`	`public void PushCommand(Command cmd)`
`@@ -49,7 +49,7 @@ public string GetCommands()`
`49`	`49`
`50`	`50`	`public void Dispose()`
`51`	`51`	`{`
`52`		`- Uptime.Stop();`
	`52`	`+ Uptime.Stop();`
`53`	`53`	`}`
`54`	`54`	`}`
`55`	`55`	`}`