Add Decorator.

DesignPatterns.sln

@@ -12,6 +12,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DesignPatterns.AbstractFact
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DesignPatterns.AbstractFactory.UnitTests", "Creational\DesignPatterns.AbstractFactory.UnitTests\DesignPatterns.AbstractFactory.UnitTests.csproj", "{1E56CC89-45C1-45F7-9EC8-88D648572816}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Structural", "Structural", "{5961ADCC-5FA6-4076-A9F4-C1D3207ABE1A}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DesignPatterns.Decorator", "Structural\DesignPatterns.Decorator\DesignPatterns.Decorator.csproj", "{FA3C4F09-104E-4F7D-9ADB-E7F22917ADF7}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -34,11 +38,16 @@ Global
 		{1E56CC89-45C1-45F7-9EC8-88D648572816}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{1E56CC89-45C1-45F7-9EC8-88D648572816}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{1E56CC89-45C1-45F7-9EC8-88D648572816}.Release|Any CPU.Build.0 = Release|Any CPU
+		{FA3C4F09-104E-4F7D-9ADB-E7F22917ADF7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{FA3C4F09-104E-4F7D-9ADB-E7F22917ADF7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{FA3C4F09-104E-4F7D-9ADB-E7F22917ADF7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{FA3C4F09-104E-4F7D-9ADB-E7F22917ADF7}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{DCE06EB6-BAB5-4573-AF67-128DBCCDB90C} = {7FF0E83F-EBEB-4103-BCD1-2F100E82FCD1}
 		{02AA0F74-2EFE-4804-8938-A92542860F74} = {7FF0E83F-EBEB-4103-BCD1-2F100E82FCD1}
 		{0C5CFC73-F6E4-4796-A11C-9CA378B80517} = {AE005ED4-5F0B-4AF9-81AE-AAE3AD6F8901}
 		{1E56CC89-45C1-45F7-9EC8-88D648572816} = {AE005ED4-5F0B-4AF9-81AE-AAE3AD6F8901}
+		{FA3C4F09-104E-4F7D-9ADB-E7F22917ADF7} = {5961ADCC-5FA6-4076-A9F4-C1D3207ABE1A}
 	EndGlobalSection
 EndGlobal

Structural/DesignPatterns.Decorator/CompressionDecorator.cs

@@ -0,0 +1,18 @@
+namespace DesignPatterns.Decorator;
+
+internal class CompressionDecorator : UploaderDecorator
+{
+    public CompressionDecorator(IFileUploader uploader)
+        : base(uploader)
+    {
+    }
+
+    public override async Task Upload(string name, Stream stream)
+    {
+        // TODO: add compression logic here.
+        Console.WriteLine($"{nameof(CompressionDecorator)}.{nameof(Upload)}: started compressing a file...");
+        await Task.Delay(1000);
+        Console.WriteLine($"{nameof(CompressionDecorator)}.{nameof(Upload)}: completed compressing a file.");
+        await base.Upload(name, stream);
+    }
+}

Structural/DesignPatterns.Decorator/DesignPatterns.Decorator.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net8.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <RootNamespace>DesignPatterns.Decorator</RootNamespace>
+    </PropertyGroup>
+
+</Project>

Structural/DesignPatterns.Decorator/EncryptionDecorator.cs

@@ -0,0 +1,18 @@
+namespace DesignPatterns.Decorator;
+
+internal class EncryptionDecorator : UploaderDecorator
+{
+    public EncryptionDecorator(IFileUploader uploader)
+        : base(uploader)
+    {
+    }
+
+    public override async Task Upload(string name, Stream stream)
+    {
+        // TODO: add encryption logic here.
+        Console.WriteLine($"{nameof(EncryptionDecorator)}.{nameof(Upload)}: started encrypting a file...");
+        await Task.Delay(1000);
+        Console.WriteLine($"{nameof(EncryptionDecorator)}.{nameof(Upload)}: completed encrypting a file.");
+        await base.Upload(name, stream);
+    }
+}

Structural/DesignPatterns.Decorator/FileUploader.cs

@@ -0,0 +1,12 @@
+namespace DesignPatterns.Decorator;
+
+internal class FileUploader : IFileUploader
+{
+    public async Task Upload(string name, Stream stream)
+    {
+        // TODO: add a client to upload files into cloud.
+        Console.WriteLine($"{nameof(FileUploader)}.{nameof(this.Upload)}: started uploading a file...");
+        await Task.Delay(1000);
+        Console.WriteLine($"{nameof(FileUploader)}.{nameof(this.Upload)}: completed uploading a file.");
+    }
+}

Structural/DesignPatterns.Decorator/IFileUploader.cs

@@ -0,0 +1,6 @@
+namespace DesignPatterns.Decorator;
+
+public interface IFileUploader
+{
+    Task Upload(string name, Stream stream);
+}

Structural/DesignPatterns.Decorator/Program.cs

@@ -0,0 +1,10 @@
+using DesignPatterns.Decorator;
+
+IFileUploader fileUploader = new FileUploader();
+fileUploader = new CompressionDecorator(fileUploader);
+fileUploader = new EncryptionDecorator(fileUploader);
+
+await using var stream = new MemoryStream(); 
+await fileUploader.Upload("file.txt", stream);
+
+Console.WriteLine();

Structural/DesignPatterns.Decorator/UploaderDecorator.cs

@@ -0,0 +1,16 @@
+namespace DesignPatterns.Decorator;
+
+abstract class UploaderDecorator : IFileUploader
+{
+    private readonly IFileUploader uploader;
+
+    public UploaderDecorator(IFileUploader uploader)
+    {
+        this.uploader = uploader;
+    }
+
+    public virtual Task Upload(string name, Stream stream)
+    {
+        return this.uploader.Upload(name, stream);
+    }
+}