feat: validate plugin dependencies during plugin loading

CPlugin.Net.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 18
-VisualStudioVersion = 18.8.11912.234 insiders
+VisualStudioVersion = 18.8.11912.234
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "CPlugin.Net.Attributes", "src\Attributes\CPlugin.Net.Attributes.csproj", "{D9737294-F5EA-4EA0-8BF2-2BF5C3954DD9}"
 EndProject
@@ -36,6 +36,10 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Example.PersonPlugin", "sam
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Example.ProgramPlugin", "samples\Plugins\ProgramPlugin\Example.ProgramPlugin.csproj", "{BA75A525-7013-4F0D-85FD-416E744098FD}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.GunGamePlugin", "samples\Plugins\GunGamePlugin\Example.GunGamePlugin.csproj", "{1DD684E8-9889-8431-95FB-DE64D8C411F7}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.WeaponsPlugin", "samples\Plugins\WeaponsPlugin\Example.WeaponsPlugin.csproj", "{17C8B89A-5ABF-CE24-3948-9ACC366D4E86}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Example.Test", "samples\Test\Example.Test.csproj", "{1E64908D-DC48-4B83-BB25-CF36821EB37F}"
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{7DC4CDB0-B0CD-48B5-91C7-40F05F662FA8}"
@@ -53,6 +57,10 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestProject.WebPlugin", "te
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestProject.HelloPlugin", "tests\Plugins\TestProject.HelloPlugin\TestProject.HelloPlugin.csproj", "{E2373A36-6D3E-44DE-99FF-4CC019E05D06}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestProject.GunGamePlugin", "tests\Plugins\TestProject.GunGamePlugin\TestProject.GunGamePlugin.csproj", "{2F4A0A4B-B028-A62A-2E6B-BF3503E25BE3}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "TestProject.WeaponsPlugin", "tests\Plugins\TestProject.WeaponsPlugin\TestProject.WeaponsPlugin.csproj", "{067880FC-D7E2-A3CE-BF10-05C2FB023F58}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestProject.Contracts", "tests\TestProject.Contracts\TestProject.Contracts.csproj", "{FEE1E508-3313-4C7A-A7E6-5EBA8D47D3FD}"
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestProject.PluginHost", "tests\TestProject.PluginHost\TestProject.PluginHost.csproj", "{0BCD3305-F0D5-43E6-B879-EEF0827558A8}"
@@ -124,6 +132,14 @@ Global
 		{BA75A525-7013-4F0D-85FD-416E744098FD}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{BA75A525-7013-4F0D-85FD-416E744098FD}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{BA75A525-7013-4F0D-85FD-416E744098FD}.Release|Any CPU.Build.0 = Release|Any CPU
+		{1DD684E8-9889-8431-95FB-DE64D8C411F7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1DD684E8-9889-8431-95FB-DE64D8C411F7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1DD684E8-9889-8431-95FB-DE64D8C411F7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1DD684E8-9889-8431-95FB-DE64D8C411F7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{17C8B89A-5ABF-CE24-3948-9ACC366D4E86}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{17C8B89A-5ABF-CE24-3948-9ACC366D4E86}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{17C8B89A-5ABF-CE24-3948-9ACC366D4E86}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{17C8B89A-5ABF-CE24-3948-9ACC366D4E86}.Release|Any CPU.Build.0 = Release|Any CPU
 		{1E64908D-DC48-4B83-BB25-CF36821EB37F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{1E64908D-DC48-4B83-BB25-CF36821EB37F}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{1E64908D-DC48-4B83-BB25-CF36821EB37F}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -152,6 +168,14 @@ Global
 		{0BCD3305-F0D5-43E6-B879-EEF0827558A8}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{0BCD3305-F0D5-43E6-B879-EEF0827558A8}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{0BCD3305-F0D5-43E6-B879-EEF0827558A8}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2F4A0A4B-B028-A62A-2E6B-BF3503E25BE3}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2F4A0A4B-B028-A62A-2E6B-BF3503E25BE3}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2F4A0A4B-B028-A62A-2E6B-BF3503E25BE3}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2F4A0A4B-B028-A62A-2E6B-BF3503E25BE3}.Release|Any CPU.Build.0 = Release|Any CPU
+		{067880FC-D7E2-A3CE-BF10-05C2FB023F58}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{067880FC-D7E2-A3CE-BF10-05C2FB023F58}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{067880FC-D7E2-A3CE-BF10-05C2FB023F58}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{067880FC-D7E2-A3CE-BF10-05C2FB023F58}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -169,6 +193,8 @@ Global
 		{2832E5C3-660E-49B9-8E62-03B11A8CC6D7} = {FA19544E-3925-4A1C-A994-CFA72FDC10AC}
 		{18534944-583B-4924-AC5B-E0655FD92AAC} = {FA19544E-3925-4A1C-A994-CFA72FDC10AC}
 		{BA75A525-7013-4F0D-85FD-416E744098FD} = {FA19544E-3925-4A1C-A994-CFA72FDC10AC}
+		{1DD684E8-9889-8431-95FB-DE64D8C411F7} = {FA19544E-3925-4A1C-A994-CFA72FDC10AC}
+		{17C8B89A-5ABF-CE24-3948-9ACC366D4E86} = {FA19544E-3925-4A1C-A994-CFA72FDC10AC}
 		{1E64908D-DC48-4B83-BB25-CF36821EB37F} = {A0059E66-B781-496A-AE13-CD83200A4612}
 		{290C410D-33F9-4C82-A334-04709D751E16} = {7DC4CDB0-B0CD-48B5-91C7-40F05F662FA8}
 		{0F27C776-F284-4C94-86C9-0FF089245E13} = {290C410D-33F9-4C82-A334-04709D751E16}
@@ -177,6 +203,8 @@ Global
 		{E2373A36-6D3E-44DE-99FF-4CC019E05D06} = {290C410D-33F9-4C82-A334-04709D751E16}
 		{FEE1E508-3313-4C7A-A7E6-5EBA8D47D3FD} = {7DC4CDB0-B0CD-48B5-91C7-40F05F662FA8}
 		{0BCD3305-F0D5-43E6-B879-EEF0827558A8} = {7DC4CDB0-B0CD-48B5-91C7-40F05F662FA8}
+		{2F4A0A4B-B028-A62A-2E6B-BF3503E25BE3} = {290C410D-33F9-4C82-A334-04709D751E16}
+		{067880FC-D7E2-A3CE-BF10-05C2FB023F58} = {290C410D-33F9-4C82-A334-04709D751E16}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {67EE578E-EE0A-4E98-AE5A-1771751D8B5F}

Directory.Packages.props

@@ -7,6 +7,7 @@
     <PackageVersion Include="Microsoft.Extensions.Logging.Console" Version="6.0.0" />
     <PackageVersion Include="Microsoft.Extensions.Configuration.Abstractions" Version="6.0.0" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
+    <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="10.0.8" />
     <PackageVersion Include="Microsoft.AspNetCore.OpenApi" Version="7.0.10" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.4" />
     <PackageVersion Include="Swashbuckle.AspNetCore" Version="6.5.0" />

samples/Contracts/IPlugin.cs

@@ -0,0 +1,8 @@
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Example.Contracts;
+
+public interface IPlugin
+{
+    void ConfigureServices(IServiceCollection services);
+}

samples/Contracts/IWeapon.cs

@@ -0,0 +1,8 @@
+namespace Example.Contracts;
+
+public interface IWeapon
+{
+    string Id { get; }
+    string Name { get; }
+    int Slot { get; }
+}

samples/HostApplications/ConsoleApp/.env

@@ -1 +1,6 @@
-PLUGINS=Example.OldJsonPlugin.dll Example.JsonPlugin.dll
+PLUGINS="
+Example.OldJsonPlugin.dll
+Example.JsonPlugin.dll
+Example.GunGamePlugin.dll
+Example.WeaponsPlugin.dll
+"

samples/HostApplications/ConsoleApp/Example.HostConsoleApp.csproj

@@ -6,6 +6,7 @@
 
   <ItemGroup>
     <PackageReference Include="DotEnv.Core" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
     <PackageReference Include="CopyPluginsToPublishDirectory" />
   </ItemGroup>
 

samples/HostApplications/ConsoleApp/GlobalUsings.cs

@@ -1,3 +1,4 @@
-global using Example.Contracts;
+global using Microsoft.Extensions.DependencyInjection;
+global using Example.Contracts;
 global using CPlugin.Net;
 global using DotEnv.Core;

samples/HostApplications/ConsoleApp/Program.cs

@@ -1,13 +1,21 @@
 // See https://aka.ms/new-console-template for more information
+
 new EnvLoader().Load();
 Console.WriteLine("PLUGINS=" + EnvReader.Instance["PLUGINS"]);
 Console.WriteLine();
 
 var envConfiguration = new CPluginEnvConfiguration();
 // Loads the plugins from the .env file.
 PluginLoader.Load(envConfiguration);
-var commands = TypeFinder.FindSubtypesOf<ICommand>();
+
+var services = new ServiceCollection();
+var plugins = TypeFinder.FindSubtypesOf<IPlugin>();
+foreach (IPlugin plugin in plugins)
+    plugin.ConfigureServices(services);
+
+services.AddSubtypesOf<ICommand>(ServiceLifetime.Transient);
+
+var serviceProvider = services.BuildServiceProvider();
+var commands = serviceProvider.GetServices<ICommand>();
 foreach (ICommand command in commands)
-{
     command.Execute();
-}

samples/Plugins/GunGamePlugin/Example.GunGamePlugin.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutDir>$(ConsoleAppProjectDir)</OutDir>
+  </PropertyGroup>
+
+</Project>

samples/Plugins/GunGamePlugin/GlobalUsings.cs

@@ -0,0 +1,3 @@
+global using CPlugin.Net;
+global using Example.GunGamePlugin;
+global using Example.Contracts;

samples/Plugins/GunGamePlugin/GunGameCommand.cs

@@ -0,0 +1,30 @@
+[assembly: Plugin(typeof(GunGameCommand))]
+[assembly: DependsOn("Example.WeaponsPlugin")]
+
+namespace Example.GunGamePlugin;
+
+internal class GunGameCommand(IEnumerable<IWeapon> weapons) : ICommand
+{
+    public string Name => "gungame";
+    public string Description => "Lists the available weapons.";
+    public string Version => "1.0.0";
+
+    public int Execute()
+    {
+        Console.WriteLine();
+        Console.WriteLine("=== GunGame Plugin ===");
+        Console.WriteLine($"Command     : {Name}");
+        Console.WriteLine($"Description : {Description}");
+        Console.WriteLine($"Version     : {Version}");
+        Console.WriteLine();
+        Console.WriteLine("Registered weapons:");
+
+        foreach (IWeapon weapon in weapons.OrderBy(w => w.Slot))
+        {
+            Console.WriteLine($"  [{weapon.Slot}] {weapon.Name} (Id: {weapon.Id})");
+        }
+
+        Console.WriteLine();
+        return 0;
+    }
+}

samples/Plugins/WeaponsPlugin/Ak47.cs

@@ -0,0 +1,8 @@
+namespace Example.WeaponsPlugin;
+
+internal class Ak47 : IWeapon
+{
+    public string Id => "ak47";
+    public string Name => "AK-47";
+    public int Slot => 2;
+}

samples/Plugins/WeaponsPlugin/Example.WeaponsPlugin.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutDir>$(ConsoleAppProjectDir)</OutDir>
+  </PropertyGroup>
+
+</Project>

samples/Plugins/WeaponsPlugin/GlobalUsings.cs

@@ -0,0 +1,4 @@
+global using Microsoft.Extensions.DependencyInjection;
+global using CPlugin.Net;
+global using Example.Contracts;
+global using Example.WeaponsPlugin;

samples/Plugins/WeaponsPlugin/Pistol.cs

@@ -0,0 +1,8 @@
+namespace Example.WeaponsPlugin;
+
+internal class Pistol : IWeapon
+{
+    public string Id => "pistol";
+    public string Name => "Pistol";
+    public int Slot => 1;
+}

samples/Plugins/WeaponsPlugin/WeaponsPlugin.cs

@@ -0,0 +1,12 @@
+[assembly: Plugin(typeof(WeaponsPlugin))]
+
+namespace Example.WeaponsPlugin;
+
+internal class WeaponsPlugin : IPlugin
+{
+    public void ConfigureServices(IServiceCollection services)
+    {
+        services.AddSingleton<IWeapon, Pistol>();
+        services.AddSingleton<IWeapon, Ak47>();
+    }
+}

src/Attributes/DependsOnAttribute.cs

@@ -0,0 +1,46 @@
+using System;
+
+namespace CPlugin.Net;
+
+/// <summary>
+/// Specifies that the current plugin depends on another plugin.
+/// </summary>
+/// <remarks>
+/// Example:
+/// <para>
+/// If <c>GunGame</c> depends on <c>Weapons</c>, add this line before the namespace declaration:
+/// </para>
+/// <c>[assembly: DependsOn("Weapons")]</c>
+/// <para>
+/// During plugin loading, the specified plugin must also be present in the plugin
+/// configuration; otherwise, a <c>PluginDependencyException</c> is thrown.
+/// </para>
+/// </remarks>
+[AttributeUsage(AttributeTargets.Assembly, Inherited = false, AllowMultiple = true)]
+public class DependsOnAttribute : Attribute
+{
+    /// <summary>
+    /// Gets the name of the required plugin.
+    /// </summary>
+    public string PluginName { get; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="DependsOnAttribute"/> class.
+    /// </summary>
+    /// <param name="pluginName">
+    /// The name of the plugin that the current plugin depends on.
+    /// The <c>.dll</c> extension is optional.
+    /// </param>
+    /// <exception cref="ArgumentNullException">
+    /// <c>pluginName</c> is <c>null</c>.
+    /// </exception>
+    public DependsOnAttribute(string pluginName)
+    {
+        if (pluginName is null)
+        {
+            throw new ArgumentNullException(nameof(pluginName));
+        }
+
+        PluginName = pluginName;
+    }
+}

src/Core/Configuration/CPluginConfigurationBase.cs

@@ -40,11 +40,15 @@ protected static string GetPluginPath(string pluginFile)
         bool hasDllExtension = Path
             .GetExtension(pluginFile)
             .Equals(".dll");
+
         pluginFile = hasDllExtension ? pluginFile : pluginFile + ".dll";
+
         // Example: MyPlugin1
         var pluginDirectory = Path.GetFileNameWithoutExtension(pluginFile);
+
         // Example: /home/admin/HostApplication/bin/Debug/net7.0/plugins/MyPlugin1
         var basePath = Path.Combine(AppContext.BaseDirectory, "plugins", pluginDirectory);
+
         // Example: /home/admin/HostApplication/bin/Debug/net7.0/plugins/MyPlugin1/MyPlugin1.dll
         var pluginPath = Path.Combine(basePath, pluginFile);
         return pluginPath;

src/Core/Exceptions/PluginDependencyException.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace CPlugin.Net;
+
+/// <summary>
+/// The exception that is thrown when a plugin dependency cannot be resolved.
+/// </summary>
+public class PluginDependencyException : Exception
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PluginDependencyException"/> class.
+    /// </summary>
+    /// <param name="message">
+    /// The message that describes the error.
+    /// </param>
+    public PluginDependencyException(string message) : base(message)
+    {
+    }
+}

src/Core/PluginLoader.cs

@@ -30,25 +30,51 @@ public static class PluginLoader
     /// <exception cref="ArgumentNullException">
     /// <c>configuration</c> is <c>null</c>.
     /// </exception>
+    /// <exception cref="PluginDependencyException">
+    /// A plugin declares a dependency that cannot be resolved.
+    /// </exception>
     public static void Load(CPluginConfigurationBase configuration)
     {
         ArgumentNullException.ThrowIfNull(configuration);
-        var assemblyFiles = configuration.GetPluginFiles();
-        foreach (string assemblyFile in assemblyFiles)
+
+        string[] pluginFiles = [.. configuration.GetPluginFiles()];
+        HashSet<string> configuredPluginNames = pluginFiles
+            .Select(Path.GetFileName)
+            .ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        foreach (string pluginFile in pluginFiles)
         {
-            Assembly currentAssembly = FindAssembly(assemblyFile);
-            if (currentAssembly is null)
-                LoadAssembly(assemblyFile);
+            Assembly assembly = FindAssembly(pluginFile);
+
+            if (assembly is not null)
+                continue;
+
+            assembly = LoadAssembly(pluginFile);
+            DependsOnAttribute[] dependencies = [.. assembly.GetCustomAttributes<DependsOnAttribute>()];
+
+            foreach (DependsOnAttribute dependency in dependencies)
+            {
+                var normalizedPluginName = PluginNameNormalizer.Normalize(dependency.PluginName);
+                if (!configuredPluginNames.Contains(normalizedPluginName))
+                {
+                    var message = 
+                        $"The plugin '{assembly.GetName().Name}' depends on '{normalizedPluginName}', " +
+                        $"but '{normalizedPluginName}' was not found in the plugin configuration.";
+
+                    throw new PluginDependencyException(message);
+                }
+            }
         }
     }
 
-    private static void LoadAssembly(string assemblyFile)
+    private static Assembly LoadAssembly(string assemblyFile)
     {
         var loadContext = new PluginLoadContext(assemblyFile);
         var assemblyName = AssemblyName.GetAssemblyName(assemblyFile);
         var currentAssembly = loadContext.LoadFromAssemblyName(assemblyName);
         s_assemblies.TryAdd(assemblyFile, currentAssembly);
         PluginLogger.DefaultLogInformation(currentAssembly.GetName().Name, currentAssembly.FullName);
+        return currentAssembly;
     }
 
     private static Assembly FindAssembly(string assemblyFile)

src/Core/PluginNameNormalizer.cs

@@ -0,0 +1,9 @@
+namespace CPlugin.Net;
+
+internal class PluginNameNormalizer
+{
+    public static string Normalize(string pluginName)
+        => pluginName.EndsWith(".dll", StringComparison.OrdinalIgnoreCase)
+            ? pluginName
+            : $"{pluginName}.dll";
+}