Introduce IFalloutCommand dispatch with DI for Fallout.Cli (#392, PR 0)

.vscode/launch.json

@@ -0,0 +1,47 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      // Prompts you for the command/args each launch, e.g. ":get-configuration" or ":bogus".
+      "name": "fallout (ask for args)",
+      "type": "coreclr",
+      "request": "launch",
+      "preLaunchTask": "build-cli",
+      "program": "${workspaceFolder}/src/Fallout.Cli/bin/Debug/net10.0/Fallout.Cli.dll",
+      "args": "${input:falloutArgs}",
+      "cwd": "${workspaceFolder}",
+      "console": "integratedTerminal",
+      "stopAtEntry": false
+    },
+    {
+      // Dispatch error path — prints the command manifest, no side effects.
+      "name": "fallout :bogus",
+      "type": "coreclr",
+      "request": "launch",
+      "preLaunchTask": "build-cli",
+      "program": "${workspaceFolder}/src/Fallout.Cli/bin/Debug/net10.0/Fallout.Cli.dll",
+      "args": [":bogus"],
+      "cwd": "${workspaceFolder}",
+      "console": "integratedTerminal"
+    },
+    {
+      // Real command via the DelegateCommand path — read-only.
+      "name": "fallout :get-configuration",
+      "type": "coreclr",
+      "request": "launch",
+      "preLaunchTask": "build-cli",
+      "program": "${workspaceFolder}/src/Fallout.Cli/bin/Debug/net10.0/Fallout.Cli.dll",
+      "args": [":get-configuration"],
+      "cwd": "${workspaceFolder}",
+      "console": "integratedTerminal"
+    }
+  ],
+  "inputs": [
+    {
+      "id": "falloutArgs",
+      "type": "promptString",
+      "description": "Arguments to pass to fallout (space-separated), e.g. ':get-configuration'",
+      "default": ":bogus"
+    }
+  ]
+}

.vscode/tasks.json

@@ -0,0 +1,17 @@
+{
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "label": "build-cli",
+      "command": "dotnet",
+      "type": "process",
+      "args": [
+        "build",
+        "${workspaceFolder}/src/Fallout.Cli/Fallout.Cli.csproj",
+        "/property:GenerateFullPaths=true",
+        "/consoleloggerparameters:NoSummary"
+      ],
+      "problemMatcher": "$msCompile"
+    }
+  ]
+}

Directory.Packages.props

@@ -13,6 +13,7 @@
     <PackageVersion Include="Glob" Version="1.1.9" />
     <PackageVersion Include="HtmlAgilityPack" Version="1.11.71" />
     <PackageVersion Include="Humanizer" Version="3.0.1" />
+    <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="10.0.0" />
     <PackageVersion Include="Microsoft.Extensions.DependencyModel" Version="10.0.0" />
     <PackageVersion Include="Nerdbank.GitVersioning" Version="3.7.115" />
     <PackageVersion Include="Microsoft.SourceLink.GitHub" Version="8.0.0" />

src/Fallout.Cli/CommandDispatcher.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Fallout.Cli.Commands;
+using Fallout.Cli.Prompts;
+using Fallout.Common;
+using Fallout.Common.IO;
+using Fallout.Common.Utilities;
+using Fallout.Common.Utilities.Collections;
+
+namespace Fallout.Cli;
+
+/// <summary>
+/// Routes a command-line invocation to the matching <see cref="IFalloutCommand"/>. Commands are
+/// resolved by <see cref="IFalloutCommand.Name"/> from the registered set — dash- and
+/// case-insensitively, preserving every spelling the historical reflection dispatch accepted
+/// (e.g. <c>:add-package</c> and <c>:addpackage</c>, <c>:PopDirectory</c> and <c>:popdirectory</c>).
+/// </summary>
+internal sealed class CommandDispatcher
+{
+    private const char CommandPrefix = ':';
+
+    private readonly IReadOnlyList<IFalloutCommand> _commands;
+    private readonly IConsolePrompts _prompts;
+
+    public CommandDispatcher(IEnumerable<IFalloutCommand> commands, IConsolePrompts prompts)
+    {
+        _commands = commands.ToList();
+        _prompts = prompts;
+    }
+
+    public int Dispatch(string[] args, AbsolutePath rootDirectory, AbsolutePath buildScript)
+    {
+        var hasCommand = args.FirstOrDefault()?.StartsWithOrdinalIgnoreCase(CommandPrefix.ToString()) ?? false;
+        if (hasCommand)
+        {
+            var token = args.First().Trim(CommandPrefix);
+            if (string.IsNullOrWhiteSpace(token))
+                Assert.Fail($"No command specified. Usage is: fallout {CommandPrefix}<command> [args]");
+
+            var command = Resolve(token);
+            return command.Execute(args.Skip(count: 1).ToArray(), rootDirectory, buildScript);
+        }
+
+        if (rootDirectory == null)
+        {
+            return _prompts.PromptForConfirmation(
+                    $"Could not find {Constants.FalloutDirectoryName} directory/file. Do you want to setup a build?")
+                ? GetRequired("setup").Execute(Array.Empty<string>(), rootDirectory: null, buildScript: null)
+                : 0;
+        }
+
+        // TODO: docker
+
+        return GetRequired("run").Execute(args, rootDirectory, BuildProjectResolver.Resolve(rootDirectory));
+    }
+
+    private IFalloutCommand Resolve(string token)
+    {
+        return _commands.SingleOrDefault(x => Normalize(x.Name).EqualsOrdinalIgnoreCase(Normalize(token)))
+            .NotNull(new[] { $"Command '{token}' is not supported, available commands are:" }
+                .Concat(_commands.Select(x => $"  - {x.Name}").OrderBy(x => x)).JoinNewLine());
+    }
+
+    private IFalloutCommand GetRequired(string name)
+        => _commands.Single(x => x.Name.EqualsOrdinalIgnoreCase(name));
+
+    private static string Normalize(string value) => value.Replace("-", string.Empty);
+}

src/Fallout.Cli/Commands/DelegateCommand.cs

@@ -0,0 +1,27 @@
+using System;
+using Fallout.Common.IO;
+
+namespace Fallout.Cli.Commands;
+
+/// <summary>
+/// Transitional adapter that exposes a not-yet-extracted <c>Program.X</c> handler as an
+/// <see cref="IFalloutCommand"/>, so the dispatcher can route every command uniformly through the
+/// registry while the per-command conversion (issue #392) lands one PR at a time. Each conversion
+/// replaces one registration of this adapter with a real command type; the adapter is deleted once
+/// the last legacy handler is gone.
+/// </summary>
+internal sealed class DelegateCommand : IFalloutCommand
+{
+    private readonly Func<string[], AbsolutePath, AbsolutePath, int> _handler;
+
+    public DelegateCommand(string name, Func<string[], AbsolutePath, AbsolutePath, int> handler)
+    {
+        Name = name;
+        _handler = handler;
+    }
+
+    public string Name { get; }
+
+    public int Execute(string[] args, AbsolutePath rootDirectory, AbsolutePath buildScript)
+        => _handler(args, rootDirectory, buildScript);
+}

src/Fallout.Cli/Commands/IFalloutCommand.cs

@@ -0,0 +1,30 @@
+using Fallout.Common.IO;
+
+namespace Fallout.Cli.Commands;
+
+/// <summary>
+/// A single global-tool command (e.g. <c>fallout :run</c>, <c>fallout :setup</c>).
+/// One command = one type, resolved by <see cref="Name"/> from the dependency-injection
+/// container — replacing the historical reflection-over-<c>Program</c> dispatch.
+/// </summary>
+/// <remarks>
+/// This surface is intentionally minimal. It is <b>not</b> a stable public plugin contract yet;
+/// when a public command SDK lands (milestone #7) the API will be annotated and versioned
+/// explicitly. Until then, treat additions here as internal-by-convention.
+/// </remarks>
+public interface IFalloutCommand
+{
+    /// <summary>
+    /// The canonical command name as typed after the <c>:</c> prefix, in dash form
+    /// (e.g. <c>"run"</c>, <c>"add-package"</c>, <c>"cake-convert"</c>). Matched case-insensitively.
+    /// </summary>
+    string Name { get; }
+
+    /// <summary>
+    /// Executes the command and returns the process exit code.
+    /// </summary>
+    /// <param name="args">The arguments following the command token.</param>
+    /// <param name="rootDirectory">The resolved repository root, or <c>null</c> when none was found.</param>
+    /// <param name="buildScript">The resolved build script / project file, or <c>null</c> when none applies.</param>
+    int Execute(string[] args, AbsolutePath rootDirectory, AbsolutePath buildScript);
+}

src/Fallout.Cli/Program.Run.cs → src/Fallout.Cli/Commands/RunCommand.cs

@@ -8,11 +8,17 @@
 using Fallout.Common.Utilities;
 using static Fallout.Common.Constants;
 
-namespace Fallout.Cli;
+namespace Fallout.Cli.Commands;
 
-partial class Program
+/// <summary>
+/// <c>fallout :run</c> (and the default, command-less invocation): builds the build project and
+/// runs it, forwarding any remaining arguments to the build.
+/// </summary>
+public sealed class RunCommand : IFalloutCommand
 {
-    private static int Run(string[] forwardedArgs, AbsolutePath rootDirectory, AbsolutePath buildProjectFile)
+    public string Name => "run";
+
+    public int Execute(string[] forwardedArgs, AbsolutePath rootDirectory, AbsolutePath buildProjectFile)
     {
         var dotnet = ResolveDotnet(rootDirectory);
 
@@ -63,7 +69,7 @@ private static int StartDotnet(string dotnet, IEnumerable<string> arguments)
         startInfo.Environment["DOTNET_NOLOGO"] = "1";
         startInfo.Environment["DOTNET_ROLL_FORWARD"] = "Major";
         startInfo.Environment["FALLOUT_TELEMETRY_OPTOUT"] = "1";
-        startInfo.Environment[GlobalToolVersionEnvironmentKey] = typeof(Program).Assembly.GetVersionText();
+        startInfo.Environment[GlobalToolVersionEnvironmentKey] = typeof(RunCommand).Assembly.GetVersionText();
         startInfo.Environment[GlobalToolStartTimeEnvironmentKey] = DateTime.Now.ToString("O");
 
         var process = Process.Start(startInfo).NotNull();

src/Fallout.Cli/Fallout.Cli.csproj

@@ -17,6 +17,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" />
     <PackageReference Include="Spectre.Console" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" />
     <PackageReference Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" />

src/Fallout.Cli/Program.AddPackage.cs

@@ -45,7 +45,7 @@ public static int AddPackage(string[] args, AbsolutePath rootDirectory, Absolute
         return 0;
     }
 
-    private static void AddOrReplacePackage(string packageId, string packageVersion, string packageType, string buildProjectFile)
+    internal static void AddOrReplacePackage(string packageId, string packageVersion, string packageType, string buildProjectFile)
     {
         var buildProject = ProjectModelTasks.ParseProject(buildProjectFile).NotNull();
 

src/Fallout.Cli/Program.GetConfiguration.cs

@@ -11,7 +11,9 @@ namespace Fallout.Cli;
 
 partial class Program
 {
-    private const string BUILD_PROJECT_FILE = nameof(BUILD_PROJECT_FILE);
+    // internal (not private): shared with AddPackage/Update/Cake; will move into a configuration
+    // service in the final #392 collapse PR.
+    internal const string BUILD_PROJECT_FILE = nameof(BUILD_PROJECT_FILE);
     private const string TEMP_DIRECTORY = nameof(TEMP_DIRECTORY);
     private const string DOTNET_GLOBAL_FILE = nameof(DOTNET_GLOBAL_FILE);
     private const string DOTNET_INSTALL_URL = nameof(DOTNET_INSTALL_URL);
@@ -27,7 +29,7 @@ public static int GetConfiguration(string[] args, AbsolutePath rootDirectory, Ab
         return 0;
     }
 
-    private static Dictionary<string, string> GetConfiguration(AbsolutePath buildScript, bool evaluate)
+    internal static Dictionary<string, string> GetConfiguration(AbsolutePath buildScript, bool evaluate)
     {
         string ReplaceScriptDirectory(string value)
             => evaluate

src/Fallout.Cli/Program.Setup.cs

@@ -178,13 +178,13 @@ internal static void UpdateSolutionFileContent(
             "EndProject");
     }
 
-    private static string[] GetTemplate(string templateName)
+    internal static string[] GetTemplate(string templateName)
     {
         return ResourceUtility.GetResourceAllLines<Program>($"templates.{templateName}");
     }
 
 
-    private static void WriteBuildScripts(
+    internal static void WriteBuildScripts(
         AbsolutePath scriptDirectory,
         AbsolutePath rootDirectory,
         AbsolutePath buildDirectory,
@@ -243,7 +243,7 @@ void MakeExecutable(AbsolutePath scriptFile)
         }
     }
 
-    private static void WriteConfigurationFile(AbsolutePath rootDirectory, AbsolutePath solutionFile)
+    internal static void WriteConfigurationFile(AbsolutePath rootDirectory, AbsolutePath solutionFile)
     {
         var parametersFile = GetDefaultParametersFile(rootDirectory);
         var dictionary = new Dictionary<string, string> { ["$schema"] = BuildSchemaFileName };