WIP before line endings normalisation

.vscode/launch.json

@@ -0,0 +1,24 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": ".NET Core Launch (console)",
+            "type": "coreclr",
+            "request": "launch",
+            "preLaunchTask": "build",
+            "program": "${workspaceFolder}/tests/console.tests/bin/Debug/net5.0/console.tests.dll",
+            "args": [],
+            "cwd": "${workspaceFolder}/tests/console.tests",
+            "console": "internalConsole",
+            "stopAtEntry": false
+        },
+        {
+            "name": ".NET Core Attach",
+            "type": "coreclr",
+            "request": "attach"
+        }
+    ]
+}

tests/console.tests/CommandTreeTests.cs

@@ -1,18 +1,228 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
 using NUnit.Framework;
 
 namespace Shamir.Console.Tests
 {
-    public class Tests
+    public class CommandTreeTests
     {
         [SetUp]
         public void Setup()
         {
+            tree = new DefaultCommandTree(
+                "root",
+                "top level",
+                ImmutableArray.Create<ICommandTree>(
+                    new DefaultCommandTree(
+                        "bar",
+                        "child command tree",
+                        ImmutableArray<ICommandTree>.Empty,
+                        ImmutableArray.Create<ICommand>(
+                            new SimpleTextCommand("one", "bar/1 command"),
+                            new SimpleTextCommand("two", "bar/2 command")
+                        ))),
+                ImmutableArray.Create<ICommand>(
+                    new SimpleTextCommand("foo", "foo command")
+                ));
+        }
+
+        ICommandTree tree;
+
+        [Test]
+        public void ConstructsHelpTextWithNoArgs()
+        {
+            var command = tree.FindCommand(Array.Empty<string>());
+            Assert.That(command, Is.InstanceOf<DefaultHelpTextCommand>());
+            var helpText = ((DefaultHelpTextCommand)command).GetHelpText();
+            Assert.That(helpText, Is.EqualTo(@"
+Group
+    root : top level
+
+Subgroups:
+    bar : child command tree
+
+Commands:
+    foo : foo command
+".TrimStart()));
         }
         
         [Test]
-        public void Test1()
+        public void ConstructsHelpTextForSubTree()
         {
-            Assert.Pass();
+            var command = tree.FindCommand(new[] { "bar" });
+            Assert.That(command, Is.InstanceOf<DefaultHelpTextCommand>());
+            var helpText = ((DefaultHelpTextCommand)command).GetHelpText();
+            Assert.That(helpText, Is.EqualTo(@"
+Group
+    root bar : child command tree
+
+Commands:
+    one : bar/1 command
+    two : bar/1 command
+"));
+        }
+
+        [TestCase((object)new string[] { "foo" }, ExpectedResult = "foo command")]
+        [TestCase((object)new string[] { "bar", "one" }, ExpectedResult = "bar/1 command")]
+        [TestCase((object)new string[] { "bar", "two" }, ExpectedResult = "bar/2 command")]
+        public string FindsCommand(string[] args)
+        {
+            var command = tree.FindCommand(args);
+            return command?.Description;
+        }
+
+
+        class SimpleTextCommand : ICommand
+        {
+            public SimpleTextCommand(string name, string description)
+            {
+                Name = name ?? throw new ArgumentNullException(nameof(name));
+                Description = description ?? throw new ArgumentNullException(nameof(description));
+            }
+
+            public string Name { get; }
+
+            public string Description { get; }
+
+            public ValueTask<int> ExecuteAsync()
+            {
+                return ValueTask.FromResult(0);
+            }
+        }
+    }
+
+    interface IOperationsNode
+    {
+        string Name { get; }
+        string Description { get; }
+    }
+
+    interface ICommand : IOperationsNode
+    {
+        ValueTask<int> ExecuteAsync();
+    }
+
+    interface ICommandTree : IOperationsNode
+    {
+        ImmutableArray<ICommandTree> SubTrees { get; }
+        ImmutableArray<ICommand> Commands { get; }
+        ICommand FindCommand(ReadOnlySpan<string> args);
+    }
+
+    class DefaultCommandTree : ICommandTree
+    {
+        public DefaultCommandTree(string name, string description, ImmutableArray<ICommandTree> subtrees, ImmutableArray<ICommand> commands)
+        {
+            this.Name = name ?? throw new ArgumentNullException(nameof(name));
+            this.Description = description ?? throw new ArgumentNullException(nameof(description));
+            this.SubTrees = subtrees;
+            this.Commands = commands;
+        }
+
+        public string Name { get; }
+        public string Description { get; }
+        public ImmutableArray<ICommandTree> SubTrees { get; }
+        public ImmutableArray<ICommand> Commands { get; }
+
+        public ICommand FindCommand(ReadOnlySpan<string> args)
+        {
+            if (args.Length > 0)
+            {
+                foreach (var command in Commands)
+                {
+                    if (command.Name == args[0])
+                    {
+                        return command;
+                    }
+                }
+
+                foreach (var tree in SubTrees)
+                {
+                    if (tree.Name == args[0])
+                    {
+                        return tree.FindCommand(args[1..]);
+                    }
+                }
+            }
+
+            return new DefaultHelpTextCommand(this);
+        }
+    }
+
+    class DefaultHelpTextCommand : ICommand
+    {
+        public DefaultHelpTextCommand(ICommandTree tree)
+        {
+            this.CommandTree = tree ?? throw new ArgumentNullException(nameof(tree));
+        }
+
+        public string Name => "help";
+        public string Description => "Print help text";
+
+        public ICommandTree CommandTree { get; }
+
+        public ValueTask<int> ExecuteAsync()
+        {
+            System.Console.Error.WriteLine(GetHelpText());
+            return ValueTask.FromResult(1); // TODO: const
+        }
+
+        public string GetHelpText() => CommandTree.BuildHelpText();
+    }
+
+    static class ICommandTreeExtensions
+    {
+        public static string BuildHelpText(this ICommandTree tree)
+        {
+            var sb = new StringBuilder();
+            sb.AppendLine("Group");
+            sb.Append("    ");
+            sb.AppendLine(tree.Name);
+            sb.AppendLine();
+
+            if (!tree.SubTrees.IsEmpty)
+            {
+                sb.AppendLine("Subgroups:");
+
+                var maxSpacing = tree.SubTrees.Max(c => c.Name.Length) + 1;
+                
+                foreach (var child in tree.SubTrees)
+                {
+                    sb.Append("    ");
+                    sb.Append(child.Name);
+                    for (var i = 0; i < maxSpacing; i++)
+                    {
+                        sb.Append(' ');
+                    }
+                    sb.Append(": ");
+                    sb.AppendLine(child.Description);
+                }
+            }
+
+            if (!tree.Commands.IsEmpty)
+            {
+                sb.AppendLine("Commands:");
+
+                var maxSpacing = tree.Commands.Max(c => c.Name.Length) + 1;
+                
+                foreach (var command in tree.Commands)
+                {
+                    sb.Append("    ");
+                    sb.Append(command.Name);
+                    for (var i = 0; i < maxSpacing; i++)
+                    {
+                        sb.Append(' ');
+                    }
+                    sb.Append(": ");
+                    sb.AppendLine(command.Description);
+                }
+            }
+            
+            return sb.ToString();
         }
     }
 }

tests/console.tests/console.tests.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <TargetFramework>net5.0</TargetFramework>
     <IsPackable>false</IsPackable>
-    <RootNamespace>Shamir.Console.Tests
+    <RootNamespace>Shamir.Console.Tests</RootNamespace>
   </PropertyGroup>
 
   <ItemGroup>