feat: add watch command

readme.md

@@ -103,6 +103,8 @@ The host supports a small set of commands that were useful to me:
 
 `reset`: resets the state of the incremental compiler - removes all trees and references, and asks the target to resend dependencies. 
 
+`watch {path}`: relative to the last changed file's directory, recursively finds all .cs in at `path` and below and adds them to the incremental compilation. e.g. `watch .` to include all files in the same directory as the current file being changed, without having to trigger changes against them all individually
+
 ### target commands
 
 Commands prefixed with '!' will be sent to targets rather than the host. There are no built-in commands supported by the target, but you can add support for arbitrary commands to your `IReloadManager` by implementing the `ExecuteCommand` method. For example, a `goto` command in a prism app could be implemented using the code below, which walks the service container for pages and allows them to be chosen from a menu (if not specified as an argument to the command):

src/components/tbc.host/Components/FileWatcher/FileWatcher.cs

@@ -1,23 +1,29 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.IO.Abstractions;
 using System.Linq;
 using System.Reactive.Linq;
+using System.Reactive.Subjects;
+using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
 using RxFileSystemWatcher;
 using Tbc.Host.Components.Abstractions;
+using Tbc.Host.Components.CommandProcessor.Models;
 using Tbc.Host.Components.FileWatcher.Models;
 using Tbc.Host.Config;
 
 namespace Tbc.Host.Components.FileWatcher
 {
-    public class FileWatcher : ComponentBase<FileWatcher>, IFileWatcher
+    public class FileWatcher : ComponentBase<FileWatcher>, IFileWatcher, IExposeCommands
     {
         private readonly FileWatchConfig _config;
         private readonly IFileSystem _fileSystem;
 
         public string WatchPath { get; private set; }
-
+        public ChangedFile LastChangedFile { get; private set; }
+
+        private Subject<ChangedFile> _manualWatchFiles = new Subject<ChangedFile>();
         public IObservable<ChangedFile> Changes { get; set; }
 
         public FileWatcher(FileWatchConfig config, IFileSystem fileSystem, ILogger<FileWatcher> logger) : base(logger)
@@ -30,7 +36,10 @@ public FileWatcher(FileWatchConfig config, IFileSystem fileSystem, ILogger<FileW
 
         private void Init()
         {
-            Changes = CreateFileSystemWatcher(_config.RootPath, _config.FileMask);
+            Changes =
+                Observable.Merge(
+                    _manualWatchFiles, // files added to the incremental by a 'watch' command
+                    CreateFileSystemWatcher(_config.RootPath, _config.FileMask)); // files actually changed
         }
 
         public IObservable<ChangedFile> CreateFileSystemWatcher(string path, string mask)
@@ -53,37 +62,82 @@ public IObservable<ChangedFile> CreateFileSystemWatcher(string path, string mask
 
             Logger.LogInformation("File watcher {FileWatcher} started with config {@Config}", ofsw, _config);
 
-            var ret = 
+            var ret =
                 Observable
                     .Merge(ofsw.Changed, ofsw.Created, ofsw.Renamed, ofsw.Deleted)
                     .Where(x => !_config.Ignore.Any(i => x.FullPath.Contains((string) i)))
+                    .Select(x => x.FullPath)
                     .Select(TryGetChangedFile)
                     .Where(x => x != null)
                     .Do(f => Logger.LogInformation("Changed File: {ChangedFile}", f.Path.Substring(WatchPath.Length)));
-            
+
             ofsw.Start();
-            
+
             return ret;
         }
 
-        private ChangedFile TryGetChangedFile(FileSystemEventArgs x)
+        private ChangedFile TryGetChangedFile(string filePath)
         {
             try
             {
-                return new ChangedFile
+                return LastChangedFile = new ChangedFile
                 {
-                    Path = x.FullPath,
-                    Contents = _fileSystem.File.ReadAllText(x.FullPath)
+                    Path = filePath,
+                    Contents = _fileSystem.File.ReadAllText(filePath)
                 };
             }
             catch (Exception ex)
             {
                 Logger.LogError(ex,
                     "An error occurred when attempting to read changed file at '{FilePath}'",
-                    x.FullPath);
+                    filePath);
 
                 return null;
             }
         }
+
+        public string Identifier => $"fw";
+        public IEnumerable<TbcCommand> Commands => new[]
+        {
+            new TbcCommand
+            {
+                Command = "watch",
+                Execute = HandleWatchCommand
+            }
+        };
+
+        private Task HandleWatchCommand(string cmd, string[] args)
+        {
+            if (args.Length != 1)
+            {
+                Logger.LogWarning("Need exactly one argument ('relative path') for command 'watch'");
+                return Task.CompletedTask;
+            }
+
+            if (LastChangedFile is null)
+            {
+                Logger.LogWarning("No previously changed file relative to which to watch");
+                return Task.CompletedTask;
+            }
+
+            var inputPath = args[0];
+
+            var lastPath = LastChangedFile.Path;
+            var lastDirectory = Path.GetDirectoryName(lastPath);
+
+            var targetPath = Path.Combine(lastDirectory, inputPath);
+            var filesInPath =
+                _fileSystem.Directory.GetFiles(targetPath, "*.cs", SearchOption.AllDirectories)
+                   .Select(x => new FileInfo(x).FullName)
+                   .ToList();
+
+            Logger.LogInformation("Watch with target {Target} resolve to {ResolvedPath} and includes files {@Files}",
+                inputPath, targetPath, filesInPath);
+
+            foreach (var file in filesInPath)
+                _manualWatchFiles.OnNext(TryGetChangedFile(file));
+
+            return Task.CompletedTask;
+        }
     }
 }