fix: Better safeguards for HOME directory usage

- Attempt to detect if `HOME` is defined and available. If not, error
  out.
- Attempt to create `$HOME/.config` if `$HOME` is available.
- If logic in code attempts to grab the app data dir path before it's
  set up, an exception is thrown.

CHANGELOG.md

@@ -24,6 +24,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Version information in help output has been fixed.
+- If a HOME directory is not available, throw an error to the user (use `--app-data` instead).
+- Create `$HOME/.config` (on Linux) if it does not exist.
 
 [appdata]: https://github.com/recyclarr/recyclarr/wiki/File-Structure
 

src/Common/DefaultEnvironment.cs

@@ -1,4 +1,4 @@
-namespace Common;
+namespace Common;
 
 internal class DefaultEnvironment : IEnvironment
 {
@@ -6,4 +6,9 @@ internal class DefaultEnvironment : IEnvironment
     {
         return Environment.GetFolderPath(folder);
     }
+
+    public string GetFolderPath(Environment.SpecialFolder folder, Environment.SpecialFolderOption option)
+    {
+        return Environment.GetFolderPath(folder, option);
+    }
 }

src/Common/IEnvironment.cs

@@ -1,6 +1,7 @@
-namespace Common;
+namespace Common;
 
 public interface IEnvironment
 {
     public string GetFolderPath(Environment.SpecialFolder folder);
+    string GetFolderPath(Environment.SpecialFolder folder, Environment.SpecialFolderOption option);
 }

src/Recyclarr.Tests/Command/Initialization/Init/InitializeAppDataPathTest.cs

@@ -1,4 +1,5 @@
 using AutoFixture.NUnit3;
+using Common;
 using NSubstitute;
 using NUnit.Framework;
 using Recyclarr.Command;
@@ -13,25 +14,29 @@ namespace Recyclarr.Tests.Command.Initialization.Init;
 public class InitializeAppDataPathTest
 {
     [Test, AutoMockData]
-    public void Do_not_override_path_if_null(
+    public void Use_default_app_data_if_not_specified(
+        [Frozen] IEnvironment env,
         [Frozen] IAppPaths paths,
         SonarrCommand cmd,
         InitializeAppDataPath sut)
     {
+        env.GetFolderPath(Arg.Any<Environment.SpecialFolder>(), Arg.Any<Environment.SpecialFolderOption>())
+            .Returns("app_data");
+
         sut.Initialize(cmd);
 
-        paths.DidNotReceiveWithAnyArgs().SetAppDataPath(default!);
+        env.Received().GetFolderPath(Environment.SpecialFolder.ApplicationData, Environment.SpecialFolderOption.Create);
+        paths.Received().SetAppDataPath("app_data");
     }
 
     [Test, AutoMockData]
-    public void Override_path_if_not_null(
+    public void Use_specified_app_data_if_user_provided(
         [Frozen] IAppPaths paths,
         SonarrCommand cmd,
         InitializeAppDataPath sut)
     {
         cmd.AppDataDirectory = "path";
         sut.Initialize(cmd);
-
         paths.Received().SetAppDataPath("path");
     }
 }

src/Recyclarr/AppPaths.cs

@@ -1,3 +1,4 @@
+using System.Diagnostics.CodeAnalysis;
 using System.IO.Abstractions;
 using TrashLib;
 
@@ -6,6 +7,7 @@ namespace Recyclarr;
 public class AppPaths : IAppPaths
 {
     private readonly IFileSystem _fs;
+    private string? _appDataPath;
 
     public AppPaths(IFileSystem fs)
     {
@@ -14,12 +16,15 @@ public class AppPaths : IAppPaths
 
     public string DefaultConfigFilename => "recyclarr.yml";
 
-    public void SetAppDataPath(string path) => AppDataPath = path;
+    public void SetAppDataPath(string path) => _appDataPath = path;
 
-    public string AppDataPath { get; private set; } = "";
-    public string ConfigPath => _fs.Path.Combine(AppDataPath, DefaultConfigFilename);
-    public string SettingsPath => _fs.Path.Combine(AppDataPath, "settings.yml");
-    public string LogDirectory => _fs.Path.Combine(AppDataPath, "logs");
-    public string RepoDirectory => _fs.Path.Combine(AppDataPath, "repo");
-    public string CacheDirectory => _fs.Path.Combine(AppDataPath, "cache");
+    [SuppressMessage("Design", "CA1024:Use properties where appropriate")]
+    public string GetAppDataPath()
+        => _appDataPath ?? throw new DirectoryNotFoundException("Application data directory not set!");
+
+    public string ConfigPath => _fs.Path.Combine(GetAppDataPath(), DefaultConfigFilename);
+    public string SettingsPath => _fs.Path.Combine(GetAppDataPath(), "settings.yml");
+    public string LogDirectory => _fs.Path.Combine(GetAppDataPath(), "logs");
+    public string RepoDirectory => _fs.Path.Combine(GetAppDataPath(), "repo");
+    public string CacheDirectory => _fs.Path.Combine(GetAppDataPath(), "cache");
 }

src/Recyclarr/Command/Initialization/Init/InitializeAppDataPath.cs

@@ -1,4 +1,6 @@
 using System.IO.Abstractions;
+using CliFx.Exceptions;
+using Common;
 using TrashLib;
 
 namespace Recyclarr.Command.Initialization.Init;
@@ -7,20 +9,40 @@ public class InitializeAppDataPath : IServiceInitializer
 {
     private readonly IFileSystem _fs;
     private readonly IAppPaths _paths;
+    private readonly IEnvironment _env;
 
-    public InitializeAppDataPath(IFileSystem fs, IAppPaths paths)
+    public InitializeAppDataPath(IFileSystem fs, IAppPaths paths, IEnvironment env)
     {
         _fs = fs;
         _paths = paths;
+        _env = env;
     }
 
     public void Initialize(ServiceCommand cmd)
     {
+        // If the user did not explicitly specify an app data directory, perform some system introspection to verify if
+        // the user has a home directory.
         if (string.IsNullOrEmpty(cmd.AppDataDirectory))
         {
+            // If we can't even get the $HOME directory value, throw an exception. User must explicitly specify it with
+            // --app-data.
+            var home = _env.GetFolderPath(Environment.SpecialFolder.UserProfile);
+            if (string.IsNullOrEmpty(home))
+            {
+                throw new CommandException(
+                    "The system does not have a HOME directory, so the application cannot determine where to place " +
+                    "data files. Please use the --app-data option to explicitly set a location for these files.");
+            }
+
+            // Set app data path to application directory value (e.g. `$HOME/.config` on Linux) and ensure it is
+            // created.
+            _paths.SetAppDataPath(_env.GetFolderPath(Environment.SpecialFolder.ApplicationData,
+                Environment.SpecialFolderOption.Create));
+
             return;
         }
 
+        // Ensure user-specified app data directory is created and use it.
         _fs.Directory.CreateDirectory(cmd.AppDataDirectory);
         _paths.SetAppDataPath(cmd.AppDataDirectory);
     }

src/TrashLib/IAppPaths.cs

@@ -3,7 +3,7 @@ namespace TrashLib;
 public interface IAppPaths
 {
     void SetAppDataPath(string path);
-    string AppDataPath { get; }
+    string GetAppDataPath();
     string ConfigPath { get; }
     string SettingsPath { get; }
     string LogDirectory { get; }