Add command line options

Api/Api.csproj

@@ -12,6 +12,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="8.0.0" />
     <PackageReference Include="Microsoft.Net.Http.Headers" Version="8.0.2" />
+    <PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />
   </ItemGroup>
 
 </Project>

Api/Program.cs

@@ -1,14 +1,38 @@
-using Microsoft.Extensions.Logging.Abstractions;
+using System.CommandLine;
+using Microsoft.Extensions.Logging.Abstractions;
 
 namespace Api;
 
 public class Program
 {
     public static async Task Main(string[] args)
     {
-        var username = Environment.GetEnvironmentVariable("BANDCAMP_USERNAME");
-        var password = Environment.GetEnvironmentVariable("BANDCAMP_PASSWORD");
+        var username = CreateOption("--username", "Your Bandcamp account username.");
+        var password = CreateOption("--password", "Your Bandcamp account password.");
+        var album = CreateOption("--album", "ID of the album you want to download.");
 
+        var listCommand = new RootCommand("List all albums in your Bandcamp collection.")
+        {
+            username,
+            password,
+        };
+
+        var downloadCommand = new Command("download", "Download the album with the specified ID.")
+        {
+            username,
+            password,
+            album
+        };
+
+        listCommand.AddCommand(downloadCommand);
+        listCommand.SetHandler(List, username, password);
+        downloadCommand.SetHandler(Download, username, password, album);
+
+        await listCommand.InvokeAsync(args);
+    }
+
+    private static async Task List(string username, string password)
+    {
         using var client = new Client(username, password, NullLoggerFactory.Instance);
 
         await foreach (var item in client.GetCollection())
@@ -20,4 +44,17 @@ public static async Task Main(string[] args)
             Console.WriteLine($"{id,10} {artist} — {album}");
         }
     }
+
+    private static void Download(string username, string password, string album)
+    {
+        throw new NotImplementedException();
+    }
+
+    private static Option<string> CreateOption(string name, string description)
+    {
+        return new Option<string>(name, description)
+        {
+            IsRequired = true
+        };
+    }
 }