**Refactor command usage printing into CommandUsageFormatter**

Extracted command usage formatting logic from `CommandContainer` into a dedicated `CommandUsageFormatter` class, improving separation of concerns and maintainability. Updated `CommandManager` initialization and added comprehensive unit tests to validate the formatter's functionality.

src/main/java/me/bobert/netneutrality/core/command/CommandContainer.java

@@ -5,7 +5,6 @@ package me.bobert.netneutrality.core.command;
  * https://discord.gg/qUa6zNFZsd
  */
 
-import net.dv8tion.jda.api.entities.channel.ChannelType;
 import net.dv8tion.jda.api.interactions.commands.build.OptionData;
 import net.dv8tion.jda.api.interactions.commands.build.SlashCommandData;
 import net.dv8tion.jda.api.interactions.commands.build.SubcommandData;
@@ -13,25 +12,47 @@ import net.dv8tion.jda.api.interactions.commands.build.SubcommandGroupData;
 import net.dv8tion.jda.internal.interactions.CommandDataImpl;
 
 import java.util.List;
-import java.util.Set;
-import java.util.StringJoiner;
 
 public class CommandContainer {
     public static final CommandContainer NULL_COMMAND = new CommandContainer(null);
+    private static final CommandUsageFormatter USAGE_FORMATTER = new CommandUsageFormatter();
     private final Command command;
-    private CommandDataImpl commandData;
+    private final CommandDataImpl commandData;
-    private List<OptionData> options;
+    private final List<OptionData> options;
-    private List<SubcommandData> subcommands;
+    private final List<SubcommandData> subcommands;
-    private List<SubcommandGroupData> subcommandGroups;
+    private final List<SubcommandGroupData> subcommandGroups;
 
     public CommandContainer(Command command) {
-        this.command = command;
+        this(command, build(command));
-
-        if (command != null) {
-            CommandOptionsBuilder commandOptionsBuilder = new CommandOptionsBuilder(command.getType(), command);
-            command.registerCommandOptions(commandOptionsBuilder);
-            initContainer(commandOptionsBuilder);
     }
+
+    private CommandContainer(Command command, CommandDataImpl commandData) {
+        this.command = command;
+        this.commandData = commandData;
+
+        if (commandData != null) {
+            this.options = commandData.getOptions();
+            this.subcommands = commandData.getSubcommands();
+            this.subcommandGroups = commandData.getSubcommandGroups();
+        } else {
+            this.options = List.of();
+            this.subcommands = List.of();
+            this.subcommandGroups = List.of();
+        }
+    }
+
+    public static CommandContainer of(Command command) {
+        return new CommandContainer(command);
+    }
+
+    private static CommandDataImpl build(Command command) {
+        if (command == null) {
+            return null;
+        }
+
+        CommandOptionsBuilder builder = new CommandOptionsBuilder(command.getType(), command);
+        command.registerCommandOptions(builder);
+        return builder.build();
     }
 
     public Command getCommand() {
@@ -54,129 +75,11 @@ public class CommandContainer {
         return subcommandGroups;
     }
 
-    private void initContainer(CommandOptionsBuilder builder) {
-        this.commandData = builder.build();
-        this.options = commandData.getOptions();
-        this.subcommands = commandData.getSubcommands();
-        this.subcommandGroups = commandData.getSubcommandGroups();
-    }
-
     public boolean isEmpty() {
         return options.isEmpty() && subcommands.isEmpty() && subcommandGroups.isEmpty();
     }
 
     public String printUsage() {
-        StringBuilder usage = new StringBuilder();
+        return USAGE_FORMATTER.format(this);
-        if (!options.isEmpty()) {
-            usage.append("- Usage: /").append(command.getCommandName());
-            for (OptionData option : options) {
-                usage.append(" <").append(option.getName()).append(">");
-            }
-
-            usage.append(printOptions(options, null, false));
-        }
-
-        if (!subcommands.isEmpty()) {
-            for (SubcommandData subcommand : subcommands) {
-                usage.append("- Usage: /").append(command.getCommandName()).append(" ").append(subcommand.getName());
-
-                for (OptionData option : subcommand.getOptions()) {
-                    usage.append(" <").append(option.getName()).append(">");
-                }
-
-                usage.append(" (").append(subcommand.getDescription()).append(")");
-                usage.append(printOptions(subcommand.getOptions(), null, false));
-
-                usage.append("\n");
-            }
-        }
-
-        if (!subcommandGroups.isEmpty()) {
-            for (SubcommandGroupData subcommandGroup : subcommandGroups) {
-                usage.append("- Subcommand: /").append(command.getCommandName())
-                    .append(" ").append(subcommandGroup.getName())
-                    .append(" (").append(subcommandGroup.getDescription()).append(")")
-                    .append("\n");
-
-                for (SubcommandData subcommand : subcommandGroup.getSubcommands()) {
-                    usage.append("  - Usage: /").append(command.getCommandName())
-                        .append(" ").append(subcommandGroup.getName())
-                        .append(" ").append(subcommand.getName());
-
-                    for (OptionData option : subcommand.getOptions()) {
-                        usage.append(" <").append(option.getName()).append(">");
-                    }
-
-                    usage.append(printOptions(subcommand.getOptions(), subcommand.getDescription(), true));
-
-                    usage.append("\n");
-                }
-            }
-        }
-
-        if (!isEmpty()) {
-            usage.append("\n\n-# *: required argument");
-        }
-
-        return usage.toString();
-    }
-
-    private String printOptions(List<OptionData> options, String description, boolean group) {
-        StringBuilder usage = new StringBuilder();
-
-        if (description != null) {
-            usage.append(" (").append(description).append(")");
-        }
-
-        for (OptionData option : options) {
-            usage.append("\n");
-            if (group) {
-                usage.append("  ");
-            }
-
-            usage.append("  - ");
-            if (option.isRequired()) {
-                usage.append("*");
-            }
-            usage.append(option.getName()).append(": ").append(option.getDescription());
-
-            if (option.getMinValue() != null) {
-                usage.append(" [Min value: ").append(option.getMinValue().longValue()).append("]");
-            }
-
-            if (option.getMaxValue() != null) {
-                usage.append(" [Max value: ").append(option.getMaxValue().longValue()).append("]");
-            }
-
-            if (option.getMinLength() != null) {
-                usage.append(" [Min length: ").append(option.getMinLength().longValue()).append("]");
-            }
-
-            if (option.getMaxLength() != null) {
-                usage.append(" [Max length: ").append(option.getMaxLength().longValue()).append("]");
-            }
-
-            List<net.dv8tion.jda.api.interactions.commands.Command.Choice> choices = option.getChoices();
-            if (!choices.isEmpty()) {
-                StringJoiner joiner = new StringJoiner(", ");
-                for (net.dv8tion.jda.api.interactions.commands.Command.Choice choice : choices) {
-                    joiner.add(choice.getAsString());
-                }
-
-                usage.append(" [Available choices: ").append(joiner).append("]");
-            }
-
-            Set<ChannelType> requiredChannelTypes = option.getChannelTypes();
-            if (!requiredChannelTypes.isEmpty()) {
-                StringJoiner joiner = new StringJoiner(", ");
-                for (ChannelType type : requiredChannelTypes) {
-                    joiner.add(type.name());
-                }
-
-                usage.append(" [Required channel types: ").append(joiner).append("]");
-            }
-        }
-
-        return usage.toString();
     }
 }

src/main/java/me/bobert/netneutrality/core/command/CommandManager.java

@@ -57,7 +57,7 @@ public class CommandManager implements CommandRegistry {
     public void init() {
         logger.info("Loading commands..");
 
-        initCommands();
+        ReflectionHelper.loadCommands(Command.class, context, this::onCommandLoaded);
 
         logger.info("Loaded {} commands!", commands.size());
     }
@@ -84,12 +84,6 @@ public class CommandManager implements CommandRegistry {
         return commands;
     }
 
-    public void initCommands() {
-        Consumer<Command> onLoaded = this::onCommandLoaded;
-
-        ReflectionHelper.loadCommands(Command.class, context, onLoaded);
-    }
-
     void onCommandLoaded(Command command) {
         if (!command.isEnabled()) {
             logger.info("Skipping command {} as it is disabled", command.getClass().getName());

src/main/java/me/bobert/netneutrality/core/command/CommandUsageFormatter.java

@@ -0,0 +1,151 @@
+package me.bobert.netneutrality.core.command;
+/*
+ * Copyright (c) anthorob
+ *
+ * https://discord.gg/qUa6zNFZsd
+ */
+
+import net.dv8tion.jda.api.entities.channel.ChannelType;
+import net.dv8tion.jda.api.interactions.commands.build.OptionData;
+import net.dv8tion.jda.api.interactions.commands.build.SubcommandData;
+import net.dv8tion.jda.api.interactions.commands.build.SubcommandGroupData;
+
+import java.util.List;
+import java.util.Set;
+import java.util.StringJoiner;
+
+final class CommandUsageFormatter {
+    private static final String REQUIRED_LEGEND = "\n\n-# *: required argument";
+
+    String format(CommandContainer container) {
+        if (container.isEmpty()) {
+            return "";
+        }
+
+        String commandName = container.getCommand().getCommandName();
+        StringBuilder usage = new StringBuilder();
+        appendOptions(usage, commandName, container.getOptions());
+        appendSubcommands(usage, commandName, container.getSubcommands());
+        appendGroups(usage, commandName, container.getSubcommandGroups());
+        usage.append(REQUIRED_LEGEND);
+
+        return usage.toString();
+    }
+
+    private void appendOptions(StringBuilder usage, String commandName, List<OptionData> options) {
+        if (options.isEmpty()) {
+            return;
+        }
+
+        usage.append("- Usage: /").append(commandName);
+        appendArgs(usage, options);
+        usage.append(describeOptions(options, null, false));
+    }
+
+    private void appendSubcommands(StringBuilder usage, String commandName, List<SubcommandData> subcommands) {
+        for (SubcommandData subcommand : subcommands) {
+            usage.append("- Usage: /").append(commandName).append(" ").append(subcommand.getName());
+            appendArgs(usage, subcommand.getOptions());
+            usage.append(" (").append(subcommand.getDescription()).append(")");
+            usage.append(describeOptions(subcommand.getOptions(), null, false));
+            usage.append("\n");
+        }
+    }
+
+    private void appendGroups(StringBuilder usage, String commandName, List<SubcommandGroupData> groups) {
+        for (SubcommandGroupData group : groups) {
+            usage.append("- Subcommand: /").append(commandName)
+                .append(" ").append(group.getName())
+                .append(" (").append(group.getDescription()).append(")")
+                .append("\n");
+
+            for (SubcommandData subcommand : group.getSubcommands()) {
+                usage.append("  - Usage: /").append(commandName)
+                    .append(" ").append(group.getName())
+                    .append(" ").append(subcommand.getName());
+                appendArgs(usage, subcommand.getOptions());
+                usage.append(describeOptions(subcommand.getOptions(), subcommand.getDescription(), true));
+                usage.append("\n");
+            }
+        }
+    }
+
+    private void appendArgs(StringBuilder usage, List<OptionData> options) {
+        for (OptionData option : options) {
+            usage.append(" <").append(option.getName()).append(">");
+        }
+    }
+
+    private String describeOptions(List<OptionData> options, String description, boolean group) {
+        StringBuilder usage = new StringBuilder();
+
+        if (description != null) {
+            usage.append(" (").append(description).append(")");
+        }
+
+        for (OptionData option : options) {
+            usage.append("\n");
+            if (group) {
+                usage.append("  ");
+            }
+
+            usage.append("  - ");
+            if (option.isRequired()) {
+                usage.append("*");
+            }
+            usage.append(option.getName()).append(": ").append(option.getDescription());
+
+            appendConstraints(usage, option);
+            appendChoices(usage, option);
+            appendChannelTypes(usage, option);
+        }
+
+        return usage.toString();
+    }
+
+    private void appendConstraints(StringBuilder usage, OptionData option) {
+        if (option.getMinValue() != null) {
+            usage.append(" [Min value: ").append(option.getMinValue().longValue()).append("]");
+        }
+
+        if (option.getMaxValue() != null) {
+            usage.append(" [Max value: ").append(option.getMaxValue().longValue()).append("]");
+        }
+
+        if (option.getMinLength() != null) {
+            usage.append(" [Min length: ").append(option.getMinLength().longValue()).append("]");
+        }
+
+        if (option.getMaxLength() != null) {
+            usage.append(" [Max length: ").append(option.getMaxLength().longValue()).append("]");
+        }
+    }
+
+    private void appendChoices(StringBuilder usage, OptionData option) {
+        List<net.dv8tion.jda.api.interactions.commands.Command.Choice> choices = option.getChoices();
+        if (choices.isEmpty()) {
+            return;
+        }
+
+        StringJoiner joiner = new StringJoiner(", ");
+        for (net.dv8tion.jda.api.interactions.commands.Command.Choice choice : choices) {
+            joiner.add(choice.getAsString());
+        }
+
+        usage.append(" [Available choices: ").append(joiner).append("]");
+    }
+
+    private void appendChannelTypes(StringBuilder usage, OptionData option) {
+        Set<ChannelType> types = option.getChannelTypes();
+        if (types.isEmpty()) {
+            return;
+        }
+
+        StringJoiner joiner = new StringJoiner(", ");
+        for (ChannelType type : types) {
+            joiner.add(type.name());
+        }
+
+        usage.append(" [Required channel types: ").append(joiner).append("]");
+    }
+}

src/test/java/me/bobert/netneutrality/core/command/CommandContainerTest.java

@@ -60,6 +60,26 @@ class CommandContainerTest {
         assertNull(CommandContainer.NULL_COMMAND.getCommand());
     }
 
+    @Test
+    void nullCommandShouldBeEmptyAndPrintNothing() {
+        assertTrue(CommandContainer.NULL_COMMAND.isEmpty());
+        assertEquals("", CommandContainer.NULL_COMMAND.printUsage());
+    }
+
+    @Test
+    void ofShouldBuildTheSameAsTheConstructor() {
+        doAnswer(invocation -> {
+            ((CommandOptionsBuilder) invocation.getArgument(0))
+                .addOptions(new OptionData(OptionType.STRING, "text", "Text"));
+            return null;
+        }).when(command).registerCommandOptions(org.mockito.ArgumentMatchers.any());
+
+        CommandContainer container = CommandContainer.of(command);
+
+        assertSame(command, container.getCommand());
+        assertEquals(1, container.getOptions().size());
+    }
+
     @Test
     void shouldExposeTheCommand() {
         assertSame(command, container(_ -> { }).getCommand());
@@ -192,6 +212,41 @@ class CommandContainerTest {
         assertTrue(usage.endsWith("-# *: required argument"), usage);
     }
 
+    @Test
+    void shouldPrintExactSubcommandUsage() {
+        CommandContainer container = container(builder -> builder.addSubcommands(
+            new SubcommandData("add", "Adds").addOptions(new OptionData(OptionType.STRING, "name", "Name", true))));
+
+        assertEquals("- Usage: /test add <name> (Adds)\n  - *name: Name\n\n\n-# *: required argument",
+            container.printUsage());
+    }
+
+    @Test
+    void shouldPrintExactSubcommandGroupUsage() {
+        CommandContainer container = container(builder -> builder.addSubcommandGroups(
+            new SubcommandGroupData("grp", "Group").addSubcommands(
+                new SubcommandData("add", "Adds").addOptions(new OptionData(OptionType.STRING, "name", "Name", true)))));
+
+        assertEquals("- Subcommand: /test grp (Group)\n"
+            + "  - Usage: /test grp add <name> (Adds)\n"
+            + "    - *name: Name\n\n\n-# *: required argument", container.printUsage());
+    }
+
+    @Test
+    void shouldPrintExactAnnotations() {
+        CommandContainer container = container(builder -> builder.addOptions(
+            new OptionData(OptionType.STRING, "mode", "Mode").setMinLength(1).setMaxLength(5)
+                .addChoice("One", "one").addChoice("Two", "two"),
+            new OptionData(OptionType.INTEGER, "n", "N").setMinValue(1).setMaxValue(9),
+            new OptionData(OptionType.CHANNEL, "ch", "Ch").setChannelTypes(ChannelType.TEXT)));
+
+        assertEquals("- Usage: /test <mode> <n> <ch>\n"
+            + "  - mode: Mode [Min length: 1] [Max length: 5] [Available choices: one, two]\n"
+            + "  - n: N [Min value: 1] [Max value: 9]\n"
+            + "  - ch: Ch [Required channel types: TEXT]\n\n"
+            + "-# *: required argument", container.printUsage());
+    }
+
     @Test
     void shouldNotPrintTheRequiredLegendForUsagelessCommands() {
         assertFalse(container(_ -> { }).printUsage().contains("required argument"));

src/test/java/me/bobert/netneutrality/core/command/CommandUsageFormatterTest.java

@@ -0,0 +1,47 @@
+package me.bobert.netneutrality.core.command;
+
+/*
+ * Copyright (c) anthorob
+ *
+ * https://discord.gg/qUa6zNFZsd
+ */
+
+import net.dv8tion.jda.api.interactions.commands.OptionType;
+import net.dv8tion.jda.api.interactions.commands.build.OptionData;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.doAnswer;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class CommandUsageFormatterTest {
+
+    private final CommandUsageFormatter formatter = new CommandUsageFormatter();
+
+    private Command command() {
+        Command command = mock(Command.class);
+        when(command.getCommandName()).thenReturn("test");
+        when(command.getDescription()).thenReturn("A test command");
+        when(command.getType()).thenReturn(Command.Type.CHAT);
+        return command;
+    }
+
+    @Test
+    void shouldFormatEmptyContainerAsEmptyString() {
+        assertEquals("", formatter.format(new CommandContainer(command())));
+    }
+
+    @Test
+    void shouldFormatOptionsWithRequiredMarkerAndLegend() {
+        Command command = command();
+        doAnswer(invocation -> {
+            CommandOptionsBuilder builder = invocation.getArgument(0);
+            builder.addOptions(new OptionData(OptionType.STRING, "text", "Text", true));
+            return null;
+        }).when(command).registerCommandOptions(org.mockito.ArgumentMatchers.any());
+
+        assertEquals("- Usage: /test <text>\n  - *text: Text\n\n-# *: required argument",
+            formatter.format(new CommandContainer(command)));
+    }
+}