feat: enhanced dynamic help command with descriptions (fixes #5)

src/main/java/com/mycmd/commands/HelpCommand.java

@@ -5,17 +5,10 @@
 import java.util.Map;
 
 /**
- * Displays a list of all available commands in the shell.
- * 
- * This command provides users with an overview of commands registered in
- * the shell. It requires access to the command registry (Map) which is
- * provided during construction. Each command name is printed on a separate
- * line with a bullet point prefix.
- * 
- * Usage: help
- * 
- * The command iterates through all keys in the command registry and displays
- * them in the order provided by the map's key set.
+ * Enhanced HelpCommand
+ * --------------------
+ * Dynamically lists all available commands with their descriptions.
+ * Supports detailed help for individual commands using 'help <command>'.
  */
 public class HelpCommand implements Command {
     private final Map<String, Command> commands;
@@ -26,9 +19,41 @@ public HelpCommand(Map<String, Command> commands) {
 
     @Override
     public void execute(String[] args, ShellContext context) {
-        System.out.println("Available commands:");
-        for (String key : commands.keySet()) {
-            System.out.println(" - " + key);
+        // Detailed help for a specific command
+        if (args.length > 1) {
+            String cmdName = args[1];
+            Command cmd = commands.get(cmdName);
+
+            if (cmd != null) {
+                System.out.println("\nCommand: " + cmdName);
+                System.out.println("Description: " + cmd.description());
+                System.out.println("Usage: " + (cmd.usage() != null ? cmd.usage() : cmdName + " [options]"));
+            } else {
+                System.out.println("No such command: " + cmdName);
+            }
+            return;
+        }
+
+        // General help listing all commands
+        System.out.println("\nMyCMD — Available Commands:\n");
+        for (Map.Entry<String, Command> entry : commands.entrySet()) {
+            String name = entry.getKey();
+            Command cmd = entry.getValue();
+            String description = (cmd.description() != null && !cmd.description().isEmpty())
+                    ? cmd.description()
+                    : "No description available";
+            System.out.printf("  %-12s : %s%n", name, description);
         }
+        System.out.println("\nType 'help <command>' for detailed info about a specific command.\n");
+    }
+
+    @Override
+    public String description() {
+        return "Show list of available commands and their descriptions.";
+    }
+
+    @Override
+    public String usage() {
+        return "help [command]";
     }
-}
+}