Add tab completion for commands and arguments

src/main/java/dansplugins/mailboxes/Mailboxes.java

@@ -1,6 +1,7 @@
 package dansplugins.mailboxes;
 
 import dansplugins.mailboxes.bstats.Metrics;
+import dansplugins.mailboxes.commands.*;
 import dansplugins.mailboxes.data.PersistentData;
 import dansplugins.mailboxes.externalapi.MailboxesAPI;
 import dansplugins.mailboxes.factories.MailboxFactory;
@@ -13,6 +14,9 @@
 import org.bukkit.plugin.java.JavaPlugin;
 
 import java.io.File;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
 
 public final class Mailboxes extends JavaPlugin {
     private final String pluginVersion = "v" + getDescription().getVersion();
@@ -82,4 +86,79 @@ public MailboxesAPI getAPI() {
     private boolean isVersionMismatched() {
         return !getConfig().getString("version").equalsIgnoreCase(getVersion());
     }
+
+    @Override
+    public List<String> onTabComplete(CommandSender sender, Command cmd, String label, String[] args) {
+        if (label.equalsIgnoreCase("mailboxes") || label.equalsIgnoreCase("m")) {
+            return getTabCompletions(sender, args);
+        }
+        return null;
+    }
+
+    private List<String> getTabCompletions(CommandSender sender, String[] args) {
+        if (args.length == 1) {
+            // Main subcommands - filter by permissions
+            List<String> subcommands = new ArrayList<>();
+            if (sender.hasPermission("mailboxes.help")) subcommands.add("help");
+            if (sender.hasPermission("mailboxes.config")) subcommands.add("config");
+            if (sender.hasPermission("mailboxes.list")) subcommands.add("list");
+            if (sender.hasPermission("mailboxes.send")) subcommands.add("send");
+            if (sender.hasPermission("mailboxes.open")) subcommands.add("open");
+            if (sender.hasPermission("mailboxes.delete")) subcommands.add("delete");
+            if (sender.hasPermission("mailboxes.archive")) subcommands.add("archive");
+            return filterCompletions(subcommands, args[0]);
+        }
+
+        if (args.length >= 2) {
+            String subcommand = args[0].toLowerCase();
+
+            switch (subcommand) {
+                case "config":
+                    if (sender.hasPermission("mailboxes.config")) {
+                        ConfigCommand configCommand = new ConfigCommand(configService);
+                        return configCommand.getTabCompletions(args);
+                    }
+                    break;
+                case "list":
+                    if (sender.hasPermission("mailboxes.list")) {
+                        ListCommand listCommand = new ListCommand(logger, persistentData);
+                        return listCommand.getTabCompletions(args);
+                    }
+                    break;
+                case "send":
+                    if (sender.hasPermission("mailboxes.send")) {
+                        SendCommand sendCommand = new SendCommand(logger, uuidChecker, configService, argumentParser, messageFactory, mailService);
+                        return sendCommand.getTabCompletions(sender, args);
+                    }
+                    break;
+                case "open":
+                    if (sender.hasPermission("mailboxes.open")) {
+                        OpenCommand openCommand = new OpenCommand(logger, persistentData);
+                        return openCommand.getTabCompletions(sender, args);
+                    }
+                    break;
+                case "delete":
+                    if (sender.hasPermission("mailboxes.delete")) {
+                        DeleteCommand deleteCommand = new DeleteCommand(persistentData);
+                        return deleteCommand.getTabCompletions(sender, args);
+                    }
+                    break;
+                case "archive":
+                    if (sender.hasPermission("mailboxes.archive")) {
+                        ArchiveCommand archiveCommand = new ArchiveCommand(persistentData);
+                        return archiveCommand.getTabCompletions(sender, args);
+                    }
+                    break;
+            }
+        }
+
+        return new ArrayList<>();
+    }
+
+    private List<String> filterCompletions(List<String> options, String input) {
+        String lowerInput = input.toLowerCase();
+        return options.stream()
+            .filter(option -> option.toLowerCase().startsWith(lowerInput))
+            .collect(Collectors.toList());
+    }
 }

src/main/java/dansplugins/mailboxes/commands/ArchiveCommand.java

@@ -7,6 +7,12 @@
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
 public class ArchiveCommand {
     private final PersistentData persistentData;
 
@@ -53,4 +59,31 @@ public boolean execute(CommandSender sender, String[] args) {
         return true;
     }
 
+    public List<String> getTabCompletions(CommandSender sender, String[] args) {
+        if (args.length == 2 && sender instanceof Player) {
+            Player player = (Player) sender;
+            Mailbox mailbox = persistentData.getMailbox(player);
+
+            if (mailbox != null) {
+                // Use Set to avoid duplicates (though unlikely based on design)
+                Set<String> messageIds = new HashSet<>();
+
+                // Add active message IDs (only active messages can be archived)
+                for (Message message : mailbox.getActiveMessages()) {
+                    messageIds.add(String.valueOf(message.getID()));
+                }
+
+                return filterCompletions(new ArrayList<>(messageIds), args[1]);
+            }
+        }
+        return new ArrayList<>();
+    }
+
+    private List<String> filterCompletions(List<String> options, String input) {
+        String lowerInput = input.toLowerCase();
+        return options.stream()
+            .filter(option -> option.toLowerCase().startsWith(lowerInput))
+            .collect(Collectors.toList());
+    }
+
 }

src/main/java/dansplugins/mailboxes/commands/ConfigCommand.java

@@ -4,9 +4,43 @@
 import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
 public class ConfigCommand {
     private final ConfigService configService;
 
+    // Config option names for tab completion (in camelCase to match config file)
+    // Note: 'version' is intentionally excluded as it cannot be set by users
+    private static final List<String> CONFIG_OPTIONS = Arrays.asList(
+        "debugMode",
+        "maxMessageIDNumber",
+        "maxMailboxIDNumber",
+        "preventSendingMessagesToSelf",
+        "assignmentAlertEnabled",
+        "unreadMessagesAlertEnabled",
+        "welcomeMessageEnabled",
+        "quotesEnabled",
+        "attachmentsEnabled",
+        "maxAttachmentStackSize"
+    );
+
+    // Boolean config options (stored in lowercase for case-insensitive comparison)
+    // These are derived from CONFIG_OPTIONS to maintain consistency
+    private static final Set<String> BOOLEAN_CONFIG_OPTIONS = new HashSet<>(Arrays.asList(
+        "debugmode",
+        "preventsendingmessagestoself",
+        "assignmentalertenabled",
+        "unreadmessagesalertenabled",
+        "welcomemessageenabled",
+        "quotesenabled",
+        "attachmentsenabled"
+    ));
+
     public ConfigCommand(ConfigService configService) {
         this.configService = configService;
     }
@@ -39,4 +73,30 @@ else if (args[0].equalsIgnoreCase("set")) {
         }
     }
 
+    public List<String> getTabCompletions(String[] args) {
+        if (args.length == 2) {
+            // Config subcommands
+            return filterCompletions(Arrays.asList("show", "set"), args[1]);
+        }
+        if (args.length == 3 && args[1].equalsIgnoreCase("set")) {
+            // Config options
+            return filterCompletions(CONFIG_OPTIONS, args[2]);
+        }
+        if (args.length == 4 && args[1].equalsIgnoreCase("set")) {
+            // Suggest values based on the config option type
+            String option = args[2];
+            if (BOOLEAN_CONFIG_OPTIONS.contains(option.toLowerCase())) {
+                return filterCompletions(Arrays.asList("true", "false"), args[3]);
+            }
+        }
+        return new ArrayList<>();
+    }
+
+    private List<String> filterCompletions(List<String> options, String input) {
+        String lowerInput = input.toLowerCase();
+        return options.stream()
+            .filter(option -> option.toLowerCase().startsWith(lowerInput))
+            .collect(Collectors.toList());
+    }
+
 }

src/main/java/dansplugins/mailboxes/commands/DeleteCommand.java

@@ -7,6 +7,12 @@
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
 public class DeleteCommand {
     private final PersistentData persistentData;
 
@@ -48,4 +54,36 @@ public boolean execute(CommandSender sender, String[] args) {
         return true;
     }
 
+    public List<String> getTabCompletions(CommandSender sender, String[] args) {
+        if (args.length == 2 && sender instanceof Player) {
+            Player player = (Player) sender;
+            Mailbox mailbox = persistentData.getMailbox(player);
+
+            if (mailbox != null) {
+                // Use Set to avoid duplicates (though unlikely based on design)
+                Set<String> messageIds = new HashSet<>();
+
+                // Add active message IDs
+                for (Message message : mailbox.getActiveMessages()) {
+                    messageIds.add(String.valueOf(message.getID()));
+                }
+
+                // Add archived message IDs
+                for (Message message : mailbox.getArchivedMessages()) {
+                    messageIds.add(String.valueOf(message.getID()));
+                }
+
+                return filterCompletions(new ArrayList<>(messageIds), args[1]);
+            }
+        }
+        return new ArrayList<>();
+    }
+
+    private List<String> filterCompletions(List<String> options, String input) {
+        String lowerInput = input.toLowerCase();
+        return options.stream()
+            .filter(option -> option.toLowerCase().startsWith(lowerInput))
+            .collect(Collectors.toList());
+    }
+
 }

src/main/java/dansplugins/mailboxes/commands/ListCommand.java

@@ -7,6 +7,11 @@
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
 public class ListCommand {
     private final Logger logger;
     private final PersistentData persistentData;
@@ -53,4 +58,18 @@ else if (list.equalsIgnoreCase("unread")) {
         return true;
     }
 
+    public List<String> getTabCompletions(String[] args) {
+        if (args.length == 2) {
+            return filterCompletions(Arrays.asList("active", "archived", "unread"), args[1]);
+        }
+        return new ArrayList<>();
+    }
+
+    private List<String> filterCompletions(List<String> options, String input) {
+        String lowerInput = input.toLowerCase();
+        return options.stream()
+            .filter(option -> option.toLowerCase().startsWith(lowerInput))
+            .collect(Collectors.toList());
+    }
+
 }

src/main/java/dansplugins/mailboxes/commands/OpenCommand.java

@@ -11,7 +11,10 @@
 
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
 
 public class OpenCommand {
     private final Logger logger;
@@ -77,4 +80,36 @@ public boolean execute(CommandSender sender, String[] args) {
         return true;
     }
 
+    public List<String> getTabCompletions(CommandSender sender, String[] args) {
+        if (args.length == 2 && sender instanceof Player) {
+            Player player = (Player) sender;
+            Mailbox mailbox = persistentData.getMailbox(player);
+
+            if (mailbox != null) {
+                // Use Set to avoid duplicates (though unlikely based on design)
+                Set<String> messageIds = new HashSet<>();
+
+                // Add active message IDs
+                for (Message message : mailbox.getActiveMessages()) {
+                    messageIds.add(String.valueOf(message.getID()));
+                }
+
+                // Add archived message IDs
+                for (Message message : mailbox.getArchivedMessages()) {
+                    messageIds.add(String.valueOf(message.getID()));
+                }
+
+                return filterCompletions(new ArrayList<>(messageIds), args[1]);
+            }
+        }
+        return new ArrayList<>();
+    }
+
+    private List<String> filterCompletions(List<String> options, String input) {
+        String lowerInput = input.toLowerCase();
+        return options.stream()
+            .filter(option -> option.toLowerCase().startsWith(lowerInput))
+            .collect(Collectors.toList());
+    }
+
 }