Basic Command System

- Implemented a basic command system.
 - Reimplemented the clear chat command.

.gitignore

@@ -27,3 +27,5 @@ bin/
 
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
+
+/target

src/main/java/me/ryandw11/ultrachat/UltraChat.java

@@ -1,9 +1,18 @@
 package me.ryandw11.ultrachat;
 
+import me.ryandw11.ultrachat.commands.ChatCommand;
 import org.bukkit.plugin.java.JavaPlugin;
 
+import java.util.Objects;
+
 /**
  * The main class of UltraChat.
  */
 public class UltraChat extends JavaPlugin {
+
+    @Override
+    public void onEnable() {
+        Objects.requireNonNull(getCommand("chat")).setExecutor(new ChatCommand(this));
+        getLogger().info("UltraChat v" + getDescription().getVersion() + " was successfully enabled.");
+    }
 }

src/main/java/me/ryandw11/ultrachat/commands/ChatCommand.java

@@ -0,0 +1,51 @@
+package me.ryandw11.ultrachat.commands;
+
+import me.ryandw11.ultrachat.UltraChat;
+import me.ryandw11.ultrachat.commands.chat.ClearCommand;
+import org.bukkit.ChatColor;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandSender;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * The main chat command for the plugin.
+ */
+public class ChatCommand implements CommandExecutor {
+    private final UltraChat plugin;
+    private final CommandHandler commandHandler;
+
+    public ChatCommand(UltraChat plugin) {
+        this.plugin = plugin;
+        this.commandHandler = new CommandHandler();
+        this.commandHandler.registerCommand(new ClearCommand(), "clear");
+    }
+
+    @Override
+    public boolean onCommand(@NotNull CommandSender sender, @NotNull Command cmd, @NotNull String s, @NotNull String[] args) {
+        try {
+            if (args.length != 0)
+                return commandHandler.handleCommand(sender, cmd, s, args);
+        } catch (IllegalArgumentException ex) {
+            // Do nothing as this exception was triggered purposefully.
+        }
+
+        if (sender.hasPermission("ultrachat.command.help")) {
+            sender.sendMessage(ChatColor.translateAlternateColorCodes('&',
+                    "&3=============[&2UltraChat&3]============="));
+            sender.sendMessage(ChatColor.translateAlternateColorCodes('&', "&3Created by: &2Ryandw11"));
+            sender.sendMessage(ChatColor.translateAlternateColorCodes('&',
+                    "&3Version: &2" + plugin.getDescription().getVersion()));
+            sender.sendMessage(ChatColor.translateAlternateColorCodes('&',
+                    "&3Github wiki:&2 https://github.com/ryandw11/CustomStructures/wiki"));
+            sender.sendMessage(ChatColor.translateAlternateColorCodes('&', "&3Commands:"));
+
+            for (SubCommand command : commandHandler.getSubCommands()) {
+                if (!sender.hasPermission(command.commandPermission())) continue;
+                sender.sendMessage(ChatColor.translateAlternateColorCodes('&',
+                        command.helpMessage()));
+            }
+        }
+        return false;
+    }
+}

src/main/java/me/ryandw11/ultrachat/commands/CommandHandler.java

@@ -0,0 +1,78 @@
+package me.ryandw11.ultrachat.commands;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+/**
+ * An extremely primitive command handler.
+ */
+public class CommandHandler {
+    private final Map<List<String>, SubCommand> commandMap;
+
+    public CommandHandler() {
+        commandMap = new HashMap<>();
+    }
+
+    /**
+     * Register a command.
+     *
+     * @param s          The command to register.
+     * @param subCommand The sub command.
+     */
+    public void registerCommand(String s, SubCommand subCommand) {
+        if (commandMap.containsKey(Collections.singletonList(s.toLowerCase())))
+            throw new IllegalArgumentException("Command already exists!");
+
+        commandMap.put(Collections.singletonList(s.toLowerCase()), subCommand);
+    }
+
+    /**
+     * Register a command.
+     *
+     * @param subCommand The sub command.
+     * @param args The aliases to register.
+     */
+    public void registerCommand(SubCommand subCommand, String... args) {
+        List<String> list = new ArrayList<>(Arrays.asList(args));
+        list = list.stream().map(String::toLowerCase).collect(Collectors.toList());
+        if (commandMap.containsKey(list))
+            throw new IllegalArgumentException("Command already exists!");
+
+        commandMap.put(list, subCommand);
+    }
+
+    /**
+     * Handle a command.
+     *
+     * <p>Throws IllegalArgumentException if sub command does not exist.</p>
+     *
+     * @param sender The command sender.
+     * @param cmd    The command.
+     * @param s      The string.
+     * @param args   The arguments.
+     * @return If the command is valid.
+     */
+    public boolean handleCommand(CommandSender sender, Command cmd, String s, String[] args) {
+        if (args.length == 0)
+            return false;
+        for (Map.Entry<List<String>, SubCommand> entry : commandMap.entrySet()) {
+            if (entry.getKey().contains(args[0].toLowerCase())) {
+                String[] newArgs = new String[args.length - 1];
+                if (newArgs.length > 0) {
+                    System.arraycopy(args, 1, newArgs, 0, newArgs.length);
+                }
+                return entry.getValue().subCommand(sender, cmd, s, newArgs);
+            }
+        }
+        throw new IllegalArgumentException("Invalid command");
+    }
+
+    public Collection<SubCommand> getSubCommands() {
+        return commandMap.values();
+    }
+
+
+}

src/main/java/me/ryandw11/ultrachat/commands/SubCommand.java

@@ -0,0 +1,30 @@
+package me.ryandw11.ultrachat.commands;
+
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+
+public interface SubCommand {
+
+    /**
+     * Get the help message for the command.
+     * @return The help message for the command.
+     */
+    String helpMessage();
+
+    /**
+     * The permission for the command.
+     * @return The permission for the command.
+     */
+    String commandPermission();
+
+    /**
+     * The sub command.
+     *
+     * @param sender The sender.
+     * @param cmd    The command.
+     * @param s      The command string.
+     * @param args   The arguments. (Does not include the subcommand name. So args.length for `/chat color` is 0.)
+     * @return If the sub-command is valid.
+     */
+    boolean subCommand(CommandSender sender, Command cmd, String s, String[] args);
+}

src/main/java/me/ryandw11/ultrachat/commands/chat/ClearCommand.java

@@ -0,0 +1,49 @@
+package me.ryandw11.ultrachat.commands.chat;
+
+import me.ryandw11.ultrachat.commands.SubCommand;
+import org.bukkit.Bukkit;
+import org.bukkit.ChatColor;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+
+/**
+ * This is the clear command for UltraChat.
+ * <p>/chat clear</p>
+ * <p>Permission:</p>
+ * <code>
+ *     ultrachat.command.clear
+ * </code>
+ */
+public class ClearCommand implements SubCommand {
+    @Override
+    public String helpMessage() {
+        return "&2/chat clear &3- &bClear all messages from the chat.";
+    }
+
+    @Override
+    public String commandPermission() {
+        return "ultrachat.command.clear";
+    }
+
+    @Override
+    public boolean subCommand(CommandSender sender, Command cmd, String s, String[] args) {
+        if(!sender.hasPermission(commandPermission())) {
+            sender.sendMessage(ChatColor.RED + "You do not have permission for this command!");
+            return true;
+        }
+
+        for(int i = 0; i < 100; i++) {
+            for(Player player : Bukkit.getOnlinePlayers()) {
+                player.sendMessage(" ");
+            }
+        }
+
+        Bukkit.getServer().broadcastMessage(String.format("%s%s%s has cleared the chat!",
+                ChatColor.GOLD,
+                sender.getName(),
+                ChatColor.GREEN));
+
+        return false;
+    }
+}

src/main/resources/plugin.yml

@@ -1,8 +1,12 @@
 name: UltraChat
 version: 3.0.0
-main: me.ryandw11.ultrachat
+main: me.ryandw11.ultrachat.UltraChat
 author: Ryandw11
 description: An advanced chat management plugin.
 depend: [Vault]
 softdepend: [PlaceholderAPI]
 api-version: 1.13
+commands:
+  chat:
+    description: The main command for Ultra Chat.
+    aliases: [uchat, ultrac, ultrachat]