Move to using Brigadier for bot commands

Brigadier is a command parsing and execution library made by Mojang for their game Minecraft. Licensed under MIT license.

build.gradle

@@ -12,6 +12,10 @@ buildscript {
 repositories {
     mavenCentral()
     jcenter()
+    maven {
+        name = "Minecraft Libraries"
+        url = "https://libraries.minecraft.net"
+    }
 }
 
 apply plugin: 'com.github.johnrengelman.shadow'
@@ -33,6 +37,7 @@ dependencies {
     implementation "com.google.guava:guava:${guava_version}"
     implementation "com.google.code.gson:gson:${gson_version}"
     implementation "ch.qos.logback:logback-classic:${logback_version}"
+    implementation "com.mojang:brigadier:${brigadier_version}"
 
     testImplementation "junit:junit:${junit_version}"
 }

gradle.properties

@@ -7,4 +7,5 @@ jopt_version=6.0-alpha-3
 guava_version=29.0-jre
 gson_version=2.8.6
 logback_version=1.3.0-alpha5
+brigadier_version=1.0.17
 junit_version=4.13

src/main/java/sciwhiz12/janitor/commands/BaseCommand.java

@@ -1,13 +1,23 @@
 package sciwhiz12.janitor.commands;
 
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
 import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import sciwhiz12.janitor.JanitorBot;
 
 public abstract class BaseCommand {
-    protected final CommandRegistry registry;
+    private final CommandRegistry registry;
 
     public BaseCommand(CommandRegistry registry) {
         this.registry = registry;
     }
 
-    public abstract void onCommand(MessageReceivedEvent event);
+    public CommandRegistry getRegistry() {
+        return registry;
+    }
+
+    public JanitorBot getBot() {
+        return registry.getBot();
+    }
+
+    public abstract LiteralArgumentBuilder<MessageReceivedEvent> getNode();
 }

src/main/java/sciwhiz12/janitor/commands/CommandRegistry.java

@@ -1,14 +1,20 @@
 package sciwhiz12.janitor.commands;
 
+import com.mojang.brigadier.CommandDispatcher;
+import com.mojang.brigadier.ParseResults;
+import com.mojang.brigadier.StringReader;
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
 import org.jetbrains.annotations.NotNull;
 import sciwhiz12.janitor.JanitorBot;
+import sciwhiz12.janitor.commands.bot.ShutdownCommand;
+import sciwhiz12.janitor.commands.misc.OKCommand;
+import sciwhiz12.janitor.commands.misc.PingCommand;
 import sciwhiz12.janitor.listeners.BaseListener;
 import sciwhiz12.janitor.utils.Util;
 
 import java.util.HashMap;
 import java.util.Map;
-import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import static sciwhiz12.janitor.Logging.COMMANDS;
@@ -16,44 +22,53 @@ import static sciwhiz12.janitor.Logging.JANITOR;
 
 public class CommandRegistry extends BaseListener {
     private final Pattern pattern;
+    private final String prefix;
     private final Map<String, BaseCommand> registry = new HashMap<>();
+    private final CommandDispatcher<MessageReceivedEvent> dispatcher;
 
     public CommandRegistry(JanitorBot bot, String prefix) {
         super(bot);
         this.pattern = Pattern.compile("^" + prefix + "([A-Za-z0-9]+).*$");
+        this.prefix = prefix;
+        this.dispatcher = new CommandDispatcher<>();
 
-        addCommand("ping", new PingCommand(this, "Pong!"));
-        addCommand("pong", new PingCommand(this, "Ping!"));
-        addCommand("ok", new OKCommand(this));
+        addCommand(new PingCommand(this, "ping", "Pong!"));
+        addCommand(new PingCommand(this, "pong", "Ping!"));
+        addCommand(new OKCommand(this));
         if (bot.getConfig().getOwnerID().isPresent()) {
-            addCommand("shutdown", new ShutdownCommand(this, bot.getConfig().getOwnerID().get()));
+            addCommand(new ShutdownCommand(this, bot.getConfig().getOwnerID().get()));
         }
+
+    }
+
+    public CommandDispatcher<MessageReceivedEvent> getDispatcher() {
+        return this.dispatcher;
     }
 
     public JanitorBot getBot() {
         return this.bot;
     }
 
-    public void addCommand(String cmd, BaseCommand instance) {
-        registry.put(cmd, instance);
+    public void addCommand(BaseCommand instance) {
+        dispatcher.register(instance.getNode());
     }
 
     @Override
     public void onMessageReceived(@NotNull MessageReceivedEvent event) {
+        String msg = event.getMessage().getContentDisplay();
+        if (!msg.startsWith(this.prefix)) return;
         try {
-            String msg = event.getMessage().getContentDisplay();
-            Matcher matcher = pattern.matcher(msg);
-            if (matcher.matches()) {
-                String cmd = matcher.group(1);
-                if (registry.containsKey(cmd)) {
-                    JANITOR.debug(COMMANDS, "Received command: {}; author: {}, full message: {}", cmd,
-                        Util.toString(event.getAuthor()), msg);
-                    registry.get(cmd).onCommand(event);
-                }
+            StringReader command = new StringReader(msg.substring(this.prefix.length()));
+            ParseResults<MessageReceivedEvent> parseResults = this.dispatcher.parse(command, event);
+            if (parseResults.getReader().canRead()) {
+                // Parsing did not succeed, i.e. command not found
+                // TODO: add separate code path when insufficient permissions / requires fails
+                return;
             }
-        } catch (Exception e) {
-            JANITOR.error(COMMANDS, "Error while parsing message: {}",
-                event.getMessage().getContentStripped(), e);
+            JANITOR.debug(COMMANDS, "Received command and executing. Author: {}, full message: {}", Util.toString(event.getAuthor()), msg);
+            dispatcher.execute(parseResults);
+        } catch (CommandSyntaxException ex) {
+            JANITOR.error(COMMANDS, "Error while parsing message and executing command", ex);
         }
     }
 }

src/main/java/sciwhiz12/janitor/commands/OKCommand.java

@@ -1,14 +0,0 @@
-package sciwhiz12.janitor.commands;
-
-import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
-
-public class OKCommand extends BaseCommand {
-    public OKCommand(CommandRegistry registry) {
-        super(registry);
-    }
-
-    @Override
-    public void onCommand(MessageReceivedEvent event) {
-        event.getMessage().addReaction("\uD83D\uDC4C").queue();
-    }
-}

src/main/java/sciwhiz12/janitor/commands/PingCommand.java

@@ -1,17 +0,0 @@
-package sciwhiz12.janitor.commands;
-
-import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
-
-public class PingCommand extends BaseCommand {
-    private final String message;
-
-    public PingCommand(CommandRegistry registry, String message) {
-        super(registry);
-        this.message = message;
-    }
-
-    @Override
-    public void onCommand(MessageReceivedEvent event) {
-        event.getMessage().getChannel().sendMessage(message).queue();
-    }
-}

src/main/java/sciwhiz12/janitor/commands/ShutdownCommand.java

@@ -1,22 +0,0 @@
-package sciwhiz12.janitor.commands;
-
-import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
-
-public class ShutdownCommand extends BaseCommand {
-    private final long ownerID;
-
-    public ShutdownCommand(CommandRegistry registry, long ownerID) {
-        super(registry);
-        this.ownerID = ownerID;
-    }
-
-    @Override
-    public void onCommand(MessageReceivedEvent event) {
-        if (event.getAuthor().getIdLong() == ownerID) {
-            event.getMessage().getChannel()
-                .sendMessage("Shutting down, in accordance with the owner's command. Goodbye all!")
-                .complete();
-            registry.getBot().shutdown();
-        }
-    }
-}

src/main/java/sciwhiz12/janitor/commands/bot/ShutdownCommand.java

@@ -0,0 +1,42 @@
+package sciwhiz12.janitor.commands.bot;
+
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
+import com.mojang.brigadier.context.CommandContext;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import sciwhiz12.janitor.commands.BaseCommand;
+import sciwhiz12.janitor.commands.CommandRegistry;
+import sciwhiz12.janitor.utils.Util;
+
+import static sciwhiz12.janitor.Logging.JANITOR;
+import static sciwhiz12.janitor.utils.CommandHelper.literal;
+
+public class ShutdownCommand extends BaseCommand {
+    private final long ownerID;
+
+    public ShutdownCommand(CommandRegistry registry, long ownerID) {
+        super(registry);
+        this.ownerID = ownerID;
+    }
+
+    @Override
+    public LiteralArgumentBuilder<MessageReceivedEvent> getNode() {
+        return literal("shutdown")
+            .requires(ctx -> ctx.getAuthor().getIdLong() == ownerID)
+            .executes(this::run);
+    }
+
+    int run(final CommandContext<MessageReceivedEvent> ctx) {
+        ctx.getSource()
+            .getMessage()
+            .getChannel()
+            .sendMessage("Shutting down, in accordance with the owner's command. Goodbye all!")
+            .submit()
+            .whenComplete(Util.handle(
+                success -> JANITOR.debug("Sent shutdown message to channel {}", Util.toString(ctx.getSource().getAuthor())),
+                err -> JANITOR.error("Error while sending ping message to bot owner {}", Util.toString(ctx.getSource().getAuthor()))
+                )
+            ).join();
+        getBot().shutdown();
+        return 1;
+    }
+}

src/main/java/sciwhiz12/janitor/commands/misc/OKCommand.java

@@ -0,0 +1,39 @@
+package sciwhiz12.janitor.commands.misc;
+
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
+import com.mojang.brigadier.context.CommandContext;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import sciwhiz12.janitor.commands.BaseCommand;
+import sciwhiz12.janitor.commands.CommandRegistry;
+import sciwhiz12.janitor.utils.Util;
+
+import static sciwhiz12.janitor.Logging.JANITOR;
+import static sciwhiz12.janitor.utils.CommandHelper.literal;
+
+public class OKCommand extends BaseCommand {
+    public OKCommand(CommandRegistry registry) {
+        super(registry);
+    }
+
+    public LiteralArgumentBuilder<MessageReceivedEvent> getNode() {
+        return literal("ok")
+            .executes(this::run);
+    }
+
+    int run(final CommandContext<MessageReceivedEvent> ctx) {
+        ctx.getSource()
+            .getMessage()
+            .addReaction("\uD83D\uDC4C")
+            .submit()
+            .whenComplete(Util.handle(
+                success -> JANITOR.debug("Reacted :ok_hand: to {}'s message", Util.toString(ctx.getSource().getAuthor())),
+                err -> JANITOR.error("Error while reacting :ok_hand: to {}'s message", Util.toString(ctx.getSource().getAuthor()))
+                )
+            );
+        return 1;
+    }
+
+    public void onCommand(MessageReceivedEvent event) {
+        event.getMessage().addReaction("\uD83D\uDC4C").queue();
+    }
+}

src/main/java/sciwhiz12/janitor/commands/misc/PingCommand.java

@@ -0,0 +1,41 @@
+package sciwhiz12.janitor.commands.misc;
+
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
+import com.mojang.brigadier.context.CommandContext;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import sciwhiz12.janitor.commands.BaseCommand;
+import sciwhiz12.janitor.commands.CommandRegistry;
+import sciwhiz12.janitor.utils.Util;
+
+import static sciwhiz12.janitor.Logging.JANITOR;
+import static sciwhiz12.janitor.utils.CommandHelper.literal;
+
+public class PingCommand extends BaseCommand {
+    private final String command;
+    private final String reply;
+
+    public PingCommand(CommandRegistry registry, String command, String reply) {
+        super(registry);
+        this.command = command;
+        this.reply = reply;
+    }
+
+    public LiteralArgumentBuilder<MessageReceivedEvent> getNode() {
+        return literal(command)
+            .executes(this::run);
+    }
+
+    int run(final CommandContext<MessageReceivedEvent> ctx) {
+        ctx.getSource()
+            .getMessage()
+            .getChannel()
+            .sendMessage(reply)
+            .submit()
+            .whenComplete(Util.handle(
+                success -> JANITOR.debug("Sent ping message to {}: {}", Util.toString(ctx.getSource().getAuthor()), reply),
+                err -> JANITOR.error("Error while sending ping message to {}", Util.toString(ctx.getSource().getAuthor()))
+                )
+            );
+        return 1;
+    }
+}

src/main/java/sciwhiz12/janitor/utils/CommandHelper.java

@@ -0,0 +1,10 @@
+package sciwhiz12.janitor.utils;
+
+import com.mojang.brigadier.builder.LiteralArgumentBuilder;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+
+public class CommandHelper {
+    public static LiteralArgumentBuilder<MessageReceivedEvent> literal(String command) {
+        return LiteralArgumentBuilder.literal(command);
+    }
+}