Improve help command with embeds and pagination.

src/main/java/com/mcmoddev/mmdbot/modules/commands/CommandModule.java

@@ -25,6 +25,7 @@
 import com.jagrosh.jdautilities.command.CommandClientBuilder;
 import com.mcmoddev.mmdbot.MMDBot;
 import com.mcmoddev.mmdbot.modules.commands.bot.info.CmdAbout;
+import com.mcmoddev.mmdbot.modules.commands.bot.info.CmdHelp;
 import com.mcmoddev.mmdbot.modules.commands.bot.info.CmdUptime;
 import com.mcmoddev.mmdbot.modules.commands.bot.management.CmdAvatar;
 import com.mcmoddev.mmdbot.modules.commands.bot.management.CmdRename;
@@ -88,6 +89,7 @@ public static void setupCommandModule() {
             .setOwnerId(MMDBot.getConfig().getOwnerID())
             .setPrefix(MMDBot.getConfig().getMainPrefix())
             .setAlternativePrefix(MMDBot.getConfig().getAlternativePrefix())
+            .setHelpConsumer(CmdHelp::execute)
             .addCommand(new CmdGuild())
             .addCommand(new CmdAbout())
             .addCommand(new CmdMe())
@@ -131,6 +133,7 @@ public static void setupCommandModule() {
             MMDBot.getInstance().addEventListener(CmdTranslateMappings.ButtonListener.INSTANCE);
             MMDBot.getInstance().addEventListener(new CmdListTricks.ButtonListener());
             MMDBot.getInstance().addEventListener(new CmdListQuotes.ButtonListener());
+            MMDBot.getInstance().addEventListener(new CmdHelp.ButtonListener());
             MMDBot.LOGGER.warn("Command module enabled and loaded.");
         } else {
             MMDBot.LOGGER.warn("Command module disabled via config, commands will not work at this time!");

src/main/java/com/mcmoddev/mmdbot/modules/commands/bot/info/CmdHelp.java

@@ -0,0 +1,157 @@
+/*
+ * MMDBot - https://github.com/MinecraftModDevelopment/MMDBot
+ * Copyright (C) 2016-2021 <MMD - MinecraftModDevelopment>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+ * USA
+ * https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
+ */
+package com.mcmoddev.mmdbot.modules.commands.bot.info;
+
+import com.jagrosh.jdautilities.command.Command;
+import com.jagrosh.jdautilities.command.CommandEvent;
+import com.mcmoddev.mmdbot.MMDBot;
+import com.mcmoddev.mmdbot.core.References;
+import com.mcmoddev.mmdbot.modules.commands.CommandModule;
+import net.dv8tion.jda.api.EmbedBuilder;
+import net.dv8tion.jda.api.entities.Emoji;
+import net.dv8tion.jda.api.events.interaction.ButtonClickEvent;
+import net.dv8tion.jda.api.hooks.ListenerAdapter;
+import net.dv8tion.jda.api.interactions.components.Button;
+import net.dv8tion.jda.api.interactions.components.Component;
+import net.dv8tion.jda.api.requests.restaction.MessageAction;
+import org.jetbrains.annotations.NotNull;
+
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This command doesn't use the normal syntax.
+ * Instead, it provides a single Consumer<CommandEvent> that the CommandClient can use.
+ *
+ * This should not be turned into a normal Command.
+ *
+ * @author Curle
+ */
+public class CmdHelp {
+
+        private static final int COMMANDS_PER_PAGE = 25;
+
+        /**
+         * Prepare the potential scrolling buttons for a help command,
+         *  and send the message with the proper embeds.
+         *
+         * See {@link #getHelpStartingAt(int)} for the implementation.
+         * @param e
+         */
+        public static void execute(CommandEvent e) {
+            MessageAction reply = e.getChannel().sendMessageEmbeds(getHelpStartingAt(0).build());
+            Component[] buttons = createScrollButtons(0);
+            if (buttons.length > 0)
+                reply.setActionRow(buttons);
+
+            reply.queue();
+        }
+
+        /**
+         * Create the row of Component interaction buttons.
+         * <p>
+         * Currently, this just creates a left and right arrow.
+         * Left arrow scrolls back a page. Right arrow scrolls forward a page.
+         *
+         * @param start The quote number at the start of the current page.
+         * @return A row of buttons to go back and forth by one page in a quote list.
+         */
+        private static Component[] createScrollButtons(int start) {
+            List<Component> components = new ArrayList<>();
+            if (start != 0) {
+                components.add(Button.secondary(ButtonListener.BUTTON_ID_PREFIX + "-" + start + "-prev",
+                    Emoji.fromUnicode("◀️")));
+            }
+            if (start + COMMANDS_PER_PAGE < CommandModule.getCommandClient().getCommands().size() + CommandModule.getCommandClient().getSlashCommands().size()) {
+                components.add(Button.primary(ButtonListener.BUTTON_ID_PREFIX + "-" + start + "-next",
+                    Emoji.fromUnicode("▶️")));
+            }
+            return components.toArray(new Component[0]);
+        }
+
+        /**
+         * Given a starting index, build an embed that we can display for users
+         *  to summarise all available commands.
+         * Intended to be used with pagination in the case of servers with LOTS of commands.
+         */
+        private static EmbedBuilder getHelpStartingAt(int index) {
+            EmbedBuilder embed = new EmbedBuilder();
+            embed.setAuthor(References.NAME, References.ISSUE_TRACKER, MMDBot.getInstance().getSelfUser().getAvatarUrl());
+            embed.setDescription("All registered commands:");
+
+            List<Command> commandList = CommandModule.getCommandClient().getCommands();
+            commandList.addAll(CommandModule.getCommandClient().getSlashCommands());
+
+            // Embeds have a 25 field limit. We need to make sure we don't exceed that.
+            if(commandList.size() < 25) {
+                for (Command c : commandList)
+                    embed.addField(c.getName(), c.getHelp(), true);
+            } else {
+                // Make sure we only go up to the limit.
+                for (int i = index; i < index + 25; i++)
+                    if (i < commandList.size())
+                        embed.addField(commandList.get(i).getName(), commandList.get(i).getHelp(), true);
+            }
+
+            embed.setFooter(References.NAME).setTimestamp(Instant.now());
+
+            return embed;
+        }
+
+        public static class ButtonListener extends ListenerAdapter {
+            private static final String BUTTON_ID_PREFIX = "help";
+
+            @Override
+            public void onButtonClick(@NotNull final ButtonClickEvent event) {
+                var button = event.getButton();
+                if (button == null || button.getId() == null) {
+                    return;
+                }
+
+                String[] idParts = button.getId().split("-");
+                if (idParts.length != 3) {
+                    return;
+                }
+
+                if (!idParts[0].equals(BUTTON_ID_PREFIX)) {
+                    return;
+                }
+
+                int current = Integer.parseInt(idParts[1]);
+
+                if (idParts[2].equals("next")) {
+                    event
+                        .editMessageEmbeds(getHelpStartingAt(current + COMMANDS_PER_PAGE).build())
+                        .setActionRow(createScrollButtons(current + COMMANDS_PER_PAGE))
+                        .queue();
+                } else {
+                    if (idParts[2].equals("prev")) {
+                        event
+                            .editMessageEmbeds(getHelpStartingAt(current - COMMANDS_PER_PAGE).build())
+                            .setActionRow(createScrollButtons(current - COMMANDS_PER_PAGE))
+                            .queue();
+                    }
+                }
+            }
+        }
+    }
+