feat: interactions (#5448)

Co-authored-by: izexi <43889168+izexi@users.noreply.github.com>
Co-authored-by: Sugden <28943913+NotSugden@users.noreply.github.com>
Co-authored-by: Advaith <advaithj1@gmail.com>
Co-authored-by: Shiaupiau <stu43005@gmail.com>
Co-authored-by: monbrey <rsm999@uowmail.edu.au>
Co-authored-by: Tiemen <ThaTiemsz@users.noreply.github.com>
Co-authored-by: Carter <carter@elhnet.net>

src/client/websocket/handlers/INTERACTION_CREATE.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const { Events, InteractionTypes } = require('../../../util/Constants');
+let Structures;
+
+module.exports = (client, { d: data }) => {
+  if (data.type === InteractionTypes.APPLICATION_COMMAND) {
+    if (!Structures) Structures = require('../../../util/Structures');
+    const CommandInteraction = Structures.get('CommandInteraction');
+
+    const interaction = new CommandInteraction(client, data);
+
+    /**
+     * Emitted when an interaction is created.
+     * @event Client#interaction
+     * @param {Interaction} interaction The interaction which was created
+     */
+    client.emit(Events.INTERACTION_CREATE, interaction);
+    return;
+  }
+
+  client.emit(Events.DEBUG, `[INTERACTION] Received interaction with unknown type: ${data.type}`);
+};

src/errors/Messages.js

@@ -110,6 +110,8 @@ const Messages = {
   FETCH_GROUP_DM_CHANNEL: "Bots don't have access to Group DM Channels and cannot fetch them",
 
   MEMBER_FETCH_NONCE_LENGTH: 'Nonce length must not exceed 32 characters.',
+
+  INTERACTION_ALREADY_REPLIED: 'This interaction has already been deferred or replied to.',
 };
 
 for (const [name, message] of Object.entries(Messages)) register(name, message);

src/index.js

@@ -33,8 +33,10 @@ module.exports = {
   version: require('../package.json').version,
 
   // Managers
+  ApplicationCommandManager: require('./managers/ApplicationCommandManager'),
   BaseGuildEmojiManager: require('./managers/BaseGuildEmojiManager'),
   ChannelManager: require('./managers/ChannelManager'),
+  GuildApplicationCommandManager: require('./managers/GuildApplicationCommandManager'),
   GuildChannelManager: require('./managers/GuildChannelManager'),
   GuildEmojiManager: require('./managers/GuildEmojiManager'),
   GuildEmojiRoleManager: require('./managers/GuildEmojiRoleManager'),
@@ -58,6 +60,7 @@ module.exports = {
 
   // Structures
   Application: require('./structures/interfaces/Application'),
+  ApplicationCommand: require('./structures/ApplicationCommand'),
   Base: require('./structures/Base'),
   Activity: require('./structures/Presence').Activity,
   APIMessage: require('./structures/APIMessage'),
@@ -71,6 +74,7 @@ module.exports = {
     return require('./structures/ClientUser');
   },
   Collector: require('./structures/interfaces/Collector'),
+  CommandInteraction: require('./structures/CommandInteraction'),
   DMChannel: require('./structures/DMChannel'),
   Emoji: require('./structures/Emoji'),
   Guild: require('./structures/Guild'),
@@ -82,6 +86,7 @@ module.exports = {
   GuildTemplate: require('./structures/GuildTemplate'),
   Integration: require('./structures/Integration'),
   IntegrationApplication: require('./structures/IntegrationApplication'),
+  Interaction: require('./structures/Interaction'),
   Invite: require('./structures/Invite'),
   Message: require('./structures/Message'),
   MessageAttachment: require('./structures/MessageAttachment'),

src/managers/ApplicationCommandManager.js

@@ -0,0 +1,301 @@
+'use strict';
+
+const BaseManager = require('./BaseManager');
+const { TypeError } = require('../errors');
+const ApplicationCommand = require('../structures/ApplicationCommand');
+const Collection = require('../util/Collection');
+const { ApplicationCommandPermissionTypes } = require('../util/Constants');
+
+/**
+ * Manages API methods for application commands and stores their cache.
+ * @extends {BaseManager}
+ */
+class ApplicationCommandManager extends BaseManager {
+  constructor(client, iterable) {
+    super(client, iterable, ApplicationCommand);
+  }
+
+  /**
+   * The cache of this manager
+   * @type {Collection<Snowflake, ApplicationCommand>}
+   * @name ApplicationCommandManager#cache
+   */
+
+  add(data, cache) {
+    return super.add(data, cache, { extras: [this.guild] });
+  }
+
+  /**
+   * The APIRouter path to the commands
+   * @type {Object}
+   * @readonly
+   * @private
+   */
+  get commandPath() {
+    let path = this.client.api.applications(this.client.application.id);
+    if (this.guild) path = path.guilds(this.guild.id);
+    return path.commands;
+  }
+
+  /**
+   * Data that resolves to give an ApplicationCommand object. This can be:
+   * * An ApplicationCommand object
+   * * A Snowflake
+   * @typedef {ApplicationCommand|Snowflake} ApplicationCommandResolvable
+   */
+
+  /**
+   * Obtains one or multiple application commands from Discord, or the cache if it's already available.
+   * @param {Snowflake} [id] ID of the application command
+   * @param {boolean} [cache=true] Whether to cache the new application commands if they weren't already
+   * @param {boolean} [force=false] Whether to skip the cache check and request the API
+   * @returns {Promise<ApplicationCommand|Collection<Snowflake, ApplicationCommand>>}
+   * @example
+   * // Fetch a single command
+   * client.application.commands.fetch('123456789012345678')
+   *   .then(command => console.log(`Fetched command ${command.name}`))
+   *   .catch(console.error);
+   * @example
+   * // Fetch all commands
+   * guild.commands.fetch()
+   *   .then(commands => console.log(`Fetched ${commands.size} commands`))
+   *   .catch(console.error);
+   */
+  async fetch(id, cache = true, force = false) {
+    if (id) {
+      if (!force) {
+        const existing = this.cache.get(id);
+        if (existing) return existing;
+      }
+      const command = await this.commandPath(id).get();
+      return this.add(command, cache);
+    }
+
+    const data = await this.commandPath.get();
+    return data.reduce((coll, command) => coll.set(command.id, this.add(command, cache)), new Collection());
+  }
+
+  /**
+   * Creates an application command.
+   * @param {ApplicationCommandData} command The command
+   * @returns {Promise<ApplicationCommand>}
+   * @example
+   * // Create a new command
+   * client.application.commands.create({
+   *   name: 'test',
+   *   description: 'A test command',
+   * })
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async create(command) {
+    const data = await this.commandPath.post({
+      data: this.constructor.transformCommand(command),
+    });
+    return this.add(data);
+  }
+
+  /**
+   * Sets all the commands for this application or guild.
+   * @param {ApplicationCommandData[]} commands The commands
+   * @returns {Promise<Collection<Snowflake, ApplicationCommand>>}
+   * @example
+   * // Set all commands to just this one
+   * client.application.commands.set([
+   *   {
+   *     name: 'test',
+   *     description: 'A test command',
+   *   },
+   * ])
+   *   .then(console.log)
+   *   .catch(console.error);
+   * @example
+   * // Remove all commands
+   * guild.commands.set([])
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async set(commands) {
+    const data = await this.commandPath.put({
+      data: commands.map(c => this.constructor.transformCommand(c)),
+    });
+    return data.reduce((coll, command) => coll.set(command.id, this.add(command)), new Collection());
+  }
+
+  /**
+   * Edits an application command.
+   * @param {ApplicationCommandResolvable} command The command to edit
+   * @param {ApplicationCommandData} data The data to update the command with
+   * @returns {Promise<ApplicationCommand>}
+   * @example
+   * // Edit an existing command
+   * client.application.commands.edit('123456789012345678', {
+   *   description: 'New description',
+   * })
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async edit(command, data) {
+    const id = this.resolveID(command);
+    if (!id) throw new TypeError('INVALID_TYPE', 'command', 'ApplicationCommandResolvable');
+
+    const patched = await this.commandPath(id).patch({ data: this.constructor.transformCommand(data) });
+    return this.add(patched);
+  }
+
+  /**
+   * Deletes an application command.
+   * @param {ApplicationCommandResolvable} command The command to delete
+   * @returns {Promise<?ApplicationCommand>}
+   * @example
+   * // Delete a command
+   * guild.commands.delete('123456789012345678')
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async delete(command) {
+    const id = this.resolveID(command);
+    if (!id) throw new TypeError('INVALID_TYPE', 'command', 'ApplicationCommandResolvable');
+
+    await this.commandPath(id).delete();
+
+    const cached = this.cache.get(id);
+    this.cache.delete(id);
+    return cached ?? null;
+  }
+
+  /**
+   * Fetches the permissions for one or multiple commands.
+   * @param {ApplicationCommandResolvable} [command] The command to get the permissions from
+   * @returns {Promise<ApplicationCommandPermissions[]|Collection<Snowflake, ApplicationCommandPermissions[]>>}
+   * @example
+   * // Fetch permissions for one command
+   * guild.commands.fetchPermissions('123456789012345678')
+   *   .then(perms => console.log(`Fetched permissions for ${perms.length} users`))
+   *   .catch(console.error);
+   * @example
+   * // Fetch permissions for all commands
+   * client.application.commands.fetchPermissions()
+   *   .then(perms => console.log(`Fetched permissions for ${perms.size} commands`))
+   *   .catch(console.error);
+   */
+  async fetchPermissions(command) {
+    if (command) {
+      const id = this.resolveID(command);
+      if (!id) throw new TypeError('INVALID_TYPE', 'command', 'ApplicationCommandResolvable');
+
+      const data = await this.commandPath(id).permissions.get();
+      return data.permissions.map(perm => this.constructor.transformPermissions(perm, true));
+    }
+
+    const data = await this.commandPath.permissions.get();
+    return data.reduce(
+      (coll, perm) =>
+        coll.set(
+          perm.id,
+          perm.permissions.map(p => this.constructor.transformPermissions(p, true)),
+        ),
+      new Collection(),
+    );
+  }
+
+  /**
+   * Data used for overwriting the permissions for all application commands in a guild.
+   * @typedef {object} GuildApplicationCommandPermissionData
+   * @prop {Snowflake} command The ID of the command
+   * @prop {ApplicationCommandPermissionData[]} permissions The permissions for this command
+   */
+
+  /**
+   * Sets the permissions for a command.
+   * @param {ApplicationCommandResolvable|GuildApplicationCommandPermissionData[]} command The command to edit the
+   * permissions for, or an array of guild application command permissions to set the permissions of all commands
+   * @param {ApplicationCommandPermissionData[]} permissions The new permissions for the command
+   * @returns {Promise<ApplicationCommandPermissions[]|Collection<Snowflake, ApplicationCommandPermissions[]>>}
+   * @example
+   * // Set the permissions for one command
+   * client.commands.setPermissions('123456789012345678', [
+   *   {
+   *     id: '876543210987654321',
+   *     type: 'USER',
+   *     permission: false,
+   *   },
+   * ])
+   *   .then(console.log)
+   *   .catch(console.error);
+   * @example
+   * // Set the permissions for all commands
+   * guild.commands.setPermissions([
+   *   {
+   *     id: '123456789012345678',
+   *     permissions: [{
+   *       id: '876543210987654321',
+   *       type: 'USER',
+   *       permission: false,
+   *     }],
+   *   },
+   * ])
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async setPermissions(command, permissions) {
+    const id = this.resolveID(command);
+
+    if (id) {
+      const data = await this.commandPath(id).permissions.put({
+        data: { permissions: permissions.map(perm => this.constructor.transformPermissions(perm)) },
+      });
+      return data.permissions.map(perm => this.constructor.transformPermissions(perm, true));
+    }
+
+    const data = await this.commandPath.permissions.put({
+      data: command.map(perm => ({
+        id: perm.id,
+        permissions: perm.permissions.map(p => this.constructor.transformPermissions(p)),
+      })),
+    });
+    return data.reduce(
+      (coll, perm) =>
+        coll.set(
+          perm.id,
+          perm.permissions.map(p => this.constructor.transformPermissions(p, true)),
+        ),
+      new Collection(),
+    );
+  }
+
+  /**
+   * Transforms an {@link ApplicationCommandData} object into something that can be used with the API.
+   * @param {ApplicationCommandData} command The command to transform
+   * @returns {Object}
+   * @private
+   */
+  static transformCommand(command) {
+    return {
+      name: command.name,
+      description: command.description,
+      options: command.options?.map(o => ApplicationCommand.transformOption(o)),
+      default_permission: command.defaultPermission,
+    };
+  }
+
+  /**
+   * Transforms an {@link ApplicationCommandPermissionData} object into something that can be used with the API.
+   * @param {ApplicationCommandPermissionData} permissions The permissions to transform
+   * @param {boolean} [received] Whether these permissions have been received from Discord
+   * @returns {Object}
+   * @private
+   */
+  static transformPermissions(permissions, received) {
+    return {
+      id: permissions.id,
+      permission: permissions.permission,
+      type:
+        typeof permissions.type === 'number' && !received
+          ? permissions.type
+          : ApplicationCommandPermissionTypes[permissions.type],
+    };
+  }
+}
+
+module.exports = ApplicationCommandManager;

src/managers/GuildApplicationCommandManager.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const ApplicationCommandManager = require('./ApplicationCommandManager');
+
+/**
+ * An extension for guild-specific application commands.
+ * @extends {ApplicationCommandManager}
+ */
+class GuildApplicationCommandManager extends ApplicationCommandManager {
+  constructor(guild, iterable) {
+    super(guild.client, iterable);
+
+    /**
+     * The guild that this manager belongs to
+     * @type {Guild}
+     */
+    this.guild = guild;
+  }
+}
+
+module.exports = GuildApplicationCommandManager;

src/rest/RESTManager.js

@@ -18,9 +18,10 @@ class RESTManager {
     this.globalReset = null;
     this.globalDelay = null;
     if (client.options.restSweepInterval > 0) {
-      client.setInterval(() => {
+      const interval = client.setInterval(() => {
         this.handlers.sweep(handler => handler._inactive);
       }, client.options.restSweepInterval * 1000);
+      interval.unref();
     }
   }
 

src/structures/APIMessage.js

@@ -73,6 +73,16 @@ class APIMessage {
     return this.target instanceof Message;
   }
 
+  /**
+   * Whether or not the target is an interaction
+   * @type {boolean}
+   * @readonly
+   */
+  get isInteraction() {
+    const Interaction = require('./Interaction');
+    return this.target instanceof Interaction;
+  }
+
   /**
    * Makes the content of this message.
    * @returns {?(string|string[])}
@@ -129,7 +139,7 @@ class APIMessage {
     }
 
     const embedLikes = [];
-    if (this.isWebhook) {
+    if (this.isInteraction || this.isWebhook) {
       if (this.options.embeds) {
         embedLikes.push(...this.options.embeds);
       }
@@ -149,6 +159,8 @@ class APIMessage {
     if (this.isMessage) {
       // eslint-disable-next-line eqeqeq
       flags = this.options.flags != null ? new MessageFlags(this.options.flags).bitfield : this.target.flags.bitfield;
+    } else if (this.isInteraction && this.options.ephemeral) {
+      flags = MessageFlags.FLAGS.EPHEMERAL;
     }
 
     let allowedMentions =
@@ -196,7 +208,7 @@ class APIMessage {
     if (this.files) return this;
 
     const embedLikes = [];
-    if (this.isWebhook) {
+    if (this.isInteraction || this.isWebhook) {
       if (this.options.embeds) {
         embedLikes.push(...this.options.embeds);
       }
@@ -348,10 +360,11 @@ class APIMessage {
    * @returns {MessageOptions|WebhookMessageOptions}
    */
   static create(target, content, options, extra = {}) {
+    const Interaction = require('./Interaction');
     const Webhook = require('./Webhook');
     const WebhookClient = require('../client/WebhookClient');
 
-    const isWebhook = target instanceof Webhook || target instanceof WebhookClient;
+    const isWebhook = target instanceof Interaction || target instanceof Webhook || target instanceof WebhookClient;
     const transformed = this.transformOptions(content, options, extra, isWebhook);
     return new this(target, transformed);
   }

src/structures/ApplicationCommand.js

@@ -0,0 +1,218 @@
+'use strict';
+
+const Base = require('./Base');
+const { ApplicationCommandOptionTypes } = require('../util/Constants');
+const SnowflakeUtil = require('../util/SnowflakeUtil');
+
+/**
+ * Represents an application command.
+ * @extends {Base}
+ */
+class ApplicationCommand extends Base {
+  constructor(client, data, guild) {
+    super(client);
+
+    /**
+     * The ID of this command
+     * @type {Snowflake}
+     */
+    this.id = data.id;
+
+    /**
+     * The guild this command is part of
+     * @type {?Guild}
+     */
+    this.guild = guild ?? null;
+
+    this._patch(data);
+  }
+
+  _patch(data) {
+    /**
+     * The name of this command
+     * @type {string}
+     */
+    this.name = data.name;
+
+    /**
+     * The description of this command
+     * @type {string}
+     */
+    this.description = data.description;
+
+    /**
+     * The options of this command
+     * @type {ApplicationCommandOption[]}
+     */
+    this.options = data.options?.map(o => this.constructor.transformOption(o, true)) ?? [];
+
+    /**
+     * Whether the command is enabled by default when the app is added to a guild
+     * @type {boolean}
+     */
+    this.defaultPermission = data.default_permission;
+  }
+
+  /**
+   * The timestamp the command was created at
+   * @type {number}
+   * @readonly
+   */
+  get createdTimestamp() {
+    return SnowflakeUtil.deconstruct(this.id).timestamp;
+  }
+
+  /**
+   * The time the command was created at
+   * @type {Date}
+   * @readonly
+   */
+  get createdAt() {
+    return new Date(this.createdTimestamp);
+  }
+
+  /**
+   * The manager that this command belongs to
+   * @type {ApplicationCommandManager}
+   * @readonly
+   */
+  get manager() {
+    return (this.guild ?? this.client.application).commands;
+  }
+
+  /**
+   * Data for creating or editing an application command.
+   * @typedef {Object} ApplicationCommandData
+   * @property {string} name The name of the command
+   * @property {string} description The description of the command
+   * @property {ApplicationCommandOptionData[]} [options] Options for the command
+   * @property {boolean} [defaultPermission] Whether the command is enabled by default when the app is added to a guild
+   */
+
+  /**
+   * An option for an application command or subcommand.
+   * @typedef {Object} ApplicationCommandOptionData
+   * @property {ApplicationCommandOptionType|number} type The type of the option
+   * @property {string} name The name of the option
+   * @property {string} description The description of the option
+   * @property {boolean} [required] Whether the option is required
+   * @property {ApplicationCommandOptionChoice[]} [choices] The choices of the option for the user to pick from
+   * @property {ApplicationCommandOptionData[]} [options] Additional options if this option is a subcommand (group)
+   */
+
+  /**
+   * Edits this application command.
+   * @param {ApplicationCommandData} data The data to update the command with
+   * @returns {Promise<ApplicationCommand>}
+   * @example
+   * // Edit the description of this command
+   * command.edit({
+   *   description: 'New description',
+   * })
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  edit(data) {
+    return this.manager.edit(this, data);
+  }
+
+  /**
+   * Deletes this command.
+   * @returns {Promise<ApplicationCommand>}
+   * @example
+   * // Delete this command
+   * command.delete()
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  delete() {
+    return this.manager.delete(this);
+  }
+
+  /**
+   * The object returned when fetching permissions for an application command.
+   * @typedef {object} ApplicationCommandPermissionData
+   * @property {Snowflake} id The ID of the role or user
+   * @property {ApplicationCommandPermissionType|number} type Whether this permission if for a role or a user
+   * @property {boolean} permission Whether the role or user has the permission to use this command
+   */
+
+  /**
+   * The object returned when fetching permissions for an application command.
+   * @typedef {object} ApplicationCommandPermissions
+   * @property {Snowflake} id The ID of the role or user
+   * @property {ApplicationCommandPermissionType} type Whether this permission if for a role or a user
+   * @property {boolean} permission Whether the role or user has the permission to use this command
+   */
+
+  /**
+   * Fetches the permissions for this command.
+   * @returns {Promise<ApplicationCommandPermissions[]>}
+   * @example
+   * // Fetch permissions for this command
+   * command.fetchPermissions()
+   *   .then(perms => console.log(`Fetched permissions for ${perms.length} users`))
+   *   .catch(console.error);
+   */
+  fetchPermissions() {
+    return this.manager.fetchPermissions(this);
+  }
+
+  /**
+   * Sets the permissions for this command.
+   * @param {ApplicationCommandPermissionData[]} permissions The new permissions for the command
+   * @returns {Promise<ApplicationCommandPermissions[]>}
+   * @example
+   * // Set the permissions for this command
+   * command.setPermissions([
+   *   {
+   *     id: '876543210987654321',
+   *     type: 'USER',
+   *     permission: false,
+   *   },
+   * ])
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  setPermissions(permissions) {
+    return this.manager.setPermissions(this, permissions);
+  }
+
+  /**
+   * An option for an application command or subcommand.
+   * @typedef {Object} ApplicationCommandOption
+   * @property {ApplicationCommandOptionType} type The type of the option
+   * @property {string} name The name of the option
+   * @property {string} description The description of the option
+   * @property {boolean} [required] Whether the option is required
+   * @property {ApplicationCommandOptionChoice[]} [choices] The choices of the option for the user to pick from
+   * @property {ApplicationCommandOption[]} [options] Additional options if this option is a subcommand (group)
+   */
+
+  /**
+   * A choice for an application command option.
+   * @typedef {Object} ApplicationCommandOptionChoice
+   * @property {string} name The name of the choice
+   * @property {string|number} value The value of the choice
+   */
+
+  /**
+   * Transforms an {@link ApplicationCommandOptionData} object into something that can be used with the API.
+   * @param {ApplicationCommandOptionData} option The option to transform
+   * @param {boolean} [received] Whether this option has been received from Discord
+   * @returns {Object}
+   * @private
+   */
+  static transformOption(option, received) {
+    return {
+      type: typeof option.type === 'number' && !received ? option.type : ApplicationCommandOptionTypes[option.type],
+      name: option.name,
+      description: option.description,
+      required: option.required,
+      choices: option.choices,
+      options: option.options?.map(o => this.transformOption(o)),
+    };
+  }
+}
+
+module.exports = ApplicationCommand;

src/structures/ClientApplication.js

@@ -2,6 +2,7 @@
 
 const Team = require('./Team');
 const Application = require('./interfaces/Application');
+const ApplicationCommandManager = require('../managers/ApplicationCommandManager');
 const ApplicationFlags = require('../util/ApplicationFlags');
 
 /**
@@ -9,6 +10,16 @@ const ApplicationFlags = require('../util/ApplicationFlags');
  * @extends {Application}
  */
 class ClientApplication extends Application {
+  constructor(client, data) {
+    super(client, data);
+
+    /**
+     * The application command manager for this application
+     * @type {ApplicationCommandManager}
+     */
+    this.commands = new ApplicationCommandManager(this.client);
+  }
+
   _patch(data) {
     super._patch(data);
 

src/structures/CommandInteraction.js

@@ -0,0 +1,222 @@
+'use strict';
+
+const APIMessage = require('./APIMessage');
+const Interaction = require('./Interaction');
+const WebhookClient = require('../client/WebhookClient');
+const { Error } = require('../errors');
+const { ApplicationCommandOptionTypes, InteractionResponseTypes } = require('../util/Constants');
+const MessageFlags = require('../util/MessageFlags');
+
+/**
+ * Represents a command interaction.
+ * @extends {Interaction}
+ */
+class CommandInteraction extends Interaction {
+  constructor(client, data) {
+    super(client, data);
+
+    /**
+     * The ID of the invoked application command
+     * @type {Snowflake}
+     */
+    this.commandID = data.data.id;
+
+    /**
+     * The name of the invoked application command
+     * @type {string}
+     */
+    this.commandName = data.data.name;
+
+    /**
+     * Whether the reply to this interaction has been deferred
+     * @type {boolean}
+     */
+    this.deferred = false;
+
+    /**
+     * The options passed to the command.
+     * @type {CommandInteractionOption[]}
+     */
+    this.options = data.data.options?.map(o => this.transformOption(o, data.data.resolved)) ?? [];
+
+    /**
+     * Whether this interaction has already been replied to
+     * @type {boolean}
+     */
+    this.replied = false;
+
+    /**
+     * An associated webhook client, can be used to create deferred replies
+     * @type {WebhookClient}
+     */
+    this.webhook = new WebhookClient(this.applicationID, this.token, this.client.options);
+  }
+
+  /**
+   * The invoked application command, if it was fetched before
+   * @type {?ApplicationCommand}
+   */
+  get command() {
+    const id = this.commandID;
+    return this.guild?.commands.cache.get(id) ?? this.client.application.commands.cache.get(id) ?? null;
+  }
+
+  /**
+   * Defers the reply to this interaction.
+   * @param {boolean} [ephemeral] Whether the reply should be ephemeral
+   * @returns {Promise<void>}
+   * @example
+   * // Defer the reply to this interaction
+   * interaction.defer()
+   *   .then(console.log)
+   *   .catch(console.error)
+   * @example
+   * // Defer to send an ephemeral reply later
+   * interaction.defer(true)
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async defer(ephemeral) {
+    if (this.deferred || this.replied) throw new Error('INTERACTION_ALREADY_REPLIED');
+    await this.client.api.interactions(this.id, this.token).callback.post({
+      data: {
+        type: InteractionResponseTypes.DEFERRED_CHANNEL_MESSAGE_WITH_SOURCE,
+        data: {
+          flags: ephemeral ? MessageFlags.FLAGS.EPHEMERAL : undefined,
+        },
+      },
+    });
+    this.deferred = true;
+  }
+
+  /**
+   * Options for a reply to an interaction.
+   * @typedef {WebhookMessageOptions} InteractionReplyOptions
+   * @property {boolean} [ephemeral] Whether the reply should be ephemeral
+   */
+
+  /**
+   * Creates a reply to this interaction.
+   * @param {string|APIMessage|MessageAdditions} content The content for the reply
+   * @param {InteractionReplyOptions} [options] Additional options for the reply
+   * @returns {Promise<void>}
+   * @example
+   * // Reply to the interaction with an embed
+   * const embed = new MessageEmbed().setDescription('Pong!');
+   *
+   * interaction.reply(embed)
+   *   .then(console.log)
+   *   .catch(console.error);
+   * @example
+   * // Create an ephemeral reply
+   * interaction.reply('Pong!', { ephemeral: true })
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async reply(content, options) {
+    if (this.deferred || this.replied) throw new Error('INTERACTION_ALREADY_REPLIED');
+    const apiMessage = content instanceof APIMessage ? content : APIMessage.create(this, content, options);
+    const { data, files } = await apiMessage.resolveData().resolveFiles();
+
+    await this.client.api.interactions(this.id, this.token).callback.post({
+      data: {
+        type: InteractionResponseTypes.CHANNEL_MESSAGE_WITH_SOURCE,
+        data,
+      },
+      files,
+    });
+    this.replied = true;
+  }
+
+  /**
+   * Fetches the initial reply to this interaction.
+   * @see Webhook#fetchMessage
+   * @returns {Promise<Message|Object>}
+   * @example
+   * // Fetch the reply to this interaction
+   * interaction.fetchReply()
+   *   .then(reply => console.log(`Replied with ${reply.content}`))
+   *   .catch(console.error);
+   */
+  async fetchReply() {
+    const raw = await this.webhook.fetchMessage('@original');
+    return this.channel?.messages.add(raw) ?? raw;
+  }
+
+  /**
+   * Edits the initial reply to this interaction.
+   * @see Webhook#editMessage
+   * @param {string|APIMessage|MessageEmbed|MessageEmbed[]} content The new content for the message
+   * @param {WebhookEditMessageOptions} [options] The options to provide
+   * @returns {Promise<Message|Object>}
+   * @example
+   * // Edit the reply to this interaction
+   * interaction.editReply('New content')
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async editReply(content, options) {
+    const raw = await this.webhook.editMessage('@original', content, options);
+    return this.channel?.messages.add(raw) ?? raw;
+  }
+
+  /**
+   * Deletes the initial reply to this interaction.
+   * @see Webhook#deleteMessage
+   * @returns {Promise<void>}
+   * @example
+   * // Delete the reply to this interaction
+   * interaction.deleteReply()
+   *   .then(console.log)
+   *   .catch(console.error);
+   */
+  async deleteReply() {
+    await this.webhook.deleteMessage('@original');
+  }
+
+  /**
+   * Represents an option of a received command interaction.
+   * @typedef {Object} CommandInteractionOption
+   * @property {string} name The name of the option
+   * @property {ApplicationCommandOptionType} type The type of the option
+   * @property {string|number|boolean} [value] The value of the option
+   * @property {CommandInteractionOption[]} [options] Additional options if this option is a subcommand (group)
+   * @property {User} [user] The resolved user
+   * @property {GuildMember|Object} [member] The resolved member
+   * @property {GuildChannel|Object} [channel] The resolved channel
+   * @property {Role|Object} [role] The resolved role
+   */
+
+  /**
+   * Transforms an option received from the API.
+   * @param {Object} option The received option
+   * @param {Object} resolved The resolved interaction data
+   * @returns {CommandInteractionOption}
+   * @private
+   */
+  transformOption(option, resolved) {
+    const result = {
+      name: option.name,
+      type: ApplicationCommandOptionTypes[option.type],
+    };
+
+    if ('value' in option) result.value = option.value;
+    if ('options' in option) result.options = option.options.map(o => this.transformOption(o, resolved));
+
+    const user = resolved?.users?.[option.value];
+    if (user) result.user = this.client.users.add(user);
+
+    const member = resolved?.members?.[option.value];
+    if (member) result.member = this.guild?.members.add({ user, ...member }) ?? member;
+
+    const channel = resolved?.channels?.[option.value];
+    if (channel) result.channel = this.client.channels.add(channel, this.guild) ?? channel;
+
+    const role = resolved?.roles?.[option.value];
+    if (role) result.role = this.guild?.roles.add(role) ?? role;
+
+    return result;
+  }
+}
+
+module.exports = CommandInteraction;

src/structures/Guild.js

@@ -9,6 +9,7 @@ const Invite = require('./Invite');
 const VoiceRegion = require('./VoiceRegion');
 const Webhook = require('./Webhook');
 const { Error, TypeError } = require('../errors');
+const GuildApplicationCommandManager = require('../managers/GuildApplicationCommandManager');
 const GuildChannelManager = require('../managers/GuildChannelManager');
 const GuildEmojiManager = require('../managers/GuildEmojiManager');
 const GuildMemberManager = require('../managers/GuildMemberManager');
@@ -42,6 +43,12 @@ class Guild extends Base {
   constructor(client, data) {
     super(client);
 
+    /**
+     * A manager of the application commands belonging to this guild
+     * @type {GuildApplicationCommandManager}
+     */
+    this.commands = new GuildApplicationCommandManager(this);
+
     /**
      * A manager of the members belonging to this guild
      * @type {GuildMemberManager}

src/structures/Interaction.js

@@ -0,0 +1,117 @@
+'use strict';
+
+const Base = require('./Base');
+const { InteractionTypes } = require('../util/Constants');
+const SnowflakeUtil = require('../util/SnowflakeUtil');
+
+/**
+ * Represents an interaction.
+ * @extends {Base}
+ */
+class Interaction extends Base {
+  constructor(client, data) {
+    super(client);
+
+    /**
+     * The type of this interaction
+     * @type {InteractionType}
+     */
+    this.type = InteractionTypes[data.type];
+
+    /**
+     * The ID of this interaction
+     * @type {Snowflake}
+     */
+    this.id = data.id;
+
+    /**
+     * The token of this interaction
+     * @type {string}
+     * @name Interaction#token
+     * @readonly
+     */
+    Object.defineProperty(this, 'token', { value: data.token });
+
+    /**
+     * The ID of the application
+     * @type {Snowflake}
+     */
+    this.applicationID = data.application_id;
+
+    /**
+     * The ID of the channel this interaction was sent in
+     * @type {?Snowflake}
+     */
+    this.channelID = data.channel_id ?? null;
+
+    /**
+     * The ID of the guild this interaction was sent in
+     * @type {?Snowflake}
+     */
+    this.guildID = data.guild_id ?? null;
+
+    /**
+     * The user which sent this interaction
+     * @type {User}
+     */
+    this.user = this.client.users.add(data.user ?? data.member.user);
+
+    /**
+     * If this interaction was sent in a guild, the member which sent it
+     * @type {?GuildMember|Object}
+     */
+    this.member = data.member ? this.guild?.members.add(data.member) ?? data.member : null;
+
+    /**
+     * The version
+     * @type {number}
+     */
+    this.version = data.version;
+  }
+
+  /**
+   * The timestamp the interaction was created at
+   * @type {number}
+   * @readonly
+   */
+  get createdTimestamp() {
+    return SnowflakeUtil.deconstruct(this.id).timestamp;
+  }
+
+  /**
+   * The time the interaction was created at
+   * @type {Date}
+   * @readonly
+   */
+  get createdAt() {
+    return new Date(this.createdTimestamp);
+  }
+
+  /**
+   * The channel this interaction was sent in
+   * @type {?Channel}
+   * @readonly
+   */
+  get channel() {
+    return this.client.channels.cache.get(this.channelID) ?? null;
+  }
+
+  /**
+   * The guild this interaction was sent in
+   * @type {?Guild}
+   * @readonly
+   */
+  get guild() {
+    return this.client.guilds.cache.get(this.guildID) ?? null;
+  }
+
+  /**
+   * Indicates whether this interaction is a command interaction.
+   * @returns {boolean}
+   */
+  isCommand() {
+    return InteractionTypes[this.type] === InteractionTypes.APPLICATION_COMMAND;
+  }
+}
+
+module.exports = Interaction;

src/structures/Message.js

@@ -11,7 +11,7 @@ const Sticker = require('./Sticker');
 const { Error, TypeError } = require('../errors');
 const ReactionManager = require('../managers/ReactionManager');
 const Collection = require('../util/Collection');
-const { MessageTypes, SystemMessageTypes } = require('../util/Constants');
+const { InteractionTypes, MessageTypes, SystemMessageTypes } = require('../util/Constants');
 const MessageFlags = require('../util/MessageFlags');
 const Permissions = require('../util/Permissions');
 const SnowflakeUtil = require('../util/SnowflakeUtil');
@@ -232,6 +232,30 @@ class Message extends Base {
     if (data.referenced_message) {
       this.channel.messages.add(data.referenced_message);
     }
+
+    /**
+     * Partial data of the interaction that a message is a reply to
+     * @typedef {object} MessageInteraction
+     * @property {Snowflake} id The ID of the interaction
+     * @property {InteractionType} type The type of the interaction
+     * @property {string} commandName The name of the interaction's application command
+     * @property {User} user The user that invoked the interaction
+     */
+
+    if (data.interaction) {
+      /**
+       * Partial data of the interaction that this message is a reply to
+       * @type {?MessageInteraction}
+       */
+      this.interaction = {
+        id: data.interaction.id,
+        type: InteractionTypes[data.interaction.type],
+        commandName: data.interaction.name,
+        user: this.client.users.add(data.interaction.user),
+      };
+    } else if (!this.interaction) {
+      this.interaction = null;
+    }
   }
 
   /**

src/structures/Webhook.js

@@ -238,7 +238,7 @@ class Webhook {
 
   /**
    * Gets a message that was sent by this webhook.
-   * @param {Snowflake} message The ID of the message to fetch
+   * @param {Snowflake|'@original'} message The ID of the message to fetch
    * @param {boolean} [cache=true] Whether to cache the message
    * @returns {Promise<Message|Object>} Returns the raw message data if the webhook was instantiated as a
    * {@link WebhookClient} or if the channel is uncached, otherwise a {@link Message} will be returned
@@ -250,7 +250,7 @@ class Webhook {
 
   /**
    * Edits a message that was sent by this webhook.
-   * @param {MessageResolvable} message The message to edit
+   * @param {MessageResolvable|'@original'} message The message to edit
    * @param {StringResolvable|APIMessage} [content] The new content for the message
    * @param {WebhookEditMessageOptions|MessageEmbed|MessageEmbed[]} [options] The options to provide
    * @returns {Promise<Message|Object>} Returns the raw message data if the webhook was instantiated as a
@@ -287,7 +287,7 @@ class Webhook {
 
   /**
    * Delete a message that was sent by this webhook.
-   * @param {MessageResolvable} message The message to delete
+   * @param {MessageResolvable|'@original'} message The message to delete
    * @returns {Promise<void>}
    */
   async deleteMessage(message) {

src/util/Constants.js

@@ -271,6 +271,7 @@ exports.Events = {
   TYPING_START: 'typingStart',
   TYPING_STOP: 'typingStop',
   WEBHOOKS_UPDATE: 'webhookUpdate',
+  INTERACTION_CREATE: 'interaction',
   ERROR: 'error',
   WARN: 'warn',
   DEBUG: 'debug',
@@ -343,6 +344,7 @@ exports.PartialTypes = keyMirror(['USER', 'CHANNEL', 'GUILD_MEMBER', 'MESSAGE',
  * * VOICE_STATE_UPDATE
  * * VOICE_SERVER_UPDATE
  * * WEBHOOKS_UPDATE
+ * * INTERACTION_CREATE
  * @typedef {string} WSEventType
  */
 exports.WSEvents = keyMirror([
@@ -382,6 +384,7 @@ exports.WSEvents = keyMirror([
   'VOICE_STATE_UPDATE',
   'VOICE_SERVER_UPDATE',
   'WEBHOOKS_UPDATE',
+  'INTERACTION_CREATE',
 ]);
 
 /**
@@ -434,6 +437,7 @@ exports.InviteScopes = [
  * * GUILD_DISCOVERY_GRACE_PERIOD_INITIAL_WARNING
  * * GUILD_DISCOVERY_GRACE_PERIOD_FINAL_WARNING
  * * REPLY
+ * * APPLICATION_COMMAND
  * @typedef {string} MessageType
  */
 exports.MessageTypes = [
@@ -457,15 +461,19 @@ exports.MessageTypes = [
   'GUILD_DISCOVERY_GRACE_PERIOD_FINAL_WARNING',
   null,
   'REPLY',
+  'APPLICATION_COMMAND',
 ];
 
 /**
  * The types of messages that are `System`. The available types are `MessageTypes` excluding:
  * * DEFAULT
  * * REPLY
+ * * APPLICATION_COMMAND
  * @typedef {string} SystemMessageType
  */
-exports.SystemMessageTypes = exports.MessageTypes.filter(type => type && type !== 'DEFAULT' && type !== 'REPLY');
+exports.SystemMessageTypes = exports.MessageTypes.filter(
+  type => type && !['DEFAULT', 'REPLY', 'APPLICATION_COMMAND'].includes(type),
+);
 
 /**
  * <info>Bots cannot set a `CUSTOM_STATUS`, it is only for custom statuses received from users</info>
@@ -742,6 +750,64 @@ exports.StickerFormatTypes = createEnum([null, 'PNG', 'APNG', 'LOTTIE']);
  */
 exports.OverwriteTypes = createEnum(['role', 'member']);
 
+/**
+ * The type of an {@link ApplicationCommandOption} object:
+ * * SUB_COMMAND
+ * * SUB_COMMAND_GROUP
+ * * STRING
+ * * INTEGER
+ * * BOOLEAN
+ * * USER
+ * * CHANNEL
+ * * ROLE
+ * * MENTIONABLE
+ * @typedef {string} ApplicationCommandOptionType
+ */
+exports.ApplicationCommandOptionTypes = createEnum([
+  null,
+  'SUB_COMMAND',
+  'SUB_COMMAND_GROUP',
+  'STRING',
+  'INTEGER',
+  'BOOLEAN',
+  'USER',
+  'CHANNEL',
+  'ROLE',
+  'MENTIONABLE',
+]);
+
+/**
+ * The type of an {@link ApplicationCommandPermissions} object:
+ * * ROLE
+ * * USER
+ * @typedef {string} ApplicationCommandPermissionType
+ */
+exports.ApplicationCommandPermissionTypes = createEnum([null, 'ROLE', 'USER']);
+
+/**
+ * The type of an {@link Interaction} object:
+ * * PING
+ * * APPLICATION_COMMAND
+ * @typedef {string} InteractionType
+ */
+exports.InteractionTypes = createEnum([null, 'PING', 'APPLICATION_COMMAND']);
+
+/**
+ * The type of an interaction response:
+ * * PONG
+ * * CHANNEL_MESSAGE_WITH_SOURCE
+ * * DEFERRED_CHANNEL_MESSAGE_WITH_SOURCE
+ * @typedef {string} InteractionResponseType
+ */
+exports.InteractionResponseTypes = createEnum([
+  null,
+  'PONG',
+  null,
+  null,
+  'CHANNEL_MESSAGE_WITH_SOURCE',
+  'DEFERRED_CHANNEL_MESSAGE_WITH_SOURCE',
+]);
+
 function keyMirror(arr) {
   let tmp = Object.create(null);
   for (const value of arr) tmp[value] = value;

src/util/MessageFlags.js

@@ -28,6 +28,8 @@ class MessageFlags extends BitField {}
  * * `SUPPRESS_EMBEDS`
  * * `SOURCE_MESSAGE_DELETED`
  * * `URGENT`
+ * * `EPHEMERAL`
+ * * `LOADING`
  * @type {Object}
  * @see {@link https://discord.com/developers/docs/resources/channel#message-object-message-flags}
  */
@@ -37,6 +39,8 @@ MessageFlags.FLAGS = {
   SUPPRESS_EMBEDS: 1 << 2,
   SOURCE_MESSAGE_DELETED: 1 << 3,
   URGENT: 1 << 4,
+  EPHEMERAL: 1 << 6,
+  LOADING: 1 << 7,
 };
 
 module.exports = MessageFlags;

src/util/Permissions.js

@@ -78,6 +78,7 @@ class Permissions extends BitField {
  * * `MANAGE_ROLES`
  * * `MANAGE_WEBHOOKS`
  * * `MANAGE_EMOJIS`
+ * * `USE_APPLICATION_COMMANDS`
  * * `REQUEST_TO_SPEAK`
  * @type {Object<string, bigint>}
  * @see {@link https://discord.com/developers/docs/topics/permissions}
@@ -114,6 +115,7 @@ Permissions.FLAGS = {
   MANAGE_ROLES: 1n << 28n,
   MANAGE_WEBHOOKS: 1n << 29n,
   MANAGE_EMOJIS: 1n << 30n,
+  USE_APPLICATION_COMMANDS: 1n << 31n,
   REQUEST_TO_SPEAK: 1n << 32n,
 };
 

src/util/Structures.js

@@ -19,6 +19,7 @@
  * * **`VoiceState`**
  * * **`Role`**
  * * **`User`**
+ * * **`CommandInteraction`**
  * @typedef {string} ExtendableStructure
  */
 
@@ -109,6 +110,7 @@ const structures = {
   VoiceState: require('../structures/VoiceState'),
   Role: require('../structures/Role'),
   User: require('../structures/User'),
+  CommandInteraction: require('../structures/CommandInteraction'),
 };
 
 module.exports = Structures;