feat(Invite): add deletable getter (#3203)

* add Invite#deletable

* fix ci

* reee

* since guild is nullable

* accommodate for external invites

* nit(Invite): use guild instead of channel.guild

src/structures/Invite.js

@@ -1,6 +1,7 @@
 'use strict';
 
 const { Endpoints } = require('../util/Constants');
+const Permissions = require('../util/Permissions');
 const Base = require('./Base');
 
 /**
@@ -91,6 +92,18 @@ class Invite extends Base {
     return this.createdTimestamp ? new Date(this.createdTimestamp) : null;
   }
 
+  /**
+   * Whether the invite is deletable by the client user
+   * @type {boolean}
+   * @readonly
+   */
+  get deletable() {
+    const guild = this.guild;
+    if (!guild || !this.client.guilds.has(guild.id)) return false;
+    return this.channel.permissionsFor(this.client.user).has(Permissions.FLAGS.MANAGE_CHANNELS, false) ||
+      guild.me.permissions.has(Permissions.FLAGS.MANAGE_GUILD);
+  }
+
   /**
    * The timestamp the invite will expire at
    * @type {?number}

typings/index.d.ts

@@ -615,7 +615,8 @@ declare module 'discord.js' {
 		constructor(client: Client, data: object);
 		public channel: GuildChannel;
 		public code: string;
-		public readonly createdAt: Date;
+		public readonly deletable: boolean;
+		public readonly createdAt: Date | null;
 		public createdTimestamp: number | null;
 		public readonly expiresAt: Date | null;
 		public readonly expiresTimestamp: number | null;