From bb78120283b671d1926c8707a17a9d4d515aafdd Mon Sep 17 00:00:00 2001
From: X-Classified <chaikohen@gmail.com>
Date: Sat, 12 Dec 2020 13:40:39 -0800
Subject: [PATCH] fix(Message): #system non-zero message types are not
 guaranteed to be system (#5108)

* fix(Message): #system not all nonzero message types are system

* feat(Message): introduce system message types

* refactor(Constants): change SystemMessageTypes to be exclusionary

* fix(Constants): only need to check if type exists

Co-authored-by: Jan <66554238+Vaporox@users.noreply.github.com>

* fix(Constants): lint

* fix(Typings): add SystemMessageTypees to Constants

Co-authored-by: Jan <66554238+Vaporox@users.noreply.github.com>
---
 src/structures/Message.js | 4 ++--
 src/util/Constants.js     | 8 ++++++++
 typings/index.d.ts        | 3 +++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/structures/Message.js b/src/structures/Message.js
index 3f420e322c27..63494f9df500 100644
--- a/src/structures/Message.js
+++ b/src/structures/Message.js
@@ -10,7 +10,7 @@ const ReactionCollector = require('./ReactionCollector');
 const { Error, TypeError } = require('../errors');
 const ReactionManager = require('../managers/ReactionManager');
 const Collection = require('../util/Collection');
-const { MessageTypes } = require('../util/Constants');
+const { MessageTypes, SystemMessageTypes } = require('../util/Constants');
 const MessageFlags = require('../util/MessageFlags');
 const Permissions = require('../util/Permissions');
 const SnowflakeUtil = require('../util/Snowflake');
@@ -62,7 +62,7 @@ class Message extends Base {
        * Whether or not this message was sent by Discord, not actually a user (e.g. pin notifications)
        * @type {?boolean}
        */
-      this.system = data.type !== 0;
+      this.system = SystemMessageTypes.includes(this.type);
     } else if (typeof this.type !== 'string') {
       this.system = null;
       this.type = null;
diff --git a/src/util/Constants.js b/src/util/Constants.js
index 1d84a51eb200..84a1599f27e5 100644
--- a/src/util/Constants.js
+++ b/src/util/Constants.js
@@ -429,6 +429,14 @@ exports.MessageTypes = [
   'REPLY',
 ];
 
+/**
+ * The types of messages that are `System`. The available types are `MessageTypes` excluding:
+ * * DEFAULT
+ * * REPLY
+ * @typedef {string} SystemMessageType
+ */
+exports.SystemMessageTypes = exports.MessageTypes.filter(type => type && type !== 'DEFAULT' && type !== 'REPLY');
+
 /**
  * <info>Bots cannot set a `CUSTOM_STATUS`, it is only for custom statuses received from users</info>
  * The type of an activity of a users presence, e.g. `PLAYING`. Here are the available types:
diff --git a/typings/index.d.ts b/typings/index.d.ts
index 11c0190b2f78..1806074be46c 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -516,6 +516,7 @@ declare module 'discord.js' {
       BIG: 2;
     };
     MessageTypes: MessageType[];
+    SystemMessageTypes: SystemMessageType[];
     ActivityTypes: ActivityType[];
     ExplicitContentFilterLevels: ExplicitContentFilterLevel[];
     DefaultMessageNotifications: DefaultMessageNotifications[];
@@ -3147,6 +3148,8 @@ declare module 'discord.js' {
 
   type SystemChannelFlagsResolvable = BitFieldResolvable<SystemChannelFlagsString>;
 
+  type SystemMessageType = Exclude<MessageType, 'DEFAULT' | 'REPLY'>;
+
   type TargetUser = number;
 
   interface TypingData {