refactor: move Message#cleanContent function to Util (#2703)

* refactor: move Message#cleanContent function to Util

* suggested changes

src/structures/Message.js

@@ -257,35 +257,7 @@ class Message extends Base {
    * @readonly
    */
   get cleanContent() {
-    return this.content
+    return Util.cleanContent(this.content, this);
-      .replace(/@(everyone|here)/g, '@\u200b$1')
-      .replace(/<@!?[0-9]+>/g, input => {
-        const id = input.replace(/<|!|>|@/g, '');
-        if (this.channel.type === 'dm' || this.channel.type === 'group') {
-          return this.client.users.has(id) ? `@${this.client.users.get(id).username}` : input;
-        }
-
-        const member = this.channel.guild.members.get(id);
-        if (member) {
-          if (member.nickname) return `@${member.nickname}`;
-          return `@${member.user.username}`;
-        } else {
-          const user = this.client.users.get(id);
-          if (user) return `@${user.username}`;
-          return input;
-        }
-      })
-      .replace(/<#[0-9]+>/g, input => {
-        const channel = this.client.channels.get(input.replace(/<|#|>/g, ''));
-        if (channel) return `#${channel.name}`;
-        return input;
-      })
-      .replace(/<@&[0-9]+>/g, input => {
-        if (this.channel.type === 'dm' || this.channel.type === 'group') return input;
-        const role = this.guild.roles.get(input.replace(/<|@|>|&/g, ''));
-        if (role) return `@${role.name}`;
-        return input;
-      });
   }
 
   /**

src/util/Util.js

@@ -382,6 +382,41 @@ class Util {
     return dec;
   }
 
+  /**
+   * The content to have all mentions replaced by the equivalent text.
+   * @param {string} str The string to be converted
+   * @param {Message} message The message object to reference
+   * @returns {string}
+   */
+  static cleanContent(str, message) {
+    return str
+      .replace(/@(everyone|here)/g, '@\u200b$1')
+      .replace(/<@!?[0-9]+>/g, input => {
+        const id = input.replace(/<|!|>|@/g, '');
+        if (message.channel.type === 'dm' || message.channel.type === 'group') {
+          const user = message.client.users.get(id);
+          return user ? `@${user.username}` : input;
+        }
+
+        const member = message.channel.guild.members.get(id);
+        if (member) {
+          return member.displayName;
+        } else {
+          const user = message.client.users.get(id);
+          return user ? `@${user.username}` : input;
+        }
+      })
+      .replace(/<#[0-9]+>/g, input => {
+        const channel = message.client.channels.get(input.replace(/<|#|>/g, ''));
+        return channel ? `#${channel.name}` : input;
+      })
+      .replace(/<@&[0-9]+>/g, input => {
+        if (message.channel.type === 'dm' || message.channel.type === 'group') return input;
+        const role = message.guild.roles.get(input.replace(/<|@|>|&/g, ''));
+        return role ? `@${role.name}` : input;
+      });
+  }
+
   /**
    * Creates a Promise that resolves after a specified duration.
    * @param {number} ms How long to wait before resolving (in milliseconds)