Add message.pin() and .unpin();

src/client/rest/RESTMethods.js

@@ -476,6 +476,22 @@ class RESTMethods {
         .catch(reject);
     });
   }
+
+  pinMessage(message) {
+    return new Promise((resolve, reject) => {
+      this.rest.makeRequest('put', `${Constants.Endpoints.channel(message.channel.id)}/pins/${message.id}`, true)
+        .then(() => resolve(message))
+        .catch(reject);
+    });
+  }
+
+  unpinMessage(message) {
+    return new Promise((resolve, reject) => {
+      this.rest.makeRequest('del', `${Constants.Endpoints.channel(message.channel.id)}/pins/${message.id}`, true)
+        .then(() => resolve(message))
+        .catch(reject);
+    });
+  }
 }
 
 module.exports = RESTMethods;

src/structures/Message.js

@@ -265,6 +265,22 @@ class Message {
     const newContent = this.guild ? `${this.author}, ${content}` : content;
     return this.client.rest.methods.sendMessage(this.channel, newContent, options.tts);
   }
+
+  /**
+   * Pins this message to the channel's pinned messages
+   * @returns {Promise<Message, Error>}
+   */
+  pin() {
+    return this.client.rest.methods.pinMessage(this);
+  }
+
+  /**
+   * Unpins this message from the channel's pinned messages
+   * @returns {Promise<Message, Error>}
+   */
+  unpin() {
+    return this.client.rest.methods.unpinMessage(this);
+  }
 }
 
 module.exports = Message;