new application stuff very hype (#1764)

* application stuff, more to come

* docstrings

* Update Message.js

src/structures/ClientApplication.js

@@ -126,7 +126,36 @@ class OAuth2Application {
    */
   iconURL({ format, size } = {}) {
     if (!this.icon) return null;
-    return Constants.Endpoints.CDN(this.client.options.http.cdn).AppIcon(this.id, this.icon, format, size);
+    return Constants.Endpoints.CDN(this.client.options.http.cdn).AppIcon(this.id, this.icon, { format, size });
+  }
+
+  /**
+   * Get rich presence assets
+   * @returns {Promise<Object>}
+   */
+  fetchAssets() {
+    return this.client.api.applications(this.id).assets.get()
+      .then(assets => assets.map(a => ({
+        id: a.id,
+        name: a.name,
+        type: Object.keys(Constants.ClientApplicationAssetTypes)[a.type - 1],
+      })));
+  }
+
+  /**
+   * Create a rich presence asset
+   * @param {string} name Name of the asset
+   * @param {Base64Resolvable} data Data of the asset
+   * @param {string} type Type of the asset. `big`, or `small`
+   * @returns {Promise}
+   */
+  createAsset(name, data, type) {
+    return this.client.resolveBase64(data).then(b64 =>
+      this.client.api.applications(this.id).assets.post({ data: {
+        name,
+        data: b64,
+        type: Constants.ClientApplicationAssetTypes[type.toUpperCase()],
+      } }));
   }
 
   /**

src/structures/Message.js

@@ -3,6 +3,7 @@ const Attachment = require('./MessageAttachment');
 const Embed = require('./MessageEmbed');
 const MessageReaction = require('./MessageReaction');
 const ReactionCollector = require('./ReactionCollector');
+const ClientApplication = require('./ClientApplication');
 const Util = require('../util/Util');
 const Collection = require('../util/Collection');
 const Constants = require('../util/Constants');
@@ -137,6 +138,21 @@ class Message {
      */
     this.webhookID = data.webhook_id || null;
 
+    /**
+     * Supplimental application information for group activities
+     * @type {?ClientApplication}
+     */
+    this.application = data.application ? new ClientApplication(this.client, data.application) : null;
+
+    /**
+     * Group activity
+     * @type {?Object}
+     */
+    this.activiy = data.activity ? {
+      partyID: data.activity.party_id,
+      type: data.activity.type,
+    } : null;
+
     /**
      * Whether this message is a hit in a search
      * @type {?boolean}