feat: add a helper function for crossposting

src/controls/post.ts

@@ -9,6 +9,7 @@ import type { PostData } from "../objects/post";
 import type Client from "../client";
 import { camelCaseKeys } from "../helper/util";
 import { fakeListingAfter } from "../listings/util";
+import { LinkPostOptions } from "./subreddit";
 import CommentListing from "../listings/comment";
 import Listing from "../listings/listing";
 import Post from "../objects/post";
@@ -110,6 +111,25 @@ export default class PostControls extends VoteableControls {
     await this.client.post("api/distinguish", body);
   }
 
+  /**
+   * Crosspost a post.
+   *
+   * @param id The ID of the post to crosspost.
+   * @param subreddit The name of the subreddit to crosspost to.
+   * @param title The title of the crosspost.
+   * @param opts Any extra options.
+   *
+   * * @returns A promise that resolves to the ID of the newly created post.
+   */
+  async crosspostTo(
+    id: string,
+    subreddit: string,
+    title: string,
+    opts: LinkPostOptions = {}
+  ): Promise<string> {
+    return this.client.subreddits.postCrosspost(subreddit, title, id, opts);
+  }
+
   /**
    * Turn contest mode on/off.
    *

src/objects/post.ts

@@ -1,5 +1,6 @@
 import type { VoteableData } from "./voteable";
 // import type { VoteableData, RichTextFlair } from "./voteable";
+import { LinkPostOptions } from "../controls/subreddit";
 import Listing from "../listings/listing";
 import PostControls from "../controls/post";
 import Voteable from "./voteable";
@@ -382,6 +383,23 @@ export default class Post extends Voteable implements PostData {
     return this.controls.undistinguish(this.id);
   }
 
+  /**
+   * Crosspost this post.
+   *
+   * @param subreddit The name of the subreddit to crosspost to.
+   * @param title The title of the crosspost.
+   * @param opts Any extra options.
+   *
+   * @returns A promise that resolves to the ID of the newly created post.
+   */
+  async crosspostTo(
+    subreddit: string,
+    title: string,
+    opts: LinkPostOptions = {}
+  ): Promise<string> {
+    return this.controls.crosspostTo(this.id, subreddit, title, opts);
+  }
+
   /**
    * Turn contest mode on/off.
    *