refactor: improve home feed parsing (#234)

* chore: update tests

* style: format code

* docs: update API ref

src/parser/youtube/HomeFeed.ts

@@ -0,0 +1,42 @@
+import Actions from '../../core/Actions';
+import FilterableFeed from '../../core/FilterableFeed';
+import ChipCloudChip from '../classes/ChipCloudChip';
+import FeedTabbedHeader from '../classes/FeedTabbedHeader';
+import RichGrid from '../classes/RichGrid';
+
+import { ReloadContinuationItemsCommand, AppendContinuationItemsAction } from '..';
+
+export default class HomeFeed extends FilterableFeed {
+  contents: RichGrid | AppendContinuationItemsAction | ReloadContinuationItemsCommand;
+  header: FeedTabbedHeader;
+
+  constructor(actions: Actions, data: any, already_parsed = false) {
+    super(actions, data, already_parsed);
+    this.header = this.memo.getType<FeedTabbedHeader>(FeedTabbedHeader)?.[0];
+    this.contents =
+      this.memo.getType<RichGrid>(RichGrid)?.[0] ||
+      this.page.on_response_received_actions?.[0];
+  }
+
+  /**
+   * Applies given filter to the feed.
+   * @param filter - Filter to apply.
+   */
+  async applyFilter(filter: string | ChipCloudChip): Promise<HomeFeed> {
+    const feed = await super.getFilteredFeed(filter);
+    return new HomeFeed(this.actions, feed.page, true);
+  }
+
+  /**
+   * Retrieves next batch of contents.
+   */
+  async getContinuation(): Promise<HomeFeed> {
+    const feed = await super.getContinuation();
+
+    // Keep the page header
+    feed.page.header = this.page.header;
+    feed.page.header_memo.set(this.header.type, [ this.header ]);
+
+    return new HomeFeed(this.actions, feed.page, true);
+  }
+}