auto-loading completely done

src/views/components/injected/AutoLoad/AutoLoad.tsx

@@ -0,0 +1,73 @@
+import React, { useEffect, useState } from 'react';
+import { createPortal } from 'react-dom';
+import { ScrapedRow } from 'src/shared/types/Course';
+import useInfiniteScroll from 'src/views/hooks/useInfiniteScroll';
+import { CourseCatalogScraper } from 'src/views/lib/CourseCatalogScraper';
+import { SiteSupport } from 'src/views/lib/getSiteSupport';
+import { loadNextCourseCatalogPage, AutoLoadStatus } from 'src/views/lib/loadNextCourseCatalogPage';
+import Spinner from '../../common/Spinner/Spinner';
+import styles from './AutoLoad.module.scss';
+
+type Props = {
+    addRows: (rows: ScrapedRow[]) => void;
+};
+
+/**
+ * This component is responsible for loading the next page of courses when the user scrolls to the bottom of the page.
+ * @returns
+ */
+export default function AutoLoad({ addRows }: Props) {
+    const [container, setContainer] = useState<HTMLDivElement | null>(null);
+    const [status, setStatus] = useState<AutoLoadStatus>(AutoLoadStatus.IDLE);
+
+    useEffect(() => {
+        const portalContainer = document.createElement('div');
+        const lastTableCell = document.querySelector('table')!;
+        lastTableCell!.after(portalContainer);
+        setContainer(portalContainer);
+    }, []);
+
+    // FOR DEBUGGING
+    useEffect(() => {
+        console.log(`AutoLoad is now ${status}`);
+    }, [status]);
+
+    // This hook will call the callback when the user scrolls to the bottom of the page.
+    useInfiniteScroll(async () => {
+        // fetch the next page of courses
+        const [status, nextRows] = await loadNextCourseCatalogPage();
+        setStatus(status);
+        if (!nextRows) {
+            return;
+        }
+        // scrape the courses from the page
+        const ccs = new CourseCatalogScraper(SiteSupport.COURSE_CATALOG_LIST);
+        const scrapedRows = ccs.scrape(nextRows);
+
+        // add the scraped courses to the current page
+        addRows(scrapedRows);
+    }, [addRows]);
+
+    if (!container || status === AutoLoadStatus.IDLE) {
+        return null;
+    }
+
+    return createPortal(
+        <div>
+            {status === AutoLoadStatus.LOADING && (
+                <div>
+                    <Spinner />
+                    <h2>Loading Next Page...</h2>
+                </div>
+            )}
+            {status === AutoLoadStatus.ERROR && (
+                <div className={styles.error}>
+                    <h2>Something went wrong</h2>
+                    <p>Try refreshing the page</p>
+                    <button onClick={() => window.location.reload()}>Refresh</button>
+                </div>
+            )}
+        </div>,
+        container
+    );
+}