Apply pagination to news list + scroll observer

package.json

@@ -30,6 +30,7 @@
     "react-async-loader": "^0.1.2",
     "react-dom": "^17.0.2",
     "react-i18next": "^14.1.1",
+    "react-intersection-observer": "^9.13.1",
     "react-leaflet": "3.2.5",
     "react-leaflet-google-layer": "^2.2.0",
     "react-router-dom": "^6.23.0",
@@ -133,7 +134,7 @@
       "prettier --write"
     ]
   },
-"overrides": {
-  "react-refresh": "0.11.0"
-}
+  "overrides": {
+    "react-refresh": "0.11.0"
+  }
 }

src/App.tsx

@@ -11,7 +11,7 @@ import { useTranslation } from 'react-i18next';
 import { useTheme } from '@material-ui/core/styles';
 import PopUpRedirect from './components/atoms/PopUpRedirect';
 import WidgetsTemplate from './components/organisms/WidgetsTemplate';
-import {observer} from "mobx-react-lite";
+import { observer } from 'mobx-react-lite';
 // main components height - must add up to 100
 
 const headerHeight = '5vh';
@@ -31,7 +31,6 @@ const App: FC = () => {
   const classes = useStyles();
   const store = useStore();
   const theme = useTheme();
-
   const appDir = i18n.dir();
 
   useEffect(() => {

src/components/atoms/index.ts

@@ -7,7 +7,6 @@ export { default as Textbox } from './Textbox';
 export { default as ErrorBoundary } from './ErrorBoundary';
 export { default as MetaTag } from './MetaTag';
 export { default as Loader } from './Loader';
-export { default as InfiniteScroll } from './InfiniteScroll';
 export { default as Dialog } from './Dialog';
 export { default as AppBar } from './AppBar';
 export { default as Logo } from './Logo';

src/components/molecules/NewsFlashComp.tsx

@@ -57,7 +57,7 @@ const NewsFlashComp: FC<IProps> = ({ news }) => {
   const verificationIcon = getVerificationIcon(news.newsflash_location_qualification);
   const criticalIcon = news.critical && <CriticalIcon className={classes.icon} />;
   const {newsId} = useParams()
-  const newsID = newsId ? parseInt(newsId) : '' 
+  const newsID = newsId ? parseInt(newsId) : '';
   const className = news.id === newsID ? classes.activeNewsFlash : '';
   const date = news.date == null ? '' : dateFormat(new Date(news.date.replace(/-/g, '/')), locale);
   const handleLocationEditorOpen = () => setOpen(true);

src/components/organisms/News.tsx

@@ -1,4 +1,4 @@
-import React, { FC } from 'react';
+import { FC, useRef } from 'react';
 import { Typography } from 'components/atoms';
 import { Box, makeStyles } from '@material-ui/core';
 import { useStore } from 'store/storeConfig';
@@ -7,41 +7,65 @@ import RootStore from 'store/root.store';
 import { observer } from 'mobx-react-lite';
 import LocationSearchIndicator from 'components/molecules/LocationSearchIndicator';
 import { IRouteProps } from 'models/Route';
-import NewsFlashComp from "components/molecules/NewsFlashComp";
-
+import NewsFlashComp from 'components/molecules/NewsFlashComp';
+import { useScrollObserver } from 'hooks/useScrollObserver.hooks';
+import { Direction } from 'models/ScrollObserver.model';
+import { combineRefs } from 'utils/element.util';
 
 const useStyles = makeStyles({
   container: {},
   newsFeed: {
+    display: 'flex',
+    flexDirection: 'column',
+    flexGrow: 1,
     overflow: 'auto',
   },
 });
 
-<img src="" alt="" />
-const News: FC = () => {
+interface InfiniteScrollProps {
+  onScroll: (direction: Direction) => void;
+}
+
+const News: FC<InfiniteScrollProps> = ({ onScroll }) => {
   const store: RootStore = useStore();
   const classes = useStyles();
-  const { gpsId, street, city } = useParams<IRouteProps>();
+  const { gpsId, street, city, newsId = '' } = useParams<IRouteProps>();
   const { newsFlashStore } = store;
+  const containerRef = useRef<HTMLDivElement>(null);
+
+  const { firstItemRef, lastItemRef, selectedItemRef } = useScrollObserver({
+    newsId,
+    onScroll,
+    containerRef,
+    newsData: newsFlashStore.newsFlashCollection.data,
+    newsLoading: newsFlashStore.newsFlashLoading,
+  });
 
   return (
-    <Box flexGrow={1} display="flex" flexDirection="column" className={classes.newsFeed}>
-      <Box flexGrow={1}>
-        <Box className={classes.container} flexDirection={'column'}>
-          {gpsId && <LocationSearchIndicator searchType={'gps'} />}
-          {street && city && <LocationSearchIndicator searchType={'cityAndStreet'} />}
-          {newsFlashStore.newsFlashCollection.length > 0 ? (
-            newsFlashStore.newsFlashCollection.map((news) =>
-              <NewsFlashComp news={news} /> 
-            )
-          ) : (
-            <Box p={1}>
-              <Typography.Body4>לא נמצאו תוצאות מהמקור המבוקש</Typography.Body4>
-            </Box>
-          )}
+    <div ref={containerRef} className={classes.newsFeed}>
+      {gpsId && <LocationSearchIndicator searchType={'gps'} />}
+      {street && city && <LocationSearchIndicator searchType={'cityAndStreet'} />}
+      {newsFlashStore.newsFlashCollection.data.length > 0 ? (
+        newsFlashStore.newsFlashCollection.data.map((news, index) => {
+          const isFirst = index === 0;
+          const isLast = index === newsFlashStore.newsFlashCollection.data.length - 1;
+          const selectedItem = news.id === +newsId ? selectedItemRef : undefined;
+
+          return (
+            <div
+              key={news.id}
+              ref={combineRefs(isFirst ? firstItemRef : undefined, isLast ? lastItemRef : undefined, selectedItem)}
+            >
+              <NewsFlashComp news={news} />
+            </div>
+          );
+        })
+      ) : (
+        <Box p={1}>
+          <Typography.Body4>לא נמצאו תוצאות מהמקור המבוקש</Typography.Body4>
         </Box>
-      </Box>
-    </Box>
+      )}
+    </div>
   );
 };
 

src/components/organisms/SideBar.tsx

@@ -8,11 +8,9 @@ import { Typography, ErrorBoundary } from 'components/atoms';
 import { observer } from 'mobx-react-lite';
 import { useStore } from 'store/storeConfig';
 import RootStore from 'store/root.store';
-import { InfiniteScroll } from 'components/atoms';
 import SideBarMap from 'components/molecules/SideBarMap';
 import { useTranslation } from 'react-i18next';
-
-const INFINITE_SCROLL_FETCH_SIZE = 100;
+import { Direction } from 'models/ScrollObserver.model';
 
 interface IProps {}
 
@@ -37,10 +35,23 @@ const SideBar: FC<IProps> = () => {
   const mapTitle = `${t('sideBar')}`;
   const location = newsFlashStore.activeNewsFlashLocation;
   const loading = newsFlashStore.newsFlashLoading;
+  const currentPageNumber = newsFlashStore.newsFlashPageNumber;
+  const lastPrevPage = newsFlashStore.newsFlashLastPrevPage;
+  const totalPages = newsFlashStore.newsFlashCollection.pagination.totalPages;
 
-  const fetchMoreNewsItems = useCallback(() => {
-    newsFlashStore.infiniteFetchLimit(INFINITE_SCROLL_FETCH_SIZE);
-  }, [newsFlashStore]);
+  const fetchMoreNewsItems = useCallback(
+    (direction: Direction) => {
+      if (loading) return;
+      if (direction === Direction.PREV && currentPageNumber > 1 && lastPrevPage > 1) {
+        newsFlashStore.filterNewsFlashCollection(direction);
+        return;
+      }
+      if (direction === Direction.NEXT && totalPages > currentPageNumber) {
+        newsFlashStore.filterNewsFlashCollection(direction);
+      }
+    },
+    [currentPageNumber, lastPrevPage, loading, newsFlashStore, totalPages],
+  );
 
   return (
     <Box display="flex" flexDirection="column" justifyContent="center" alignItems="stretch">
@@ -51,9 +62,7 @@ const SideBar: FC<IProps> = () => {
             <NewsFlashFilterPanel />
           </ErrorBoundary>
         </Box>
-        <InfiniteScroll onScrollEnd={fetchMoreNewsItems}>
-          <News />
-        </InfiniteScroll>
+        <News onScroll={fetchMoreNewsItems} />
       </Box>
       <Box borderTop={`1px solid ${silverSmokeColor}`} flexShrink={0} flexGrow={0} p={1}>
         <Typography.Body4 children={mapTitle} />
@@ -62,7 +71,7 @@ const SideBar: FC<IProps> = () => {
         {location && (
           <ErrorBoundary>
             <SideBarMap items={[location]} />
-          </ErrorBoundary>  
+          </ErrorBoundary>
         )}
       </Box>
     </Box>

src/hooks/useScrollObserver.hooks.ts

@@ -0,0 +1,87 @@
+import { Direction } from 'models/ScrollObserver.model';
+import { useEffect, useRef } from 'react';
+import { useInView } from 'react-intersection-observer';
+
+interface IProps {
+  newsId: string;
+  containerRef: React.RefObject<HTMLDivElement>;
+  newsData: any[];
+  newsLoading: boolean;
+  onScroll: (direction: Direction) => void;
+}
+
+export const useScrollObserver = ({ newsId, onScroll, containerRef, newsData, newsLoading }: IProps) => {
+  const selectedItemRef = useRef<HTMLDivElement>(null);
+  const isFirstRender = useRef(true);
+  const isInViewFirstRender = useRef(true);
+
+  useEffect(() => {
+    if (isFirstRender.current && newsId && newsData.length > 0 && !newsLoading) {
+      const itemIndex = newsData.findIndex((item) => item.id.toString() === newsId);
+
+      if (itemIndex !== -1) {
+        requestAnimationFrame(() => {
+          selectedItemRef.current?.scrollIntoView({
+            behavior: 'smooth',
+            block: 'center',
+          });
+        });
+      }
+      isFirstRender.current = false;
+    }
+  }, [newsId, newsData, newsLoading]);
+
+  const [firstItemRef] = useInView({
+    threshold: 0.1,
+    delay: 100,
+    onChange: (inView) => {
+      if (isInViewFirstRender.current) {
+        isInViewFirstRender.current = false;
+        return;
+      }
+      if (inView && !newsLoading) {
+        const container = containerRef.current;
+        if (!container) return;
+
+        const oldScrollHeight = container.scrollHeight;
+        const oldScrollTop = container.scrollTop;
+
+        // Create mutation observer before fetching
+        const observer = new MutationObserver(() => {
+          const newScrollHeight = container.scrollHeight;
+          const heightDiff = newScrollHeight - oldScrollHeight;
+
+          // Adjust scroll position to prevent jump
+          container.scrollTop = oldScrollTop + heightDiff;
+          observer.disconnect();
+        });
+        // Start observing before fetch
+        observer.observe(container, { childList: true, subtree: true });
+
+        onScroll(Direction.PREV);
+        isInViewFirstRender.current = true;
+      }
+    },
+  });
+
+  const [lastItemRef] = useInView({
+    threshold: 0.1,
+    delay: 100,
+    onChange: (inView) => {
+      if (isInViewFirstRender.current) {
+        isInViewFirstRender.current = false;
+        return;
+      }
+      if (inView && !newsLoading) {
+        onScroll(Direction.NEXT);
+        isInViewFirstRender.current = true;
+      }
+    },
+  });
+
+  return {
+    firstItemRef,
+    lastItemRef,
+    selectedItemRef,
+  };
+};

src/models/NewFlash.ts

@@ -17,3 +17,15 @@ export interface INewsFlash {
   source: string;
   critical?: boolean;
 }
+
+export interface IPagination {
+  pageNumber: number;
+  pageSize: number;
+  totalRecords: number;
+  totalPages: number;
+}
+
+export interface INewsFlashCollection {
+  data: INewsFlash[];
+  pagination: IPagination;
+}

src/models/ScrollObserver.model.ts

@@ -0,0 +1,4 @@
+export enum Direction {
+  PREV = 'PREV',
+  NEXT = 'NEXT',
+}