From d51150b7848cf7a6596bbba7c015328a578dfd16 Mon Sep 17 00:00:00 2001
From: schroda <50052685+schroda@users.noreply.github.com>
Date: Wed, 5 Apr 2023 13:37:12 +0200
Subject: [PATCH] Feature/reader skip duplicate chapters (#262)

* Skip duplicate chapters in the Reader

* Debounce "end of page" handling in the reader

* Update keyboard event listener

In case the "go" function changed, the listeners have to be updated
---
 src/components/navbar/ReaderNavBar.tsx        | 66 ++++++++-----
 .../reader/ReaderSettingsOptions.tsx          | 11 +++
 .../reader/pager/DoublePagedPager.tsx         |  2 +-
 .../reader/pager/HorizontalPager.tsx          |  2 +-
 src/components/reader/pager/PagedPager.tsx    |  2 +-
 src/components/reader/pager/VerticalPager.tsx | 13 ++-
 src/i18n/locale/en.json                       |  9 +-
 src/screens/Reader.tsx                        | 92 ++++++++++++++++---
 .../settings/DefaultReaderSettings.tsx        |  1 +
 src/typings.ts                                |  6 ++
 src/util/readerSettings.ts                    |  1 +
 11 files changed, 165 insertions(+), 40 deletions(-)

diff --git a/src/components/navbar/ReaderNavBar.tsx b/src/components/navbar/ReaderNavBar.tsx
index 44976b66..2fb81f9c 100644
--- a/src/components/navbar/ReaderNavBar.tsx
+++ b/src/components/navbar/ReaderNavBar.tsx
@@ -25,7 +25,7 @@ import Collapse from '@mui/material/Collapse';
 import { styled } from '@mui/system';
 import useBackTo from 'util/useBackTo';
 import ReaderSettingsOptions from 'components/reader/ReaderSettingsOptions';
-import { IChapter, IManga, IMangaCard, IReaderSettings } from 'typings';
+import { ChapterOffset, IChapter, IManga, IMangaCard, IReaderSettings } from 'typings';
 import { useTranslation } from 'react-i18next';
 
 const Root = styled('div')(({ theme }) => ({
@@ -119,6 +119,8 @@ interface IProps {
     chapter: IChapter;
     curPage: number;
     scrollToPage: (page: number) => void;
+    openNextChapter: (offset: ChapterOffset, setHistory: (nextChapterIndex: number) => void) => Promise<void>;
+    retrievingNextChapter: boolean;
 }
 
 export default function ReaderNavBar(props: IProps) {
@@ -131,7 +133,8 @@ export default function ReaderNavBar(props: IProps) {
     }>();
     const { prevDrawerOpen, prevSettingsCollapseOpen } = location.state ?? {};
 
-    const { settings, setSettingValue, manga, chapter, curPage, scrollToPage } = props;
+    const { settings, setSettingValue, manga, chapter, curPage, scrollToPage, openNextChapter, retrievingNextChapter } =
+        props;
 
     const [drawerOpen, setDrawerOpen] = useState(settings.staticNav || prevDrawerOpen);
     const [updateDrawerOnRender, setUpdateDrawerOnRender] = useState(true);
@@ -139,6 +142,8 @@ export default function ReaderNavBar(props: IProps) {
     const [prevScrollPos, setPrevScrollPos] = useState(0);
     const [settingsCollapseOpen, setSettingsCollapseOpen] = useState(prevSettingsCollapseOpen ?? true);
 
+    const disableChapterNavButtons = retrievingNextChapter;
+
     const updateSettingValue = (key: keyof IReaderSettings, value: string | boolean) => {
         // prevent closing the navBar when updating the "staticNav" setting
         setUpdateDrawerOnRender(key !== 'staticNav');
@@ -254,6 +259,7 @@ export default function ReaderNavBar(props: IProps) {
                             staticNav={settings.staticNav}
                             showPageNumber={settings.showPageNumber}
                             loadNextOnEnding={settings.loadNextOnEnding}
+                            skipDupChapters={settings.skipDupChapters}
                             readerType={settings.readerType}
                         />
                     </Collapse>
@@ -261,7 +267,11 @@ export default function ReaderNavBar(props: IProps) {
                     <Navigation>
                         <PageNavigation>
                             <span>{t('reader.page_info.label.currently_on_page')}</span>
-                            <FormControl size="small" sx={{ margin: '0 5px' }} disabled={chapter.pageCount === -1}>
+                            <FormControl
+                                size="small"
+                                sx={{ margin: '0 5px' }}
+                                disabled={disableChapterNavButtons || chapter.pageCount === -1}
+                            >
                                 <Select
                                     MenuProps={MenuProps}
                                     value={chapter.pageCount > -1 ? curPage : ''}
@@ -286,20 +296,26 @@ export default function ReaderNavBar(props: IProps) {
                             <IconButton
                                 title={t('reader.button.previous_chapter')}
                                 sx={{ gridArea: 'pre' }}
-                                disabled={chapter.index <= 1}
-                                onClick={() => {
-                                    history.replace({
-                                        pathname: `/manga/${manga.id}/chapter/${chapter.index - 1}`,
-                                        state: {
-                                            prevDrawerOpen: drawerOpen,
-                                            prevSettingsCollapseOpen: settingsCollapseOpen,
-                                        },
-                                    });
-                                }}
+                                disabled={disableChapterNavButtons || chapter.index <= 1}
+                                onClick={() =>
+                                    openNextChapter(ChapterOffset.PREV, (prevChapterIndex) => {
+                                        history.replace({
+                                            pathname: `/manga/${manga.id}/chapter/${prevChapterIndex}`,
+                                            state: {
+                                                prevDrawerOpen: drawerOpen,
+                                                prevSettingsCollapseOpen: settingsCollapseOpen,
+                                            },
+                                        });
+                                    })
+                                }
                             >
                                 <KeyboardArrowLeftIcon />
                             </IconButton>
-                            <FormControl sx={{ gridArea: 'current' }} size="small" disabled={chapter.index < 1}>
+                            <FormControl
+                                sx={{ gridArea: 'current' }}
+                                size="small"
+                                disabled={disableChapterNavButtons || chapter.index < 1}
+                            >
                                 <Select
                                     MenuProps={MenuProps}
                                     value={chapter.index >= 1 ? chapter.index : ''}
@@ -328,15 +344,21 @@ export default function ReaderNavBar(props: IProps) {
                             <IconButton
                                 title={t('reader.button.next_chapter')}
                                 sx={{ gridArea: 'next' }}
-                                disabled={chapter.index < 1 || chapter.index >= chapter.chapterCount}
+                                disabled={
+                                    disableChapterNavButtons ||
+                                    chapter.index < 1 ||
+                                    chapter.index >= chapter.chapterCount
+                                }
                                 onClick={() => {
-                                    history.replace({
-                                        pathname: `/manga/${manga.id}/chapter/${chapter.index + 1}`,
-                                        state: {
-                                            prevDrawerOpen: drawerOpen,
-                                            prevSettingsCollapseOpen: settingsCollapseOpen,
-                                        },
-                                    });
+                                    openNextChapter(ChapterOffset.NEXT, (nextChapterIndex) =>
+                                        history.replace({
+                                            pathname: `/manga/${manga.id}/chapter/${nextChapterIndex}`,
+                                            state: {
+                                                prevDrawerOpen: drawerOpen,
+                                                prevSettingsCollapseOpen: settingsCollapseOpen,
+                                            },
+                                        }),
+                                    );
                                 }}
                             >
                                 <KeyboardArrowRightIcon />
diff --git a/src/components/reader/ReaderSettingsOptions.tsx b/src/components/reader/ReaderSettingsOptions.tsx
index 1aa5c408..6133938e 100644
--- a/src/components/reader/ReaderSettingsOptions.tsx
+++ b/src/components/reader/ReaderSettingsOptions.tsx
@@ -23,6 +23,7 @@ export default function ReaderSettingsOptions({
     loadNextOnEnding,
     readerType,
     showPageNumber,
+    skipDupChapters,
     setSettingValue,
 }: IProps) {
     const { t } = useTranslation();
@@ -59,6 +60,16 @@ export default function ReaderSettingsOptions({
                     />
                 </ListItemSecondaryAction>
             </ListItem>
+            <ListItem>
+                <ListItemText primary={t('reader.settings.label.skip_dup_chapters')} />
+                <ListItemSecondaryAction>
+                    <Switch
+                        edge="end"
+                        checked={skipDupChapters}
+                        onChange={(e) => setSettingValue('skipDupChapters', e.target.checked)}
+                    />
+                </ListItemSecondaryAction>
+            </ListItem>
             <ListItem>
                 <ListItemText primary={t('reader.settings.label.reader_type')} />
                 <Select
diff --git a/src/components/reader/pager/DoublePagedPager.tsx b/src/components/reader/pager/DoublePagedPager.tsx
index 01a33b43..e319db13 100644
--- a/src/components/reader/pager/DoublePagedPager.tsx
+++ b/src/components/reader/pager/DoublePagedPager.tsx
@@ -185,7 +185,7 @@ export default function DoublePagedPager(props: IReaderProps) {
             document.removeEventListener('keydown', keyboardControl);
             selfRef.current?.removeEventListener('click', clickControl);
         };
-    }, [selfRef, curPage, settings.readerType]);
+    }, [selfRef, curPage, settings.readerType, prevChapter, nextChapter]);
 
     useEffect(() => {
         setCurPage(initialPage);
diff --git a/src/components/reader/pager/HorizontalPager.tsx b/src/components/reader/pager/HorizontalPager.tsx
index f878123d..ec88e5e6 100644
--- a/src/components/reader/pager/HorizontalPager.tsx
+++ b/src/components/reader/pager/HorizontalPager.tsx
@@ -134,7 +134,7 @@ export default function HorizontalPager(props: IReaderProps) {
             document.removeEventListener('scroll', handleLoadNextonEnding);
             selfRef.current?.removeEventListener('mousedown', clickControl);
         };
-    }, [selfRef, curPage]);
+    }, [selfRef, curPage, prevChapter, nextChapter]);
 
     useEffect(() => {
         const handleScroll = () => {
diff --git a/src/components/reader/pager/PagedPager.tsx b/src/components/reader/pager/PagedPager.tsx
index 189a0781..0e49670e 100644
--- a/src/components/reader/pager/PagedPager.tsx
+++ b/src/components/reader/pager/PagedPager.tsx
@@ -85,7 +85,7 @@ export default function PagedReader(props: IReaderProps) {
             document.removeEventListener('keydown', keyboardControl);
             selfRef.current?.removeEventListener('click', clickControl);
         };
-    }, [selfRef, curPage, settings.readerType]);
+    }, [selfRef, curPage, settings.readerType, prevChapter, nextChapter]);
 
     useEffect(() => {
         // Delay scrolling to next cycle
diff --git a/src/components/reader/pager/VerticalPager.tsx b/src/components/reader/pager/VerticalPager.tsx
index 422c7c2a..1fc7acf8 100644
--- a/src/components/reader/pager/VerticalPager.tsx
+++ b/src/components/reader/pager/VerticalPager.tsx
@@ -42,10 +42,17 @@ export default function VerticalPager(props: IReaderProps) {
     const pagesRef = useRef<HTMLDivElement[]>([]);
 
     useEffect(() => {
+        let handlingEndOfPage = false;
         const handleScroll = () => {
             if (!selfRef.current) return;
 
             if (isAtBottom()) {
+                if (handlingEndOfPage) {
+                    return;
+                }
+
+                handlingEndOfPage = true;
+
                 // If scroll is moved all the way to the bottom
                 // This handles cases when last page is show, but is smaller then
                 // window, in which case it would never get marked as read.
@@ -58,6 +65,8 @@ export default function VerticalPager(props: IReaderProps) {
                     nextChapter();
                 }
             } else {
+                handlingEndOfPage = false;
+
                 // Update current page in parent
                 const currentPage = findCurrentPageIndex(selfRef.current);
                 if (currentPage !== currentPageRef.current) {
@@ -71,7 +80,7 @@ export default function VerticalPager(props: IReaderProps) {
         return () => {
             window.removeEventListener('scroll', handleScroll);
         };
-    }, [settings.loadNextOnEnding]);
+    }, [settings.loadNextOnEnding, nextChapter]);
 
     const go = useCallback(
         (direction: 'up' | 'down') => {
@@ -114,7 +123,7 @@ export default function VerticalPager(props: IReaderProps) {
         return () => {
             document.removeEventListener('keydown', handleKeyboard);
         };
-    }, []);
+    }, [go]);
 
     useEffect(() => {
         // Delay scrolling to next cycle
diff --git a/src/i18n/locale/en.json b/src/i18n/locale/en.json
index d0b043c9..348603b4 100644
--- a/src/i18n/locale/en.json
+++ b/src/i18n/locale/en.json
@@ -304,6 +304,12 @@
       "next_chapter": "Next Chapter",
       "previous_chapter": "Previous Chapter"
     },
+    "error": {
+      "label": {
+        "unable_to_get_next_chapter_skip_dup": "Unable to get the next chapter - \"$t(reader.settings.label.skip_dup_chapters)\" option is enabled",
+        "unable_to_get_prev_chapter_skip_dup": "Unable to get the previous chapter - \"$t(reader.settings.label.skip_dup_chapters)\" option is enabled"
+      }
+    },
     "page_info": {
       "label": {
         "currently_on_page": "Currently on page",
@@ -321,6 +327,7 @@
         "load_next_chapter": "Load next chapter at ending",
         "reader_type": "Reader Type",
         "show_page_number": "Show page number",
+        "skip_dup_chapters": "Skip duplicate chapters",
         "static_navigation": "Static Navigation"
       },
       "reader_type": {
@@ -424,4 +431,4 @@
     },
     "title": "Updates"
   }
-}
+}
\ No newline at end of file
diff --git a/src/screens/Reader.tsx b/src/screens/Reader.tsx
index 7e0ad86c..095df777 100644
--- a/src/screens/Reader.tsx
+++ b/src/screens/Reader.tsx
@@ -25,9 +25,44 @@ import {
     useDefaultReaderSettings,
 } from 'util/readerSettings';
 import makeToast from 'components/util/Toast';
-import { IChapter, IManga, IMangaCard, IPartialChapter, IReaderSettings, ReaderType } from 'typings';
+import {
+    ChapterOffset,
+    IChapter,
+    IManga,
+    IMangaCard,
+    IPartialChapter,
+    IReaderSettings,
+    ReaderType,
+    TranslationKey,
+} from 'typings';
 import { useTranslation } from 'react-i18next';
 
+const isDupChapter = async (chapterIndex: number, currentChapter: IChapter) => {
+    const nextChapter = (await client.get<IChapter>(`/api/v1/manga/${currentChapter.mangaId}/chapter/${chapterIndex}`))
+        .data;
+
+    return nextChapter.chapterNumber === currentChapter.chapterNumber;
+};
+
+/**
+ * In case duplicated chapters should be skipped the function will check all next/prev chapters until
+ *  - a non duplicated chapter was found
+ *  - no prev/next chapter exists => chapter request will fail and error will be raised up
+ */
+const getOffsetChapter = async (
+    chapterIndex: number,
+    currentChapter: IChapter,
+    skipDupChapters: boolean,
+    offset: ChapterOffset,
+): Promise<number> => {
+    const shouldSkipChapter = skipDupChapters && (await isDupChapter(chapterIndex, currentChapter));
+    if (shouldSkipChapter) {
+        return getOffsetChapter(chapterIndex + offset, currentChapter, skipDupChapters, offset);
+    }
+
+    return chapterIndex;
+};
+
 const getReaderComponent = (readerType: ReaderType) => {
     switch (readerType) {
         case 'ContinuesVertical':
@@ -81,6 +116,7 @@ export default function Reader() {
     const [curPage, setCurPage] = useState<number>(0);
     const [pageToScrollTo, setPageToScrollTo] = useState<number | undefined>(undefined);
     const { setOverride, setTitle } = useContext(NavbarContext);
+    const [retrievingNextChapter, setRetrievingNextChapter] = useState(false);
 
     const { settings: defaultSettings, loading: areDefaultSettingsLoading } = useDefaultReaderSettings();
     const [settings, setSettings] = useState(getReaderSettingsFor(manga, defaultSettings));
@@ -93,6 +129,32 @@ export default function Reader() {
         );
     };
 
+    const openNextChapter = useCallback(
+        async (offset: ChapterOffset, setHistory: (nextChapterIndex: number) => void) => {
+            setRetrievingNextChapter(true);
+            try {
+                setHistory(
+                    await getOffsetChapter(
+                        chapter.index + offset,
+                        chapter as IChapter,
+                        settings.skipDupChapters,
+                        offset,
+                    ),
+                );
+            } catch (error) {
+                const offsetToTranslationKeyMap: { [chapterOffset in ChapterOffset]: TranslationKey } = {
+                    [ChapterOffset.PREV]: 'reader.error.label.unable_to_get_prev_chapter_skip_dup',
+                    [ChapterOffset.NEXT]: 'reader.error.label.unable_to_get_next_chapter_skip_dup',
+                };
+
+                makeToast(t(offsetToTranslationKeyMap[offset]) as string, 'error');
+            } finally {
+                setRetrievingNextChapter(false);
+            }
+        },
+        [chapter, settings],
+    );
+
     useEffect(() => {
         if (!manga?.title || (chapter as IChapter)?.name === t('global.label.loading')) {
             setTitle(t('reader.title'));
@@ -120,13 +182,15 @@ export default function Reader() {
                     chapter={chapter as IChapter}
                     curPage={curPage}
                     scrollToPage={setPageToScrollTo}
+                    openNextChapter={openNextChapter}
+                    retrievingNextChapter={retrievingNextChapter}
                 />
             ),
         });
 
         // clean up for when we leave the reader
         return () => setOverride({ status: false, value: <div /> });
-    }, [manga, chapter, settings, curPage, chapterIndex]);
+    }, [manga, chapter, settings, curPage, chapterIndex, retrievingNextChapter]);
 
     useEffect(() => {
         setIsMangaLoading(true);
@@ -175,21 +239,25 @@ export default function Reader() {
             formData.append('read', 'true');
             client.patch(`/api/v1/manga/${manga.id}/chapter/${chapter.index}`, formData);
 
-            history.replace({
-                pathname: `/manga/${manga.id}/chapter/${chapter.index + 1}`,
-                state: history.location.state,
-            });
+            openNextChapter(ChapterOffset.NEXT, (nextChapterIndex) =>
+                history.replace({
+                    pathname: `/manga/${manga.id}/chapter/${nextChapterIndex}`,
+                    state: history.location.state,
+                }),
+            );
         }
-    }, [chapter.index, chapter.chapterCount, chapter.pageCount, manga.id]);
+    }, [chapter.index, chapter.chapterCount, chapter.pageCount, manga.id, settings.skipDupChapters]);
 
     const prevChapter = useCallback(() => {
         if (chapter.index > 1) {
-            history.replace({
-                pathname: `/manga/${manga.id}/chapter/${chapter.index - 1}`,
-                state: history.location.state,
-            });
+            openNextChapter(ChapterOffset.PREV, (prevChapterIndex) =>
+                history.replace({
+                    pathname: `/manga/${manga.id}/chapter/${prevChapterIndex}`,
+                    state: history.location.state,
+                }),
+            );
         }
-    }, [chapter.index, manga.id]);
+    }, [chapter.index, manga.id, settings.skipDupChapters]);
 
     // return spinner while chpater data is loading
     if (chapter.pageCount === -1) {
diff --git a/src/screens/settings/DefaultReaderSettings.tsx b/src/screens/settings/DefaultReaderSettings.tsx
index edd9a98e..d3dedc3d 100644
--- a/src/screens/settings/DefaultReaderSettings.tsx
+++ b/src/screens/settings/DefaultReaderSettings.tsx
@@ -62,6 +62,7 @@ export default function DefaultReaderSettings() {
             staticNav={settings.staticNav}
             showPageNumber={settings.showPageNumber}
             loadNextOnEnding={settings.loadNextOnEnding}
+            skipDupChapters={settings.skipDupChapters}
             readerType={settings.readerType}
         />
     );
diff --git a/src/typings.ts b/src/typings.ts
index 4c0cb781..20a3b03f 100644
--- a/src/typings.ts
+++ b/src/typings.ts
@@ -202,9 +202,15 @@ export interface IReaderSettings {
     staticNav: boolean;
     showPageNumber: boolean;
     loadNextOnEnding: boolean;
+    skipDupChapters: boolean;
     readerType: ReaderType;
 }
 
+export enum ChapterOffset {
+    PREV = -1,
+    NEXT = 1,
+}
+
 export interface ISearchSettings {
     ignoreFilters: boolean;
 }
diff --git a/src/util/readerSettings.ts b/src/util/readerSettings.ts
index 60384362..e6cae1d2 100644
--- a/src/util/readerSettings.ts
+++ b/src/util/readerSettings.ts
@@ -16,6 +16,7 @@ export const getDefaultSettings = (forceUndefined: boolean = false) =>
         showPageNumber: forceUndefined ? undefined : true,
         continuesPageGap: forceUndefined ? undefined : false,
         loadNextOnEnding: forceUndefined ? undefined : false,
+        skipDupChapters: forceUndefined ? undefined : true,
         readerType: forceUndefined ? undefined : 'ContinuesVertical',
     } as IReaderSettings);