Clean up the reader filter logic (#444)

* move chapter filtering to its own class and injekt it.
Clean up the logic around the filter to prevent unneeded filtering and to make it more understandable

* switch to .not

app/src/main/java/eu/kanade/tachiyomi/AppModule.kt

@@ -12,6 +12,7 @@ import eu.kanade.tachiyomi.data.track.TrackManager
 import eu.kanade.tachiyomi.extension.ExtensionManager
 import eu.kanade.tachiyomi.network.NetworkHelper
 import eu.kanade.tachiyomi.source.SourceManager
+import eu.kanade.tachiyomi.ui.reader.ReaderChapterFilter
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
 import uy.kohesive.injekt.api.InjektModule
@@ -48,6 +49,8 @@ class AppModule(val app: Application) : InjektModule {
 
         addSingletonFactory { Gson() }
 
+        addSingletonFactory { ReaderChapterFilter() }
+
         // Asynchronously init expensive components for a faster cold start
 
         GlobalScope.launch { get<PreferencesHelper>() }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderChapterFilter.kt

@@ -0,0 +1,66 @@
+package eu.kanade.tachiyomi.ui.reader
+
+import eu.kanade.tachiyomi.data.database.models.Chapter
+import eu.kanade.tachiyomi.data.database.models.Manga
+import eu.kanade.tachiyomi.data.download.DownloadManager
+import eu.kanade.tachiyomi.data.preference.PreferencesHelper
+import uy.kohesive.injekt.Injekt
+import uy.kohesive.injekt.api.get
+
+/**
+ * This class filters chapters for the reader based on the user enabled preferences and filters
+ */
+class ReaderChapterFilter(
+    private val downloadManager: DownloadManager = Injekt.get(),
+    private val preferences: PreferencesHelper = Injekt.get()
+) {
+
+    fun filterChapter(
+        dbChapters: List<Chapter>,
+        manga: Manga,
+        chapterId: Long,
+        selectedChapter: Chapter?
+    ): List<Chapter> {
+
+        // if neither preference is enabled dont even filter
+        if (!preferences.skipRead() && !preferences.skipFiltered()) {
+            return dbChapters
+        }
+
+        var filteredChapters = dbChapters
+        if (preferences.skipRead()) {
+            filteredChapters = filteredChapters.filter { !it.read }
+            // add the selected chapter to the list in case it was read and user clicked it
+            if (chapterId != -1L) {
+                val find = filteredChapters.find { it.id == chapterId }
+                if (find == null) {
+                    val mutableList = filteredChapters.toMutableList()
+                    selectedChapter?.let { mutableList.add(it) }
+                    filteredChapters = mutableList.toList()
+                }
+            }
+        }
+        if (preferences.skipFiltered()) {
+            val readEnabled = manga.readFilter == Manga.SHOW_READ
+            val unreadEnabled = manga.readFilter == Manga.SHOW_UNREAD
+            val downloadEnabled = manga.downloadedFilter == Manga.SHOW_DOWNLOADED
+            val bookmarkEnabled = manga.bookmarkedFilter == Manga.SHOW_BOOKMARKED
+
+            // if none of the filters are enabled skip the filtering of them
+            if (readEnabled || unreadEnabled || downloadEnabled || bookmarkEnabled) {
+
+                filteredChapters = filteredChapters.filter {
+                    if (readEnabled && it.read.not() ||
+                        (unreadEnabled && it.read) ||
+                        (bookmarkEnabled && it.bookmark.not()) ||
+                        (downloadEnabled && downloadManager.isChapterDownloaded(it, manga).not())
+                    ) {
+                        return@filter false
+                    }
+                    return@filter true
+                }
+            }
+        }
+        return filteredChapters
+    }
+}

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderPresenter.kt

@@ -27,7 +27,6 @@ import eu.kanade.tachiyomi.ui.reader.model.ReaderPage
 import eu.kanade.tachiyomi.ui.reader.model.ViewerChapters
 import eu.kanade.tachiyomi.util.storage.DiskUtil
 import eu.kanade.tachiyomi.util.system.ImageUtil
-import eu.kanade.tachiyomi.util.system.executeOnIO
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
@@ -52,7 +51,8 @@ class ReaderPresenter(
     private val sourceManager: SourceManager = Injekt.get(),
     private val downloadManager: DownloadManager = Injekt.get(),
     private val coverCache: CoverCache = Injekt.get(),
-    private val preferences: PreferencesHelper = Injekt.get()
+    private val preferences: PreferencesHelper = Injekt.get(),
+    private val readerChapterFilter: ReaderChapterFilter = Injekt.get()
 ) : BasePresenter<ReaderActivity>() {
 
     /**
@@ -97,38 +97,8 @@ class ReaderPresenter(
         val selectedChapter = dbChapters.find { it.id == chapterId }
             ?: error("Requested chapter of id $chapterId not found in chapter list")
 
-        val chaptersForReader =
-            if (preferences.skipRead() || preferences.skipFiltered()) {
-                val list = dbChapters
-                    .filter {
-                        if (preferences.skipRead() && it.read) {
-                            return@filter false
-                        } else if (preferences.skipFiltered()) {
-                            if (
-                                (manga.readFilter == Manga.SHOW_READ && !it.read) ||
-                                (manga.readFilter == Manga.SHOW_UNREAD && it.read) ||
-                                (
-                                    manga.downloadedFilter == Manga.SHOW_DOWNLOADED &&
-                                        !downloadManager.isChapterDownloaded(it, manga)
-                                    ) ||
-                                (manga.bookmarkedFilter == Manga.SHOW_BOOKMARKED && !it.bookmark)
-                            ) {
-                                return@filter false
-                            }
-                        }
-
-                        true
-                    }
-                    .toMutableList()
-
-                val find = list.find { it.id == chapterId }
-                if (find == null) {
-                    list.add(selectedChapter)
-                }
-                list
-            } else {
-                dbChapters
-            }
+        val chaptersForReader = readerChapterFilter
+            .filterChapter(dbChapters, manga, chapterId, selectedChapter)
 
         when (manga.sorting) {
             Manga.SORTING_SOURCE -> ChapterLoadBySource().get(chaptersForReader)
@@ -212,33 +182,26 @@ class ReaderPresenter(
     suspend fun getChapters(): List<ReaderChapterItem> {
         val manga = manga ?: return emptyList()
         chapterItems = withContext(Dispatchers.IO) {
-            val list = db.getChapters(manga).executeOnIO().filter {
-                if (preferences.skipFiltered()) {
-                    if ((manga.readFilter == Manga.SHOW_READ && !it.read) ||
-                        (manga.readFilter == Manga.SHOW_UNREAD && it.read) ||
-                        (manga.downloadedFilter == Manga.SHOW_DOWNLOADED &&
-                            !downloadManager.isChapterDownloaded(it, manga)) ||
-                        (manga.bookmarkedFilter == Manga.SHOW_BOOKMARKED && !it.bookmark)) {
-                        return@filter false
+            val dbChapters = db.getChapters(manga).executeAsBlocking()
+            val list = readerChapterFilter
+                .filterChapter(dbChapters, manga, -1L, null)
+                .sortedBy {
+                    when (manga.sorting) {
+                        Manga.SORTING_NUMBER -> it.chapter_number
+                        else -> it.source_order.toFloat()
                     }
-                    true
-                } else {
-                    true
+                }.map {
+                    ReaderChapterItem(
+                        it, manga, it.id == getCurrentChapter()?.chapter?.id ?: chapterId
+                    )
                 }
-            }.sortedBy {
-                when (manga.sorting) {
-                    Manga.SORTING_NUMBER -> it.chapter_number
-                    else -> it.source_order.toFloat()
-                }
-            }.map {
-                ReaderChapterItem(
-                    it, manga, it.id == getCurrentChapter()?.chapter?.id ?: chapterId
-                )
-            }
-            if (!manga.sortDescending(preferences.chaptersDescAsDefault().getOrDefault()))
+            if (!manga.sortDescending(preferences.chaptersDescAsDefault().getOrDefault())) {
                 list.reversed()
-            else list
+            } else {
+                list
+            }
         }
+
         return chapterItems
     }