Rewrite IndexPresenter in flow

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/index/IndexPresenter.kt

@@ -14,23 +14,30 @@ import eu.kanade.tachiyomi.source.model.toSManga
 import eu.kanade.tachiyomi.ui.base.presenter.BasePresenter
 import eu.kanade.tachiyomi.ui.browse.source.browse.BrowseSourcePresenter.Companion.toItems
 import eu.kanade.tachiyomi.util.lang.awaitSingle
-import eu.kanade.tachiyomi.util.lang.runAsObservable
+import eu.kanade.tachiyomi.util.lang.launchIO
 import eu.kanade.tachiyomi.util.lang.withUIContext
 import eu.kanade.tachiyomi.util.system.logcat
 import exh.log.xLogE
 import exh.savedsearches.EXHSavedSearch
 import exh.savedsearches.JsonSavedSearch
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.channels.Channel
+import kotlinx.coroutines.flow.MutableSharedFlow
 import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.asFlow
+import kotlinx.coroutines.flow.buffer
+import kotlinx.coroutines.flow.catch
+import kotlinx.coroutines.flow.filter
+import kotlinx.coroutines.flow.flatMapConcat
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.serialization.decodeFromString
 import kotlinx.serialization.json.Json
 import logcat.LogPriority
-import rx.Observable
-import rx.Subscription
-import rx.android.schedulers.AndroidSchedulers
-import rx.schedulers.Schedulers
-import rx.subjects.PublishSubject
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get
 import xyz.nulldev.ts.api.http.serializer.FilterSerializer
@@ -50,15 +57,10 @@ open class IndexPresenter(
     val preferences: PreferencesHelper = Injekt.get()
 ) : BasePresenter<IndexController>() {
 
-    /**
-     * Fetches the different sources by user settings.
-     */
-    private var fetchSourcesSubscription: Subscription? = null
-
     /**
      * Subject which fetches image of given manga.
      */
-    private val fetchImageSubject = PublishSubject.create<List<Pair<Manga, Boolean>>>()
+    private val fetchImageFlow = MutableSharedFlow<Pair<List<Manga>, Boolean>>()
 
     /**
      * Modifiable list of filters.
@@ -74,7 +76,7 @@ open class IndexPresenter(
     /**
      * Subscription for fetching images of manga.
      */
-    private var fetchImageSubscription: Subscription? = null
+    private var fetchImageJob: Job? = null
 
     val latestItems = MutableStateFlow<List<IndexCardItem>?>(null)
 
@@ -84,12 +86,6 @@ open class IndexPresenter(
         query = ""
     }
 
-    override fun onDestroy() {
-        fetchSourcesSubscription?.unsubscribe()
-        fetchImageSubscription?.unsubscribe()
-        super.onDestroy()
-    }
-
     override fun onCreate(savedState: Bundle?) {
         super.onCreate(savedState)
 
@@ -150,30 +146,35 @@ open class IndexPresenter(
      * @param manga the list of manga to initialize.
      */
     private fun fetchImage(manga: List<Manga>, isLatest: Boolean) {
-        fetchImageSubject.onNext(manga.map { it to isLatest })
+        presenterScope.launchIO {
+            fetchImageFlow.emit(manga to isLatest)
+        }
     }
 
     /**
      * Subscribes to the initializer of manga details and updates the view if needed.
      */
     private fun initializeFetchImageSubscription() {
-        fetchImageSubscription?.unsubscribe()
-        fetchImageSubscription = fetchImageSubject.observeOn(Schedulers.io())
-            .flatMap { pair ->
-                Observable.from(pair).filter { it.first.thumbnail_url == null && !it.first.initialized }
-                    .concatMap { getMangaDetailsObservable(it.first, source, it.second) }
+        fetchImageJob?.cancel()
+        fetchImageFlow
+            .flatMapConcat { (manga, isLatest) ->
+                manga.asFlow()
+                    .filter { it.thumbnail_url == null && !it.initialized }
+                    .map {
+                        getMangaDetailsFlow(it, source, isLatest)
+                    }
             }
-            .onBackpressureBuffer()
-            .observeOn(AndroidSchedulers.mainThread())
-            .subscribe(
-                { pair ->
-                    @Suppress("DEPRECATION")
-                    view?.onMangaInitialized(pair.first, pair.second)
-                },
-                { error ->
-                    logcat(LogPriority.ERROR, error)
+            .buffer(Channel.RENDEZVOUS)
+            .flowOn(Dispatchers.IO)
+            .onEach { (manga, isLatest) ->
+                withUIContext {
+                    view?.onMangaInitialized(manga, isLatest)
                 }
-            )
+            }
+            .catch {
+                logcat(LogPriority.ERROR, it)
+            }
+            .launchIn(presenterScope)
     }
 
     /**
@@ -182,15 +183,12 @@ open class IndexPresenter(
      * @param manga the manga to initialize.
      * @return an observable of the manga to initialize
      */
-    private fun getMangaDetailsObservable(manga: Manga, source: Source, isLatest: Boolean): Observable<Pair<Manga, Boolean>> {
-        return runAsObservable {
-            val networkManga = source.getMangaDetails(manga.toMangaInfo())
-            manga.copyFrom(networkManga.toSManga())
-            manga.initialized = true
-            db.insertManga(manga).executeAsBlocking()
-            manga to isLatest
-        }
-            .onErrorResumeNext { Observable.just(manga to isLatest) }
+    private suspend fun getMangaDetailsFlow(manga: Manga, source: Source, isLatest: Boolean): Pair<Manga, Boolean> {
+        val networkManga = source.getMangaDetails(manga.toMangaInfo())
+        manga.copyFrom(networkManga.toSManga())
+        manga.initialized = true
+        db.insertManga(manga).executeAsBlocking()
+        return manga to isLatest
     }
 
     /**