Fix empty chapters label

app/src/main/java/org/koitharu/kotatsu/details/ui/ChaptersFragment.kt

@@ -9,7 +9,6 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.view.ActionMode
 import androidx.appcompat.widget.SearchView
 import androidx.core.graphics.Insets
-import androidx.core.view.isGone
 import androidx.core.view.isVisible
 import androidx.core.view.updatePadding
 import org.koin.androidx.viewmodel.ext.android.sharedViewModel
@@ -67,8 +66,8 @@ class ChaptersFragment :
 		viewModel.isChaptersReversed.observe(viewLifecycleOwner) {
 			activity?.invalidateOptionsMenu()
 		}
-		viewModel.hasChapters.observe(viewLifecycleOwner) {
-			binding.textViewHolder.isGone = it
+		viewModel.isChaptersEmpty.observe(viewLifecycleOwner) {
+			binding.textViewHolder.isVisible = it
 			activity?.invalidateOptionsMenu()
 		}
 	}
@@ -94,7 +93,7 @@ class ChaptersFragment :
 	override fun onPrepareOptionsMenu(menu: Menu) {
 		super.onPrepareOptionsMenu(menu)
 		menu.findItem(R.id.action_reversed).isChecked = viewModel.isChaptersReversed.value == true
-		menu.findItem(R.id.action_search).isVisible = viewModel.hasChapters.value == true
+		menu.findItem(R.id.action_search).isVisible = viewModel.isChaptersEmpty.value == false
 	}
 
 	override fun onOptionsItemSelected(item: MenuItem) = when (item.itemId) {

app/src/main/java/org/koitharu/kotatsu/details/ui/DetailsViewModel.kt

@@ -4,7 +4,6 @@ import androidx.core.os.LocaleListCompat
 import androidx.lifecycle.asFlow
 import androidx.lifecycle.asLiveData
 import androidx.lifecycle.viewModelScope
-import java.io.IOException
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.flow.*
@@ -29,7 +28,9 @@ import org.koitharu.kotatsu.parsers.util.mapToSet
 import org.koitharu.kotatsu.parsers.util.toTitleCase
 import org.koitharu.kotatsu.tracker.domain.TrackingRepository
 import org.koitharu.kotatsu.utils.SingleLiveEvent
+import org.koitharu.kotatsu.utils.ext.asLiveDataDistinct
 import org.koitharu.kotatsu.utils.ext.iterator
+import java.io.IOException
 
 class DetailsViewModel(
 	private val intent: MangaIntent,
@@ -89,18 +90,18 @@ class DetailsViewModel(
 
 	val branches = mangaData.map {
 		it?.chapters?.mapToSet { x -> x.branch }?.sortedBy { x -> x }.orEmpty()
-	}.asLiveData(viewModelScope.coroutineContext + Dispatchers.Default)
+	}.asLiveDataDistinct(viewModelScope.coroutineContext + Dispatchers.Default)
 
 	val selectedBranchIndex = combine(
 		branches.asFlow(),
 		selectedBranch
 	) { branches, selected ->
 		branches.indexOf(selected)
-	}.asLiveData(viewModelScope.coroutineContext + Dispatchers.Default)
+	}.asLiveDataDistinct(viewModelScope.coroutineContext + Dispatchers.Default)
 
-	val hasChapters = mangaData.map {
-		!(it?.chapters.isNullOrEmpty())
-	}.asLiveData(viewModelScope.coroutineContext + Dispatchers.Default)
+	val isChaptersEmpty = mangaData.mapNotNull { m ->
+		m?.run { chapters.isNullOrEmpty() }
+	}.asLiveDataDistinct(viewModelScope.coroutineContext + Dispatchers.Default, false)
 
 	val chapters = combine(
 		combine(

app/src/main/java/org/koitharu/kotatsu/utils/PausingDispatcher.kt

@@ -0,0 +1,50 @@
+package org.koitharu.kotatsu.utils
+
+import androidx.annotation.MainThread
+import java.util.concurrent.ConcurrentLinkedQueue
+import kotlin.coroutines.CoroutineContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Runnable
+
+class PausingDispatcher(
+	private val dispatcher: CoroutineDispatcher,
+) : CoroutineDispatcher() {
+
+	@Volatile
+	private var isPaused = false
+	private val queue = ConcurrentLinkedQueue<Task>()
+
+	override fun isDispatchNeeded(context: CoroutineContext): Boolean {
+		return isPaused || super.isDispatchNeeded(context)
+	}
+
+	override fun dispatch(context: CoroutineContext, block: Runnable) {
+		if (isPaused) {
+			queue.add(Task(context, block))
+		} else {
+			dispatcher.dispatch(context, block)
+		}
+	}
+
+	@MainThread
+	fun pause() {
+		isPaused = true
+	}
+
+	@MainThread
+	fun resume() {
+		if (!isPaused) {
+			return
+		}
+		isPaused = false
+		while (true) {
+			val task = queue.poll() ?: break
+			dispatcher.dispatch(task.context, task.block)
+		}
+	}
+
+	private class Task(
+		val context: CoroutineContext,
+		val block: Runnable,
+	)
+}

app/src/main/res/drawable/ic_pause.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="24dp"
+	android:height="24dp"
+	android:tint="?colorControlNormal"
+	android:viewportWidth="24"
+	android:viewportHeight="24">
+	<path
+		android:fillColor="#000"
+		android:pathData="M14,19H18V5H14M6,19H10V5H6V19Z" />
+</vector>

app/src/main/res/drawable/ic_resume.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="24dp"
+	android:height="24dp"
+	android:tint="?colorControlNormal"
+	android:viewportWidth="24"
+	android:viewportHeight="24">
+	<path
+		android:fillColor="#000"
+		android:pathData="M8,5.14V19.14L19,12.14L8,5.14Z" />
+</vector>

app/src/main/res/menu/opt_downloads.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto">
+
+	<item
+		android:icon="@drawable/ic_pause"
+		android:id="@+id/action_pause"
+		android:title="Pause"
+		app:showAsAction="ifRoom|withText" />
+
+	<item
+		android:icon="@drawable/ic_resume"
+		android:id="@+id/action_resume"
+		android:title="Resume"
+		app:showAsAction="ifRoom|withText" />
+
+</menu>