Improve network state observer

app/src/main/java/org/koitharu/kotatsu/core/os/NetworkState.kt

@@ -0,0 +1,54 @@
+package org.koitharu.kotatsu.core.os
+
+import android.content.Context
+import android.net.ConnectivityManager.NetworkCallback
+import android.net.Network
+import android.net.NetworkRequest
+import dagger.hilt.android.qualifiers.ApplicationContext
+import kotlinx.coroutines.flow.first
+import org.koitharu.kotatsu.utils.MediatorStateFlow
+import org.koitharu.kotatsu.utils.ext.connectivityManager
+import org.koitharu.kotatsu.utils.ext.isNetworkAvailable
+import javax.inject.Inject
+import javax.inject.Singleton
+
+@Singleton
+class NetworkState @Inject constructor(
+	@ApplicationContext context: Context,
+) : MediatorStateFlow<Boolean>() {
+
+	private val connectivityManager = context.connectivityManager
+	private val callback = NetworkCallbackImpl()
+
+	override val initialValue: Boolean
+		get() = connectivityManager.isNetworkAvailable
+
+	override fun onActive() {
+		val request = NetworkRequest.Builder().build()
+		connectivityManager.registerNetworkCallback(request, callback)
+	}
+
+	override fun onInactive() {
+		connectivityManager.unregisterNetworkCallback(callback)
+	}
+
+	suspend fun awaitForConnection() {
+		if (value) {
+			return
+		}
+		first { it }
+	}
+
+	private inner class NetworkCallbackImpl : NetworkCallback() {
+
+		override fun onAvailable(network: Network) = update()
+
+		override fun onLost(network: Network) = update()
+
+		override fun onUnavailable() = update()
+
+		private fun update() {
+			publishValue(connectivityManager.isNetworkAvailable)
+		}
+	}
+}

app/src/main/java/org/koitharu/kotatsu/core/os/NetworkStateObserver.kt

@@ -1,78 +0,0 @@
-package org.koitharu.kotatsu.core.os
-
-import android.content.Context
-import android.net.ConnectivityManager.NetworkCallback
-import android.net.Network
-import android.net.NetworkRequest
-import dagger.hilt.android.qualifiers.ApplicationContext
-import kotlinx.coroutines.channels.ProducerScope
-import kotlinx.coroutines.channels.awaitClose
-import kotlinx.coroutines.channels.onSuccess
-import kotlinx.coroutines.channels.trySendBlocking
-import kotlinx.coroutines.flow.FlowCollector
-import kotlinx.coroutines.flow.StateFlow
-import kotlinx.coroutines.flow.callbackFlow
-import kotlinx.coroutines.flow.first
-import org.koitharu.kotatsu.utils.ext.connectivityManager
-import org.koitharu.kotatsu.utils.ext.isNetworkAvailable
-import javax.inject.Inject
-import javax.inject.Singleton
-
-@Singleton
-class NetworkStateObserver @Inject constructor(
-	@ApplicationContext context: Context,
-) : StateFlow<Boolean> {
-
-	private val connectivityManager = context.connectivityManager
-
-	override val replayCache: List<Boolean>
-		get() = listOf(value)
-
-	override val value: Boolean
-		get() = connectivityManager.isNetworkAvailable
-
-	override suspend fun collect(collector: FlowCollector<Boolean>): Nothing {
-		collector.emit(value)
-		while (true) {
-			observeImpl().collect(collector)
-		}
-	}
-
-	suspend fun awaitForConnection(): Unit {
-		if (value) {
-			return
-		}
-		first { it }
-	}
-
-	private fun observeImpl() = callbackFlow<Boolean> {
-		val request = NetworkRequest.Builder().build()
-		val callback = FlowNetworkCallback(this)
-		connectivityManager.registerNetworkCallback(request, callback)
-		awaitClose {
-			connectivityManager.unregisterNetworkCallback(callback)
-		}
-	}
-
-	private inner class FlowNetworkCallback(
-		private val producerScope: ProducerScope<Boolean>,
-	) : NetworkCallback() {
-
-		private var prevValue = value
-
-		override fun onAvailable(network: Network) = update()
-
-		override fun onLost(network: Network) = update()
-
-		override fun onUnavailable() = update()
-
-		private fun update() {
-			val newValue = connectivityManager.isNetworkAvailable
-			if (newValue != prevValue) {
-				producerScope.trySendBlocking(newValue).onSuccess {
-					prevValue = newValue
-				}
-			}
-		}
-	}
-}

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/BasePageHolder.kt

@@ -5,7 +5,7 @@ import androidx.annotation.CallSuper
 import androidx.recyclerview.widget.RecyclerView
 import androidx.viewbinding.ViewBinding
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.LayoutPageInfoBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -14,12 +14,12 @@ abstract class BasePageHolder<B : ViewBinding>(
 	protected val binding: B,
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkStateObserver: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : RecyclerView.ViewHolder(binding.root), PageHolderDelegate.Callback {
 
 	@Suppress("LeakingThis")
-	protected val delegate = PageHolderDelegate(loader, settings, this, networkStateObserver, exceptionResolver)
+	protected val delegate = PageHolderDelegate(loader, settings, this, networkState, exceptionResolver)
 	protected val bindingInfo = LayoutPageInfoBinding.bind(binding.root)
 
 	val context: Context

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/BaseReaderAdapter.kt

@@ -5,7 +5,7 @@ import androidx.recyclerview.widget.AsyncListDiffer
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.RecyclerView
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
 import org.koitharu.kotatsu.utils.ext.resetTransformations
@@ -16,7 +16,7 @@ import kotlin.coroutines.suspendCoroutine
 abstract class BaseReaderAdapter<H : BasePageHolder<*>>(
 	private val loader: PageLoader,
 	private val readerSettings: ReaderSettings,
-	private val networkState: NetworkStateObserver,
+	private val networkState: NetworkState,
 	private val exceptionResolver: ExceptionResolver,
 ) : RecyclerView.Adapter<H>() {
 
@@ -70,7 +70,7 @@ abstract class BaseReaderAdapter<H : BasePageHolder<*>>(
 		parent: ViewGroup,
 		loader: PageLoader,
 		settings: ReaderSettings,
-		networkState: NetworkStateObserver,
+		networkState: NetworkState,
 		exceptionResolver: ExceptionResolver,
 	): H
 

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/PageHolderDelegate.kt

@@ -17,7 +17,7 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.plus
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.parsers.model.MangaPage
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -28,7 +28,7 @@ class PageHolderDelegate(
 	private val loader: PageLoader,
 	private val readerSettings: ReaderSettings,
 	private val callback: Callback,
-	private val networkState: NetworkStateObserver,
+	private val networkState: NetworkState,
 	private val exceptionResolver: ExceptionResolver,
 ) : DefaultOnImageEventListener, Observer<ReaderSettings> {
 

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/reversed/ReversedPageHolder.kt

@@ -6,7 +6,7 @@ import android.widget.FrameLayout
 import com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
 import org.koitharu.kotatsu.core.model.ZoomMode
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.ItemPageBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -16,7 +16,7 @@ class ReversedPageHolder(
 	binding: ItemPageBinding,
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkState: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : PageHolder(binding, loader, settings, networkState, exceptionResolver) {
 

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/reversed/ReversedPagesAdapter.kt

@@ -3,7 +3,7 @@ package org.koitharu.kotatsu.reader.ui.pager.reversed
 import android.view.LayoutInflater
 import android.view.ViewGroup
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.ItemPageBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -12,7 +12,7 @@ import org.koitharu.kotatsu.reader.ui.pager.BaseReaderAdapter
 class ReversedPagesAdapter(
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkState: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : BaseReaderAdapter<ReversedPageHolder>(loader, settings, networkState, exceptionResolver) {
 
@@ -20,7 +20,7 @@ class ReversedPagesAdapter(
 		parent: ViewGroup,
 		loader: PageLoader,
 		settings: ReaderSettings,
-		networkState: NetworkStateObserver,
+		networkState: NetworkState,
 		exceptionResolver: ExceptionResolver,
 	) = ReversedPageHolder(
 		binding = ItemPageBinding.inflate(LayoutInflater.from(parent.context), parent, false),

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/reversed/ReversedReaderFragment.kt

@@ -8,7 +8,7 @@ import android.view.ViewGroup
 import androidx.core.view.children
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.async
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.FragmentReaderStandardBinding
 import org.koitharu.kotatsu.reader.ui.ReaderState
 import org.koitharu.kotatsu.reader.ui.pager.BaseReader
@@ -26,7 +26,7 @@ import kotlin.math.absoluteValue
 class ReversedReaderFragment : BaseReader<FragmentReaderStandardBinding>() {
 
 	@Inject
-	lateinit var networkStateObserver: NetworkStateObserver
+	lateinit var networkState: NetworkState
 
 	private var pagerAdapter: ReversedPagesAdapter? = null
 
@@ -41,7 +41,7 @@ class ReversedReaderFragment : BaseReader<FragmentReaderStandardBinding>() {
 		pagerAdapter = ReversedPagesAdapter(
 			viewModel.pageLoader,
 			viewModel.readerSettings,
-			networkStateObserver,
+			networkState,
 			exceptionResolver,
 		)
 		with(binding.pager) {

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/standard/PageHolder.kt

@@ -10,7 +10,7 @@ import com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
 import org.koitharu.kotatsu.core.model.ZoomMode
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.ItemPageBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -22,7 +22,7 @@ open class PageHolder(
 	binding: ItemPageBinding,
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkState: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : BasePageHolder<ItemPageBinding>(binding, loader, settings, networkState, exceptionResolver),
 	View.OnClickListener {

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/standard/PagerReaderFragment.kt

@@ -8,7 +8,7 @@ import android.view.ViewGroup
 import androidx.core.view.children
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.async
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.FragmentReaderStandardBinding
 import org.koitharu.kotatsu.reader.ui.ReaderState
 import org.koitharu.kotatsu.reader.ui.pager.BaseReader
@@ -25,7 +25,7 @@ import kotlin.math.absoluteValue
 class PagerReaderFragment : BaseReader<FragmentReaderStandardBinding>() {
 
 	@Inject
-	lateinit var networkStateObserver: NetworkStateObserver
+	lateinit var networkState: NetworkState
 
 	private var pagesAdapter: PagesAdapter? = null
 
@@ -40,7 +40,7 @@ class PagerReaderFragment : BaseReader<FragmentReaderStandardBinding>() {
 		pagesAdapter = PagesAdapter(
 			viewModel.pageLoader,
 			viewModel.readerSettings,
-			networkStateObserver,
+			networkState,
 			exceptionResolver,
 		)
 		with(binding.pager) {

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/standard/PagesAdapter.kt

@@ -3,7 +3,7 @@ package org.koitharu.kotatsu.reader.ui.pager.standard
 import android.view.LayoutInflater
 import android.view.ViewGroup
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.ItemPageBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -12,15 +12,15 @@ import org.koitharu.kotatsu.reader.ui.pager.BaseReaderAdapter
 class PagesAdapter(
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkStateObserver: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
-) : BaseReaderAdapter<PageHolder>(loader, settings, networkStateObserver, exceptionResolver) {
+) : BaseReaderAdapter<PageHolder>(loader, settings, networkState, exceptionResolver) {
 
 	override fun onCreateViewHolder(
 		parent: ViewGroup,
 		loader: PageLoader,
 		settings: ReaderSettings,
-		networkState: NetworkStateObserver,
+		networkState: NetworkState,
 		exceptionResolver: ExceptionResolver,
 	) = PageHolder(
 		binding = ItemPageBinding.inflate(LayoutInflater.from(parent.context), parent, false),

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/webtoon/WebtoonAdapter.kt

@@ -3,7 +3,7 @@ package org.koitharu.kotatsu.reader.ui.pager.webtoon
 import android.view.LayoutInflater
 import android.view.ViewGroup
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.ItemPageWebtoonBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -12,7 +12,7 @@ import org.koitharu.kotatsu.reader.ui.pager.BaseReaderAdapter
 class WebtoonAdapter(
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkState: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : BaseReaderAdapter<WebtoonHolder>(loader, settings, networkState, exceptionResolver) {
 
@@ -20,7 +20,7 @@ class WebtoonAdapter(
 		parent: ViewGroup,
 		loader: PageLoader,
 		settings: ReaderSettings,
-		networkState: NetworkStateObserver,
+		networkState: NetworkState,
 		exceptionResolver: ExceptionResolver,
 	) = WebtoonHolder(
 		binding = ItemPageWebtoonBinding.inflate(

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/webtoon/WebtoonHolder.kt

@@ -8,7 +8,7 @@ import com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
 import com.davemorrissey.labs.subscaleview.decoder.SkiaPooledImageRegionDecoder
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.ItemPageWebtoonBinding
 import org.koitharu.kotatsu.reader.domain.PageLoader
 import org.koitharu.kotatsu.reader.ui.config.ReaderSettings
@@ -25,7 +25,7 @@ class WebtoonHolder(
 	binding: ItemPageWebtoonBinding,
 	loader: PageLoader,
 	settings: ReaderSettings,
-	networkState: NetworkStateObserver,
+	networkState: NetworkState,
 	exceptionResolver: ExceptionResolver,
 ) : BasePageHolder<ItemPageWebtoonBinding>(binding, loader, settings, networkState, exceptionResolver),
 	View.OnClickListener {

app/src/main/java/org/koitharu/kotatsu/reader/ui/pager/webtoon/WebtoonReaderFragment.kt

@@ -7,7 +7,7 @@ import android.view.ViewGroup
 import android.view.animation.AccelerateDecelerateInterpolator
 import dagger.hilt.android.AndroidEntryPoint
 import kotlinx.coroutines.async
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.databinding.FragmentReaderWebtoonBinding
 import org.koitharu.kotatsu.reader.ui.ReaderState
 import org.koitharu.kotatsu.reader.ui.pager.BaseReader
@@ -22,7 +22,7 @@ import javax.inject.Inject
 class WebtoonReaderFragment : BaseReader<FragmentReaderWebtoonBinding>() {
 
 	@Inject
-	lateinit var networkStateObserver: NetworkStateObserver
+	lateinit var networkState: NetworkState
 
 	private val scrollInterpolator = AccelerateDecelerateInterpolator()
 	private var webtoonAdapter: WebtoonAdapter? = null
@@ -37,7 +37,7 @@ class WebtoonReaderFragment : BaseReader<FragmentReaderWebtoonBinding>() {
 		webtoonAdapter = WebtoonAdapter(
 			viewModel.pageLoader,
 			viewModel.readerSettings,
-			networkStateObserver,
+			networkState,
 			exceptionResolver,
 		)
 		with(binding.recyclerView) {

app/src/main/java/org/koitharu/kotatsu/shelf/ui/ShelfViewModel.kt

@@ -12,7 +12,7 @@ import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.base.ui.BaseViewModel
 import org.koitharu.kotatsu.base.ui.util.ReversibleAction
 import org.koitharu.kotatsu.core.model.FavouriteCategory
-import org.koitharu.kotatsu.core.os.NetworkStateObserver
+import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.core.prefs.ListMode
 import org.koitharu.kotatsu.core.prefs.observeAsFlow
@@ -46,14 +46,14 @@ class ShelfViewModel @Inject constructor(
 	private val favouritesRepository: FavouritesRepository,
 	private val trackingRepository: TrackingRepository,
 	private val settings: AppSettings,
-	networkStateObserver: NetworkStateObserver,
+	networkState: NetworkState,
 ) : BaseViewModel(), ListExtraProvider {
 
 	val onActionDone = SingleLiveEvent<ReversibleAction>()
 
 	val content: LiveData<List<ListModel>> = combine(
 		settings.observeAsFlow(AppSettings.KEY_SHELF_SECTIONS) { shelfSections },
-		networkStateObserver,
+		networkState,
 		repository.observeShelfContent(),
 	) { sections, isConnected, content ->
 		mapList(content, sections, isConnected)

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

@@ -0,0 +1,42 @@
+package org.koitharu.kotatsu.utils
+
+import kotlinx.coroutines.flow.FlowCollector
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import java.util.concurrent.atomic.AtomicInteger
+
+abstract class MediatorStateFlow<T> : StateFlow<T> {
+
+	@Suppress("LeakingThis")
+	private val delegate = MutableStateFlow(initialValue)
+	private val collectors = AtomicInteger(0)
+
+	protected abstract val initialValue: T
+
+	final override val replayCache: List<T>
+		get() = delegate.replayCache
+
+	final override val value: T
+		get() = delegate.value
+
+	final override suspend fun collect(collector: FlowCollector<T>): Nothing {
+		try {
+			if (collectors.getAndIncrement() == 0) {
+				onActive()
+			}
+			delegate.collect(collector)
+		} finally {
+			if (collectors.decrementAndGet() == 0) {
+				onInactive()
+			}
+		}
+	}
+
+	protected fun publishValue(v: T) {
+		delegate.value = v
+	}
+
+	abstract fun onActive()
+
+	abstract fun onInactive()
+}