Refactor reading time estimator

app/src/main/kotlin/org/koitharu/kotatsu/details/data/ReadingTime.kt

@@ -0,0 +1,21 @@
+package org.koitharu.kotatsu.details.data
+
+import android.content.res.Resources
+import org.koitharu.kotatsu.R
+
+data class ReadingTime(
+	val minutes: Int,
+	val hours: Int,
+	val isContinue: Boolean,
+) {
+
+	fun format(resources: Resources): String = when {
+		hours == 0 -> resources.getQuantityString(R.plurals.minutes, minutes, minutes)
+		minutes == 0 -> resources.getQuantityString(R.plurals.hours, hours, hours)
+		else -> resources.getString(
+			R.string.remaining_time_pattern,
+			resources.getQuantityString(R.plurals.hours, hours, hours),
+			resources.getQuantityString(R.plurals.minutes, minutes, minutes),
+		)
+	}
+}

app/src/main/kotlin/org/koitharu/kotatsu/details/domain/ReadingTimeUseCase.kt

@@ -0,0 +1,33 @@
+package org.koitharu.kotatsu.details.domain
+
+import org.koitharu.kotatsu.core.model.MangaHistory
+import org.koitharu.kotatsu.core.model.findById
+import org.koitharu.kotatsu.details.data.MangaDetails
+import org.koitharu.kotatsu.details.data.ReadingTime
+import javax.inject.Inject
+import kotlin.math.roundToInt
+
+class ReadingTimeUseCase @Inject constructor() {
+
+	fun invoke(manga: MangaDetails?, branch: String?, history: MangaHistory?): ReadingTime? {
+		// FIXME MAXIMUM HARDCODE!!! To do calculation with user's page read speed and his favourites/history mangas average pages in chapter
+		val chapters = manga?.chapters?.get(branch)
+		if (chapters.isNullOrEmpty()) {
+			return null
+		}
+		val isOnHistoryBranch = history != null && chapters.findById(history.chapterId) != null
+		// Impossible task, I guess. Good luck on this.
+		var averageTimeSec: Int = 20 * 10 * chapters.size // 20 pages, 10 seconds per page
+		if (isOnHistoryBranch) {
+			averageTimeSec = (averageTimeSec * (1f - checkNotNull(history).percent)).roundToInt()
+		}
+		if (averageTimeSec < 60) {
+			return null
+		}
+		return ReadingTime(
+			minutes = averageTimeSec / 60,
+			hours = averageTimeSec / 3600,
+			isContinue = isOnHistoryBranch,
+		)
+	}
+}

app/src/main/kotlin/org/koitharu/kotatsu/details/ui/DetailsFragment.kt

@@ -48,6 +48,7 @@ import org.koitharu.kotatsu.core.util.ext.scaleUpActivityOptionsOf
 import org.koitharu.kotatsu.core.util.ext.showOrHide
 import org.koitharu.kotatsu.core.util.ext.textAndVisible
 import org.koitharu.kotatsu.databinding.FragmentDetailsBinding
+import org.koitharu.kotatsu.details.data.ReadingTime
 import org.koitharu.kotatsu.details.ui.model.ChapterListItem
 import org.koitharu.kotatsu.details.ui.model.HistoryInfo
 import org.koitharu.kotatsu.details.ui.related.RelatedMangaActivity
@@ -70,6 +71,8 @@ import org.koitharu.kotatsu.scrobbling.common.domain.model.ScrobblingInfo
 import org.koitharu.kotatsu.scrobbling.common.ui.selector.ScrobblingSelectorSheet
 import org.koitharu.kotatsu.search.ui.MangaListActivity
 import org.koitharu.kotatsu.search.ui.SearchActivity
+import java.text.SimpleDateFormat
+import java.util.Date
 import javax.inject.Inject
 
 @AndroidEntryPoint
@@ -118,6 +121,7 @@ class DetailsFragment :
 		viewModel.localSize.observe(viewLifecycleOwner, ::onLocalSizeChanged)
 		viewModel.relatedManga.observe(viewLifecycleOwner, ::onRelatedMangaChanged)
 		viewModel.chapters.observe(viewLifecycleOwner, ::onChaptersChanged)
+		viewModel.readingTime.observe(viewLifecycleOwner, ::onReadingTimeChanged)
 	}
 
 	override fun onItemClick(item: Bookmark, view: View) {
@@ -201,32 +205,29 @@ class DetailsFragment :
 
 	private fun onChaptersChanged(chapters: List<ChapterListItem>?) {
 		val infoLayout = requireViewBinding().infoLayout
-		val tv = requireViewBinding().approximateReadTime
 		if (chapters.isNullOrEmpty()) {
 			infoLayout.textViewChapters.isVisible = false
-			tv.text = "..."
 		} else {
 			val count = chapters.countChaptersByBranch()
-
-			// FIXME MAXIMUM HARDCODE!!! To do calculation with user's page read speed and his favourites/history mangas average pages in chapter
-			// Impossible task, I guess. Good luck on this.
-			val averageTime: Int = 20 * 10 * (count) // 20 pages, 10 seconds per page
-			val hours = averageTime / 3600
-			val minutes = averageTime % 3600 / 60
-
-			tv.text = buildString {
-				append(resources.getQuantityString(R.plurals.hour, hours, hours))
-				append(" ")
-				append(resources.getQuantityString(R.plurals.minute, minutes, minutes))
-			}
-
-			// Info
 			infoLayout.textViewChapters.isVisible = true
 			val chaptersText = resources.getQuantityString(R.plurals.chapters, count, count)
 			infoLayout.textViewChapters.text = chaptersText
 		}
 	}
 
+	private fun onReadingTimeChanged(time: ReadingTime?) {
+		val binding = viewBinding ?: return
+		if (time == null) {
+			binding.approximateReadTimeLayout.isVisible = false
+			return
+		}
+		binding.approximateReadTime.text = time.format(resources)
+		binding.approximateReadTimeTitle.setText(
+			if (time.isContinue) R.string.approximate_remaining_time else R.string.approximate_reading_time
+		)
+		binding.approximateReadTimeLayout.isVisible = true
+	}
+
 	private fun onDescriptionChanged(description: CharSequence?) {
 		val tv = requireViewBinding().textViewDescription
 		if (description.isNullOrBlank()) {

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

@@ -42,6 +42,7 @@ import org.koitharu.kotatsu.details.domain.BranchComparator
 import org.koitharu.kotatsu.details.domain.DetailsInteractor
 import org.koitharu.kotatsu.details.domain.DetailsLoadUseCase
 import org.koitharu.kotatsu.details.domain.ProgressUpdateUseCase
+import org.koitharu.kotatsu.details.domain.ReadingTimeUseCase
 import org.koitharu.kotatsu.details.domain.RelatedMangaUseCase
 import org.koitharu.kotatsu.details.ui.model.ChapterListItem
 import org.koitharu.kotatsu.details.ui.model.HistoryInfo
@@ -76,6 +77,7 @@ class DetailsViewModel @Inject constructor(
 	private val extraProvider: ListExtraProvider,
 	private val detailsLoadUseCase: DetailsLoadUseCase,
 	private val progressUpdateUseCase: ProgressUpdateUseCase,
+	private val readingTimeUseCase: ReadingTimeUseCase,
 ) : BaseViewModel() {
 
 	private val intent = MangaIntent(savedStateHandle)
@@ -200,6 +202,14 @@ class DetailsViewModel @Inject constructor(
 		(if (reversed) list.asReversed() else list).filterSearch(query)
 	}.stateIn(viewModelScope, SharingStarted.Eagerly, emptyList())
 
+	val readingTime = combine(
+		details,
+		selectedBranch,
+		history,
+	) { m, b, h ->
+		readingTimeUseCase.invoke(m, b, h)
+	}.stateIn(viewModelScope, SharingStarted.Lazily, null)
+
 	val selectedBranchValue: String?
 		get() = selectedBranch.value
 

app/src/main/res/layout/fragment_details.xml

@@ -147,9 +147,11 @@
 			android:gravity="center_vertical"
 			android:orientation="horizontal"
 			android:paddingHorizontal="16dp"
+			android:visibility="gone"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@id/chips_tags">
+			app:layout_constraintTop_toBottomOf="@id/chips_tags"
+			tools:visibility="visible">
 
 			<ImageView
 				android:layout_width="wrap_content"
@@ -164,12 +166,13 @@
 				android:orientation="vertical">
 
 				<TextView
+					android:id="@+id/approximate_read_time_title"
 					android:layout_width="match_parent"
 					android:layout_height="wrap_content"
 					android:ellipsize="end"
-					android:maxLines="1"
 					android:paddingVertical="2dp"
-					android:text="@string/approximate_reading_time"
+					android:singleLine="true"
+					tools:text="@string/approximate_reading_time"
 					android:textAppearance="?attr/textAppearanceBodyLarge" />
 
 				<TextView
@@ -177,6 +180,7 @@
 					android:layout_width="match_parent"
 					android:layout_height="wrap_content"
 					android:paddingVertical="2dp"
+					android:singleLine="true"
 					android:textAppearance="?attr/textAppearanceBodySmall"
 					tools:text="12 minutes" />
 

app/src/main/res/values/plurals.xml

@@ -28,11 +28,11 @@
 		<item quantity="one">%1$d month ago</item>
 		<item quantity="other">%1$d months ago</item>
 	</plurals>
-	<plurals name="hour">
+	<plurals name="hours">
 		<item quantity="one">%1$d hour</item>
 		<item quantity="other">%1$d hours</item>
 	</plurals>
-	<plurals name="minute">
+	<plurals name="minutes">
 		<item quantity="one">%1$d minute</item>
 		<item quantity="other">%1$d minutes</item>
 	</plurals>

app/src/main/res/values/strings.xml

@@ -560,4 +560,6 @@
     <string name="mark_as_completed_prompt">Mark selected manga as completely read?\n\nWarning: current reading progress will be lost.</string>
 	<string name="category_hidden_done">This category was hidden from the main screen and is accessible through Menu → Manage categories</string>
 	<string name="approximate_reading_time">Approximate reading time</string>
+	<string name="approximate_remaining_time">Approximate remaining time</string>
+	<string name="remaining_time_pattern">%1$s %2$s</string>
 </resources>