Estimate remeaning download time

.gitignore

@@ -9,6 +9,7 @@
 /.idea/workspace.xml
 /.idea/navEditor.xml
 /.idea/assetWizardSettings.xml
+/.idea/kotlinScripting.xml
 .DS_Store
 /build
 /captures

app/src/main/java/org/koitharu/kotatsu/download/ui/service/DownloadNotification.kt

@@ -6,6 +6,7 @@ import android.app.NotificationManager
 import android.app.PendingIntent
 import android.content.Context
 import android.os.Build
+import android.text.format.DateUtils
 import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationManagerCompat
 import androidx.core.content.ContextCompat
@@ -49,7 +50,7 @@ class DownloadNotification(private val context: Context, startId: Int) {
 		builder.setSilent(true)
 	}
 
-	fun create(state: DownloadState): Notification {
+	fun create(state: DownloadState, timeLeft: Long): Notification {
 		builder.setContentTitle(state.manga.title)
 		builder.setContentText(context.getString(R.string.manga_downloading_))
 		builder.setProgress(1, 0, true)
@@ -117,7 +118,13 @@ class DownloadNotification(private val context: Context, startId: Int) {
 			}
 			is DownloadState.Progress -> {
 				builder.setProgress(state.max, state.progress, false)
-				builder.setContentText((state.percent * 100).format() + "%")
+				if (timeLeft > 0L) {
+					val eta = DateUtils.getRelativeTimeSpanString(timeLeft, 0L, DateUtils.SECOND_IN_MILLIS)
+					builder.setContentText(eta)
+				} else {
+					val percent = (state.percent * 100).format()
+					builder.setContentText(context.getString(R.string.percent_string_pattern, percent))
+				}
 				builder.setCategory(NotificationCompat.CATEGORY_PROGRESS)
 				builder.setStyle(null)
 				builder.setOngoing(true)

app/src/main/java/org/koitharu/kotatsu/download/ui/service/DownloadService.kt

@@ -11,10 +11,7 @@ import android.widget.Toast
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.lifecycleScope
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
-import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.*
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.mapLatest
-import kotlinx.coroutines.flow.transformWhile
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.plus
 import org.koin.android.ext.android.get
@@ -32,6 +29,7 @@ import org.koitharu.kotatsu.parsers.model.Manga
 import org.koitharu.kotatsu.utils.ext.connectivityManager
 import org.koitharu.kotatsu.utils.ext.throttle
 import org.koitharu.kotatsu.utils.progress.ProgressJob
+import org.koitharu.kotatsu.utils.progress.TimeLeftEstimator
 import java.util.concurrent.TimeUnit
 
 class DownloadService : BaseService() {
@@ -99,13 +97,22 @@ class DownloadService : BaseService() {
 	private fun listenJob(job: ProgressJob<DownloadState>) {
 		lifecycleScope.launch {
 			val startId = job.progressValue.startId
+			val timeLeftEstimator = TimeLeftEstimator()
 			val notification = DownloadNotification(this@DownloadService, startId)
-			notificationSwitcher.notify(startId, notification.create(job.progressValue))
+			notificationSwitcher.notify(startId, notification.create(job.progressValue, -1L))
 			job.progressAsFlow()
+				.onEach { state ->
+					if (state is DownloadState.Progress) {
+						timeLeftEstimator.tick(value = state.progress, total = state.max)
+					} else {
+						timeLeftEstimator.emptyTick()
+					}
+				}
 				.throttle { state -> if (state is DownloadState.Progress) 400L else 0L }
 				.whileActive()
 				.collect { state ->
-					notificationSwitcher.notify(startId, notification.create(state))
+					val timeLeft = timeLeftEstimator.getEstimatedTimeLeft()
+					notificationSwitcher.notify(startId, notification.create(state, timeLeft))
 				}
 			job.join()
 			(job.progressValue as? DownloadState.Done)?.let {
@@ -119,7 +126,7 @@ class DownloadService : BaseService() {
 				if (job.isCancelled) {
 					null
 				} else {
-					notification.create(job.progressValue)
+					notification.create(job.progressValue, -1L)
 				}
 			)
 			stopSelf(startId)

app/src/main/java/org/koitharu/kotatsu/utils/progress/Progress.kt

@@ -6,7 +6,7 @@ import kotlinx.parcelize.Parcelize
 @Parcelize
 data class Progress(
 	val value: Int,
-	val total: Int
+	val total: Int,
 ) : Parcelable, Comparable<Progress> {
 
 	override fun compareTo(other: Progress): Int {

app/src/main/java/org/koitharu/kotatsu/utils/progress/TimeLeftEstimator.kt

@@ -0,0 +1,47 @@
+package org.koitharu.kotatsu.utils.progress
+
+import android.os.SystemClock
+import kotlin.math.roundToInt
+import kotlin.math.roundToLong
+
+private const val MIN_ESTIMATE_TICKS = 4
+private const val NO_TIME = -1L
+
+class TimeLeftEstimator {
+
+	private var times = ArrayList<Int>()
+	private var lastTick: Tick? = null
+
+	fun tick(value: Int, total: Int) {
+		if (total < 0) {
+			emptyTick()
+			return
+		}
+		val tick = Tick(value, total, SystemClock.elapsedRealtime())
+		lastTick?.let {
+			val ticksCount = value - it.value
+			times.add(((tick.time - it.time) / ticksCount.toDouble()).roundToInt())
+		}
+		lastTick = tick
+	}
+
+	fun emptyTick() {
+		lastTick = null
+	}
+
+	fun getEstimatedTimeLeft(): Long {
+		val progress = lastTick ?: return NO_TIME
+		if (times.size < MIN_ESTIMATE_TICKS) {
+			return NO_TIME
+		}
+		val timePerTick = times.average()
+		val ticksLeft = progress.total - progress.value
+		return (ticksLeft * timePerTick).roundToLong()
+	}
+
+	private class Tick(
+		val value: Int,
+		val total: Int,
+		val time: Long,
+	)
+}