Only launch FlashActivity if app is foreground

app/src/main/java/com/topjohnwu/magisk/model/download/NotificationService.kt

@@ -40,7 +40,7 @@ abstract class NotificationService : Service() {
         }
     }
 
-    protected fun finishWork(
+    protected fun finishNotify(
         id: Int,
         editBody: (NotificationCompat.Builder) -> NotificationCompat.Builder? = { null }
     ) : Int {

app/src/main/java/com/topjohnwu/magisk/model/download/RemoteFileService.kt

@@ -1,5 +1,6 @@
 package com.topjohnwu.magisk.model.download
 
+import android.app.Activity
 import android.content.Intent
 import androidx.core.app.NotificationCompat
 import com.skoumal.teanity.extensions.subscribeK
@@ -7,6 +8,7 @@ import com.topjohnwu.magisk.Config
 import com.topjohnwu.magisk.R
 import com.topjohnwu.magisk.data.network.GithubRawServices
 import com.topjohnwu.magisk.extensions.firstMap
+import com.topjohnwu.magisk.extensions.get
 import com.topjohnwu.magisk.extensions.writeTo
 import com.topjohnwu.magisk.model.entity.internal.DownloadSubject
 import com.topjohnwu.magisk.model.entity.internal.DownloadSubject.Magisk
@@ -15,7 +17,6 @@ import com.topjohnwu.magisk.utils.ProgInputStream
 import com.topjohnwu.magisk.view.Notifications
 import com.topjohnwu.superuser.ShellUtils
 import io.reactivex.Single
-import io.reactivex.android.schedulers.AndroidSchedulers
 import okhttp3.ResponseBody
 import org.koin.android.ext.android.inject
 import timber.log.Timber
@@ -47,12 +48,15 @@ abstract class RemoteFileService : NotificationService() {
     private fun start(subject: DownloadSubject) = search(subject)
         .onErrorResumeNext(download(subject))
         .doOnSubscribe { update(subject.hashCode()) { it.setContentTitle(subject.title) } }
-        .observeOn(AndroidSchedulers.mainThread())
-        .doOnError { remove(subject.hashCode()) }
-        .doOnSuccess {
-            val id = finish(it, subject)
-            runCatching { onFinished(it, subject, id) }.onFailure { Timber.e(it) }
-        }.subscribeK()
+        .subscribeK(onError = {
+            Timber.e(it)
+            remove(subject.hashCode())
+        }) {
+            val newId = finishNotify(it, subject)
+            get<Activity?>()?.run {
+                onFinished(it, subject, newId)
+            }
+        }
 
     private fun search(subject: DownloadSubject) = Single.fromCallable {
         if (!Config.isDownloadCacheEnabled) {
@@ -98,7 +102,7 @@ abstract class RemoteFileService : NotificationService() {
         }
     }
 
-    private fun finish(file: File, subject: DownloadSubject) = finishWork(subject.hashCode()) {
+    private fun finishNotify(file: File, subject: DownloadSubject) = finishNotify(subject.hashCode()) {
         it.addActions(file, subject)
             .setContentText(getString(R.string.download_complete))
             .setSmallIcon(android.R.drawable.stat_sys_download_done)