feat: sync collection in the background

aimed only to be used with autosync, so the user can leave the app without having to wait the synchronization to be complete.

I combined the SyncMediaWorker into it to use the same notification and reduce noise

AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt

@@ -116,7 +116,7 @@ import com.ichi2.anki.snackbar.showSnackbar
 import com.ichi2.anki.ui.dialogs.storageMigrationFailedDialogIsShownOrPending
 import com.ichi2.anki.utils.SECONDS_PER_DAY
 import com.ichi2.anki.widgets.DeckAdapter
-import com.ichi2.anki.worker.SyncMediaWorker
+import com.ichi2.anki.worker.SyncWorker
 import com.ichi2.annotations.NeedsTest
 import com.ichi2.async.*
 import com.ichi2.compat.CompatHelper.Companion.getSerializableCompat
@@ -1202,7 +1202,7 @@ open class DeckPicker :
         }
     }
 
-    private suspend fun automaticSync() {
+    private suspend fun automaticSync(runInBackground: Boolean = false) {
         Timber.v("automaticSync()")
 
         /**
@@ -1247,12 +1247,18 @@ open class DeckPicker :
                 Timber.d("autoSync: no collection changes to sync. Syncing media if set")
                 if (shouldFetchMedia(sharedPrefs())) {
                     val auth = syncAuth() ?: return
-                    SyncMediaWorker.start(this, auth)
+                    SyncWorker.startMediaSync(this, auth)
                 }
             }
             else -> {
-                Timber.i("Triggering Automatic Sync")
-                sync()
+                if (runInBackground) {
+                    Timber.i("Triggering background automatic sync")
+                    val auth = syncAuth() ?: return
+                    SyncWorker.startCollectionSync(this, auth, shouldFetchMedia(sharedPrefs()))
+                } else {
+                    Timber.i("Triggering foreground automatic sync")
+                    sync()
+                }
             }
         }
     }
@@ -1272,8 +1278,10 @@ open class DeckPicker :
                         false
                     ) || backButtonPressedToExit
                 ) {
+                    // can't use launchCatchingTask because any errors
+                    // would need to be shown in the UI
                     lifecycleScope.launch {
-                        automaticSync()
+                        automaticSync(runInBackground = true)
                     }.invokeOnCompletion {
                         finish()
                     }

AnkiDroid/src/main/java/com/ichi2/anki/Sync.kt

@@ -32,7 +32,7 @@ import com.ichi2.anki.dialogs.SyncErrorDialog
 import com.ichi2.anki.preferences.sharedPrefs
 import com.ichi2.anki.servicelayer.ScopedStorageService
 import com.ichi2.anki.snackbar.showSnackbar
-import com.ichi2.anki.worker.SyncMediaWorker
+import com.ichi2.anki.worker.SyncWorker
 import com.ichi2.async.AsyncOperation
 import com.ichi2.libanki.createBackup
 import com.ichi2.libanki.fullUploadOrDownload
@@ -208,7 +208,7 @@ private suspend fun handleNormalSync(
         manualCancelButton = R.string.dialog_cancel
     ) {
         withCol {
-            syncCollection(auth2, media = false) // media is synced by SyncMediaWorker
+            syncCollection(auth2, media = false) // media is synced in the background by SyncWorker
         }
     }
 
@@ -228,7 +228,7 @@ private suspend fun handleNormalSync(
             deckPicker.showSyncLogMessage(R.string.sync_database_acknowledge, output.serverMessage)
             deckPicker.refreshState()
             if (syncMedia) {
-                SyncMediaWorker.start(deckPicker, auth2)
+                SyncWorker.startMediaSync(deckPicker, auth2)
             }
         }
 
@@ -286,7 +286,7 @@ private suspend fun handleDownload(
         }
         deckPicker.refreshState()
         if (mediaUsn != null) {
-            SyncMediaWorker.start(deckPicker, auth)
+            SyncWorker.startMediaSync(deckPicker, auth)
         }
     }
 
@@ -313,7 +313,7 @@ private suspend fun handleUpload(
         }
         deckPicker.refreshState()
         if (mediaUsn != null) {
-            SyncMediaWorker.start(deckPicker, auth)
+            SyncWorker.startMediaSync(deckPicker, auth)
         }
     }
     Timber.i("Full Upload Completed")

AnkiDroid/src/main/java/com/ichi2/anki/notifications/NotificationId.kt

@@ -16,5 +16,5 @@
 package com.ichi2.anki.notifications
 
 object NotificationId {
-    const val SYNC_MEDIA = 123
+    const val SYNC = 123
 }

AnkiDroid/src/main/java/com/ichi2/anki/ui/dialogs/ActivityAgnosticDialogs.kt

@@ -27,13 +27,28 @@ import androidx.core.os.bundleOf
 import androidx.core.text.parseAsHtml
 import androidx.fragment.app.DialogFragment
 import androidx.fragment.app.FragmentActivity
+import androidx.lifecycle.flowWithLifecycle
+import androidx.lifecycle.lifecycleScope
 import androidx.preference.PreferenceManager.getDefaultSharedPreferences
+import androidx.work.WorkInfo
+import androidx.work.WorkManager
+import com.google.android.material.snackbar.Snackbar
+import com.ichi2.anki.CollectionManager
 import com.ichi2.anki.R
 import com.ichi2.anki.preferences.sharedPrefs
+import com.ichi2.anki.snackbar.showSnackbar
 import com.ichi2.anki.ui.dialogs.ActivityAgnosticDialogs.Companion.MIGRATION_FAILED_DIALOG_ERROR_TEXT_KEY
 import com.ichi2.anki.utils.getUserFriendlyErrorText
+import com.ichi2.anki.withProgress
+import com.ichi2.anki.worker.UniqueWorkNames
 import com.ichi2.utils.copyToClipboard
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.withContext
 import makeLinksClickable
+import timber.log.Timber
 
 // TODO BEFORE-RELEASE Dismiss the related notification, if any, when the dialog is dismissed.
 //   Currently we are leaving the notification dangling after the migration has completed.
@@ -183,6 +198,50 @@ class ActivityAgnosticDialogs private constructor(private val application: Appli
                 }
             }
         })
+
+        // Shows a progress dialog if the user tries to open the app
+        // while the collection is being synced in the background
+        // COULD_BE_BETTER: get the progress directly from the Worker instead of
+        //  retrieving it again from the backend
+        application.registerActivityLifecycleCallbacks(object : DefaultActivityLifecycleCallbacks {
+            override fun onActivityStarted(activity: Activity) {
+                if (activity !is FragmentActivity) return
+
+                val workManager = WorkManager.getInstance(activity)
+                val workInfoFlow = workManager.getWorkInfosForUniqueWorkFlow(UniqueWorkNames.SYNC)
+                val backend = CollectionManager.getBackend() // just for checking progress
+
+                workInfoFlow.flowWithLifecycle(activity.lifecycle).onEach { workInfoList ->
+                    val workInfo = workInfoList.firstOrNull()
+                    Timber.v("Sync last work: $workInfo")
+
+                    if (workInfo?.state == WorkInfo.State.RUNNING) {
+                        val progress = withContext(Dispatchers.IO) {
+                            backend.latestProgress()
+                        }
+                        if (!progress.hasNormalSync() || progress.hasMediaSync()) {
+                            return@onEach
+                        }
+
+                        Timber.d("Showing background sync dialog")
+                        activity.withProgress(extractProgress = {
+                            if (progress.hasNormalSync()) {
+                                text = progress.normalSync.run { "$added\n$removed" }
+                            }
+                        }, onCancel = {
+                                workManager.cancelWorkById(workInfo.id)
+                                activity.showSnackbar(R.string.sync_cancelled, Snackbar.LENGTH_SHORT)
+                            }, manualCancelButton = R.string.dialog_cancel) {
+                            withContext(Dispatchers.IO) {
+                                while (backend.latestProgress().hasNormalSync()) {
+                                    delay(100)
+                                }
+                            }
+                        }
+                    }
+                }.launchIn(activity.lifecycleScope)
+            }
+        })
     }
 
     companion object {