Improve android AutoBackup support

app/src/main/java/org/koitharu/kotatsu/core/db/DatabaseModule.kt

@@ -1,28 +1,9 @@
 package org.koitharu.kotatsu.core.db
 
-import androidx.room.Room
 import org.koin.android.ext.koin.androidContext
 import org.koin.dsl.module
-import org.koitharu.kotatsu.core.db.migrations.*
 
 val databaseModule
 	get() = module {
-		single {
-			Room.databaseBuilder(
-				androidContext(),
-				MangaDatabase::class.java,
-				"kotatsu-db"
-			).addMigrations(
-				Migration1To2(),
-				Migration2To3(),
-				Migration3To4(),
-				Migration4To5(),
-				Migration5To6(),
-				Migration6To7(),
-				Migration7To8(),
-				Migration8To9(),
-			).addCallback(
-				DatabasePrePopulateCallback(androidContext().resources)
-			).build()
-		}
+		single { MangaDatabase.create(androidContext()) }
 	}

app/src/main/java/org/koitharu/kotatsu/core/db/MangaDatabase.kt

@@ -1,9 +1,12 @@
 package org.koitharu.kotatsu.core.db
 
+import android.content.Context
 import androidx.room.Database
+import androidx.room.Room
 import androidx.room.RoomDatabase
 import org.koitharu.kotatsu.core.db.dao.*
 import org.koitharu.kotatsu.core.db.entity.*
+import org.koitharu.kotatsu.core.db.migrations.*
 import org.koitharu.kotatsu.favourites.data.FavouriteCategoriesDao
 import org.koitharu.kotatsu.favourites.data.FavouriteCategoryEntity
 import org.koitharu.kotatsu.favourites.data.FavouriteEntity
@@ -40,4 +43,24 @@ abstract class MangaDatabase : RoomDatabase() {
 	abstract val trackLogsDao: TrackLogsDao
 
 	abstract val suggestionDao: SuggestionDao
+
+	companion object {
+
+		fun create(context: Context): MangaDatabase = Room.databaseBuilder(
+			context,
+			MangaDatabase::class.java,
+			"kotatsu-db"
+		).addMigrations(
+			Migration1To2(),
+			Migration2To3(),
+			Migration3To4(),
+			Migration4To5(),
+			Migration5To6(),
+			Migration6To7(),
+			Migration7To8(),
+			Migration8To9(),
+		).addCallback(
+			DatabasePrePopulateCallback(context.resources)
+		).build()
+	}
 }

app/src/main/java/org/koitharu/kotatsu/settings/backup/AppBackupAgent.kt

@@ -0,0 +1,107 @@
+package org.koitharu.kotatsu.settings.backup
+
+import android.app.backup.BackupAgent
+import android.app.backup.BackupDataInput
+import android.app.backup.BackupDataOutput
+import android.app.backup.FullBackupDataOutput
+import android.os.ParcelFileDescriptor
+import kotlinx.coroutines.NonCancellable
+import kotlinx.coroutines.runBlocking
+import org.koitharu.kotatsu.core.backup.BackupArchive
+import org.koitharu.kotatsu.core.backup.BackupEntry
+import org.koitharu.kotatsu.core.backup.BackupRepository
+import org.koitharu.kotatsu.core.backup.RestoreRepository
+import org.koitharu.kotatsu.core.db.MangaDatabase
+import java.io.*
+
+class AppBackupAgent : BackupAgent() {
+
+	override fun onBackup(
+		oldState: ParcelFileDescriptor?,
+		data: BackupDataOutput?,
+		newState: ParcelFileDescriptor?
+	) = Unit
+
+	override fun onRestore(
+		data: BackupDataInput?,
+		appVersionCode: Int,
+		newState: ParcelFileDescriptor?
+	) = Unit
+
+	override fun onFullBackup(data: FullBackupDataOutput) {
+		super.onFullBackup(data)
+		val file = createBackupFile()
+		try {
+			fullBackupFile(file, data)
+		} finally {
+			file.delete()
+		}
+	}
+
+	override fun onRestoreFile(
+		data: ParcelFileDescriptor,
+		size: Long,
+		destination: File?,
+		type: Int,
+		mode: Long,
+		mtime: Long
+	) {
+		if (destination?.name?.endsWith(".bak") == true) {
+			restoreBackupFile(data.fileDescriptor, size)
+			destination.delete()
+		} else {
+			super.onRestoreFile(data, size, destination, type, mode, mtime)
+		}
+	}
+
+	private fun createBackupFile() = runBlocking {
+		val repository = BackupRepository(MangaDatabase.create(applicationContext))
+		val backup = BackupArchive.createNew(this@AppBackupAgent)
+		backup.put(repository.createIndex())
+		backup.put(repository.dumpHistory())
+		backup.put(repository.dumpCategories())
+		backup.put(repository.dumpFavourites())
+		backup.flush()
+		backup.cleanup()
+		backup.file
+	}
+
+	private fun restoreBackupFile(fd: FileDescriptor, size: Long) {
+		val repository = RestoreRepository(MangaDatabase.create(applicationContext))
+		val tempFile = File.createTempFile("backup_", ".tmp")
+		FileInputStream(fd).use { input ->
+			tempFile.outputStream().use { output ->
+				input.copyLimitedTo(output, size)
+			}
+		}
+		val backup = BackupArchive(tempFile)
+		try {
+			runBlocking {
+				backup.unpack()
+				repository.upsertHistory(backup.getEntry(BackupEntry.HISTORY))
+				repository.upsertCategories(backup.getEntry(BackupEntry.CATEGORIES))
+				repository.upsertFavourites(backup.getEntry(BackupEntry.FAVOURITES))
+			}
+		} finally {
+			runBlocking(NonCancellable) {
+				backup.cleanup()
+			}
+			tempFile.delete()
+		}
+	}
+
+	private fun InputStream.copyLimitedTo(out: OutputStream, limit: Long) {
+		var bytesCopied: Long = 0
+		val buffer = ByteArray(DEFAULT_BUFFER_SIZE.coerceAtMost(limit.toInt()))
+		var bytes = read(buffer)
+		while (bytes >= 0) {
+			out.write(buffer, 0, bytes)
+			bytesCopied += bytes
+			val bytesLeft = (limit - bytesCopied).toInt()
+			if (bytesLeft <= 0) {
+				break
+			}
+			bytes = read(buffer, 0, buffer.size.coerceAtMost(bytesLeft))
+		}
+	}
+}

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

@@ -1,6 +1,5 @@
 package org.koitharu.kotatsu.utils
 
-import androidx.annotation.CheckResult
 import androidx.annotation.WorkerThread
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.runInterruptible
@@ -44,7 +43,6 @@ open class MutableZipFile(val file: File) {
 		dir.deleteRecursively()
 	}
 
-	@CheckResult
 	suspend fun flush(): Boolean = runInterruptible(Dispatchers.IO) {
 		val tempFile = File(file.path + ".tmp")
 		if (tempFile.exists()) {