When restoring, ask for location first and then restore code

This also checks if there's a backup at the chosen location
and requires the user to select another once,
if we can not find a backup.

app/src/main/java/com/stevesoltys/backup/restore/RestoreActivity.kt

@@ -1,10 +1,14 @@
 package com.stevesoltys.backup.restore
 
 import android.os.Bundle
+import androidx.annotation.CallSuper
+import androidx.appcompat.app.AlertDialog
 import androidx.lifecycle.Observer
 import androidx.lifecycle.ViewModelProviders
 import com.stevesoltys.backup.R
+import com.stevesoltys.backup.transport.backup.plugins.DIRECTORY_ROOT
 import com.stevesoltys.backup.ui.BackupActivity
+import com.stevesoltys.backup.ui.BackupLocationFragment
 import com.stevesoltys.backup.ui.BackupViewModel
 
 class RestoreActivity : BackupActivity() {
@@ -15,8 +19,6 @@ class RestoreActivity : BackupActivity() {
 
     override fun getInitialFragment() = RestoreSetFragment()
 
-    override fun isRestoreOperation() = true
-
     override fun onCreate(savedInstanceState: Bundle?) {
         viewModel = ViewModelProviders.of(this).get(RestoreViewModel::class.java)
         super.onCreate(savedInstanceState)
@@ -32,8 +34,25 @@ class RestoreActivity : BackupActivity() {
         }
     }
 
+    @CallSuper
+    override fun onStart() {
+        super.onStart()
+        if (isFinishing) return
+
+        // check that backup is provisioned
+        if (!viewModel.validLocationIsSet()) {
+            showFragment(BackupLocationFragment())
+        } else if (!viewModel.recoveryCodeIsSet()) {
+            showRecoveryCodeActivity()
+        }
+    }
+
     override fun onInvalidLocation() {
-        // TODO alert dialog?
+        AlertDialog.Builder(this)
+                .setTitle(getString(R.string.restore_invalid_location_title))
+                .setMessage(getString(R.string.restore_invalid_location_message, DIRECTORY_ROOT))
+                .setPositiveButton(android.R.string.ok) { dialog, _ -> dialog.dismiss() }
+                .show()
     }
 
 }

app/src/main/java/com/stevesoltys/backup/restore/RestoreViewModel.kt

@@ -4,16 +4,23 @@ import android.app.Application
 import android.app.backup.IRestoreObserver
 import android.app.backup.IRestoreSession
 import android.app.backup.RestoreSet
+import android.content.Intent
 import android.net.Uri
 import android.util.Log
 import androidx.annotation.WorkerThread
+import androidx.documentfile.provider.DocumentFile
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
 import com.stevesoltys.backup.Backup
 import com.stevesoltys.backup.R
 import com.stevesoltys.backup.session.backup.BackupMonitor
+import com.stevesoltys.backup.settings.setBackupFolderUri
+import com.stevesoltys.backup.transport.ConfigurableBackupTransportService
 import com.stevesoltys.backup.transport.TRANSPORT_ID
+import com.stevesoltys.backup.transport.backup.plugins.DIRECTORY_ROOT
+import com.stevesoltys.backup.transport.restore.plugins.DocumentsProviderRestorePlugin.Companion.getBackups
 import com.stevesoltys.backup.ui.BackupViewModel
+import com.stevesoltys.backup.ui.LocationResult
 
 private val TAG = RestoreViewModel::class.java.simpleName
 
@@ -21,6 +28,8 @@ class RestoreViewModel(app: Application) : BackupViewModel(app), RestoreSetClick
 
     private val backupManager = Backup.backupManager
 
+    override val isRestoreOperation = true
+
     private var session: IRestoreSession? = null
     private var observer: RestoreObserver? = null
     private val monitor = BackupMonitor()
@@ -41,9 +50,39 @@ class RestoreViewModel(app: Application) : BackupViewModel(app), RestoreSetClick
     // Zero on success; a nonzero error code if the restore operation as a whole failed.
     internal val restoreFinished: LiveData<Int> get() = mRestoreFinished
 
-    override fun acceptBackupLocation(folderUri: Uri): Boolean {
+    override fun onLocationSet(folderUri: Uri, isInitialSetup: Boolean) {
-        // TODO search if there's really a backup available in this location and see if we can decrypt it
+        if (hasBackup(folderUri)) {
-        return true
+            // store backup folder location in settings
+            setBackupFolderUri(app, folderUri)
+
+            // stop backup service to be sure the old location will get updated
+            app.stopService(Intent(app, ConfigurableBackupTransportService::class.java))
+
+            Log.d(TAG, "New storage location chosen: $folderUri")
+
+            mLocationSet.setEvent(LocationResult(false, isInitialSetup))
+        } else {
+            Log.w(TAG, "Location was rejected: $folderUri")
+
+            // notify the UI that the location was invalid
+            mLocationSet.setEvent(LocationResult(false, isInitialSetup))
+        }
+    }
+
+    /**
+     * Searches if there's really a backup available in the given location.
+     * Returns true if at least one was found and false otherwise.
+     *
+     * This method is not plugin-agnostic and breaks encapsulation.
+     * It is specific to the (currently only) DocumentsProvider plugin.
+     *
+     * TODO maybe move this to the RestoreCoordinator once we can inject it
+     */
+    private fun hasBackup(folderUri: Uri): Boolean {
+        val parent = DocumentFile.fromTreeUri(app, folderUri) ?: throw AssertionError()
+        val rootDir = parent.findFile(DIRECTORY_ROOT) ?: return false
+        val backupSets = getBackups(rootDir)
+        return backupSets.isNotEmpty()
     }
 
     internal fun loadRestoreSets() {

app/src/main/java/com/stevesoltys/backup/settings/SettingsActivity.kt

@@ -1,9 +1,12 @@
 package com.stevesoltys.backup.settings
 
 import android.os.Bundle
+import androidx.annotation.CallSuper
 import androidx.lifecycle.ViewModelProviders
+import com.stevesoltys.backup.Backup
 import com.stevesoltys.backup.R
 import com.stevesoltys.backup.ui.BackupActivity
+import com.stevesoltys.backup.ui.BackupLocationFragment
 import com.stevesoltys.backup.ui.BackupViewModel
 
 class SettingsActivity : BackupActivity() {
@@ -14,8 +17,6 @@ class SettingsActivity : BackupActivity() {
 
     override fun getInitialFragment() = SettingsFragment()
 
-    override fun isRestoreOperation() = false
-
     override fun onCreate(savedInstanceState: Bundle?) {
         viewModel = ViewModelProviders.of(this).get(SettingsViewModel::class.java)
         super.onCreate(savedInstanceState)
@@ -27,4 +28,19 @@ class SettingsActivity : BackupActivity() {
         if (savedInstanceState == null) showFragment(getInitialFragment())
     }
 
+    @CallSuper
+    override fun onStart() {
+        super.onStart()
+        if (isFinishing) return
+
+        // check that backup is provisioned
+        if (!viewModel.recoveryCodeIsSet()) {
+            showRecoveryCodeActivity()
+        } else if (!viewModel.validLocationIsSet()) {
+            showFragment(BackupLocationFragment())
+            // remove potential error notifications
+            (application as Backup).notificationManager.onBackupErrorSeen()
+        }
+    }
+
 }

app/src/main/java/com/stevesoltys/backup/settings/SettingsViewModel.kt

@@ -1,11 +1,61 @@
 package com.stevesoltys.backup.settings
 
 import android.app.Application
+import android.app.backup.BackupProgress
+import android.app.backup.IBackupObserver
+import android.content.Intent
+import android.net.Uri
+import android.util.Log
+import androidx.annotation.WorkerThread
+import com.stevesoltys.backup.Backup
+import com.stevesoltys.backup.transport.ConfigurableBackupTransportService
+import com.stevesoltys.backup.transport.TRANSPORT_ID
 import com.stevesoltys.backup.transport.requestBackup
 import com.stevesoltys.backup.ui.BackupViewModel
+import com.stevesoltys.backup.ui.LocationResult
+
+private val TAG = SettingsViewModel::class.java.simpleName
 
 class SettingsViewModel(app: Application) : BackupViewModel(app) {
 
+    override val isRestoreOperation = false
+
     fun backupNow() = Thread { requestBackup(app) }.start()
 
+    override fun onLocationSet(folderUri: Uri, isInitialSetup: Boolean) {
+        // store backup folder location in settings
+        setBackupFolderUri(app, folderUri)
+
+        // stop backup service to be sure the old location will get updated
+        app.stopService(Intent(app, ConfigurableBackupTransportService::class.java))
+
+        Log.d(TAG, "New storage location chosen: $folderUri")
+
+        // initialize the new location
+        val observer = InitializationObserver(isInitialSetup)
+        Backup.backupManager.initializeTransports(arrayOf(TRANSPORT_ID), observer)
+    }
+
+    @WorkerThread
+    private inner class InitializationObserver(private val initialSetUp: Boolean) : IBackupObserver.Stub() {
+        override fun onUpdate(currentBackupPackage: String, backupProgress: BackupProgress) {
+            // noop
+        }
+        override fun onResult(target: String, status: Int) {
+            // noop
+        }
+        override fun backupFinished(status: Int) {
+            if (Log.isLoggable(TAG, Log.INFO)) {
+                Log.i(TAG, "Initialization finished. Status: $status")
+            }
+            if (status == 0) {
+                // notify the UI that the location has been set
+                mLocationSet.postEvent(LocationResult(true, initialSetUp))
+            } else {
+                // notify the UI that the location was invalid
+                mLocationSet.postEvent(LocationResult(false, initialSetUp))
+            }
+        }
+    }
+
 }

app/src/main/java/com/stevesoltys/backup/transport/backup/plugins/DocumentsStorage.kt

@@ -10,11 +10,11 @@ import java.io.IOException
 import java.io.InputStream
 import java.io.OutputStream
 
+const val DIRECTORY_ROOT = ".AndroidBackup"
 const val DIRECTORY_FULL_BACKUP = "full"
 const val DIRECTORY_KEY_VALUE_BACKUP = "kv"
 const val FILE_BACKUP_METADATA = ".backup.metadata"
 const val FILE_NO_MEDIA = ".nomedia"
-private const val ROOT_DIR_NAME = ".AndroidBackup"
 private const val MIME_TYPE = "application/octet-stream"
 
 private val TAG = DocumentsStorage::class.java.simpleName
@@ -26,7 +26,7 @@ class DocumentsStorage(private val context: Context, parentFolder: Uri?, token:
         // [fromTreeUri] should only return null when SDK_INT < 21
         val parent = DocumentFile.fromTreeUri(context, folderUri) ?: throw AssertionError()
         try {
-            val rootDir = parent.createOrGetDirectory(ROOT_DIR_NAME)
+            val rootDir = parent.createOrGetDirectory(DIRECTORY_ROOT)
             // create .nomedia file to prevent Android's MediaScanner from trying to index the backup
             rootDir.createOrGetFile(FILE_NO_MEDIA)
             rootDir

app/src/main/java/com/stevesoltys/backup/transport/restore/plugins/DocumentsProviderRestorePlugin.kt

@@ -25,7 +25,24 @@ class DocumentsProviderRestorePlugin(private val storage: DocumentsStorage) : Re
 
     override fun getAvailableBackups(): Sequence<EncryptedBackupMetadata>? {
         val rootDir = storage.rootBackupDir ?: return null
-        val files = ArrayList<Pair<Long, DocumentFile>>()
+        val backupSets = getBackups(rootDir)
+        val iterator = backupSets.iterator()
+        return generateSequence {
+            if (!iterator.hasNext()) return@generateSequence null  // end sequence
+            val backupSet = iterator.next()
+            try {
+                val stream = storage.getInputStream(backupSet.metadataFile)
+                EncryptedBackupMetadata(backupSet.token, stream)
+            } catch (e: IOException) {
+                Log.e(TAG, "Error getting InputStream for backup metadata.", e)
+                EncryptedBackupMetadata(backupSet.token)
+            }
+        }
+    }
+
+    companion object {
+        fun getBackups(rootDir: DocumentFile): List<BackupSet> {
+            val backupSets = ArrayList<BackupSet>()
             for (set in rootDir.listFiles()) {
                 if (!set.isDirectory || set.name == null) {
                     if (set.name != FILE_NO_MEDIA) {
@@ -43,23 +60,13 @@ class DocumentsProviderRestorePlugin(private val storage: DocumentsStorage) : Re
                 if (metadata == null) {
                     Log.w(TAG, "Missing metadata file in backup set folder: ${set.name}")
                 } else {
-                files.add(Pair(token, metadata))
+                    backupSets.add(BackupSet(token, metadata))
                 }
             }
-        val iterator = files.iterator()
+            return backupSets
-        return generateSequence {
-            if (!iterator.hasNext()) return@generateSequence null  // end sequence
-            val pair = iterator.next()
-            val token = pair.first
-            val metadata = pair.second
-            try {
-                val stream = storage.getInputStream(metadata)
-                EncryptedBackupMetadata(token, stream)
-            } catch (e: IOException) {
-                Log.e(TAG, "Error getting InputStream for backup metadata.", e)
-                EncryptedBackupMetadata(token)
-            }
         }
     }
 
 }
+
+class BackupSet(val token: Long, val metadataFile: DocumentFile)

app/src/main/java/com/stevesoltys/backup/ui/BackupActivity.kt

@@ -9,7 +9,6 @@ import android.widget.Toast.LENGTH_LONG
 import androidx.annotation.CallSuper
 import androidx.appcompat.app.AppCompatActivity
 import androidx.fragment.app.Fragment
-import com.stevesoltys.backup.Backup
 import com.stevesoltys.backup.R
 
 const val REQUEST_CODE_OPEN_DOCUMENT_TREE = 1
@@ -27,13 +26,11 @@ abstract class BackupActivity : AppCompatActivity() {
 
     protected abstract fun getInitialFragment(): Fragment
 
-    protected abstract fun isRestoreOperation(): Boolean
-
     @CallSuper
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
-        getViewModel().onLocationSet.observeEvent(this, LiveEventHandler { result ->
+        getViewModel().locationSet.observeEvent(this, LiveEventHandler { result ->
             if (result.validLocation) {
                 if (result.initialSetup) showFragment(getInitialFragment())
                 else supportFragmentManager.popBackStack()
@@ -44,21 +41,6 @@ abstract class BackupActivity : AppCompatActivity() {
         })
     }
 
-    @CallSuper
-    override fun onStart() {
-        super.onStart()
-        if (isFinishing) return
-
-        // check that backup is provisioned
-        if (!getViewModel().recoveryCodeIsSet()) {
-            showRecoveryCodeActivity()
-        } else if (!getViewModel().validLocationIsSet()) {
-            showFragment(BackupLocationFragment())
-            // remove potential error notifications
-            (application as Backup).notificationManager.onBackupErrorSeen()
-        }
-    }
-
     @CallSuper
     override fun onActivityResult(requestCode: Int, resultCode: Int, result: Intent?) {
         if (resultCode == RESULT_OK && requestCode == REQUEST_CODE_OPEN_DOCUMENT_TREE) {
@@ -80,9 +62,9 @@ abstract class BackupActivity : AppCompatActivity() {
         else -> super.onOptionsItemSelected(item)
     }
 
-    private fun showRecoveryCodeActivity() {
+    protected fun showRecoveryCodeActivity() {
         val intent = Intent(this, RecoveryCodeActivity::class.java)
-        intent.putExtra(INTENT_EXTRA_IS_RESTORE, isRestoreOperation())
+        intent.putExtra(INTENT_EXTRA_IS_RESTORE, getViewModel().isRestoreOperation)
         startActivityForResult(intent, REQUEST_CODE_RECOVERY_CODE)
     }
 

app/src/main/java/com/stevesoltys/backup/ui/BackupViewModel.kt

@@ -1,32 +1,26 @@
 package com.stevesoltys.backup.ui
 
 import android.app.Application
-import android.app.backup.BackupProgress
-import android.app.backup.IBackupObserver
 import android.content.Intent
 import android.content.Intent.FLAG_GRANT_READ_URI_PERMISSION
 import android.content.Intent.FLAG_GRANT_WRITE_URI_PERMISSION
 import android.net.Uri
-import android.util.Log
 import androidx.documentfile.provider.DocumentFile
 import androidx.lifecycle.AndroidViewModel
 import com.stevesoltys.backup.Backup
 import com.stevesoltys.backup.isOnExternalStorage
 import com.stevesoltys.backup.settings.getBackupFolderUri
-import com.stevesoltys.backup.settings.setBackupFolderUri
-import com.stevesoltys.backup.transport.ConfigurableBackupTransportService
-import com.stevesoltys.backup.transport.TRANSPORT_ID
 
 private val TAG = BackupViewModel::class.java.simpleName
 
 abstract class BackupViewModel(protected val app: Application) : AndroidViewModel(app) {
 
-    private val locationWasSet = MutableLiveEvent<LocationResult>()
+    protected val mLocationSet = MutableLiveEvent<LocationResult>()
     /**
      * Will be set to true if this is the initial location.
      * It will be false if an existing location was changed.
      */
-    internal val onLocationSet: LiveEvent<LocationResult> get() = locationWasSet
+    internal val locationSet: LiveEvent<LocationResult> get() = mLocationSet
 
     private val mChooseBackupLocation = MutableLiveEvent<Boolean>()
     internal val chooseBackupLocation: LiveEvent<Boolean> get() = mChooseBackupLocation
@@ -41,6 +35,8 @@ abstract class BackupViewModel(protected val app: Application) : AndroidViewMode
         return file.isDirectory
     }
 
+    abstract val isRestoreOperation: Boolean
+
     internal fun handleChooseFolderResult(result: Intent?) {
         val folderUri = result?.data ?: return
 
@@ -48,53 +44,10 @@ abstract class BackupViewModel(protected val app: Application) : AndroidViewMode
         val takeFlags = result.flags and (FLAG_GRANT_READ_URI_PERMISSION or FLAG_GRANT_WRITE_URI_PERMISSION)
         app.contentResolver.takePersistableUriPermission(folderUri, takeFlags)
 
-        // check if this is initial set-up or a later change
+        onLocationSet(folderUri, !validLocationIsSet())
-        val initialSetUp = !validLocationIsSet()
-
-        if (acceptBackupLocation(folderUri)) {
-            // store backup folder location in settings
-            setBackupFolderUri(app, folderUri)
-
-            // stop backup service to be sure the old location will get updated
-            app.stopService(Intent(app, ConfigurableBackupTransportService::class.java))
-
-            Log.d(TAG, "New storage location chosen: $folderUri")
-
-            // initialize the new location
-            // TODO don't do this when restoring
-            Backup.backupManager.initializeTransports(arrayOf(TRANSPORT_ID), InitializationObserver(initialSetUp))
-        } else {
-            Log.w(TAG, "Location was rejected: $folderUri")
-
-            // notify the UI that the location was invalid
-            locationWasSet.setEvent(LocationResult(false, initialSetUp))
-        }
     }
 
-    protected open fun acceptBackupLocation(folderUri: Uri): Boolean {
+    abstract fun onLocationSet(folderUri: Uri, isInitialSetup: Boolean)
-        return true
-    }
-
-    private inner class InitializationObserver(private val initialSetUp: Boolean) : IBackupObserver.Stub() {
-        override fun onUpdate(currentBackupPackage: String, backupProgress: BackupProgress) {
-            // noop
-        }
-        override fun onResult(target: String, status: Int) {
-            // noop
-        }
-        override fun backupFinished(status: Int) {
-            if (Log.isLoggable(TAG, Log.INFO)) {
-                Log.i(TAG, "Initialization finished. Status: $status")
-            }
-            if (status == 0) {
-                // notify the UI that the location has been set
-                locationWasSet.postEvent(LocationResult(true, initialSetUp))
-            } else {
-                // notify the UI that the location was invalid
-                locationWasSet.postEvent(LocationResult(false, initialSetUp))
-            }
-        }
-    }
 
 }
 

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

@@ -75,6 +75,8 @@
     <string name="restore_title">Restore from Backup</string>
     <string name="restore_choose_restore_set">Choose a backup to restore</string>
     <string name="restore_back">Don\'t restore</string>
+    <string name="restore_invalid_location_title">No backups found</string>
+    <string name="restore_invalid_location_message">We could not find any backups at this location.\n\nPlease choose another location that contains a %s folder.</string>
     <string name="restore_set_error">An error occurred loading the backups.</string>
     <string name="restore_set_empty_result">No backups found at given location.</string>
     <string name="restore_restoring">Restoring Backup</string>