From 189f92d7e8f9b0588ae7c0727e2ad7f6d03b0a90 Mon Sep 17 00:00:00 2001
From: arkon <eugcheung94@gmail.com>
Date: Sun, 17 Apr 2022 11:51:24 -0400
Subject: [PATCH] Show better error message when empty backup creation is
 attempted (closes #6941)

---
 .../kanade/tachiyomi/data/backup/full/FullBackupManager.kt   | 5 +++++
 app/src/main/res/values/strings.xml                          | 1 +
 2 files changed, 6 insertions(+)

diff --git a/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/FullBackupManager.kt b/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/FullBackupManager.kt
index c1807cdee..f12047891 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/FullBackupManager.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/data/backup/full/FullBackupManager.kt
@@ -3,6 +3,7 @@ package eu.kanade.tachiyomi.data.backup.full
 import android.content.Context
 import android.net.Uri
 import com.hippo.unifile.UniFile
+import eu.kanade.tachiyomi.R
 import eu.kanade.tachiyomi.data.backup.AbstractBackupManager
 import eu.kanade.tachiyomi.data.backup.BackupConst.BACKUP_CATEGORY
 import eu.kanade.tachiyomi.data.backup.BackupConst.BACKUP_CATEGORY_MASK
@@ -90,6 +91,10 @@ class FullBackupManager(context: Context) : AbstractBackupManager(context) {
             }
 
             val byteArray = parser.encodeToByteArray(BackupSerializer, backup!!)
+            if (byteArray.isEmpty()) {
+                throw IllegalStateException(context.getString(R.string.empty_backup_error))
+            }
+
             file.openOutputStream().also {
                 // Force overwrite old file
                 (it as? FileOutputStream)?.channel?.truncate(0)
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 53d22ee6f..19fca94e6 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -451,6 +451,7 @@
     <string name="backup_choice">What do you want to backup?</string>
     <string name="creating_backup">Creating backup</string>
     <string name="creating_backup_error">Backup failed</string>
+    <string name="empty_backup_error">No library entries to back up</string>
     <string name="restore_miui_warning">Backup/restore may not function properly if MIUI Optimization is disabled.</string>
     <string name="restore_in_progress">Restore is already in progress</string>
     <string name="restoring_backup">Restoring backup</string>