Assign category positions inside the database

A new category's position is computed by its insert, one after the highest, so two categories created at once can't take the same one. Inserts take a NewCategory rather than a Category whose id and position would be ignored. Reordering places any category missing from the given order after the rest instead of leaving it at a stale position. Restore still creates missing categories all or none, in backup order, and the create dialog no longer accepts an empty name.

data/src/main/java/tachiyomi/data/category/CategoryRepositoryImpl.kt

@@ -10,6 +10,7 @@ import kotlinx.coroutines.flow.Flow
 import tachiyomi.data.Database
 import tachiyomi.data.subscribeToList
 import tachiyomi.domain.category.model.Category
+import tachiyomi.domain.category.model.NewCategory
 import tachiyomi.domain.category.repository.CategoryRepository
 
 @Inject
@@ -49,15 +50,11 @@ class CategoryRepositoryImpl(
             .subscribeToList()
     }
 
-    override suspend fun insert(category: Category) {
-        database.categoriesQueries.insert(
-            name = category.name,
-            order = category.order,
-            flags = category.flags,
-        )
+    override suspend fun insert(category: NewCategory) {
+        database.categoriesQueries.insert(name = category.name, flags = category.flags)
     }
 
-    override suspend fun insertAll(categories: List<Category>) {
+    override suspend fun insertAll(categories: List<NewCategory>) {
         database.transaction {
             categories.forEach { insert(it) }
         }
@@ -77,10 +74,12 @@ class CategoryRepositoryImpl(
 
     override suspend fun updateAllOrders(orderedIds: List<Long>) {
         database.transaction {
-            orderedIds.forEachIndexed { index, categoryId ->
+            val current = database.categoriesQueries.getUserCategoryIds().awaitAsList()
+            val ids = orderedIds.filter { it in current } + current.filterNot { it in orderedIds }
+            ids.forEachIndexed { index, categoryId ->
                 database.categoriesQueries.updateOrder(order = -index - 2L, categoryId = categoryId)
             }
-            orderedIds.forEachIndexed { index, categoryId ->
+            ids.forEachIndexed { index, categoryId ->
                 database.categoriesQueries.updateOrder(order = index.toLong(), categoryId = categoryId)
             }
         }

data/src/main/sqldelight/tachiyomi/data/categories.sq

@@ -44,7 +44,8 @@ WHERE MC.manga_id = :mangaId;
 
 insert:
 INSERT INTO categories(name, sort, flags)
-VALUES (:name, :order, :flags);
+SELECT :name, coalesce(max(sort), -1) + 1, :flags
+FROM categories;
 
 delete:
 DELETE FROM categories
@@ -55,6 +56,12 @@ UPDATE categories
 SET name = :name
 WHERE _id = :categoryId;
 
+getUserCategoryIds:
+SELECT _id
+FROM categories
+WHERE _id > 0
+ORDER BY sort;
+
 updateOrder:
 UPDATE categories
 SET sort = :order