feat: Implement note positioning logic and tests for position conversion

lib/data/app_database.dart

@@ -5,6 +5,8 @@ import 'package:drift/native.dart';
 import 'package:path/path.dart' as p;
 import 'package:path_provider/path_provider.dart';
 
+import 'package:notas/data/note_positioning.dart';
+
 part 'app_database.g.dart';
 
 @DataClassName('DbCategory')
@@ -48,7 +50,7 @@ class Notes extends Table {
 @DriftDatabase(tables: [Notes, Categories])
 class AppDatabase extends _$AppDatabase {
   @override
-  int get schemaVersion => 3;
+  int get schemaVersion => 4;
 
   @override
   MigrationStrategy get migration => MigrationStrategy(
@@ -69,6 +71,29 @@ class AppDatabase extends _$AppDatabase {
         await customStatement('UPDATE categories SET color_value = NULL');
         await customStatement('UPDATE categories SET icon_code_point = NULL');
       }
+      if (from < 4) {
+        final List<DbNote> activeNotes = await (select(notes)
+              ..where((n) => n.isDeleted.equals(false))
+              ..orderBy([
+                (note) => OrderingTerm(expression: note.sortIndex),
+              ]))
+            .get();
+
+        final List<int> rebalancedPositions = rebalanceNotePositions(
+          activeNotes.length,
+        );
+
+        for (var index = 0; index < activeNotes.length; index += 1) {
+          final DbNote row = activeNotes[index];
+          await (update(notes)..where((n) => n.id.equals(row.id))).write(
+            NotesCompanion(
+              sortIndex: Value(rebalancedPositions[index]),
+              updatedAt: Value(DateTime.now()),
+              isDirty: const Value(true),
+            ),
+          );
+        }
+      }
     },
   );
 
@@ -97,17 +122,37 @@ class AppDatabase extends _$AppDatabase {
   // ========== Notes ==========
   Future<List<DbNote>> getAllNotes() {
     return (select(notes)
-          ..orderBy([(note) => OrderingTerm(expression: note.sortIndex)])
+          ..orderBy([
+            (note) => OrderingTerm(
+              expression: note.sortIndex,
+              mode: OrderingMode.desc,
+            ),
+          ])
           ..where((n) => n.isDeleted.equals(false)))
         .get();
   }
 
   Future<int> insertNoteAtTop(NotesCompanion note) {
     return transaction(() async {
-      await customStatement(
+      final DbNote? topNote = await (select(notes)
-        'UPDATE notes SET sort_index = sort_index + 1, is_dirty = 1 WHERE is_deleted = 0',
+            ..where((n) => n.isDeleted.equals(false))
+            ..orderBy([
+              (note) => OrderingTerm(
+                expression: note.sortIndex,
+                mode: OrderingMode.desc,
+              ),
+            ])
+            ..limit(1))
+          .getSingleOrNull();
+
+      final int nextSortIndex = topNote == null
+          ? 0
+          : topNote.sortIndex + notePositionStep;
+
+      await into(notes).insert(
+        note.copyWith(sortIndex: Value<int>(nextSortIndex)),
       );
-      return into(notes).insert(note.copyWith(sortIndex: const Value<int>(0)));
+      return nextSortIndex;
     });
   }
 
@@ -133,11 +178,6 @@ class AppDatabase extends _$AppDatabase {
         isDirty: const Value(true),
       ),
     );
-
-    await customStatement(
-      'UPDATE notes SET sort_index = sort_index - 1, is_dirty = 1 WHERE sort_index > ? AND is_deleted = 0',
-      [removedIndex],
-    );
   }
 
   Future<void> deleteNoteAndShift({
@@ -165,44 +205,64 @@ class AppDatabase extends _$AppDatabase {
     required int oldIndex,
     required int newIndex,
   }) {
-    if (oldIndex == newIndex) {
-      return Future<void>.value();
-    }
-
     return transaction(() async {
-      final List<DbNote> all = await (select(
+      final List<DbNote> orderedNotes = await (select(notes)
-        notes,
+            ..where((n) => n.isDeleted.equals(false))
-      )..where((n) => n.isDeleted.equals(false))).get();
+            ..orderBy([
+              (note) => OrderingTerm(
+                expression: note.sortIndex,
+                mode: OrderingMode.desc,
+              ),
+            ]))
+          .get();
 
-      final int count = all.length;
+      final int currentIndex = orderedNotes.indexWhere((DbNote row) => row.id == id);
-      if (count == 0) {
+      if (currentIndex == -1) {
         return;
       }
 
-      final int maxIndex = count - 1;
+      final int safeNewIndex = newIndex.clamp(0, orderedNotes.length - 1);
-
+      if (currentIndex == safeNewIndex) {
-      final int safeOld = oldIndex.clamp(0, maxIndex);
-      final int safeNew = newIndex.clamp(0, maxIndex);
-
-      if (safeOld == safeNew) {
         return;
       }
 
-      if (safeOld < safeNew) {
+      final DbNote movedNote = orderedNotes.removeAt(currentIndex);
-        await customStatement(
+      orderedNotes.insert(safeNewIndex, movedNote);
-          'UPDATE notes SET sort_index = sort_index - 1, is_dirty = 1 WHERE sort_index > ? AND sort_index <= ? AND is_deleted = 0',
+
-          [safeOld, safeNew],
+      final int? newStoredPosition;
-        );
+      if (safeNewIndex == 0) {
+        newStoredPosition = orderedNotes[1].sortIndex + notePositionStep;
+      } else if (safeNewIndex == orderedNotes.length - 1) {
+        newStoredPosition =
+            orderedNotes[orderedNotes.length - 2].sortIndex - notePositionStep;
       } else {
-        await customStatement(
+        newStoredPosition = midpointNotePosition(
-          'UPDATE notes SET sort_index = sort_index + 1, is_dirty = 1 WHERE sort_index >= ? AND sort_index < ? AND is_deleted = 0',
+          higherPosition: orderedNotes[safeNewIndex - 1].sortIndex,
-          [safeNew, safeOld],
+          lowerPosition: orderedNotes[safeNewIndex + 1].sortIndex,
         );
       }
 
+      if (newStoredPosition == null) {
+        final List<int> rebalancedPositions = rebalanceNotePositions(
+          orderedNotes.length,
+        );
+
+        for (var index = 0; index < orderedNotes.length; index += 1) {
+          final DbNote row = orderedNotes[index];
+          await (update(notes)..where((n) => n.id.equals(row.id))).write(
+            NotesCompanion(
+              sortIndex: Value<int>(rebalancedPositions[index]),
+              updatedAt: Value<DateTime>(DateTime.now()),
+              isDirty: const Value(true),
+            ),
+          );
+        }
+        return;
+      }
+
       await (update(notes)..where((n) => n.id.equals(id))).write(
         NotesCompanion(
-          sortIndex: Value<int>(safeNew),
+          sortIndex: Value<int>(newStoredPosition),
           updatedAt: Value<DateTime>(DateTime.now()),
           isDirty: const Value(true),
         ),
@@ -221,10 +281,17 @@ class AppDatabase extends _$AppDatabase {
       // and at least one of `title` or `body` is not empty. Previously the
       // query required both title AND body to be non-empty which excluded
       // notes that had an empty body (common) from appearing in the trash.
-      return (select(notes)..where(
+      return (select(notes)
+            ..where(
               (n) => n.isDeleted.equals(true) &
                   (n.title.isNotValue('') | n.body.isNotValue('')),
-      ))
+            )
+            ..orderBy([
+              (note) => OrderingTerm(
+                expression: note.sortIndex,
+                mode: OrderingMode.desc,
+              ),
+            ]))
           .get();
   }
 

lib/data/note_positioning.dart

@@ -0,0 +1,46 @@
+const int notePositionScale = 10;
+const int notePositionStep = 1000 * notePositionScale;
+const int notePositionRebalanceThreshold = 1;
+
+int toStoredNotePosition(double position) {
+  return (position * notePositionScale).round();
+}
+
+double fromStoredNotePosition(int storedPosition) {
+  return storedPosition / notePositionScale;
+}
+
+int nextTopNotePosition(Iterable<int> storedPositions) {
+  int? highestPosition;
+
+  for (final int position in storedPositions) {
+    if (highestPosition == null || position > highestPosition) {
+      highestPosition = position;
+    }
+  }
+
+  if (highestPosition == null) {
+    return 0;
+  }
+
+  return highestPosition + notePositionStep;
+}
+
+int? midpointNotePosition({
+  required int higherPosition,
+  required int lowerPosition,
+}) {
+  final int gap = higherPosition - lowerPosition;
+  if (gap <= notePositionRebalanceThreshold) {
+    return null;
+  }
+
+  return lowerPosition + (gap ~/ 2);
+}
+
+List<int> rebalanceNotePositions(int itemCount) {
+  return List<int>.generate(
+    itemCount,
+    (int index) => (itemCount - 1 - index) * notePositionStep,
+  );
+}

lib/data/note_repository.dart

@@ -6,6 +6,7 @@ import 'dart:io' show Platform;
 import 'package:drift/drift.dart';
 import 'package:notas/data/app_database.dart';
 import 'package:notas/data/api_client.dart';
+import 'package:notas/data/note_positioning.dart';
 import 'package:notas/data/sync_models.dart';
 import 'package:notas/models/note.dart';
 import 'package:notas/models/category.dart';
@@ -91,7 +92,7 @@ class NoteRepository {
   }
 
   Future<Note> createNote(Note note) async {
-    await _database.insertNoteAtTop(
+    final int storedPosition = await _database.insertNoteAtTop(
       NotesCompanion.insert(
         id: note.id,
         title: note.title,
@@ -106,7 +107,10 @@ class NoteRepository {
       ),
     );
 
-    return note.copyWith(position: 0, isDirty: true);
+    return note.copyWith(
+      position: fromStoredNotePosition(storedPosition),
+      isDirty: true,
+    );
   }
 
   Future<Note> updateNote(Note note) async {
@@ -137,7 +141,7 @@ class NoteRepository {
       isDeleted: false,
       isPermanentlyDeleted: false,
       isDirty: true,
-      position: row.sortIndex.toDouble(),
+      position: fromStoredNotePosition(row.sortIndex),
     );
   }
 
@@ -364,7 +368,7 @@ class NoteRepository {
             body: isPermanentlyDeleted ? '' : decryptedBody,
             createdAt: existingNote.createdAt,
             updatedAt: noteResponse.updatedAt,
-            sortIndex: noteResponse.position.round(),
+            sortIndex: toStoredNotePosition(noteResponse.position),
             serverVersion: noteResponse.serverVersion,
             isDeleted: noteResponse.isDeleted,
             categoryId: isPermanentlyDeleted ? null : noteResponse.categoryId,
@@ -382,7 +386,7 @@ class NoteRepository {
                 body: Value(isPermanentlyDeleted ? '' : decryptedBody),
                 createdAt: Value(noteResponse.updatedAt),
                 updatedAt: Value(noteResponse.updatedAt),
-                sortIndex: Value(noteResponse.position.round()),
+                sortIndex: Value(toStoredNotePosition(noteResponse.position)),
                 serverVersion: Value(noteResponse.serverVersion),
                 isDeleted: Value(noteResponse.isDeleted),
                 categoryId: Value(
@@ -412,7 +416,7 @@ class NoteRepository {
       body: row.body,
       createdAt: row.createdAt,
       updatedAt: row.updatedAt,
-      position: row.sortIndex.toDouble(),
+      position: fromStoredNotePosition(row.sortIndex),
       serverVersion: row.serverVersion,
       isDeleted: row.isDeleted,
       isPermanentlyDeleted: _isPermanentlyDeleted(row),
@@ -585,7 +589,7 @@ Map<String, Object?> _dbNoteToEncryptionInput(DbNote row, int index) {
     'updatedAt': row.updatedAt.toIso8601String(),
     'categoryId': row.categoryId,
     'serverVersion': row.serverVersion,
-    'position': row.sortIndex,
+    'position': fromStoredNotePosition(row.sortIndex),
     'isDeleted': row.isDeleted,
     'isPermanentlyDeleted': isPermanentlyDeleted,
   };
@@ -635,7 +639,7 @@ Future<List<Map<String, Object?>>> _encryptNoteBatch(
       'encryptedTitle': encryptedTitle,
       'encryptedBody': encryptedBody,
       'serverVersion': note['serverVersion']! as int,
-      'position': note['position']! as int,
+      'position': (note['position'] as num).toDouble(),
       'isDeleted': note['isDeleted']! as bool,
       'isPermanentlyDeleted': isPermanentlyDeleted,
       'updatedAt': note['updatedAt']! as String,

lib/screens/home_screen.dart

@@ -87,7 +87,9 @@ class _HomeScreenState extends State<HomeScreen> {
     _loadNotesAndCategories();
   }
 
-  Future<void> _loadNotesAndCategories({bool showLoadingIndicator = true}) async {
+  Future<void> _loadNotesAndCategories({
+    bool showLoadingIndicator = true,
+  }) async {
     if (showLoadingIndicator) {
       setState(() {
         _isLoading = true;
@@ -97,8 +99,8 @@ class _HomeScreenState extends State<HomeScreen> {
     final Future<List<Note>> notesFuture = _showDeletedNotes
         ? widget.repository.loadDeletedNotes()
         : widget.repository.loadNotes();
-    final Future<List<Category>> categoriesFuture =
+    final Future<List<Category>> categoriesFuture = widget.repository
-        widget.repository.loadCategories();
+        .loadCategories();
 
     List<Note> notesResult = <Note>[];
     List<Category> categoriesResult = <Category>[];
@@ -362,7 +364,8 @@ class _HomeScreenState extends State<HomeScreen> {
     final Category? currentCategory = _currentCategory();
     final Map<String, Color> categoryBorderColors = <String, Color>{
       for (final Category category in _categories)
-        if (category.colorValue != null) category.id: Color(category.colorValue!),
+        if (category.colorValue != null)
+          category.id: Color(category.colorValue!),
     };
 
     final Widget body = _isLoading
@@ -421,9 +424,12 @@ class _HomeScreenState extends State<HomeScreen> {
                                             _lastPointerKind,
                                           );
 
-                                      final Widget draggableNote = _DraggableNote(
+                                      final Widget
+                                      draggableNote = _DraggableNote(
                                         note: filteredNotes[index],
-                                        borderColor: categoryBorderColors[filteredNotes[index].categoryId],
+                                        borderColor:
+                                            categoryBorderColors[filteredNotes[index]
+                                                .categoryId],
                                         dataIndex: _notes.indexOf(
                                           filteredNotes[index],
                                         ),
@@ -840,8 +846,7 @@ class _CategoryDialogState extends State<_CategoryDialog> {
   void initState() {
     super.initState();
     _controller = TextEditingController(text: widget.category?.name ?? '');
-    _selectedColor =
+    _selectedColor = widget.category == null
-        widget.category == null
         ? CategoryStyle.colors.first
         : widget.category!.colorValue != null
         ? Color(widget.category!.colorValue!)
@@ -906,7 +911,6 @@ class _CategoryDialogState extends State<_CategoryDialog> {
       }
 
       widget.onRequestSync().catchError((_) {});
-  
     } catch (e) {
       debugPrint('ERROR creating category: $e');
       if (mounted) {
@@ -922,24 +926,6 @@ class _CategoryDialogState extends State<_CategoryDialog> {
     }
   }
 
-  Future<void> _runPostSaveCallbacks({
-    required Future<void> Function() onCategoriesChanged,
-    required Future<void> Function() onRequestSync,
-    required Future<void> Function() onCategoryDeleted,
-  }) async {
-    try {
-      await onCategoriesChanged();
-    } catch (_) {}
-
-    try {
-      await onCategoryDeleted();
-    } catch (_) {}
-
-    unawaited(
-      onRequestSync().catchError((_) {}),
-    );
-  }
-
   Future<void> _deleteCategory() async {
     final bool? confirm = await showDialog<bool>(
       context: context,
@@ -1002,10 +988,13 @@ class _CategoryDialogState extends State<_CategoryDialog> {
                   });
                 }
               },
-              decoration: const InputDecoration(
+              decoration:
+                  const InputDecoration(
                     hintText: 'Nombre de la categoría',
                   ).copyWith(
-                errorText: _nameHasError ? 'El nombre es obligatorio' : null,
+                    errorText: _nameHasError
+                        ? 'El nombre es obligatorio'
+                        : null,
                   ),
             ),
             const SizedBox(height: 16),
@@ -1084,7 +1073,9 @@ class _CategoryDialogState extends State<_CategoryDialog> {
                               key: const ValueKey<String>('icons'),
                               spacing: 10,
                               runSpacing: 10,
-                              children: CategoryStyle.icons.map((IconData icon) {
+                              children: CategoryStyle.icons.map((
+                                IconData icon,
+                              ) {
                                 final bool isSelected = _selectedIcon == icon;
                                 return GestureDetector(
                                   onTap: () => setState(() {

lib/screens/note_editor_screen.dart

@@ -336,7 +336,9 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
 
   Widget _buildCategorySelectorBox({Category? category}) {
     final String label = category?.name ?? 'Sin categoría';
-    final IconData icon = CategoryStyle.iconForCodePoint(category?.iconCodePoint);
+    final IconData icon = CategoryStyle.iconForCodePoint(
+      category?.iconCodePoint,
+    );
     final Color backgroundColor = _categoryBackgroundColor(category);
     final Color foregroundColor = _categoryForegroundColor(category);
 
@@ -475,7 +477,9 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
   }) {
     final Color backgroundColor = _categoryBackgroundColor(category);
     final Color foregroundColor = _categoryForegroundColor(category);
-    final IconData icon = CategoryStyle.iconForCodePoint(category?.iconCodePoint);
+    final IconData icon = CategoryStyle.iconForCodePoint(
+      category?.iconCodePoint,
+    );
 
     return InkWell(
       onTap: onTap,
@@ -510,8 +514,7 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
                 ),
               ),
             ),
-            if (isSelected)
+            if (isSelected) Icon(Icons.check, color: foregroundColor, size: 18),
-              Icon(Icons.check, color: foregroundColor, size: 18),
           ],
         ),
       ),
@@ -565,6 +568,13 @@ class _NoteEditorScreenState extends State<NoteEditorScreen> {
                   crossAxisAlignment: CrossAxisAlignment.start,
                   mainAxisSize: MainAxisSize.min,
                   children: [
+                    Text(
+                      'Posicion: ${_currentNote.position}',
+                      style: const TextStyle(
+                        color: Colors.white54,
+                        fontSize: 12,
+                      ),
+                    ),
                     Text(
                       'Creado: ${_formatDate(_currentNote.createdAt)}',
                       style: const TextStyle(

test/note_positioning_test.dart

@@ -0,0 +1,23 @@
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:notas/data/note_positioning.dart';
+
+void main() {
+  test('converts between stored and displayed positions', () {
+    expect(toStoredNotePosition(1500.5), 15005);
+    expect(fromStoredNotePosition(15005), 1500.5);
+  });
+
+  test('supports descending gaps and rebalance', () {
+    expect(nextTopNotePosition(<int>[0, 10000, 20000]), 30000);
+    expect(
+      midpointNotePosition(higherPosition: 20000, lowerPosition: 10000),
+      15000,
+    );
+    expect(
+      midpointNotePosition(higherPosition: 2, lowerPosition: 1),
+      isNull,
+    );
+    expect(rebalanceNotePositions(3), <int>[20000, 10000, 0]);
+  });
+}