Fix linear forwards backwards

lib/mod_list_troubleshooter.dart

@@ -15,6 +15,7 @@ import 'package:rimworld_modman/mod_list.dart';
 class ModListTroubleshooter {
   final ModList originalModList;
   ModList currentModList;
+  // These indices should ALWAYS represent the CURRENT selection of mods
   int _startIndex = 0;
   int _endIndex = 0;
 
@@ -48,20 +49,25 @@ class ModListTroubleshooter {
     return currentModList;
   }
 
+  // If the current selection is not equal to our proposed step size
+  // We do not MOVE but instead just return the correct amount of mods from the start
   ModList linearForward({int stepSize = 20}) {
-    final totalMods = originalModList.activeMods.length;
+    // If we are not "in step"
-    
+    if (_endIndex - _startIndex == stepSize) {
-    if (_startIndex >= totalMods || _startIndex == _endIndex) {
+      // Move the indices forward by the step size, step forward
-      int newStart = totalMods - stepSize;
+      _startIndex += stepSize;
-      if (newStart < 0) {
+      _endIndex += stepSize;
-        newStart = 0;
+    } else {
+      // Correct the end index to be in step
+      _endIndex = _startIndex + stepSize;
     }
-      _startIndex = newStart;
+    if (_endIndex > originalModList.activeMods.length) {
+      // If we are at the end of the list, move the start index such that we return
+      // At most the step size amount of mods
+      _endIndex = originalModList.activeMods.length;
+      _startIndex = (_endIndex - stepSize).clamp(0, _endIndex);
     }
 
-    _startIndex = _startIndex.clamp(0, totalMods);
-    _endIndex = (_startIndex + stepSize).clamp(0, totalMods);
-
     final subset = originalModList.activeMods.keys.toList().sublist(
       _startIndex,
       _endIndex,
@@ -69,25 +75,21 @@ class ModListTroubleshooter {
 
     currentModList.disableAll();
     currentModList.enableMods(subset);
-    _startIndex = _endIndex;
-    
     return currentModList;
   }
 
   ModList linearBackward({int stepSize = 20}) {
-    final totalMods = originalModList.activeMods.length;
+    if (_endIndex - _startIndex == stepSize) {
-
+      _startIndex -= stepSize;
-    if (_endIndex <= 0 || _startIndex == _endIndex) {
+      _endIndex -= stepSize;
-      int newEnd = stepSize;
+    } else {
-      if (newEnd > totalMods) {
+      _startIndex = _endIndex - stepSize;
-        newEnd = totalMods;
     }
-      _endIndex = newEnd;
+    if (_startIndex < 0) {
+      _startIndex = 0;
+      _endIndex = stepSize.clamp(0, originalModList.activeMods.length);
     }
 
-    _endIndex = _endIndex.clamp(0, totalMods);
-    _startIndex = (_endIndex - stepSize).clamp(0, _endIndex);
-
     final subset = originalModList.activeMods.keys.toList().sublist(
       _startIndex,
       _endIndex,
@@ -95,8 +97,6 @@ class ModListTroubleshooter {
 
     currentModList.disableAll();
     currentModList.enableMods(subset);
-    _endIndex = _startIndex;
-    
     return currentModList;
   }
 

test/mod_list_troubleshooter_test.dart

@@ -75,7 +75,7 @@ void main() {
     });
 
     test(
-      'Bisect search should end up with half the mods every forward iteration until 1',
+      'Should end up with half the mods every forward iteration until 1',
       () {
         final troubleshooter = ModListTroubleshooter(modList);
 
@@ -103,7 +103,7 @@ void main() {
       },
     );
     test(
-      'Bisect search should end up with half the mods every backward iteration until 1',
+      'Should end up with half the mods every backward iteration until 1',
       () {
         final troubleshooter = ModListTroubleshooter(modList);
 
@@ -131,7 +131,7 @@ void main() {
       },
     );
     test(
-      'Bisect search should end up with half the mods every iteration until 1',
+      'Should end up with half the mods every iteration until 1',
       () {
         final troubleshooter = ModListTroubleshooter(modList);
 
@@ -158,7 +158,7 @@ void main() {
         expect(result.activeMods.keys.last, equals('test.mod9'));
       },
     );
-    test('Bisect should handle abuse gracefully', () {
+    test('Should handle abuse gracefully', () {
       final troubleshooter = ModListTroubleshooter(modList);
 
       var result = troubleshooter.binaryBackward();
@@ -225,7 +225,7 @@ void main() {
     });
 
     test(
-      'Linear search should end up with 10 mods every forward iteration',
+      'Should end up with 10 mods every forward iteration',
       () {
         final troubleshooter = ModListTroubleshooter(modList);
 
@@ -246,7 +246,7 @@ void main() {
       },
     );
     test(
-      'Linear search should end up with 10 mods every backward iteration',
+      'Should end up with 10 mods every backward iteration',
       () {
         final troubleshooter = ModListTroubleshooter(modList);
 
@@ -266,7 +266,7 @@ void main() {
         expect(result.activeMods.keys.last, equals('test.mod9'));
       },
     );
-    test('Linear search should end up with 10 mods every iteration', () {
+    test('Should end up with 10 mods every iteration', () {
       final troubleshooter = ModListTroubleshooter(modList);
 
       var result = troubleshooter.linearBackward(stepSize: 10);
@@ -281,10 +281,10 @@ void main() {
 
       result = troubleshooter.linearBackward(stepSize: 10);
       expect(result.activeMods.length, equals(10));
-      expect(result.activeMods.keys.first, equals('test.mod20'));
+      expect(result.activeMods.keys.first, equals('test.mod10'));
-      expect(result.activeMods.keys.last, equals('test.mod29'));
+      expect(result.activeMods.keys.last, equals('test.mod19'));
     });
-    test('Linear search should handle abuse gracefully', () {
+    test('Should handle abuse gracefully', () {
       final troubleshooter = ModListTroubleshooter(modList);
 
       var result = troubleshooter.linearBackward(stepSize: 10);
@@ -302,7 +302,25 @@ void main() {
       result = troubleshooter.linearForward(stepSize: 10);
       expect(result.activeMods.length, equals(10));
     });
-    test('Linear search cannot return more items than there are', () {
+    test('Should handle different step sizes', () {
+      final troubleshooter = ModListTroubleshooter(modList);
+
+      var result = troubleshooter.linearBackward(stepSize: 10);
+      expect(result.activeMods.length, equals(10));
+
+      result = troubleshooter.linearForward(stepSize: 10);
+      expect(result.activeMods.length, equals(10));
+
+      result = troubleshooter.linearBackward(stepSize: 10);
+      expect(result.activeMods.length, equals(10));
+
+      result = troubleshooter.linearForward(stepSize: 10);
+      expect(result.activeMods.length, equals(10));
+
+      result = troubleshooter.linearForward(stepSize: 10);
+      expect(result.activeMods.length, equals(10));
+    });
+    test('Cannot return more items than there are', () {
       final troubleshooter = ModListTroubleshooter(modList);
 
       var result = troubleshooter.linearBackward(stepSize: 10000);
@@ -312,6 +330,63 @@ void main() {
       expect(result.activeMods.length, equals(30));
     });
   });
+  group('Navigation tests', () {
+    late ModList modList = ModList();
+    setUp(() {
+      modList = ModList();
+
+      // Add some base mods
+      for (int i = 0; i < 20; i++) {
+        final modId = 'test.mod$i';
+        final mod = makeDummy().copyWith(name: 'Test Mod $i', id: modId);
+        modList.mods[modId] = mod;
+      }
+
+      // Add some mods with dependencies
+      for (int i = 20; i < 30; i++) {
+        final modId = 'test.mod$i';
+        final mod = makeDummy().copyWith(
+          name: 'Test Mod $i',
+          id: modId,
+          dependencies: ['test.mod${i - 20}'], // Depend on earlier mods
+        );
+        modList.mods[modId] = mod;
+      }
+      modList.enableAll();
+    });
+
+    test(
+      'Mixed navigation should work',
+      () {
+        final troubleshooter = ModListTroubleshooter(modList);
+
+        var result = troubleshooter.linearForward(stepSize: 10);
+        expect(result.activeMods.length, equals(10));
+        expect(result.activeMods.keys.first, equals('test.mod0'));
+        expect(result.activeMods.keys.last, equals('test.mod9'));
+
+        result = troubleshooter.binaryForward();
+        expect(result.activeMods.length, equals(5));
+        expect(result.activeMods.keys.first, equals('test.mod5'));
+        expect(result.activeMods.keys.last, equals('test.mod9'));
+
+        result = troubleshooter.linearBackward(stepSize: 10);
+        expect(result.activeMods.length, equals(10));
+        expect(result.activeMods.keys.first, equals('test.mod0'));
+        expect(result.activeMods.keys.last, equals('test.mod9'));
+
+        result = troubleshooter.binaryForward();
+        expect(result.activeMods.length, equals(5));
+        expect(result.activeMods.keys.first, equals('test.mod5'));
+        expect(result.activeMods.keys.last, equals('test.mod9'));
+
+        result = troubleshooter.linearForward(stepSize: 10);
+        expect(result.activeMods.length, equals(10));
+        expect(result.activeMods.keys.first, equals('test.mod5'));
+        expect(result.activeMods.keys.last, equals('test.mod14'));
+      },
+    );
+  });
   group('Loading dependencies', () {
     late ModList modList = ModList();
     setUp(() {
@@ -336,7 +411,7 @@ void main() {
       modList.enableAll();
     });
     // Not that it has any reason to since they're completely detached...
-    test('Loading dependencies should not fuck up troubleshooter', () {
+    test('Should not fuck up troubleshooter', () {
       final troubleshooter = ModListTroubleshooter(modList);
       final expectedFirst = [
         'test.mod1',