Improve version comparison and add guard

lib/models/local_app.dart

@@ -165,11 +165,11 @@ mixin LocalAppAdapter on Adapter<LocalApp> {
           ? installedVersionCode + 2000
           : installedVersionCode;
       comp = app.latestMetadata!.versionCode!.compareTo(code);
-    }
-
-    // If versionCode was not available or not enough, compare string version
-    if (comp == 0) {
-      comp = compareVersions(installedVersion, app.latestMetadata!.version!);
+    } else {
+      // If versionCode was not available, compare string version
+      try {
+        comp = compareVersions(installedVersion, app.latestMetadata!.version!);
+      } catch (_) {}
     }
 
     if (comp == 1) return AppInstallStatus.updatable;

lib/utils/version.dart

@@ -1,36 +1,36 @@
 import 'dart:math';
 
-int compareVersions(String version1, String version2) {
+int compareVersions(String installedVersion, String latestFromRemoteVersion) {
   // Split the versions into main and pre-release components
-  final parts1 = version1.split('-');
-  final parts2 = version2.split('-');
+  final parts1 = installedVersion.split('-');
+  final parts2 = latestFromRemoteVersion.split('-');
 
   // Split the main version into numeric parts
-  final mainVersion1 = parts1[0].split('.').map(int.parse).toList();
-  final mainVersion2 = parts2[0].split('.').map(int.parse).toList();
+  final mainVersion1 = parts1[0].split('.').map(int.tryParse).toList();
+  final mainVersion2 = parts2[0].split('.').map(int.tryParse).toList();
 
   // Compare the main version parts
   for (var i = 0; i < max(mainVersion1.length, mainVersion2.length); i++) {
-    final v1 = i < mainVersion1.length ? mainVersion1[i] : 0;
-    final v2 = i < mainVersion2.length ? mainVersion2[i] : 0;
+    final v1 = i < mainVersion1.length ? (mainVersion1[i] ?? 0) : 0;
+    final v2 = i < mainVersion2.length ? (mainVersion2[i] ?? 0) : 0;
 
-    if (v1 < v2) return 1; // version2 is higher
-    if (v1 > v2) return -1; // version1 is higher
+    if (v1 < v2) return 1; // upgrade
+    if (v1 > v2) return -1; // downgrade
   }
 
   // If main versions are equal, compare pre-release versions if they exist
   final preRelease1 = parts1.length > 1 ? parts1[1] : '';
   final preRelease2 = parts2.length > 1 ? parts2[1] : '';
 
-  if (preRelease1.isEmpty && preRelease2.isNotEmpty)
-    return -1; // version2 is higher
-  if (preRelease2.isEmpty && preRelease1.isNotEmpty)
-    return 1; // version1 is higher
-
-  if (preRelease1.isEmpty && preRelease2.isEmpty) return 0; // both are equal
+  if (preRelease1.isEmpty && preRelease2.isNotEmpty) {
+    return -1; // downgrade
+  }
+  if (preRelease2.isEmpty && preRelease1.isNotEmpty) {
+    return 1; // upgrade
+  }
 
   // Compare pre-release versions lexicographically
-  final comparison = preRelease1.compareTo(preRelease2);
+  final comparison = preRelease2.compareTo(preRelease1);
 
   return comparison < 0
       ? -1

test/version_test.dart

@@ -6,13 +6,14 @@ void main() {
     test('returns correct comparison', () {
       expect(compareVersions("1.2.3", "1.2.3"), 0);
       expect(compareVersions("1.2.3", "1.2.3-alpha"), -1);
-      expect(compareVersions("1.2.3-alpha", "1.2.3-beta"), -1);
-      expect(compareVersions("1.2.3-beta", "1.2.3-alpha"), 1);
+      expect(compareVersions("1.2.3-alpha", "1.2.3-beta"), 1);
+      expect(compareVersions("1.2.3-beta", "1.2.3-alpha"), -1);
       expect(compareVersions("1.9.0", "1.10.0"), 1);
       expect(compareVersions("1.26.8", "1.27.2"), 1);
       expect(compareVersions("0.2.7", "0.2.11"), 1);
       expect(compareVersions("0.2.11", "0.2.7"), -1);
       expect(compareVersions("2024.9", "2024.10-beta2"), 1);
+      expect(compareVersions("a.x", "b.y"), 0);
     });
   });
 }