feature: Added update notification and download links per platform (#362)

Co-authored-by: PartyDonut <PartyDonut@users.noreply.github.com>

lib/util/update_checker.dart

@@ -0,0 +1,150 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+
+import 'package:http/http.dart' as http;
+import 'package:package_info_plus/package_info_plus.dart';
+
+class ReleaseInfo {
+  final String version;
+  final String changelog;
+  final String url;
+  final bool isNewerThanCurrent;
+  final Map<String, String> downloads;
+
+  ReleaseInfo({
+    required this.version,
+    required this.changelog,
+    required this.url,
+    required this.isNewerThanCurrent,
+    required this.downloads,
+  });
+
+  String? downloadUrlFor(String platform) => downloads[platform];
+
+  Map<String, String> get preferredDownloads {
+    final group = _platformGroup();
+    final entries = downloads.entries.where((e) => e.key.contains(group));
+    return Map.fromEntries(entries);
+  }
+
+  Map<String, String> get otherDownloads {
+    final group = _platformGroup();
+    final entries = downloads.entries.where((e) => !e.key.contains(group));
+    return Map.fromEntries(entries);
+  }
+
+  String _platformGroup() {
+    switch (defaultTargetPlatform) {
+      case TargetPlatform.android:
+        return 'android';
+      case TargetPlatform.iOS:
+        return 'ios';
+      case TargetPlatform.windows:
+        return 'windows';
+      case TargetPlatform.macOS:
+        return 'macos';
+      case TargetPlatform.linux:
+        return 'linux';
+      default:
+        return '';
+    }
+  }
+}
+
+extension DownloadLabelFormatter on String {
+  String prettifyKey() {
+    final parts = split('_');
+    if (parts.isEmpty) return this;
+
+    final base = parts.first.capitalize();
+    if (parts.length == 1) return base;
+
+    final variant = parts.sublist(1).join(' ').capitalize();
+    return '$base ($variant)';
+  }
+
+  String capitalize() => isEmpty ? this : '${this[0].toUpperCase()}${substring(1)}';
+}
+
+class UpdateChecker {
+  final String owner = 'DonutWare';
+  final String repo = 'Fladder';
+
+  Future<List<ReleaseInfo>> fetchRecentReleases({int count = 5}) async {
+    final info = await PackageInfo.fromPlatform();
+    final currentVersion = info.version;
+
+    final url = Uri.parse('https://api.github.com/repos/$owner/$repo/releases?per_page=$count');
+    final response = await http.get(url);
+
+    if (response.statusCode != 200) {
+      print('Failed to fetch releases: ${response.statusCode}');
+      return [];
+    }
+
+    final List<dynamic> releases = jsonDecode(response.body);
+    return releases.map((json) {
+      final tag = (json['tag_name'] as String?)?.replaceFirst(RegExp(r'^v'), '');
+      final changelog = json['body'] as String? ?? '';
+      final htmlUrl = json['html_url'] as String? ?? '';
+      final assets = json['assets'] as List<dynamic>? ?? [];
+
+      final Map<String, String> downloads = {};
+      for (final asset in assets) {
+        final name = asset['name'] as String? ?? '';
+        final downloadUrl = asset['browser_download_url'] as String? ?? '';
+
+        if (name.contains('Android') && name.endsWith('.apk')) {
+          downloads['android'] = downloadUrl;
+        } else if (name.contains('iOS') && name.endsWith('.ipa')) {
+          downloads['ios'] = downloadUrl;
+        } else if (name.contains('Windows') && name.endsWith('Setup.exe')) {
+          downloads['windows_installer'] = downloadUrl;
+        } else if (name.contains('Windows') && name.endsWith('.zip')) {
+          downloads['windows_portable'] = downloadUrl;
+        } else if (name.contains('macOS') && name.endsWith('.dmg')) {
+          downloads['macos'] = downloadUrl;
+        } else if (name.contains('Linux') && name.endsWith('.AppImage')) {
+          downloads['linux_appimage'] = downloadUrl;
+        } else if (name.contains('Linux') && name.endsWith('.flatpak')) {
+          downloads['linux_flatpak'] = downloadUrl;
+        } else if (name.contains('Linux') && name.endsWith('.zip')) {
+          downloads['linux_zip'] = downloadUrl;
+        } else if (name.contains('Linux') && name.endsWith('.zsync')) {
+          downloads['linux_zsync'] = downloadUrl;
+        } else if (name.contains('Web') && name.endsWith('.zip')) {
+          downloads['web'] = downloadUrl;
+        }
+      }
+
+      bool isNewer = tag != null && _compareVersions(tag, currentVersion) > 0;
+
+      return ReleaseInfo(
+        version: tag ?? 'unknown',
+        changelog: changelog.trim(),
+        url: htmlUrl,
+        isNewerThanCurrent: isNewer,
+        downloads: downloads,
+      );
+    }).toList();
+  }
+
+  Future<bool> isUpToDate() async {
+    final releases = await fetchRecentReleases(count: 1);
+    if (releases.isEmpty) return true;
+    return !releases.first.isNewerThanCurrent;
+  }
+
+  static int _compareVersions(String a, String b) {
+    final aParts = a.split('.').map(int.tryParse).toList();
+    final bParts = b.split('.').map(int.tryParse).toList();
+
+    for (var i = 0; i < aParts.length || i < bParts.length; i++) {
+      final aVal = i < aParts.length ? (aParts[i] ?? 0) : 0;
+      final bVal = i < bParts.length ? (bParts[i] ?? 0) : 0;
+      if (aVal != bVal) return aVal.compareTo(bVal);
+    }
+    return 0;
+  }
+}