add initial project files for Flutter app with platform-specific configs and basic routing setup
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128
lib/pages/map/tiles/hive_tile_cache.dart
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128
lib/pages/map/tiles/hive_tile_cache.dart
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import 'dart:typed_data';
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import 'package:hive/hive.dart';
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import 'package:http/http.dart' as http;
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class HiveTileCache {
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HiveTileCache._();
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static const String _boxName = 'map_tile_cache_v1';
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static const int _maxEntries = 6000;
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static const Duration _staleAfter = Duration(days: 14);
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static final Map<String, Future<Uint8List?>> _inFlight =
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<String, Future<Uint8List?>>{};
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static Future<void> init() async {
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if (!Hive.isBoxOpen(_boxName)) {
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await Hive.openBox(_boxName);
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}
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}
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static Box? get _boxOrNull {
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try {
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if (!Hive.isBoxOpen(_boxName)) return null;
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return Hive.box(_boxName);
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} catch (_) {
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return null;
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}
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}
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static Future<Uint8List?> getOrFetch(String url) async {
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final now = DateTime.now().millisecondsSinceEpoch;
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final box = _boxOrNull;
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if (box == null) return _fetchWithoutCache(url);
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final cached = _freshCachedBytes(box, url, now);
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if (cached != null) return cached;
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return _fetchAndStore(box, url, now);
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}
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static void prefetchUrls(
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Iterable<String> urls, {
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int maxCount = 96,
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}) {
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final box = _boxOrNull;
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if (box == null) return;
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final now = DateTime.now().millisecondsSinceEpoch;
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var queued = 0;
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for (final url in urls) {
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if (queued >= maxCount) break;
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if (_freshCachedBytes(box, url, now) != null) continue;
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if (_inFlight.containsKey(url)) continue;
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queued += 1;
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_fetchAndStore(box, url, now);
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}
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}
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static Uint8List? _freshCachedBytes(Box box, String url, int now) {
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final cached = box.get(url);
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if (cached is! Map) return null;
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final ts = cached['ts'];
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final bytes = cached['bytes'];
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if (ts is int &&
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bytes is Uint8List &&
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now - ts <= _staleAfter.inMilliseconds) {
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return bytes;
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}
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return null;
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}
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static Future<Uint8List?> _fetchAndStore(Box box, String url, int now) {
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final inFlight = _inFlight[url];
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if (inFlight != null) return inFlight;
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final future = _fetchAndStoreInternal(box, url, now);
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_inFlight[url] = future;
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future.whenComplete(() {
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_inFlight.remove(url);
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});
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return future;
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}
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static Future<Uint8List?> _fetchAndStoreInternal(
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Box box,
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String url,
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int now,
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) async {
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try {
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final response = await http.get(Uri.parse(url));
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if (response.statusCode != 200) return null;
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final bytes = response.bodyBytes;
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await box.put(url, <String, dynamic>{'ts': now, 'bytes': bytes});
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await _pruneIfNeeded(box);
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return bytes;
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} catch (_) {
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return null;
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}
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}
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static Future<Uint8List?> _fetchWithoutCache(String url) async {
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try {
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final response = await http.get(Uri.parse(url));
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if (response.statusCode != 200) return null;
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return response.bodyBytes;
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} catch (_) {
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return null;
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}
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}
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static Future<void> _pruneIfNeeded(Box box) async {
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final overflow = box.length - _maxEntries;
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if (overflow <= 0) return;
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final entries = <MapEntry<dynamic, dynamic>>[];
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for (final key in box.keys) {
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entries.add(MapEntry(key, box.get(key)));
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}
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entries.sort((a, b) {
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final ats = (a.value is Map && a.value['ts'] is int) ? a.value['ts'] as int : 0;
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final bts = (b.value is Map && b.value['ts'] is int) ? b.value['ts'] as int : 0;
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return ats.compareTo(bts);
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});
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for (var i = 0; i < overflow; i++) {
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await box.delete(entries[i].key);
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}
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}
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}
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