116 lines
3 KiB
Dart
116 lines
3 KiB
Dart
import 'dart:convert';
|
|
|
|
import 'package:hive/hive.dart';
|
|
import 'package:latlong2/latlong.dart';
|
|
import 'package:rra_app/pages/map/tfl/tfl_bus_stop_service.dart';
|
|
|
|
class TflBusStopCache {
|
|
TflBusStopCache._();
|
|
|
|
static const _boxName = 'tfl_bus_stop_cache_v1';
|
|
static const _staleAfter = Duration(hours: 12);
|
|
static const _maxEntries = 512;
|
|
|
|
static Future<void> init() async {
|
|
if (!Hive.isBoxOpen(_boxName)) {
|
|
await Hive.openBox(_boxName);
|
|
}
|
|
}
|
|
|
|
static Box? get _box {
|
|
try {
|
|
if (!Hive.isBoxOpen(_boxName)) return null;
|
|
return Hive.box(_boxName);
|
|
} catch (_) {
|
|
return null;
|
|
}
|
|
}
|
|
|
|
// rounds to ~1km grid cells so nearby pans reuse the same cache entry
|
|
static String keyFor(LatLng center) {
|
|
final lat = (center.latitude * 100).round() / 100;
|
|
final lon = (center.longitude * 100).round() / 100;
|
|
return '$lat,$lon';
|
|
}
|
|
|
|
static List<BusStop>? peek(String key) {
|
|
final box = _box;
|
|
if (box == null) return null;
|
|
|
|
final entry = box.get(key);
|
|
if (entry is! Map) return null;
|
|
|
|
final ts = entry['ts'];
|
|
if (ts is! int) return null;
|
|
|
|
final age = DateTime.now().millisecondsSinceEpoch - ts;
|
|
if (age > _staleAfter.inMilliseconds) return null;
|
|
|
|
final raw = entry['stops'];
|
|
if (raw is! List) return null;
|
|
|
|
try {
|
|
return _decodeStops(raw);
|
|
} catch (_) {
|
|
return null;
|
|
}
|
|
}
|
|
|
|
static Future<void> store(String key, List<BusStop> stops) async {
|
|
final box = _box;
|
|
if (box == null) return;
|
|
|
|
await box.put(key, {
|
|
'ts': DateTime.now().millisecondsSinceEpoch,
|
|
'stops': _encodeStops(stops),
|
|
});
|
|
|
|
await _pruneIfNeeded(box);
|
|
}
|
|
|
|
|
|
static List<Map<String, dynamic>> _encodeStops(List<BusStop> stops) {
|
|
return stops.map((s) => {
|
|
'id': s.id,
|
|
'name': s.name,
|
|
'lat': s.position.latitude,
|
|
'lon': s.position.longitude,
|
|
if (s.stopLetter != null) 'stopLetter': s.stopLetter,
|
|
if (s.towards != null) 'towards': s.towards,
|
|
}).toList();
|
|
}
|
|
|
|
static List<BusStop> _decodeStops(List raw) {
|
|
final result = <BusStop>[];
|
|
for (final item in raw) {
|
|
if (item is! Map) continue;
|
|
final lat = (item['lat'] as num?)?.toDouble();
|
|
final lon = (item['lon'] as num?)?.toDouble();
|
|
if (lat == null || lon == null) continue;
|
|
result.add(BusStop(
|
|
id: item['id'] as String? ?? '',
|
|
name: item['name'] as String? ?? '',
|
|
position: LatLng(lat, lon),
|
|
stopLetter: item['stopLetter'] as String?,
|
|
towards: item['towards'] as String?,
|
|
));
|
|
}
|
|
return result;
|
|
}
|
|
|
|
static Future<void> _pruneIfNeeded(Box box) async {
|
|
final overflow = box.length - _maxEntries;
|
|
if (overflow <= 0) return;
|
|
|
|
final entries = box.keys.map((k) {
|
|
final v = box.get(k);
|
|
final ts = (v is Map && v['ts'] is int) ? v['ts'] as int : 0;
|
|
return MapEntry(k, ts);
|
|
}).toList()
|
|
..sort((a, b) => a.value.compareTo(b.value));
|
|
|
|
for (var i = 0; i < overflow; i++) {
|
|
await box.delete(entries[i].key);
|
|
}
|
|
}
|
|
}
|