platform/packages/file_service/lib/angel3_file_service.dart
2021-06-26 20:06:30 +08:00

146 lines
3.8 KiB
Dart

import 'dart:async';
import 'dart:convert';
import 'package:angel3_framework/angel3_framework.dart';
import 'package:file/file.dart';
import 'package:pool/pool.dart';
/// Persists in-memory changes to a file on disk.
class JsonFileService extends Service<String, Map<String, dynamic>> {
FileStat? _lastStat;
final Pool _mutex = Pool(1);
late MapService _store;
final File file;
JsonFileService(this.file,
{bool allowRemoveAll = false,
bool allowQuery = true,
MapService? store}) {
_store = store ??
MapService(
allowRemoveAll: allowRemoveAll == true,
allowQuery: allowQuery != false);
}
Map<String, dynamic> _coerceStringDynamic(Map m) {
return m.keys.fold<Map<String, dynamic>>(
<String, dynamic>{}, (out, k) => out..[k.toString()] = m[k]);
}
Future _load() {
return _mutex.withResource(() async {
if (!await file.exists()) await file.writeAsString(json.encode([]));
var stat = await file.stat();
//
if (_lastStat == null ||
stat.modified.millisecondsSinceEpoch >
_lastStat!.modified.millisecondsSinceEpoch) {
_lastStat = stat;
var contents = await file.readAsString();
var list = json.decode(contents) as Iterable;
_store.items.clear(); // Clear exist in-memory copy
_store.items.addAll(list.map((x) =>
_coerceStringDynamic(_revive(x) as Map))); // Insert all new entries
}
});
}
Future<File> _save() {
return _mutex.withResource(() {
return file
.writeAsString(json.encode(_store.items.map(_jsonify).toList()));
});
}
@override
Future close() async {
_store.close();
}
@override
Future<List<Map<String, dynamic>>> index(
[Map<String, dynamic>? params]) async =>
_load()
.then((_) => _store.index(params))
.then((it) => it.map(_jsonifyToSD).toList());
@override
Future<Map<String, dynamic>> read(id, [Map<String, dynamic>? params]) =>
_load().then((_) => _store.read(id, params)).then(_jsonifyToSD);
@override
Future<Map<String, dynamic>> create(data,
[Map<String, dynamic>? params]) async {
await _load();
var created = await _store.create(data, params).then(_jsonifyToSD);
await _save();
return created;
}
@override
Future<Map<String, dynamic>> remove(id,
[Map<String, dynamic>? params]) async {
await _load();
var r = await _store.remove(id, params).then(_jsonifyToSD);
await _save();
return r;
}
@override
Future<Map<String, dynamic>> update(id, data,
[Map<String, dynamic>? params]) async {
await _load();
var r = await _store.update(id, data, params).then(_jsonifyToSD);
await _save();
return r;
}
@override
Future<Map<String, dynamic>> modify(id, data,
[Map<String, dynamic>? params]) async {
await _load();
var r = await _store.update(id, data, params).then(_jsonifyToSD);
await _save();
return r;
}
}
dynamic _safeForJson(x) {
if (x is DateTime) {
return x.toIso8601String();
} else if (x is Map) {
return _jsonify(x);
} else if (x is num || x is String || x is bool || x == null) {
return x;
} else if (x is Iterable) {
return x.map(_safeForJson).toList();
} else {
return x.toString();
}
}
Map _jsonify(Map map) {
return map.keys.fold<Map>({}, (out, k) => out..[k] = _safeForJson(map[k]));
}
Map<String, dynamic> _jsonifyToSD(Map<String, dynamic> map) =>
_jsonify(map).cast<String, dynamic>();
dynamic _revive(x) {
if (x is Map) {
return x.keys.fold<Map<String, dynamic>>(
{}, (out, k) => out..[k.toString()] = _revive(x[k]));
} else if (x is Iterable) {
return x.map(_revive).toList();
} else if (x is String) {
try {
return DateTime.parse(x);
} catch (e) {
return x;
}
} else {
return x;
}
}