WIP: integration with ledger

frontend/pshared/lib/controllers/payment/source.dart

@@ -0,0 +1,67 @@
+import 'package:flutter/foundation.dart';
+
+import 'package:collection/collection.dart';
+
+import 'package:pshared/models/payment/source.dart';
+import 'package:pshared/provider/payment/source.dart';
+
+
+class PaymentSourceController extends ChangeNotifier {
+  PaymentSourceProvider? _provider;
+  String? _selectedSourceKey;
+
+  List<PaymentSource> get sources => _provider?.sources ?? const [];
+
+  PaymentSource? get selectedSource {
+    final key = _selectedSourceKey;
+    if (key == null) return null;
+    return sources.firstWhereOrNull((source) => source.key == key);
+  }
+
+  void update(PaymentSourceProvider provider) {
+    _provider = provider;
+    final nextSources = provider.sources;
+    final nextSelectedKey = _resolveSelectedKey(
+      currentKey: _selectedSourceKey,
+      sources: nextSources,
+    );
+
+    if (nextSelectedKey == _selectedSourceKey) return;
+    _selectedSourceKey = nextSelectedKey;
+    notifyListeners();
+  }
+
+  void selectSource(PaymentSource source) {
+    if (_selectedSourceKey == source.key) return;
+    _selectedSourceKey = source.key;
+    notifyListeners();
+  }
+
+  void selectWalletByRef(String walletRef) {
+    final source = sources.firstWhereOrNull(
+      (s) => s.type == PaymentSourceType.wallet && s.id == walletRef,
+    );
+    if (source == null) return;
+    selectSource(source);
+  }
+
+  void selectLedgerByRef(String ledgerAccountRef) {
+    final source = sources.firstWhereOrNull(
+      (s) => s.type == PaymentSourceType.ledger && s.id == ledgerAccountRef,
+    );
+    if (source == null) return;
+    selectSource(source);
+  }
+
+  String? _resolveSelectedKey({
+    required String? currentKey,
+    required List<PaymentSource> sources,
+  }) {
+    if (sources.isEmpty) return null;
+    if (currentKey != null &&
+        sources.any((source) => source.key == currentKey)) {
+      return currentKey;
+    }
+    return sources.first.key;
+  }
+}