From d920180845f51d87383b54d3442752c34d529e27 Mon Sep 17 00:00:00 2001
From: Patrick Stewart <pstewart@nogac.org>
Date: Thu, 26 Dec 2024 22:45:12 -0700
Subject: [PATCH] refactor: adding rebound callbacks

---
 .../container/lib/src/container.dart          |  68 +++++++++++
 .../container/test/rebound_test.dart          | 111 ++++++++++++++++++
 2 files changed, 179 insertions(+)
 create mode 100644 incubation/container/container/test/rebound_test.dart

diff --git a/incubation/container/container/lib/src/container.dart b/incubation/container/container/lib/src/container.dart
index 84dcc8a..2409ae2 100644
--- a/incubation/container/container/lib/src/container.dart
+++ b/incubation/container/container/lib/src/container.dart
@@ -30,6 +30,13 @@ class Container {
   /// The container's service extenders
   final Map<Type, List<dynamic Function(dynamic, Container)>> _extenders = {};
 
+  /// The container's rebound callbacks
+  final Map<Type, List<void Function(dynamic, Container)>> _reboundCallbacks =
+      {};
+
+  /// The container's refreshing instances
+  final Set<Type> _refreshing = {};
+
   /// The container's contextual bindings
   final Map<Type, Map<Type, dynamic>> _contextual = {};
 
@@ -883,6 +890,67 @@ class Container {
     return instance;
   }
 
+  /// Register a callback to be run when a type is rebound.
+  ///
+  /// The callback will be invoked whenever the type's binding is replaced
+  /// or when refresh() is called on the type.
+  ///
+  /// ```dart
+  /// container.rebinding<Logger>((logger, container) {
+  ///   print('Logger was rebound');
+  /// });
+  /// ```
+  void rebinding<T>(
+      void Function(dynamic instance, Container container) callback) {
+    _reboundCallbacks.putIfAbsent(T, () => []).add(callback);
+  }
+
+  /// Refresh an instance in the container.
+  ///
+  /// This will create a new instance and trigger any rebound callbacks.
+  /// If the instance is a singleton, it will be replaced in the container.
+  ///
+  /// ```dart
+  /// container.refresh<Logger>();
+  /// ```
+  T refresh<T>() {
+    if (_refreshing.contains(T)) {
+      throw CircularDependencyException(
+          'Circular dependency detected while refreshing $T');
+    }
+
+    _refreshing.add(T);
+    try {
+      // Create new instance
+      var instance = make<T>();
+
+      // If it's a singleton, replace it
+      if (_singletons.containsKey(T)) {
+        _singletons[T] = instance;
+      }
+
+      // Fire rebound callbacks
+      _fireReboundCallbacks(T, instance);
+
+      return instance;
+    } finally {
+      _refreshing.remove(T);
+    }
+  }
+
+  /// Fire the rebound callbacks for a type.
+  void _fireReboundCallbacks(Type type, dynamic instance) {
+    Container? search = this;
+    while (search != null) {
+      if (search._reboundCallbacks.containsKey(type)) {
+        for (var callback in search._reboundCallbacks[type]!) {
+          callback(instance, this);
+        }
+      }
+      search = search._parent;
+    }
+  }
+
   /// Check if we're in danger of a circular dependency.
   void _checkCircularDependency(Type type) {
     if (_buildStack.contains(type)) {
diff --git a/incubation/container/container/test/rebound_test.dart b/incubation/container/container/test/rebound_test.dart
new file mode 100644
index 0000000..c7ff637
--- /dev/null
+++ b/incubation/container/container/test/rebound_test.dart
@@ -0,0 +1,111 @@
+import 'package:platformed_container/container.dart';
+import 'package:test/test.dart';
+
+class MockReflector extends Reflector {
+  @override
+  String? getName(Symbol symbol) => null;
+
+  @override
+  ReflectedClass? reflectClass(Type clazz) => null;
+
+  @override
+  ReflectedType? reflectType(Type type) => null;
+
+  @override
+  ReflectedInstance? reflectInstance(Object? instance) => null;
+
+  @override
+  ReflectedFunction? reflectFunction(Function function) => null;
+
+  @override
+  ReflectedType reflectFutureOf(Type type) => throw UnimplementedError();
+}
+
+class Service {
+  String value = 'initial';
+}
+
+void main() {
+  late Container container;
+
+  setUp(() {
+    container = Container(MockReflector());
+  });
+
+  group('Rebound Tests', () {
+    test('rebinding callback is called when singleton is refreshed', () {
+      var callCount = 0;
+      var lastInstance;
+
+      container.registerSingleton<Service>(Service());
+      container.rebinding<Service>((instance, container) {
+        callCount++;
+        lastInstance = instance;
+      });
+
+      var refreshed = container.refresh<Service>();
+      expect(callCount, equals(1));
+      expect(lastInstance, equals(refreshed));
+      expect(container.make<Service>(), equals(refreshed));
+    });
+
+    test('multiple rebound callbacks are called in order', () {
+      var order = [];
+      container.registerSingleton<Service>(Service());
+
+      container.rebinding<Service>((instance, container) {
+        order.add(1);
+      });
+
+      container.rebinding<Service>((instance, container) {
+        order.add(2);
+      });
+
+      container.refresh<Service>();
+      expect(order, equals([1, 2]));
+    });
+
+    test('child container inherits parent rebound callbacks', () {
+      var parentCallCount = 0;
+      var childCallCount = 0;
+
+      container.registerSingleton<Service>(Service());
+      container.rebinding<Service>((instance, container) {
+        parentCallCount++;
+      });
+
+      var child = container.createChild();
+      child.rebinding<Service>((instance, container) {
+        childCallCount++;
+      });
+
+      child.refresh<Service>();
+      expect(parentCallCount, equals(1));
+      expect(childCallCount, equals(1));
+    });
+
+    test('refresh throws on circular dependency', () {
+      container.registerSingleton<Service>(Service());
+      container.rebinding<Service>((instance, container) {
+        container.refresh<Service>();
+      });
+
+      expect(() => container.refresh<Service>(),
+          throwsA(isA<CircularDependencyException>()));
+    });
+
+    test('refresh creates new instance for factory binding', () {
+      var count = 0;
+      container.registerFactory<Service>((c) {
+        count++;
+        return Service();
+      });
+
+      var first = container.make<Service>();
+      var second = container.refresh<Service>();
+
+      expect(count, equals(2));
+      expect(first, isNot(equals(second)));
+    });
+  });
+}