Add AsyncFacilitator to enable an async, event-driven, non-polling me…

src/darwin/Framework/CHIP/MTROTAImageTransferHandler.h

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+/**
+ *
+ *    Copyright (c) 2024 Project CHIP Authors
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
+#import <Matter/MTROTAProviderDelegate.h>
+
+#include <protocols/bdx/AsyncTransferFacilitator.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * This class inherits from the AsyncResponder class and handles the BDX messages for a BDX transfer session.
+ * It overrides the HandleTransferSessionOutput virtual method and provides an implementation for it to handle
+ * the OutputEvents that are generated by the BDX transfer session state machine.
+ *
+ * An MTROTAImageTransferHandler will be associated with a specific BDX transfer session.
+ *
+ * The lifecycle of this class is managed by the AsyncFacilitator class which calls the virtual DestroySelf method
+ * that is implemented by this class to clean up and destroy itself and the AsyncFacilitator instances.
+ * Note: An object of this class can't be used after DestroySelf has been called.
+ */
+class MTROTAImageTransferHandler : public chip::bdx::AsyncResponder
+{
+public:
+    MTROTAImageTransferHandler();
+    ~MTROTAImageTransferHandler();
+
+    void HandleTransferSessionOutput(chip::bdx::TransferSession::OutputEvent & event) override;
+    void DestroySelf() override;
+
+protected:
+    CHIP_ERROR OnMessageReceived(chip::Messaging::ExchangeContext * ec, const chip::PayloadHeader & payloadHeader,
+                                 chip::System::PacketBufferHandle && payload) override;
+
+private:
+    CHIP_ERROR PrepareForTransfer(chip::System::Layer * layer, chip::Messaging::ExchangeContext * exchangeCtx,
+                                  chip::FabricIndex fabricIndex, chip::NodeId nodeId);
+
+    CHIP_ERROR ConfigureState(chip::FabricIndex fabricIndex, chip::NodeId nodeId);
+
+    CHIP_ERROR OnMessageToSend(chip::bdx::TransferSession::OutputEvent & event);
+
+    CHIP_ERROR OnTransferSessionBegin(chip::bdx::TransferSession::OutputEvent & event);
+
+    CHIP_ERROR OnTransferSessionEnd(chip::bdx::TransferSession::OutputEvent & event);
+
+    CHIP_ERROR OnBlockQuery(chip::bdx::TransferSession::OutputEvent & event);
+
+    // The fabric index of the node with which the BDX session is established.
+    chip::Optional<chip::FabricIndex> mFabricIndex;
+
+    // The node id of the node with which the BDX session is established.
+    chip::Optional<chip::NodeId> mNodeId;
+
+    // The OTA provider delegate used by the controller.
+    id<MTROTAProviderDelegate> mDelegate = nil;
+    chip::System::Layer * mSystemLayer   = nil;
+
+    // The OTA provider delegate queue used by the controller.
+    dispatch_queue_t mDelegateNotificationQueue = nil;
+};
+
+NS_ASSUME_NONNULL_END