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/*
* Copyright (c) 2025 Project CHIP Authors
* All rights reserved.
*
* 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.
*/
#pragma once
#include <app/AttributeValueDecoder.h>
#include <app/AttributeValueEncoder.h>
#include <app/CommandHandler.h>
#include <app/ConcreteClusterPath.h>
#include <app/data-model-provider/ActionReturnStatus.h>
#include <app/data-model-provider/MetadataTypes.h>
#include <app/data-model-provider/OperationTypes.h>
#include <app/server-cluster/ServerClusterContext.h>
#include <lib/core/CHIPError.h>
#include <lib/core/DataModelTypes.h>
#include <lib/support/BitFlags.h>
#include <lib/support/ReadOnlyBuffer.h>
namespace chip {
namespace app {
/// Handles cluster interactions for a specific cluster id.
///
/// A `ServerClusterInterface` instance is associated with a single endpointId and represents
/// a cluster that exists at a given `endpointId/clusterId` path.
///
/// Provides metadata as well as interaction processing (attribute read/write and command handling).
class ServerClusterInterface
{
public:
virtual ~ServerClusterInterface() = default;
/// Starts up the server cluster interface.
///
/// The `context` lifetime must be guaranteed to last
/// until `Shutdown` is called:
///
/// - You are allowed to take and use a pointer to it until
/// shutdown is called.
/// - If context is needed, you SHOULD store a pointer rather
/// than a copy to save RAM usage.
virtual CHIP_ERROR Startup(ServerClusterContext & context) = 0;
/// A shutdown will always be paired with a corresponding Startup.
virtual void Shutdown() = 0;
///////////////////////////////////// Cluster Metadata Support //////////////////////////////////////////////////
/// The paths that this cluster interfaces handles.
///
/// - MUST contain at least one element
/// - MUST remain constant once the server cluster interface is in use.
///
[[nodiscard]] virtual Span<const ConcreteClusterPath> GetPaths() const = 0;
/// Gets the data version for this cluster instance.
///
/// Every cluster instance must have a data version.
///
/// SPEC - 7.10.3. Cluster Data Version
/// A cluster data version is a metadata increment-only counter value, maintained for each cluster instance.
/// [...]
/// A cluster data version SHALL increment or be set (wrap) to zero if incrementing would exceed its
/// maximum value. A cluster data version SHALL be maintained for each cluster instance.
/// [...]
/// A cluster data version SHALL be incremented if any attribute data changes.
///
/// Precondition:
/// - `path` parameter MUST match one of the paths returned by GetPaths.
[[nodiscard]] virtual DataVersion GetDataVersion(const ConcreteClusterPath & path) const = 0;
/// Precondition:
/// - `path` parameter MUST match one of the paths returned by GetPaths.
[[nodiscard]] virtual BitFlags<DataModel::ClusterQualityFlags> GetClusterFlags(const ConcreteClusterPath &) const = 0;
///////////////////////////////////// Attribute Support ////////////////////////////////////////////////////////
/// Indicates the start/end of a series of list operations. This function will be called either before the first
/// Write operation or after the last one of a series of consecutive attribute data values received for the same attribute.
///
/// 1) This function will be called if the client tries to set a nullable list attribute to null.
/// 2) This function will only be called at the beginning and end of a series of consecutive attribute data
/// blocks for the same attribute, no matter what list operations those data blocks represent.
/// 3) The opType argument indicates the type of notification (Start, Failure, Success).
///
/// Precondition:
/// - `path` endpoint+cluster part MUST match one of the paths returned by GetPaths.
virtual void ListAttributeWriteNotification(const ConcreteAttributePath & path, DataModel::ListWriteOperation opType) {}
/// Reads the value of an existing attribute.
///
/// ReadAttribute MUST be done on an "existent" attribute path: only on attributes that are
/// returned in an `Attributes` call for this cluster. ReadAttribute is not expected to perform
/// that verification; the caller is responsible for it.
///
/// `request.path` is expected to have `GetClusterId` as the cluster id as well as an attribute that is
/// included in an `Attributes` call.
///
/// This MUST HANDLE the following global attributes:
/// - FeatureMap::Id
/// - ClusterRevision::Id
///
/// This function WILL NOT be called for attributes that can be derived from cluster metadata.
/// Specifically this WILL NOT be called (and does not need to implement handling for) the
/// following attribute IDs:
/// - AcceptedCommandList::Id
/// - AttributeList::Id
/// - GeneratedCommandList::Id
///
/// Precondition:
/// - `request.path` endpoint+cluster part MUST match one of the paths returned by GetPaths.
virtual DataModel::ActionReturnStatus ReadAttribute(const DataModel::ReadAttributeRequest & request,
AttributeValueEncoder & encoder) = 0;
/// Writes a value to an existing attribute.
///
/// WriteAttribute MUST be done on an "existent" attribute path: only on attributes that are
/// returned in an `Attributes` call for this cluster. WriteAttribute is not expected to perform
/// that verification; the caller is responsible for it.
///
/// `request.path` is expected to have `GetClusterId` as the cluster id as well as an attribute that is
/// included in a `Attributes` call.
///
/// Precondition:
/// - `request.path` endpoint+cluster part MUST match one of the paths returned by GetPaths.
virtual DataModel::ActionReturnStatus WriteAttribute(const DataModel::WriteAttributeRequest & request,
AttributeValueDecoder & decoder) = 0;
/// Retrieves the list of attributes supported by this cluster.
///
/// Attribute list MUST contain global attributes.
///
/// Specifically these attributes MUST always exist in the list for all clusters:
/// - ClusterRevision::Id
/// - FeatureMap::Id
/// - AcceptedCommandList::Id
/// - AttributeList::Id
/// - GeneratedCommandList::Id
/// See SPEC 7.13 Global Elements: `Global Attributes` table
///
/// Precondition:
/// - `path` MUST match one of the paths returned by GetPaths.
virtual CHIP_ERROR Attributes(const ConcreteClusterPath & path, ReadOnlyBufferBuilder<DataModel::AttributeEntry> & builder) = 0;
/// Retrieve information about a specific generated event.
///
/// In particular information regarding access, so that event reads can be validated.
virtual CHIP_ERROR EventInfo(const ConcreteEventPath & path, DataModel::EventEntry & eventInfo) = 0;
///////////////////////////////////// Command Support /////////////////////////////////////////////////////////
/// Handles the invocation of a command.
///
/// `handler` is used to send back the response.
/// - returning `nullopt` means that return value was placed in handler directly.
/// This includes cases where command handling and value return will be done asynchronously.
/// - returning a value other than Success implies an error reply (error and data are mutually exclusive)
///
/// InvokeCommand MUST be done on an "existent" attribute path: only on commands that are
/// returned in an `AcceptedCommand` call for this cluster.
///
/// Return value expectations:
/// - if a response has been placed into `handler` then std::nullopt MUST be returned. In particular
/// note that CHIP_NO_ERROR is NOT the same as std::nullopt:
/// > CHIP_NO_ERROR means handler had no status set and we expect the caller to AddStatus(success)
/// > std::nullopt means that handler has added an appropriate data/status response
/// - if a value is returned (not nullopt) then the handler response MUST NOT be filled. The caller
/// will then issue `handler->AddStatus(request.path, <return_value>->GetStatusCode())`. This is a
/// convenience to make writing Invoke calls easier.
///
/// Precondition:
/// - `request.path` endpoint+cluster part MUST match one of the paths returned by GetPaths.
virtual std::optional<DataModel::ActionReturnStatus>
InvokeCommand(const DataModel::InvokeRequest & request, chip::TLV::TLVReader & input_arguments, CommandHandler * handler) = 0;
/// Retrieves a list of commands accepted by this cluster.
///
/// Returning `CHIP_NO_ERROR` without adding anything to the `builder` list is expected
/// if no commands are supported by the cluster.
///
/// Precondition:
/// - `path` MUST match one of the paths returned by GetPaths.
virtual CHIP_ERROR AcceptedCommands(const ConcreteClusterPath & path,
ReadOnlyBufferBuilder<DataModel::AcceptedCommandEntry> & builder) = 0;
/// Retrieves a list of commands generated by this cluster.
///
/// Returning `CHIP_NO_ERROR` without adding anything to the `builder` list is expected
/// if no commands are generated by processing accepted commands.
///
/// Precondition:
/// - `path` MUST match one of the paths returned by GetPaths.
virtual CHIP_ERROR GeneratedCommands(const ConcreteClusterPath & path, ReadOnlyBufferBuilder<CommandId> & builder) = 0;
/// Returns whether `GetPaths` contains the given path
bool PathsContains(const ConcreteClusterPath & path);
};
} // namespace app
} // namespace chip