#pragma once

#include <functional>

#include <memory>

#include <string>

#include "envoy/common/pure.h"

#include "envoy/config/typed_config.h"

#include "envoy/router/router.h"

#include "envoy/server/factory_context.h"

namespace Envoy {

namespace Router {

/**

 * Interface class for creating cluster specifier plugin from related route entry.

 */

class ClusterSpecifierPlugin {

public:

  /**

   * Validate if the clusters are valid in the cluster manager. The derived class

   * should override it if the validation is needed.

   *

   * @param cm cluster manager.

   * @return absl::Status status.

   */

  /**

   * Create route from related route entry and request headers.

   *

   * @param parent related route.

   * @param headers request headers.

   * @param stream_info stream info of the downstream request.

   * @param random random value for cluster selection.

   * @return RouteConstSharedPtr final route with specific cluster.

   */

  virtual RouteConstSharedPtr route(RouteEntryAndRouteConstSharedPtr parent,

                                    const Http::RequestHeaderMap& headers,

                                    const StreamInfo::StreamInfo& stream_info,

                                    uint64_t random) const PURE;

};

using ClusterSpecifierPluginSharedPtr = std::shared_ptr<ClusterSpecifierPlugin>;

/*

 * Extension configuration for cluster specifier plugin factory.

 */

class ClusterSpecifierPluginFactoryConfig : public Envoy::Config::TypedFactory {

public:

  /**

   * Creates a particular cluster specifier plugin factory implementation.

   *

   * @param config supplies the configuration for the cluster specifier plugin factory extension.

   * @return ClusterSpecifierPluginSharedPtr cluster specifier plugin use to create final route from

   * request headers.

   */

  virtual ClusterSpecifierPluginSharedPtr

  createClusterSpecifierPlugin(const Protobuf::Message& config,

                               Server::Configuration::ServerFactoryContext& context) PURE;

};

using ClusterSpecifierPluginFactoryConfigPtr = std::unique_ptr<ClusterSpecifierPluginFactoryConfig>;

} // namespace Router

} // namespace Envoy