#pragma once

#include "envoy/common/pure.h"

#include "envoy/config/typed_config.h"

#include "envoy/server/filter_config.h"

#include "envoy/tracing/tracer.h"

#include "source/common/protobuf/protobuf.h"

namespace Envoy {

namespace Server {

namespace Configuration {

/**

 * Context passed to HTTP tracers to access server resources.

 */

class TracerFactoryContext {

public:

  /**

   * @return ServerFactoryContext which lifetime is no shorter than the server.

   */

  virtual ServerFactoryContext& serverFactoryContext() PURE;

  /**

   * @return ProtobufMessage::ValidationVisitor& validation visitor for tracer configuration

   *         messages.

   */

  virtual ProtobufMessage::ValidationVisitor& messageValidationVisitor() PURE;

};

using TracerFactoryContextPtr = std::unique_ptr<TracerFactoryContext>;

/**

 * Implemented by each Tracer and registered via Registry::registerFactory() or the convenience

 * class RegisterFactory.

 */

class TracerFactory : public Config::TypedFactory {

public:

  /**

   * Create a particular trace driver implementation. If the implementation is unable to produce

   * a trace driver with the provided parameters, it should throw an EnvoyException in the case

   * of general error or a Json::Exception if the json configuration is erroneous. The returned

   * pointer should always be valid.

   *

   * NOTE: Due to the corner case of OpenCensus, who can only support a single tracing

   *       configuration per entire process, the returned Driver instance is not guaranteed

   *       to be unique.

   *       That is why the return type has been changed to std::shared_ptr<> instead of a more

   *       idiomatic std::unique_ptr<>.

   * TODO(ggreenway): `opencensus` is now removed, so convert this to a unique_ptr.

   *

   * @param config supplies the proto configuration for the Tracer

   * @param context supplies the factory context

   */

  virtual Tracing::DriverSharedPtr createTracerDriver(const Protobuf::Message& config,

                                                      TracerFactoryContext& context) PURE;

};

} // namespace Configuration

} // namespace Server

} // namespace Envoy