#pragma once

#include <memory>

#include <utility>

#include <vector>

#include "envoy/config/core/v3/http_service.pb.h"

#include "envoy/config/core/v3/http_uri.pb.h"

#include "envoy/extensions/tracers/opentelemetry/samplers/v3/dynatrace_sampler.pb.h"

#include "envoy/http/async_client.h"

#include "envoy/http/message.h"

#include "envoy/server/tracer_config.h"

#include "source/common/http/async_client_impl.h"

#include "source/common/http/async_client_utility.h"

#include "source/common/http/headers.h"

#include "source/common/http/message_impl.h"

#include "source/common/http/utility.h"

#include "source/extensions/tracers/opentelemetry/samplers/dynatrace/sampler_config.h"

namespace Envoy {

namespace Extensions {

namespace Tracers {

namespace OpenTelemetry {

/**

 * @brief The Dynatrace sampling configuration provider.

 *

 * The configuration provider obtains sampling configuration from the Dynatrace API

 * in order to dynamically tune up/down the sampling rate of spans.

 */

class SamplerConfigProvider {

public:

  /**

   * @brief Get the Dynatrace Sampler configuration.

   *

   * @return const SamplerConfig&

   */

  virtual const SamplerConfig& getSamplerConfig() const = 0;

};

class SamplerConfigProviderImpl : public SamplerConfigProvider,

                                  public Logger::Loggable<Logger::Id::tracing>,

                                  public Http::AsyncClient::Callbacks {

public:

  SamplerConfigProviderImpl(

      Server::Configuration::TracerFactoryContext& context,

      const envoy::extensions::tracers::opentelemetry::samplers::v3::DynatraceSamplerConfig&

          config);

  void onSuccess(const Http::AsyncClient::Request& request,

                 Http::ResponseMessagePtr&& response) override;

  void onFailure(const Http::AsyncClient::Request& request,

                 Http::AsyncClient::FailureReason reason) override;

  void onBeforeFinalizeUpstreamSpan(Envoy::Tracing::Span& /*span*/,

  const SamplerConfig& getSamplerConfig() const override;

  ~SamplerConfigProviderImpl() override;

private:

  Event::TimerPtr timer_;

  Upstream::ClusterManager& cluster_manager_;

  envoy::config::core::v3::HttpUri http_uri_;

  std::vector<std::pair<const Http::LowerCaseString, const std::string>> parsed_headers_to_add_;

  Http::AsyncClient::Request* active_request_{};

  SamplerConfig sampler_config_;

};

using SamplerConfigProviderPtr = std::unique_ptr<SamplerConfigProvider>;

} // namespace OpenTelemetry

} // namespace Tracers

} // namespace Extensions

} // namespace Envoy