#pragma once

#include "envoy/common/exception.h"

#include "envoy/tracing/tracer.h"

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

#include "source/extensions/tracers/opentelemetry/span_context_extractor.h"

namespace Envoy {

namespace Extensions {

namespace Tracers {

namespace Zipkin {

class SpanContext;

struct ExtractorException : public EnvoyException {

};

/**

 * This class is used to SpanContext extracted from the Http header

 */

class SpanContextExtractor {

public:

  SpanContextExtractor(Tracing::TraceContext& trace_context, bool w3c_fallback_enabled = false);

  ~SpanContextExtractor();

  absl::optional<bool> extractSampled();

  std::pair<SpanContext, bool> extractSpanContext(bool is_sampled);

private:

  /*

   * Use to SpanContext extracted from B3 single format Http header

   * b3: {x-b3-traceid}-{x-b3-spanid}-{if x-b3-flags 'd' else x-b3-sampled}-{x-b3-parentspanid}

   * See: "https://github.com/openzipkin/b3-propagation

   */

  std::pair<SpanContext, bool> extractSpanContextFromB3SingleFormat(bool is_sampled);

  /*

   * Convert W3C span context to Zipkin span context format

   */

  std::pair<SpanContext, bool>

  convertW3CToZipkin(const Extensions::Tracers::OpenTelemetry::SpanContext& w3c_context,

                     bool fallback_sampled);

  bool tryExtractSampledFromB3SingleFormat();

  const Tracing::TraceContext& trace_context_;

  bool w3c_fallback_enabled_;

};

} // namespace Zipkin

} // namespace Tracers

} // namespace Extensions

} // namespace Envoy