#pragma once

#include <memory>

#include "envoy/tracing/trace_driver.h"

#include "source/common/tracing/common_values.h"

#include "source/common/tracing/null_span_impl.h"

#include "source/common/tracing/trace_context_impl.h"

#include "source/extensions/tracers/skywalking/trace_segment_reporter.h"

#include "cpp2sky/tracing_context.h"

#include "cpp2sky/well_known_names.h"

namespace Envoy {

namespace Extensions {

namespace Tracers {

namespace SkyWalking {

using cpp2sky::TracingContextSharedPtr;

using cpp2sky::TracingSpanSharedPtr;

const Tracing::TraceContextHandler& skywalkingPropagationHeaderKey();

class Tracer {

public:

  Tracer(TraceSegmentReporterPtr reporter);

  /*

   * Report trace segment data to backend tracing service.

   *

   * @param segment_context The segment context.

   */

  void sendSegment(TracingContextSharedPtr tracing_context);

  /*

   * Create a new span based on the segment context and parent span.

   *

   * @param name Operation name of span.

   * @param tracing_context The SkyWalking tracing context. The newly created span belongs to this

   * context.

   *

   * @return The unique ptr to the newly created span.

   */

  Tracing::SpanPtr startSpan(absl::string_view name, absl::string_view protocol,

                             TracingContextSharedPtr tracing_context);

private:

  TraceSegmentReporterPtr reporter_;

};

using TracerPtr = std::unique_ptr<Tracer>;

class Span : public Tracing::Span {

public:

  Span(absl::string_view name, absl::string_view protocol, TracingContextSharedPtr tracing_context,

       Tracer& parent_tracer)

      // TraceContext.protocol of http is parsed from http message, which value could be HTTP/1.1,

      // etc.

  Span(absl::string_view name, skywalking::v3::SpanLayer span_layer, Span& parent_span,

       TracingContextSharedPtr tracing_context, Tracer& parent_tracer)

  // Tracing::Span

  void setTag(absl::string_view name, absl::string_view value) override;

  void log(SystemTime timestamp, const std::string& event) override;

  void finishSpan() override;

  void injectContext(Tracing::TraceContext& trace_context,

                     const Tracing::UpstreamContext& upstream) override;

  Tracing::SpanPtr spawnChild(const Tracing::Config& config, const std::string& name,

                              SystemTime start_time) override;

  void setSampled(bool do_sample) override;

  // TODO(wbpcode): The SkyWalking tracer may create NullSpanImpl if the tracing decision is not to

  // trace. That make it is impossible to update the sampling decision. So, the useLocalDecision()

  // always return false now. This should be resolved in the future.

private:

  Tracer& parent_tracer_;

  TracingContextSharedPtr tracing_context_;

  TracingSpanSharedPtr span_entity_;

};

} // namespace SkyWalking

} // namespace Tracers

} // namespace Extensions

} // namespace Envoy