#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/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::TracingContextPtr;

using cpp2sky::TracingSpanPtr;

const Http::LowerCaseString& skywalkingPropagationHeaderKey();

class Tracer {

public:

  Tracer(TraceSegmentReporterPtr reporter);

  /*

   * Report trace segment data to backend tracing service.

   *

   * @param segment_context The segment context.

   */

  void sendSegment(TracingContextPtr 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,

                             TracingContextPtr 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, TracingContextPtr tracing_context,

       Tracer& parent_tracer)

      : parent_tracer_(parent_tracer), tracing_context_(tracing_context),

        span_entity_(tracing_context_->createEntrySpan()) {

    span_entity_->startSpan({name.data(), name.size()});

    skywalking::v3::SpanLayer layer;

    if (absl::StrContains(protocol, "HTTP")) {

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

      // etc.

      layer = skywalking::v3::SpanLayer::Http;

    } else if (!skywalking::v3::SpanLayer_Parse(std::string(protocol), &layer)) {

      layer = skywalking::v3::SpanLayer::Unknown;

    }

    span_entity_->setSpanLayer(layer);

  }

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

       TracingContextPtr tracing_context, Tracer& parent_tracer)

      : parent_tracer_(parent_tracer), tracing_context_(tracing_context),

        span_entity_(tracing_context_->createExitSpan(parent_span.spanEntity())) {

    span_entity_->startSpan({name.data(), name.size()});

    span_entity_->setSpanLayer(span_layer);

  }

  // Tracing::Span

  void setOperation(absl::string_view) override {}

  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 Upstream::HostDescriptionConstSharedPtr& upstream) override;

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

                              SystemTime start_time) override;

  void setSampled(bool do_sample) override;

  std::string getBaggage(absl::string_view) override { return EMPTY_STRING; }

  void setBaggage(absl::string_view, absl::string_view) override {}

  std::string getTraceIdAsHex() const override { return EMPTY_STRING; }

  const TracingContextPtr tracingContext() { return tracing_context_; }

  const TracingSpanPtr spanEntity() { return span_entity_; }

private:

  Tracer& parent_tracer_;

  TracingContextPtr tracing_context_;

  TracingSpanPtr span_entity_;

};

} // namespace SkyWalking

} // namespace Tracers

} // namespace Extensions

} // namespace Envoy