// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab

#pragma once

#include "acconfig.h"
#include "include/buffer.h"

#ifdef HAVE_JAEGER
#include "opentelemetry/trace/provider.h"

using jspan = opentelemetry::nostd::shared_ptr<opentelemetry::trace::Span>;
using jspan_context = opentelemetry::trace::SpanContext;
using jspan_attribute = opentelemetry::common::AttributeValue;

namespace tracing {

class Tracer {
 private:
  const static opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> noop_tracer;
  const static jspan noop_span;
  opentelemetry::nostd::shared_ptr<opentelemetry::trace::Tracer> tracer;

 public:
  Tracer() = default;
  Tracer(opentelemetry::nostd::string_view service_name);

  void init(opentelemetry::nostd::string_view service_name);

  bool is_enabled() const;
  // creates and returns a new span with `trace_name`
  // this span represents a trace, since it has no parent.
  jspan start_trace(opentelemetry::nostd::string_view trace_name);

  // creates and returns a new span with `trace_name`
  // if false is given to `trace_is_enabled` param, noop span will be returned
  jspan start_trace(opentelemetry::nostd::string_view trace_name, bool trace_is_enabled);

  // creates and returns a new span with `span_name` which parent span is `parent_span'
  jspan add_span(opentelemetry::nostd::string_view span_name, const jspan& parent_span);
  // creates and return a new span with `span_name`
  // the span is added to the trace which it's context is `parent_ctx`.
  // parent_ctx contains the required information of the trace.
  jspan add_span(opentelemetry::nostd::string_view span_name, const jspan_context& parent_ctx);

};

void encode(const jspan_context& span, ceph::buffer::list& bl, uint64_t f = 0);
void decode(jspan_context& span_ctx, ceph::buffer::list::const_iterator& bl);

} // namespace tracing


#else  // !HAVE_JAEGER

#include <string_view>

class Value {
 public:
  template <typename T> Value(T val) {}
};

using jspan_attribute = Value;

struct jspan_context {
  jspan_context() {}
  jspan_context(bool sampled_flag, bool is_remote) {}
};

struct span_stub {
  jspan_context _ctx;
  template <typename T>
  void SetAttribute(std::string_view key, const T& value) const noexcept {}
  void AddEvent(std::string_view) {}
  void AddEvent(std::string_view, std::initializer_list<std::pair<std::string_view, jspan_attribute>> fields) {}
  template <typename T> void AddEvent(std::string_view name, const T& fields = {}) {}
  const jspan_context& GetContext() { return _ctx; }
  void UpdateName(std::string_view) {}
  bool IsRecording() { return false; }
};

class jspan {
  span_stub span;
 public:
  span_stub& operator*() { return span; }
  const span_stub& operator*() const { return span; }

  span_stub* operator->() { return &span; }
  const span_stub* operator->() const { return &span; }

  operator bool() const { return false; }
};

namespace tracing {

struct Tracer {
  bool is_enabled() const { return false; }
  jspan start_trace(std::string_view, bool enabled = true) { return {}; }
  jspan add_span(std::string_view, const jspan&) { return {}; }
  jspan add_span(std::string_view span_name, const jspan_context& parent_ctx) { return {}; }
  void init(std::string_view service_name) {}
};
  inline void encode(const jspan_context& span, bufferlist& bl, uint64_t f=0) {}
  inline void decode(jspan_context& span_ctx, ceph::buffer::list::const_iterator& bl) {}
}

#endif // !HAVE_JAEGER