/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef TRACING_H
#define TRACING_H

#include <algorithm>
#include <cstdint>
#include <cstdio>

#include "AsyncLogger.h"
#include "mozilla/Attributes.h"

#if defined(_MSC_VER)
// MSVC
#  define FUNCTION_SIGNATURE __FUNCSIG__
#elif defined(__GNUC__)
// gcc, clang
#  define FUNCTION_SIGNATURE __PRETTY_FUNCTION__
#endif

extern mozilla::AsyncLogger gAudioCallbackTraceLogger;

// This is no-op if tracing is not enabled, and is idempotent.
void StartAudioCallbackTracing();
void StopAudioCallbackTracing();

#ifdef MOZ_REAL_TIME_TRACING
#  define TRACE(aName) AutoTracer trace(gAudioCallbackTraceLogger, aName);
#  define TRACE_COMMENT(aName, aFmt, ...)                          \
    AutoTracer trace(gAudioCallbackTraceLogger, aName,             \
                     AutoTracer::DurationType::ELAPSED_TIME, aFmt, \
                     ##__VA_ARGS__);
#  define TRACE_AUDIO_CALLBACK_FRAME_COUNT(aLocation, aFrames, aSampleRate) \
    do {                                                                    \
      AutoTracer tracer(gAudioCallbackTraceLogger, aLocation,               \
                        AutoTracer::DurationType::FRAME_COUNT, aFrames,     \
                        aSampleRate);                                       \
    } while (false)
#else
#  define TRACE(aName)
#  define TRACE_COMMENT(aFmt, ...)
#  define TRACE_AUDIO_CALLBACK_FRAME_COUNT(aLocation, aFrames, aSampleRate)
#endif

class MOZ_RAII AutoTracer {
 public:
  static const int32_t BUFFER_SIZE = 256;

  enum class DurationType { ELAPSED_TIME, FRAME_COUNT };

  AutoTracer(mozilla::AsyncLogger& aLogger, const char* aLocation,
             DurationType aDurationType = DurationType::ELAPSED_TIME,
             const char* aComment = nullptr);

  template <typename... Args>
  AutoTracer(mozilla::AsyncLogger& aLogger, const char* aLocation,
             DurationType aDurationType, const char* aFormat, Args... aArgs)
      : mLogger(aLogger),
        mLocation(aLocation),
        mComment(mBuffer),
        mDurationType(aDurationType) {
    MOZ_ASSERT(aDurationType == DurationType::ELAPSED_TIME);
    if (aLogger.Enabled()) {
      int32_t size = snprintf(mBuffer, BUFFER_SIZE, aFormat, aArgs...);
      size = std::min(size, BUFFER_SIZE - 1);
      mBuffer[size] = 0;
      PrintEvent(aLocation, "perf", mComment,
                 mozilla::AsyncLogger::TracingPhase::BEGIN);
    }
  }

  AutoTracer(mozilla::AsyncLogger& aLogger, const char* aLocation,
             DurationType aDurationType, uint64_t aFrames,
             uint64_t aSampleRate);

  ~AutoTracer();

 private:
  void PrintEvent(const char* aName, const char* aCategory,
                  const char* aComment,
                  mozilla::AsyncLogger::TracingPhase aPhase);

  void PrintDuration(const char* aName, const char* aCategory,
                     uint64_t aDuration, uint64_t aFrames,
                     uint64_t aSampleRate);

  // The logger to use. It musdt have a lifetime longer than the block an
  // instance of this class traces.
  mozilla::AsyncLogger& mLogger;
  // The location for this trace point, arbitrary string literal, often the
  // name of the calling function, with a static lifetime.
  const char* mLocation;
  // A comment for this trace point, abitrary string literal with a static
  // lifetime.
  const char* mComment;
  // A buffer used to hold string-formatted traces.
  char mBuffer[BUFFER_SIZE];
  // The duration type, for now either elapsed time or frame count.
  const DurationType mDurationType;
};

#endif /* TRACING_H */