/* 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/. */

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

#ifdef __APPLE__

#  include <dlfcn.h>
#  include <CoreFoundation/CoreFoundation.h>
#  include <unistd.h>

// There are now 2 paths to the DTPerformanceSession framework. We try to load
// the one contained in /Applications/Xcode.app first, falling back to the one
// contained in /Library/Developer/4.0/Instruments.
#  define DTPerformanceLibraryPath                                   \
    "/Applications/Xcode.app/Contents/Developer/Library/Frameworks/" \
    "DTPerformanceSession.framework/Versions/Current/DTPerformanceSession"
#  define OldDTPerformanceLibraryPath                \
    "/Library/Developer/4.0/Instruments/Frameworks/" \
    "DTPerformanceSession.framework/Versions/Current/DTPerformanceSession"

extern "C" {

typedef CFTypeRef DTPerformanceSessionRef;

#  define DTPerformanceSession_TimeProfiler \
    "com.apple.instruments.dtps.timeprofiler"
// DTPerformanceSession_Option_SamplingInterval is measured in microseconds
#  define DTPerformanceSession_Option_SamplingInterval \
    "com.apple.instruments.dtps.option.samplinginterval"

typedef void (*dtps_errorcallback_t)(CFStringRef, CFErrorRef);
typedef DTPerformanceSessionRef (*DTPerformanceSessionCreateFunction)(
    CFStringRef, CFStringRef, CFDictionaryRef, CFErrorRef*);
typedef bool (*DTPerformanceSessionAddInstrumentFunction)(
    DTPerformanceSessionRef, CFStringRef, CFDictionaryRef, dtps_errorcallback_t,
    CFErrorRef*);
typedef bool (*DTPerformanceSessionIsRecordingFunction)(
    DTPerformanceSessionRef);
typedef bool (*DTPerformanceSessionStartFunction)(DTPerformanceSessionRef,
                                                  CFArrayRef, CFErrorRef*);
typedef bool (*DTPerformanceSessionStopFunction)(DTPerformanceSessionRef,
                                                 CFArrayRef, CFErrorRef*);
typedef bool (*DTPerformanceSessionSaveFunction)(DTPerformanceSessionRef,
                                                 CFStringRef, CFErrorRef*);

}  // extern "C"

namespace Instruments {

static const int kSamplingInterval = 20;  // microseconds

template <typename T>
class AutoReleased {
 public:
  MOZ_IMPLICIT AutoReleased(T aTypeRef) : mTypeRef(aTypeRef) {}
  ~AutoReleased() {
    if (mTypeRef) {
      CFRelease(mTypeRef);
    }
  }

  operator T() { return mTypeRef; }

 private:
  T mTypeRef;
};

#  define DTPERFORMANCE_SYMBOLS               \
    SYMBOL(DTPerformanceSessionCreate)        \
    SYMBOL(DTPerformanceSessionAddInstrument) \
    SYMBOL(DTPerformanceSessionIsRecording)   \
    SYMBOL(DTPerformanceSessionStart)         \
    SYMBOL(DTPerformanceSessionStop)          \
    SYMBOL(DTPerformanceSessionSave)

#  define SYMBOL(_sym) _sym##Function _sym = nullptr;

DTPERFORMANCE_SYMBOLS

#  undef SYMBOL

void* LoadDTPerformanceLibraries(bool dontLoad) {
  int flags = RTLD_LAZY | RTLD_LOCAL | RTLD_NODELETE;
  if (dontLoad) {
    flags |= RTLD_NOLOAD;
  }

  void* DTPerformanceLibrary = dlopen(DTPerformanceLibraryPath, flags);
  if (!DTPerformanceLibrary) {
    DTPerformanceLibrary = dlopen(OldDTPerformanceLibraryPath, flags);
  }
  return DTPerformanceLibrary;
}

bool LoadDTPerformanceLibrary() {
  void* DTPerformanceLibrary = LoadDTPerformanceLibraries(true);
  if (!DTPerformanceLibrary) {
    DTPerformanceLibrary = LoadDTPerformanceLibraries(false);
    if (!DTPerformanceLibrary) {
      return false;
    }
  }

#  define SYMBOL(_sym)                                                        \
    _sym =                                                                    \
        reinterpret_cast<_sym##Function>(dlsym(DTPerformanceLibrary, #_sym)); \
    if (!_sym) {                                                              \
      dlclose(DTPerformanceLibrary);                                          \
      DTPerformanceLibrary = nullptr;                                         \
      return false;                                                           \
    }

  DTPERFORMANCE_SYMBOLS

#  undef SYMBOL

  dlclose(DTPerformanceLibrary);

  return true;
}

static DTPerformanceSessionRef gSession;

bool Error(CFErrorRef error) {
  if (gSession) {
    CFErrorRef unused = nullptr;
    DTPerformanceSessionStop(gSession, nullptr, &unused);
    CFRelease(gSession);
    gSession = nullptr;
  }
#  ifdef DEBUG
  AutoReleased<CFDataRef> data = CFStringCreateExternalRepresentation(
      nullptr, CFErrorCopyDescription(error), kCFStringEncodingUTF8, '?');
  if (data != nullptr) {
    printf("%.*s\n\n", (int)CFDataGetLength(data), CFDataGetBytePtr(data));
  }
#  endif
  return false;
}

bool Start(pid_t pid) {
  if (gSession) {
    return false;
  }

  if (!LoadDTPerformanceLibrary()) {
    return false;
  }

  AutoReleased<CFStringRef> process =
      CFStringCreateWithFormat(kCFAllocatorDefault, nullptr, CFSTR("%d"), pid);
  if (!process) {
    return false;
  }
  CFErrorRef error = nullptr;
  gSession = DTPerformanceSessionCreate(nullptr, process, nullptr, &error);
  if (!gSession) {
    return Error(error);
  }

  AutoReleased<CFNumberRef> interval =
      CFNumberCreate(0, kCFNumberIntType, &kSamplingInterval);
  if (!interval) {
    return false;
  }
  CFStringRef keys[1] = {CFSTR(DTPerformanceSession_Option_SamplingInterval)};
  CFNumberRef values[1] = {interval};
  AutoReleased<CFDictionaryRef> options = CFDictionaryCreate(
      kCFAllocatorDefault, (const void**)keys, (const void**)values, 1,
      &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
  if (!options) {
    return false;
  }

  if (!DTPerformanceSessionAddInstrument(
          gSession, CFSTR(DTPerformanceSession_TimeProfiler), options, nullptr,
          &error)) {
    return Error(error);
  }

  return Resume();
}

void Pause() {
  if (gSession && DTPerformanceSessionIsRecording(gSession)) {
    CFErrorRef error = nullptr;
    if (!DTPerformanceSessionStop(gSession, nullptr, &error)) {
      Error(error);
    }
  }
}

bool Resume() {
  if (!gSession) {
    return false;
  }

  CFErrorRef error = nullptr;
  return DTPerformanceSessionStart(gSession, nullptr, &error) || Error(error);
}

void Stop(const char* profileName) {
  Pause();

  CFErrorRef error = nullptr;
  AutoReleased<CFStringRef> name =
      CFStringCreateWithFormat(kCFAllocatorDefault, nullptr, CFSTR("%s%s"),
                               "/tmp/", profileName ? profileName : "mozilla");
  if (!DTPerformanceSessionSave(gSession, name, &error)) {
    Error(error);
    return;
  }

  CFRelease(gSession);
  gSession = nullptr;
}

}  // namespace Instruments

#endif /* __APPLE__ */