////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
////////////////////////////////////////////////////////////////////////////////

#include "Basics/Common.h"

#include <thread>

////////////////////////////////////////////////////////////////////////////////
/// @brief memrchr
////////////////////////////////////////////////////////////////////////////////

#ifdef TRI_MISSING_MEMRCHR

void* memrchr(void const* block, int c, size_t size) {
  if (size) {
    unsigned char const* p = static_cast<unsigned char const*>(block);

    for (p += size - 1; size; p--, size--) {
      if (*p == c) {
        return (void*)p;
      }
    }
  }
  return nullptr;
}

#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief memmem
////////////////////////////////////////////////////////////////////////////////

#ifdef _WIN32

void* memmem(void const* haystack, size_t haystackLength, 
             void const* needle, size_t needleLength) {
  if (haystackLength == 0 || 
      needleLength == 0 || 
      haystackLength < needleLength) {
    return nullptr;
  }

  char const* n = static_cast<char const*>(needle);
 
  if (needleLength == 1) {
    return memchr(const_cast<void*>(haystack), static_cast<int>(*n), haystackLength);
  }

  char const* current = static_cast<char const*>(haystack);
  char const* end = static_cast<char const*>(haystack) + haystackLength - needleLength;

  for (; current <= end; ++current) {
    if (*current == *n &&
        memcmp(needle, current, needleLength) == 0) {
      return const_cast<void*>(static_cast<void const*>(current));
    }
  }

  return nullptr;
}

#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief get the time of day
////////////////////////////////////////////////////////////////////////////////

#ifdef TRI_HAVE_WIN32_GETTIMEOFDAY

int gettimeofday(struct timeval* tv, void* tz) {
  union {
    int64_t ns100;  // since 1.1.1601 in 100ns units
    FILETIME ft;
  } now;

  GetSystemTimeAsFileTime(&now.ft);

  tv->tv_usec = (long)((now.ns100 / 10LL) % 1000000LL);
  tv->tv_sec = (long)((now.ns100 - 116444736000000000LL) / 10000000LL);

  return 0;
}

#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief safe localtime
////////////////////////////////////////////////////////////////////////////////

void TRI_localtime(time_t tt, struct tm* tb) {
#ifdef TRI_HAVE_LOCALTIME_R

  localtime_r(&tt, tb);

#else

#ifdef ARANGODB_HAVE_LOCALTIME_S

  localtime_s(tb, &tt);

#else

  struct tm* tp = localtime(&tt);

  if (tp != nullptr) {
    memcpy(tb, tp, sizeof(struct tm));
  }

#endif
#endif
}

////////////////////////////////////////////////////////////////////////////////
/// @brief safe gmtime
////////////////////////////////////////////////////////////////////////////////

void TRI_gmtime(time_t tt, struct tm* tb) {
#ifdef TRI_HAVE_GMTIME_R

  gmtime_r(&tt, tb);

#else

#ifdef TRI_HAVE_GMTIME_S

  gmtime_s(tb, &tt);

#else

  struct tm* tp = gmtime(&tt);

  if (tp != nullptr) {
    memcpy(tb, tp, sizeof(struct tm));
  }

#endif
#endif
}

////////////////////////////////////////////////////////////////////////////////
/// @brief seconds with microsecond resolution
////////////////////////////////////////////////////////////////////////////////

double TRI_microtime() {
  struct timeval t;

  gettimeofday(&t, 0);

  return (t.tv_sec) + (t.tv_usec / 1000000.0);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief return the current time as string in format "YYYY-MM-DDTHH:MM:SSZ"
////////////////////////////////////////////////////////////////////////////////

std::string TRI_timeString() {
  time_t tt = time(0);
  struct tm tb;
  TRI_gmtime(tt, &tb);
  char buffer[32];
  size_t len = strftime(buffer, sizeof(buffer), "%Y-%m-%dT%H:%M:%SZ", &tb);

  return std::string(buffer, len);
}

////////////////////////////////////////////////////////////////////////////////
/// @brief number of processors or 0
////////////////////////////////////////////////////////////////////////////////

size_t TRI_numberProcessors() {
#ifdef TRI_SC_NPROCESSORS_ONLN

  auto n = sysconf(_SC_NPROCESSORS_ONLN);

  if (n < 0) {
    n = 0;
  }
  
  if (n > 0) {
    return n;
  }

#endif

  return static_cast<size_t>(std::thread::hardware_concurrency());
}