#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#ifdef _WIN32
#include <windows.h>
#elif defined(HAVE_PTHREAD)
#include <pthread.h>
#endif

#include <sodium/core.h>
#include <sodium/crypto_generichash.h>
#include <sodium/crypto_scalarmult.h>
#include <sodium/crypto_stream_chacha20.h>
#include <sodium/crypto_stream_salsa20.h>
#include <sodium/randombytes.h>
#include <sodium/runtime.h>
#include <sodium/utils.h>
#include <sodium/private/implementations.h>
#include <sodium/private/mutex.h>

static volatile int initialized;

int
sodium_init(void)
{
  if(sodium_crit_enter() != 0)
  {
    return -1; /* LCOV_EXCL_LINE */
  }
  if(initialized != 0)
  {
    if(sodium_crit_leave() != 0)
    {
      return -1; /* LCOV_EXCL_LINE */
    }
    /* if we're here, we already started properly */
    return initialized ? 0: -1;
  }
  _sodium_runtime_get_cpu_features();
  _crypto_generichash_blake2b_pick_best_implementation();
  _crypto_scalarmult_curve25519_pick_best_implementation();
  _crypto_stream_chacha20_pick_best_implementation();
  _crypto_stream_salsa20_pick_best_implementation();
  randombytes_stir();
  initialized = 1;
  if(sodium_crit_leave() != 0)
  {
    return -1; /* LCOV_EXCL_LINE */
  }
  return initialized ? 0 : -1;
}

#ifdef _WIN32

static CRITICAL_SECTION _sodium_lock;
static volatile LONG _sodium_lock_initialized;
static volatile int locked;

int
_sodium_crit_init(void)
{
  LONG status = 0L;

  while((status = InterlockedCompareExchange(&_sodium_lock_initialized, 1L, 0L))
        == 1L)
  {
    Sleep(0);
  }

  switch(status)
  {
    case 0L:
      InitializeCriticalSection(&_sodium_lock);
      return InterlockedExchange(&_sodium_lock_initialized, 2L) == 1L ? 0 : -1;
    case 2L:
      return 0;
    default: /* should never be reached */
      return -1;
  }
}

int
sodium_crit_enter(void)
{
  if(_sodium_crit_init() != 0)
  {
    return -1; /* LCOV_EXCL_LINE */
  }
  EnterCriticalSection(&_sodium_lock);
  assert(locked == 0);
  locked = 1;

  return 0;
}

int
sodium_crit_leave(void)
{
  if(locked == 0)
  {
#ifdef EPERM
    errno = EPERM;
#endif
    return -1;
  }
  locked = 0;
  LeaveCriticalSection(&_sodium_lock);

  return 0;
}

#elif defined(HAVE_PTHREAD) && !defined(__EMSCRIPTEN__)

static pthread_mutex_t _sodium_lock = PTHREAD_MUTEX_INITIALIZER;
static volatile int locked;

int
sodium_crit_enter(void)
{
  int ret;

  if((ret = pthread_mutex_lock(&_sodium_lock)) == 0)
  {
    assert(locked == 0);
    locked = 1;
  }
  return ret;
}

int
sodium_crit_leave(void)
{
  int ret;

  if(locked == 0)
  {
#ifdef EPERM
    errno = EPERM;
#endif
    return -1;
  }
  locked = 0;

  return pthread_mutex_unlock(&_sodium_lock);
}

#elif defined(HAVE_ATOMIC_OPS) && !defined(__EMSCRIPTEN__) \
    && !defined(__native_client__)

static volatile int _sodium_lock;

int
sodium_crit_enter(void)
{
#ifdef HAVE_NANOSLEEP
  struct timespec q;
  memset(&q, 0, sizeof q);
#endif
  while(__sync_lock_test_and_set(&_sodium_lock, 1) != 0)
  {
#ifdef HAVE_NANOSLEEP
    (void)nanosleep(&q, NULL);
#elif defined(__x86_64__) || defined(__i386__)
    __asm__ __volatile__("pause");
#endif
  }
  return 0;
}

int
sodium_crit_leave(void)
{
  __sync_lock_release(&_sodium_lock);

  return 0;
}

#else

int
sodium_crit_enter(void)
{
  return 0;
}

int
sodium_crit_leave(void)
{
  return 0;
}

#endif

static void (*_misuse_handler)(void);

void
sodium_misuse(void)
{
  void (*handler)(void);

  (void)sodium_crit_leave();
  if(sodium_crit_enter() == 0)
  {
    handler = _misuse_handler;
    if(handler != NULL)
    {
      handler();
    }
  }
  /* LCOV_EXCL_START */
  abort();
}
/* LCOV_EXCL_STOP */

int
sodium_set_misuse_handler(void (*handler)(void))
{
  if(sodium_crit_enter() != 0)
  {
    return -1; /* LCOV_EXCL_LINE */
  }
  _misuse_handler = handler;
  if(sodium_crit_leave() != 0)
  {
    return -1; /* LCOV_EXCL_LINE */
  }
  return 0;
}