//#include <stdio.h>
//#include <stdlib.h>
#include <lua.h>
#include <lauxlib.h>
#include "spinlock.h"

#include <time.h>
#if !defined(_MSC_VER)
#include <sys/time.h>
#include <uuid/uuid.h>
#else
#define gmtime_r( _clock, _result ) \
        ( *(_result) = *gmtime( (_clock) ), \
          (_result) )

#define localtime_r( _clock, _result ) \
        ( *(_result) = *localtime( (_clock) ), \
          (_result) )
#endif
#define L_RANDMAX 0x7fff

#if defined(__APPLE__)
#include <mach/task.h>
#include <mach/mach.h>
#endif

#include <unistd.h>

#define NANOSEC 1000000000
#define MICROSEC 1000000

static struct spinlock lock;
static struct random {
  unsigned int seed;
} holdrand;

static double
get_time() {
#if  !defined(__APPLE__)
  struct timespec ti;
  clock_gettime(CLOCK_MONOTONIC, &ti);

  int sec = ti.tv_sec & 0xffff;
  int nsec = ti.tv_nsec;

  return (double)sec + (double)nsec / NANOSEC;
#else
  struct task_thread_times_info aTaskInfo;
  mach_msg_type_number_t aTaskInfoCount = TASK_THREAD_TIMES_INFO_COUNT;
  if (KERN_SUCCESS != task_info(mach_task_self(), TASK_THREAD_TIMES_INFO, (task_info_t)&aTaskInfo, &aTaskInfoCount)) {
    return 0;
  }

  int sec = aTaskInfo.user_time.seconds & 0xffff;
  int msec = aTaskInfo.user_time.microseconds;

  return (double)sec + (double)msec / MICROSEC;
#endif
}

static int
_rand(unsigned int* seed) {
  return (((*seed = (*seed) * 214013L + 2531011L) >> 16) & L_RANDMAX);  /* Linear Congruence */
}

static int
lnewrandom(lua_State* L) {
  struct random * c = NULL;
  lua_Integer seed = 1L;
  if (lua_gettop(L) == 1) {
    seed = luaL_checkinteger(L, 1);
  }
  c = (struct random *)lua_newuserdata(L, sizeof(struct random));
  c->seed = (unsigned int)seed;
  return 1;
}

static int
lrand(lua_State* L) {
  lua_Integer low, up;
  double r;
  struct random * c = (struct random *)lua_touserdata(L, 1);
  if (c == NULL) {
    return luaL_argerror(L, 1, "Need an util object");
  }

  /* between 0 and 1 */
  r = (double)_rand(&c->seed) * (1.0 / ((double)L_RANDMAX + 1.0));

  switch (lua_gettop(L) - 1) {  /* check number of arguments */
    case 0: {  /* no arguments */
      lua_pushnumber(L, (lua_Number)r);  /* Number between 0 and 1 */
      return 1;
    }
    case 1: {  /* only upper limit */
      low = 1;
      up = luaL_checkinteger(L, 2);
      break;
    }
    case 2: {  /* lower and upper limits */
      low = luaL_checkinteger(L, 2);
      up = luaL_checkinteger(L, 3);
      break;
    }
    default: return luaL_error(L, "wrong number of arguments");
  }

  /* random integer in the interval [low, up] */
  luaL_argcheck(L, low <= up, 1, "interval is empty");
  luaL_argcheck(L, low >= 0 || up <= LUA_MAXINTEGER + low, 1,
      "interval too large");
  r *= (double)(up - low) + 1.0;
  lua_pushinteger(L, (lua_Integer)r + low);
  return 1;
}

static int
lsrand(lua_State* L) {
  struct random * c = (struct random *)lua_touserdata(L, 1);
  if (c == NULL) {
    return luaL_argerror(L, 1, "Need an util object");
  }
  c->seed = (unsigned int)luaL_checkinteger(L, 2);
  return 0;
}

static int
lpeekseed(lua_State* L) {
  struct random * c = (struct random *)lua_touserdata(L, 1);
  if (c == NULL) {
    return luaL_argerror(L, 1, "Need an util object");
  }
  lua_pushinteger(L, c->seed);
  return 1;
}

static int
lrandom(lua_State* L) {
  lua_Integer low, up;
  double r = 0;

  spinlock_lock(&lock);
  r = (double)_rand(&holdrand.seed) * (1.0 / ((double)L_RANDMAX + 1.0));
  spinlock_unlock(&lock);

  switch (lua_gettop(L)) {  /* check number of arguments */
  case 0: {  /* no arguments */
    lua_pushnumber(L, (lua_Number)r);  /* Number between 0 and 1 */
    lua_pushinteger(L, holdrand.seed);
    return 2;
  }
  case 1: {  /* only upper limit */
    low = 1;
    up = luaL_checkinteger(L, 1);
    break;
  }
  case 2: {  /* lower and upper limits */
    low = luaL_checkinteger(L, 1);
    up = luaL_checkinteger(L, 2);
    break;
  }
  default: return luaL_error(L, "wrong number of arguments");
  }

  /* random integer in the interval [low, up] */
  luaL_argcheck(L, low <= up, 1, "interval is empty");
  luaL_argcheck(L, low >= 0 || up <= LUA_MAXINTEGER + low, 1,
    "interval too large");
  r *= (double)(up - low) + 1.0;
  lua_pushinteger(L, (lua_Integer)r + low);
  lua_pushinteger(L, holdrand.seed);
  return 2;
}

static int
lsrandom(lua_State* L) {
  holdrand.seed = (unsigned int)luaL_checkinteger(L, 1);
  return 0;
}

static int
ltimezone(lua_State* L) {
  // Get the UTC time
  time_t time_utc;
  time(&time_utc);

  // Get the local time
  // Use localtime_r for threads safe
  struct tm tm_local;
  localtime_r(&time_utc, &tm_local);

  // Change tm to time_t
  //time_t time_local = mktime(&tm_local);

  // Get the GMT time
  // Use gmtime_r for threads safe
  struct tm tm_gmt;
  gmtime_r(&time_utc, &tm_gmt);

  // Change tm to time_t
  //time_t time_gmt = mktime(&tm_gmt);

  int time_zone = tm_local.tm_hour - tm_gmt.tm_hour;
  if (time_zone < -12) {
    time_zone += 24;
  }
  else if (time_zone > 12) {
    time_zone -= 24;
  }

  lua_pushinteger(L, time_zone);
  return 1;
}

static int
lgettime(lua_State* L) {
  double ti = get_time();
  lua_pushnumber(L, ti);
  return 1;
}

static int
luuid(lua_State *L) {
  uuid_t __uuid;
  char uuid_str[37];

  uuid_generate(__uuid);
  uuid_unparse_lower(__uuid, uuid_str);
  lua_pushstring(L, uuid_str);
  return 1;
}

static int
Hash(const char * str, int sz) {
  uint32_t hash = 0;
  int i;
  for (i=0;i<sz;i++) {
    hash = hash * 0x83 + (uint8_t)str[i];
  }
  return (hash & 0x7FFFFFFF);
}

static int
lhashcode(lua_State *L) {
  size_t sz = 0;
  const char * str = luaL_checklstring(L, 1, &sz);
  int code = Hash(str,(int)sz);
  lua_pushinteger(L, code);
  return 1;
}

static int
lgettimeofday(lua_State *L) {
  struct timeval tv;
  gettimeofday(&tv, 0);

  int64_t id = tv.tv_sec * 1000 + tv.tv_usec / 1000;
  lua_pushinteger(L, (lua_Integer)id);
  return 1;
}

int
luaopen_util_core(lua_State *L) {
  spinlock_init(&lock);
  luaL_checkversion (L);
  luaL_Reg l[] = {
    { "newrandom", lnewrandom },
    { "rand", lrand },
    { "srand", lsrand },
    { "peekseed", lpeekseed },
    { "random", lrandom },
    { "srandom", lsrandom },
    { "timezone", ltimezone },
    { "gettime", lgettime },
    { "gettimeofday", lgettimeofday },
    { "uuid", luuid },
    { "hashcode", lhashcode },
    { NULL, NULL },
  };

  luaL_newlib (L,l);
  return 1;
}