// Copyright 2017 The Abseil Authors.

//

// 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

//

//      https://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.

// The implementation of the absl::Time class, which is declared in

// //absl/time.h.

//

// The representation for an absl::Time is an absl::Duration offset from the

// epoch.  We use the traditional Unix epoch (1970-01-01 00:00:00 +0000)

// for convenience, but this is not exposed in the API and could be changed.

//

// NOTE: To keep type verbosity to a minimum, the following variable naming

// conventions are used throughout this file.

//

// tz: An absl::TimeZone

// ci: An absl::TimeZone::CivilInfo

// ti: An absl::TimeZone::TimeInfo

// cd: An absl::CivilDay or a cctz::civil_day

// cs: An absl::CivilSecond or a cctz::civil_second

// bd: An absl::Time::Breakdown

// cl: A cctz::time_zone::civil_lookup

// al: A cctz::time_zone::absolute_lookup

#include "absl/time/time.h"

#if defined(_MSC_VER)

#include <winsock2.h>  // for timeval

#endif

#include <cstring>

#include <ctime>

#include <limits>

#include "absl/time/internal/cctz/include/cctz/civil_time.h"

#include "absl/time/internal/cctz/include/cctz/time_zone.h"

namespace cctz = absl::time_internal::cctz;

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace {

inline cctz::time_point<cctz::seconds> unix_epoch() {

  return std::chrono::time_point_cast<cctz::seconds>(

      std::chrono::system_clock::from_time_t(0));

}

// Floors d to the next unit boundary closer to negative infinity.

inline int64_t FloorToUnit(absl::Duration d, absl::Duration unit) {

  absl::Duration rem;

  int64_t q = absl::IDivDuration(d, unit, &rem);

  return (q > 0 || rem >= ZeroDuration() ||

          q == std::numeric_limits<int64_t>::min())

             ? q

             : q - 1;

}

ABSL_INTERNAL_DISABLE_DEPRECATED_DECLARATION_WARNING

inline absl::Time::Breakdown InfiniteFutureBreakdown() {

  absl::Time::Breakdown bd;

  bd.year = std::numeric_limits<int64_t>::max();

  bd.month = 12;

  bd.day = 31;

  bd.hour = 23;

  bd.minute = 59;

  bd.second = 59;

  bd.subsecond = absl::InfiniteDuration();

  bd.weekday = 4;

  bd.yearday = 365;

  bd.offset = 0;

  bd.is_dst = false;

  bd.zone_abbr = "-00";

  return bd;

}

inline absl::Time::Breakdown InfinitePastBreakdown() {

  Time::Breakdown bd;

  bd.year = std::numeric_limits<int64_t>::min();

  bd.month = 1;

  bd.day = 1;

  bd.hour = 0;

  bd.minute = 0;

  bd.second = 0;

  bd.subsecond = -absl::InfiniteDuration();

  bd.weekday = 7;

  bd.yearday = 1;

  bd.offset = 0;

  bd.is_dst = false;

  bd.zone_abbr = "-00";

  return bd;

}

ABSL_INTERNAL_RESTORE_DEPRECATED_DECLARATION_WARNING

inline absl::TimeZone::CivilInfo InfiniteFutureCivilInfo() {

  TimeZone::CivilInfo ci;

  ci.cs = CivilSecond::max();

  ci.subsecond = InfiniteDuration();

  ci.offset = 0;

  ci.is_dst = false;

  ci.zone_abbr = "-00";

  return ci;

}

inline absl::TimeZone::CivilInfo InfinitePastCivilInfo() {

  TimeZone::CivilInfo ci;

  ci.cs = CivilSecond::min();

  ci.subsecond = -InfiniteDuration();

  ci.offset = 0;

  ci.is_dst = false;

  ci.zone_abbr = "-00";

  return ci;

}

ABSL_INTERNAL_DISABLE_DEPRECATED_DECLARATION_WARNING

inline absl::TimeConversion InfiniteFutureTimeConversion() {

  absl::TimeConversion tc;

  tc.pre = tc.trans = tc.post = absl::InfiniteFuture();

  tc.kind = absl::TimeConversion::UNIQUE;

  tc.normalized = true;

  return tc;

}

inline TimeConversion InfinitePastTimeConversion() {

  absl::TimeConversion tc;

  tc.pre = tc.trans = tc.post = absl::InfinitePast();

  tc.kind = absl::TimeConversion::UNIQUE;

  tc.normalized = true;

  return tc;

}

ABSL_INTERNAL_RESTORE_DEPRECATED_DECLARATION_WARNING

// Makes a Time from sec, overflowing to InfiniteFuture/InfinitePast as

// necessary. If sec is min/max, then consult cs+tz to check for overflow.

Time MakeTimeWithOverflow(const cctz::time_point<cctz::seconds>& sec,

                          const cctz::civil_second& cs,

                          const cctz::time_zone& tz,

                          bool* normalized = nullptr) {

  const auto max = cctz::time_point<cctz::seconds>::max();

  const auto min = cctz::time_point<cctz::seconds>::min();

  if (sec == max) {

    const auto al = tz.lookup(max);

    if (cs > al.cs) {

      if (normalized) *normalized = true;

      return absl::InfiniteFuture();

    }

  }

  if (sec == min) {

    const auto al = tz.lookup(min);

    if (cs < al.cs) {

      if (normalized) *normalized = true;

      return absl::InfinitePast();

    }

  }

  const auto hi = (sec - unix_epoch()).count();

  return time_internal::FromUnixDuration(time_internal::MakeDuration(hi));

}

// Returns Mon=1..Sun=7.

inline int MapWeekday(const cctz::weekday& wd) {

  switch (wd) {

    case cctz::weekday::monday:

      return 1;

    case cctz::weekday::tuesday:

      return 2;

    case cctz::weekday::wednesday:

      return 3;

    case cctz::weekday::thursday:

      return 4;

    case cctz::weekday::friday:

      return 5;

    case cctz::weekday::saturday:

      return 6;

    case cctz::weekday::sunday:

      return 7;

  }

  return 1;

}

bool FindTransition(const cctz::time_zone& tz,

                    bool (cctz::time_zone::*find_transition)(

                        const cctz::time_point<cctz::seconds>& tp,

                        cctz::time_zone::civil_transition* trans) const,

                    Time t, TimeZone::CivilTransition* trans) {

  // Transitions are second-aligned, so we can discard any fractional part.

  const auto tp = unix_epoch() + cctz::seconds(ToUnixSeconds(t));

  cctz::time_zone::civil_transition tr;

  if (!(tz.*find_transition)(tp, &tr)) return false;

  trans->from = CivilSecond(tr.from);

  trans->to = CivilSecond(tr.to);

  return true;

}

}  // namespace

//

// Time

//

ABSL_INTERNAL_DISABLE_DEPRECATED_DECLARATION_WARNING

absl::Time::Breakdown Time::In(absl::TimeZone tz) const {

  if (*this == absl::InfiniteFuture()) return InfiniteFutureBreakdown();

  if (*this == absl::InfinitePast()) return InfinitePastBreakdown();

  const auto tp = unix_epoch() + cctz::seconds(time_internal::GetRepHi(rep_));

  const auto al = cctz::time_zone(tz).lookup(tp);

  const auto cs = al.cs;

  const auto cd = cctz::civil_day(cs);

  absl::Time::Breakdown bd;

  bd.year = cs.year();

  bd.month = cs.month();

  bd.day = cs.day();

  bd.hour = cs.hour();

  bd.minute = cs.minute();

  bd.second = cs.second();

  bd.subsecond = time_internal::MakeDuration(0, time_internal::GetRepLo(rep_));

  bd.weekday = MapWeekday(cctz::get_weekday(cd));

  bd.yearday = cctz::get_yearday(cd);

  bd.offset = al.offset;

  bd.is_dst = al.is_dst;

  bd.zone_abbr = al.abbr;

  return bd;

}

ABSL_INTERNAL_RESTORE_DEPRECATED_DECLARATION_WARNING

//

// Conversions from/to other time types.

//

absl::Time FromUDate(double udate) {

  return time_internal::FromUnixDuration(absl::Milliseconds(udate));

}

absl::Time FromUniversal(int64_t universal) {

  return absl::UniversalEpoch() + 100 * absl::Nanoseconds(universal);

}

int64_t ToUnixNanos(Time t) {

  if (time_internal::GetRepHi(time_internal::ToUnixDuration(t)) >= 0 &&

      time_internal::GetRepHi(time_internal::ToUnixDuration(t)) >> 33 == 0) {

    return (time_internal::GetRepHi(time_internal::ToUnixDuration(t)) *

            1000 * 1000 * 1000) +

           (time_internal::GetRepLo(time_internal::ToUnixDuration(t)) / 4);

  }

  return FloorToUnit(time_internal::ToUnixDuration(t), absl::Nanoseconds(1));

}

int64_t ToUnixMicros(Time t) {

  if (time_internal::GetRepHi(time_internal::ToUnixDuration(t)) >= 0 &&

      time_internal::GetRepHi(time_internal::ToUnixDuration(t)) >> 43 == 0) {

    return (time_internal::GetRepHi(time_internal::ToUnixDuration(t)) *

            1000 * 1000) +

           (time_internal::GetRepLo(time_internal::ToUnixDuration(t)) / 4000);

  }

  return FloorToUnit(time_internal::ToUnixDuration(t), absl::Microseconds(1));

}

int64_t ToUnixMillis(Time t) {

  if (time_internal::GetRepHi(time_internal::ToUnixDuration(t)) >= 0 &&

      time_internal::GetRepHi(time_internal::ToUnixDuration(t)) >> 53 == 0) {

    return (time_internal::GetRepHi(time_internal::ToUnixDuration(t)) * 1000) +

           (time_internal::GetRepLo(time_internal::ToUnixDuration(t)) /

            (4000 * 1000));

  }

  return FloorToUnit(time_internal::ToUnixDuration(t), absl::Milliseconds(1));

}

int64_t ToUnixSeconds(Time t) {

  return time_internal::GetRepHi(time_internal::ToUnixDuration(t));

}

time_t ToTimeT(Time t) { return absl::ToTimespec(t).tv_sec; }

double ToUDate(Time t) {

  return absl::FDivDuration(time_internal::ToUnixDuration(t),

                            absl::Milliseconds(1));

}

int64_t ToUniversal(absl::Time t) {

  return absl::FloorToUnit(t - absl::UniversalEpoch(), absl::Nanoseconds(100));

}

absl::Time TimeFromTimespec(timespec ts) {

  return time_internal::FromUnixDuration(absl::DurationFromTimespec(ts));

}

absl::Time TimeFromTimeval(timeval tv) {

  return time_internal::FromUnixDuration(absl::DurationFromTimeval(tv));

}

timespec ToTimespec(Time t) {

  timespec ts;

  absl::Duration d = time_internal::ToUnixDuration(t);

  if (!time_internal::IsInfiniteDuration(d)) {

    ts.tv_sec = static_cast<decltype(ts.tv_sec)>(time_internal::GetRepHi(d));

    if (ts.tv_sec == time_internal::GetRepHi(d)) {  // no time_t narrowing

      ts.tv_nsec = time_internal::GetRepLo(d) / 4;  // floor

      return ts;

    }

  }

  if (d >= absl::ZeroDuration()) {

    ts.tv_sec = std::numeric_limits<time_t>::max();

    ts.tv_nsec = 1000 * 1000 * 1000 - 1;

  } else {

    ts.tv_sec = std::numeric_limits<time_t>::min();

    ts.tv_nsec = 0;

  }

  return ts;

}

timeval ToTimeval(Time t) {

  timeval tv;

  timespec ts = absl::ToTimespec(t);

  tv.tv_sec = static_cast<decltype(tv.tv_sec)>(ts.tv_sec);

  if (tv.tv_sec != ts.tv_sec) {  // narrowing

    if (ts.tv_sec < 0) {

      tv.tv_sec = std::numeric_limits<decltype(tv.tv_sec)>::min();

      tv.tv_usec = 0;

    } else {

      tv.tv_sec = std::numeric_limits<decltype(tv.tv_sec)>::max();

      tv.tv_usec = 1000 * 1000 - 1;

    }

    return tv;

  }

  tv.tv_usec = static_cast<int>(ts.tv_nsec / 1000);  // suseconds_t

  return tv;

}

Time FromChrono(const std::chrono::system_clock::time_point& tp) {

  return time_internal::FromUnixDuration(time_internal::FromChrono(

      tp - std::chrono::system_clock::from_time_t(0)));

}

std::chrono::system_clock::time_point ToChronoTime(absl::Time t) {

  using D = std::chrono::system_clock::duration;

  auto d = time_internal::ToUnixDuration(t);

  if (d < ZeroDuration()) d = Floor(d, FromChrono(D{1}));

  return std::chrono::system_clock::from_time_t(0) +

         time_internal::ToChronoDuration<D>(d);

}

//

// TimeZone

//

absl::TimeZone::CivilInfo TimeZone::At(Time t) const {

  if (t == absl::InfiniteFuture()) return InfiniteFutureCivilInfo();

  if (t == absl::InfinitePast()) return InfinitePastCivilInfo();

  const auto ud = time_internal::ToUnixDuration(t);

  const auto tp = unix_epoch() + cctz::seconds(time_internal::GetRepHi(ud));

  const auto al = cz_.lookup(tp);

  TimeZone::CivilInfo ci;

  ci.cs = CivilSecond(al.cs);

  ci.subsecond = time_internal::MakeDuration(0, time_internal::GetRepLo(ud));

  ci.offset = al.offset;

  ci.is_dst = al.is_dst;

  ci.zone_abbr = al.abbr;

  return ci;

}

absl::TimeZone::TimeInfo TimeZone::At(CivilSecond ct) const {

  const cctz::civil_second cs(ct);

  const auto cl = cz_.lookup(cs);

  TimeZone::TimeInfo ti;

  switch (cl.kind) {

    case cctz::time_zone::civil_lookup::UNIQUE:

      ti.kind = TimeZone::TimeInfo::UNIQUE;

      break;

    case cctz::time_zone::civil_lookup::SKIPPED:

      ti.kind = TimeZone::TimeInfo::SKIPPED;

      break;

    case cctz::time_zone::civil_lookup::REPEATED:

      ti.kind = TimeZone::TimeInfo::REPEATED;

      break;

  }

  ti.pre = MakeTimeWithOverflow(cl.pre, cs, cz_);

  ti.trans = MakeTimeWithOverflow(cl.trans, cs, cz_);

  ti.post = MakeTimeWithOverflow(cl.post, cs, cz_);

  return ti;

}

bool TimeZone::NextTransition(Time t, CivilTransition* trans) const {

  return FindTransition(cz_, &cctz::time_zone::next_transition, t, trans);

}

bool TimeZone::PrevTransition(Time t, CivilTransition* trans) const {

  return FindTransition(cz_, &cctz::time_zone::prev_transition, t, trans);

}

//

// Conversions involving time zones.

//

ABSL_INTERNAL_DISABLE_DEPRECATED_DECLARATION_WARNING

absl::TimeConversion ConvertDateTime(int64_t year, int mon, int day, int hour,

                                     int min, int sec, TimeZone tz) {

  // Avoids years that are too extreme for CivilSecond to normalize.

  if (year > 300000000000) return InfiniteFutureTimeConversion();

  if (year < -300000000000) return InfinitePastTimeConversion();

  const CivilSecond cs(year, mon, day, hour, min, sec);

  const auto ti = tz.At(cs);

  TimeConversion tc;

  tc.pre = ti.pre;

  tc.trans = ti.trans;

  tc.post = ti.post;

  switch (ti.kind) {

    case TimeZone::TimeInfo::UNIQUE:

      tc.kind = TimeConversion::UNIQUE;

      break;

    case TimeZone::TimeInfo::SKIPPED:

      tc.kind = TimeConversion::SKIPPED;

      break;

    case TimeZone::TimeInfo::REPEATED:

      tc.kind = TimeConversion::REPEATED;

      break;

  }

  tc.normalized = false;

  if (year != cs.year() || mon != cs.month() || day != cs.day() ||

      hour != cs.hour() || min != cs.minute() || sec != cs.second()) {

    tc.normalized = true;

  }

  return tc;

}

ABSL_INTERNAL_RESTORE_DEPRECATED_DECLARATION_WARNING

absl::Time FromTM(const struct tm& tm, absl::TimeZone tz) {

  civil_year_t tm_year = tm.tm_year;

  // Avoids years that are too extreme for CivilSecond to normalize.

  if (tm_year > 300000000000ll) return InfiniteFuture();

  if (tm_year < -300000000000ll) return InfinitePast();

  int tm_mon = tm.tm_mon;

  if (tm_mon == std::numeric_limits<int>::max()) {

    tm_mon -= 12;

    tm_year += 1;

  }

  const auto ti = tz.At(CivilSecond(tm_year + 1900, tm_mon + 1, tm.tm_mday,

                                    tm.tm_hour, tm.tm_min, tm.tm_sec));

  return tm.tm_isdst == 0 ? ti.post : ti.pre;

}

struct tm ToTM(absl::Time t, absl::TimeZone tz) {

  struct tm tm = {};

  const auto ci = tz.At(t);

  const auto& cs = ci.cs;

  tm.tm_sec = cs.second();

  tm.tm_min = cs.minute();

  tm.tm_hour = cs.hour();

  tm.tm_mday = cs.day();

  tm.tm_mon = cs.month() - 1;

  // Saturates tm.tm_year in cases of over/underflow, accounting for the fact

  // that tm.tm_year is years since 1900.

  if (cs.year() < std::numeric_limits<int>::min() + 1900) {

    tm.tm_year = std::numeric_limits<int>::min();

  } else if (cs.year() > std::numeric_limits<int>::max()) {

    tm.tm_year = std::numeric_limits<int>::max() - 1900;

  } else {

    tm.tm_year = static_cast<int>(cs.year() - 1900);

  }

  switch (GetWeekday(cs)) {

    case Weekday::sunday:

      tm.tm_wday = 0;

      break;

    case Weekday::monday:

      tm.tm_wday = 1;

      break;

    case Weekday::tuesday:

      tm.tm_wday = 2;

      break;

    case Weekday::wednesday:

      tm.tm_wday = 3;

      break;

    case Weekday::thursday:

      tm.tm_wday = 4;

      break;

    case Weekday::friday:

      tm.tm_wday = 5;

      break;

    case Weekday::saturday:

      tm.tm_wday = 6;

      break;

  }

  tm.tm_yday = GetYearDay(cs) - 1;

  tm.tm_isdst = ci.is_dst ? 1 : 0;

  return tm;

}

ABSL_NAMESPACE_END

}  // namespace absl