#ifdef USE_DATETIME
#include <regex>
#endif

#include "helpers.h"
#include "time.h"  // NOLINT

namespace esphome {

bool is_leap_year(uint32_t year) { return (year % 4) == 0 && ((year % 100) != 0 || (year % 400) == 0); }

uint8_t days_in_month(uint8_t month, uint16_t year) {
  static const uint8_t DAYS_IN_MONTH[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  uint8_t days = DAYS_IN_MONTH[month];
  if (month == 2 && is_leap_year(year))
    return 29;
  return days;
}

size_t ESPTime::strftime(char *buffer, size_t buffer_len, const char *format) {
  struct tm c_tm = this->to_c_tm();
  return ::strftime(buffer, buffer_len, format, &c_tm);
}
ESPTime ESPTime::from_c_tm(struct tm *c_tm, time_t c_time) {
  ESPTime res{};
  res.second = uint8_t(c_tm->tm_sec);
  res.minute = uint8_t(c_tm->tm_min);
  res.hour = uint8_t(c_tm->tm_hour);
  res.day_of_week = uint8_t(c_tm->tm_wday + 1);
  res.day_of_month = uint8_t(c_tm->tm_mday);
  res.day_of_year = uint16_t(c_tm->tm_yday + 1);
  res.month = uint8_t(c_tm->tm_mon + 1);
  res.year = uint16_t(c_tm->tm_year + 1900);
  res.is_dst = bool(c_tm->tm_isdst);
  res.timestamp = c_time;
  return res;
}
struct tm ESPTime::to_c_tm() {
  struct tm c_tm {};
  c_tm.tm_sec = this->second;
  c_tm.tm_min = this->minute;
  c_tm.tm_hour = this->hour;
  c_tm.tm_mday = this->day_of_month;
  c_tm.tm_mon = this->month - 1;
  c_tm.tm_year = this->year - 1900;
  c_tm.tm_wday = this->day_of_week - 1;
  c_tm.tm_yday = this->day_of_year - 1;
  c_tm.tm_isdst = this->is_dst;
  return c_tm;
}
std::string ESPTime::strftime(const std::string &format) {
  std::string timestr;
  timestr.resize(format.size() * 4);
  struct tm c_tm = this->to_c_tm();
  size_t len = ::strftime(&timestr[0], timestr.size(), format.c_str(), &c_tm);
  while (len == 0) {
    if (timestr.size() >= 128) {
      // strftime has failed for reasons unrelated to the size of the buffer
      // so return a formatting error
      return "ERROR";
    }
    timestr.resize(timestr.size() * 2);
    len = ::strftime(&timestr[0], timestr.size(), format.c_str(), &c_tm);
  }
  timestr.resize(len);
  return timestr;
}

#ifdef USE_DATETIME

bool ESPTime::strptime(const std::string &time_to_parse, ESPTime &esp_time) {
  // clang-format off
  std::regex dt_regex(R"(^
    (
      (\d{4})-(\d{1,2})-(\d{1,2})
      (?:\s(?=.+))
    )?
    (
      (\d{1,2}):(\d{2})
      (?::(\d{2}))?
    )?
  $)");
  // clang-format on

  std::smatch match;
  if (std::regex_match(time_to_parse, match, dt_regex) == 0)
    return false;

  if (match[1].matched) {  // Has date parts

    esp_time.year = parse_number<uint16_t>(match[2].str()).value_or(0);
    esp_time.month = parse_number<uint8_t>(match[3].str()).value_or(0);
    esp_time.day_of_month = parse_number<uint8_t>(match[4].str()).value_or(0);
  }
  if (match[5].matched) {  // Has time parts

    esp_time.hour = parse_number<uint8_t>(match[6].str()).value_or(0);
    esp_time.minute = parse_number<uint8_t>(match[7].str()).value_or(0);
    if (match[8].matched) {
      esp_time.second = parse_number<uint8_t>(match[8].str()).value_or(0);
    } else {
      esp_time.second = 0;
    }
  }

  return true;
}

#endif

void ESPTime::increment_second() {
  this->timestamp++;
  if (!increment_time_value(this->second, 0, 60))
    return;

  // second roll-over, increment minute
  if (!increment_time_value(this->minute, 0, 60))
    return;

  // minute roll-over, increment hour
  if (!increment_time_value(this->hour, 0, 24))
    return;

  // hour roll-over, increment day
  increment_time_value(this->day_of_week, 1, 8);

  if (increment_time_value(this->day_of_month, 1, days_in_month(this->month, this->year) + 1)) {
    // day of month roll-over, increment month
    increment_time_value(this->month, 1, 13);
  }

  uint16_t days_in_year = (this->year % 4 == 0) ? 366 : 365;
  if (increment_time_value(this->day_of_year, 1, days_in_year + 1)) {
    // day of year roll-over, increment year
    this->year++;
  }
}
void ESPTime::increment_day() {
  this->timestamp += 86400;

  // increment day
  increment_time_value(this->day_of_week, 1, 8);

  if (increment_time_value(this->day_of_month, 1, days_in_month(this->month, this->year) + 1)) {
    // day of month roll-over, increment month
    increment_time_value(this->month, 1, 13);
  }

  uint16_t days_in_year = (this->year % 4 == 0) ? 366 : 365;
  if (increment_time_value(this->day_of_year, 1, days_in_year + 1)) {
    // day of year roll-over, increment year
    this->year++;
  }
}
void ESPTime::recalc_timestamp_utc(bool use_day_of_year) {
  time_t res = 0;

  if (!this->fields_in_range()) {
    this->timestamp = -1;
    return;
  }

  for (int i = 1970; i < this->year; i++)
    res += is_leap_year(i) ? 366 : 365;

  if (use_day_of_year) {
    res += this->day_of_year - 1;
  } else {
    for (int i = 1; i < this->month; i++)
      res += days_in_month(i, this->year);

    res += this->day_of_month - 1;
  }

  res *= 24;
  res += this->hour;
  res *= 60;
  res += this->minute;
  res *= 60;
  res += this->second;
  this->timestamp = res;
}

int32_t ESPTime::timezone_offset() {
  int32_t offset = 0;
  time_t now = ::time(nullptr);
  auto local = ESPTime::from_epoch_local(now);
  auto utc = ESPTime::from_epoch_utc(now);
  bool negative = utc.hour > local.hour && local.day_of_year <= utc.day_of_year;

  if (utc.minute > local.minute) {
    local.minute += 60;
    local.hour -= 1;
  }
  offset += (local.minute - utc.minute) * 60;

  if (negative) {
    offset -= (utc.hour - local.hour) * 3600;
  } else {
    if (utc.hour > local.hour) {
      local.hour += 24;
    }
    offset += (local.hour - utc.hour) * 3600;
  }
  return offset;
}

bool ESPTime::operator<(ESPTime other) { return this->timestamp < other.timestamp; }
bool ESPTime::operator<=(ESPTime other) { return this->timestamp <= other.timestamp; }
bool ESPTime::operator==(ESPTime other) { return this->timestamp == other.timestamp; }
bool ESPTime::operator>=(ESPTime other) { return this->timestamp >= other.timestamp; }
bool ESPTime::operator>(ESPTime other) { return this->timestamp > other.timestamp; }

template<typename T> bool increment_time_value(T &current, uint16_t begin, uint16_t end) {
  current++;
  if (current >= end) {
    current = begin;
    return true;
  }
  return false;
}

}  // namespace esphome