<?php
namespace nulib\php\time;

use DateTimeImmutable;
use DateTimeInterface;
use DateTimeZone;
use InvalidArgumentException;

/**
 * Class DateTime: une date et une heure
 *
 * @property-read int $year
 * @property-read int $month
 * @property-read int $day
 * @property-read int $hour
 * @property-read int $minute
 * @property-read int $second
 * @property-read int $wday
 * @property-read int $wnum
 * @property-read string $timezone
 * @property-read string $datetime
 * @property-read string $date
 * @property-read string $Ymd
 * @property-read string $YmdHMS
 * @property-read string $YmdHMSZ
 */
class DateTime extends \DateTimeImmutable {
  use _TDateTime;

  const DEFAULT_FORMAT = "d/m/Y H:i:s";

  /**
   * $datetime est une spécification de date, avec ou sans fuseau horaire
   *
   * si $datetime ne contient pas de fuseau horaire, elle est réputée être dans
   * le fuseau $timezone, qui est le fuseau local par défaut
   *
   * si $datetime contient un fuseau horaire et si $forceTimezone est vrai,
   * alors $datetime est réexprimée dans le fuseau $timezone.
   * si $timezone est null alors $forceTimezone vaut vrai par défaut.
   *
   * datetime         | timezone | forceTimezone | résultat
   * -----------------|----------|---------------|---------
   * datetime         | any      | any           | datetime+localtz
   * datetime+origtz  | null     | null          | datetime+localtz
   * datetime+origtz  | null     | true          | datetime+localtz
   * datetime+origtz  | null     | false         | datetime+origtz
   * datetime+origtz  | newtz    | null          | datetime+origtz
   * datetime+origtz  | newtz    | false         | datetime+origtz
   * datetime+origtz  | newtz    | true          | datetime+newtz
   */
  function __construct($datetime=null, DateTimeZone $timezone=null, ?bool $forceTimezone=null) {
    $resetTimezone = null;
    $forceTimezone ??= $timezone === null;
    if ($forceTimezone) {
      $resetTimezone = $timezone ?? new DateTimeZone(date_default_timezone_get());
      $timezone = null;
    }

    $datetime ??= "now";
    if ($datetime instanceof DateTimeImmutable) {
      $datetime = \DateTime::createFromImmutable($datetime);
    } elseif ($datetime instanceof \DateTime) {
      $datetime = clone $datetime;
      #XXX sous PHP 8, remplacer les deux commandes ci-dessus par
      # DateTime::createFromInterface

    } elseif (is_int($datetime)) {
      $timestamp = $datetime;
      $datetime = new \DateTime("now", $timezone);
      $datetime->setTimestamp($timestamp);

    } elseif (is_string($datetime)) {
      $Y = $H = $Z = null;
      if (preg_match(_utils::DMY_PATTERN, $datetime, $ms)) {
        $Y = $ms[3] ?? null;
        if ($Y !== null) $Y = _utils::fix_any_year(intval($Y));
        else $Y = intval(date("Y"));
        $m = intval($ms[2]);
        $d = intval($ms[1]);
      } elseif (preg_match(_utils::YMD_PATTERN, $datetime, $ms)) {
        $Y = $ms[1];
        if (strlen($Y) == 2) $Y = _utils::fix_any_year(intval($ms[1]));
        else $Y = intval($Y);
        $m = intval($ms[2]);
        $d = intval($ms[3]);
      } elseif (preg_match(_utils::DMYHIS_PATTERN, $datetime, $ms)) {
        $Y = $ms[3];
        if ($Y !== null) $Y = _utils::fix_any_year(intval($Y));
        else $Y = intval(date("Y"));
        $m = intval($ms[2]);
        $d = intval($ms[1]);
        $H = intval($ms[4]);
        $M = intval($ms[5]);
        $S = intval($ms[6] ?? 0);
      } elseif (preg_match(_utils::YMDHISZ_PATTERN, $datetime, $ms)) {
        $Y = $ms[1];
        if (strlen($Y) == 2) $Y = _utils::fix_any_year(intval($ms[1]));
        else $Y = intval($Y);
        $m = intval($ms[2]);
        $d = intval($ms[3]);
        $H = intval($ms[4]);
        $M = intval($ms[5]);
        $S = intval($ms[6] ?? 0);
        $Z = $ms[7] ?? null;
      }
      if ($Y !== null) {
        if ($H === null) $datetime = sprintf("%04d-%02d-%02d", $Y, $m, $d);
        else $datetime = sprintf("%04d-%02d-%02d %02d:%02d:%02d", $Y, $m, $d, $H, $M, $S);
        if ($Z !== null) $timezone = new DateTimeZone(_utils::fix_z($Z));
      }
      $datetime = new \DateTime($datetime, $timezone);

    } elseif (is_array($datetime) && ($datetime = _utils::parse_array($datetime)) !== null) {
      [$Y, $m, $d, $H, $M, $S, $Z] = $datetime;
      if ($H === null && $M === null && $S === null) {
        $datetime = sprintf("%04d-%02d-%02d", $Y, $m, $d);
      } else {
        $datetime = sprintf("%04d-%02d-%02d %02d:%02d:%02d", $Y, $m, $d, $H ?? 0, $M ?? 0, $S ?? 0);
      }
      if ($Z !== null) $timezone = new DateTimeZone(_utils::fix_z($Z));
      $datetime = new \DateTime($datetime, $timezone);
    }

    if ($datetime instanceof DateTimeInterface) {
      if ($resetTimezone !== null) $datetime->setTimezone($resetTimezone);
      $datetime = $this->fix($datetime);
      parent::__construct($datetime->format("Y-m-d\\TH:i:s.uP"));
    }  else {
      throw new InvalidArgumentException("datetime must be a string or an instance of DateTimeInterface");
    }
  }

  protected function fix(DateTimeInterface $datetime): DateTimeInterface {
    return $datetime;
  }

  /** @return MutableDateTime|self */
  function clone(bool $mutable=false): DateTimeInterface {
    if ($mutable) return new MutableDateTime($this);
    else return clone $this;
  }

  /**
   * modifier cet objet pour que l'heure soit à 00:00:00 ce qui le rend propice
   * à l'utilisation comme borne inférieure d'une période
   */
  function getStartOfDay(): self {
    return new static($this->setTime(0, 0));
  }

  /**
   * modifier cet objet pour que l'heure soit à 23:59:59.999999 ce qui le rend
   * propice à l'utilisation comme borne supérieure d'une période
   */
  function getEndOfDay(): self {
    return new static($this->setTime(23, 59, 59, 999999));
  }

  function getPrevDay(int $nbDays=1, bool $skipWeekend=false): self {
    if ($nbDays == 1 && $skipWeekend && $this->wday == 1) {
      $nbDays = 3;
    }
    return new static($this->sub(new \DateInterval("P${nbDays}D")));
  }

  function getNextDay(int $nbDays=1, bool $skipWeekend=false): self {
    if ($nbDays == 1 && $skipWeekend) {
      $wday = $this->wday;
      if ($wday > 5) $nbDays = 8 - $this->wday;
    }
    return new static($this->add(new \DateInterval("P${nbDays}D")));
  }
}