<?php
  
  /**
   * This file is part of the Carbon package.
   *
   * (c) Brian Nesbitt <brian@nesbot.com>
   *
   * For the full copyright and license information, please view the LICENSE
   * file that was distributed with this source code.
   */
  
  namespace Carbon\Traits;
  
  /**
   * Trait Week.
   *
   * week and ISO week number, year and count in year.
   *
   * Depends on the following properties:
   *
   * @property int $daysInYear
   * @property int $dayOfWeek
   * @property int $dayOfYear
   * @property int $year
   *
   * Depends on the following methods:
   *
   * @method static addWeeks(int $weeks = 1)
   * @method static copy()
   * @method static dayOfYear(int $dayOfYear)
   * @method string getTranslationMessage(string $key, ?string $locale = null, ?string $default = null, $translator = null)
   * @method static next(int|string $day = null)
   * @method static startOfWeek(int $day = 1)
   * @method static subWeeks(int $weeks = 1)
   * @method static year(int $year = null)
   */
  trait Week
  {
      /**
       * Set/get the week number of year using given first day of week and first
       * day of year included in the first week. Or use ISO format if no settings
       * given.
       *
       * @param int|null $year      if null, act as a getter, if not null, set the year and return current instance.
       * @param int|null $dayOfWeek first date of week from 0 (Sunday) to 6 (Saturday)
       * @param int|null $dayOfYear first day of year included in the week #1
       *
       * @return int|static
       */
      public function isoWeekYear($year = null, $dayOfWeek = null, $dayOfYear = null)
      {
          return $this->weekYear(
              $year,
              $dayOfWeek ?? 1,
              $dayOfYear ?? 4
          );
      }
  
      /**
       * Set/get the week number of year using given first day of week and first
       * day of year included in the first week. Or use US format if no settings
       * given (Sunday / Jan 6).
       *
       * @param int|null $year      if null, act as a getter, if not null, set the year and return current instance.
       * @param int|null $dayOfWeek first date of week from 0 (Sunday) to 6 (Saturday)
       * @param int|null $dayOfYear first day of year included in the week #1
       *
       * @return int|static
       */
      public function weekYear($year = null, $dayOfWeek = null, $dayOfYear = null)
      {
          $dayOfWeek = $dayOfWeek ?? $this->getTranslationMessage('first_day_of_week') ?? 0;
          $dayOfYear = $dayOfYear ?? $this->getTranslationMessage('day_of_first_week_of_year') ?? 1;
  
          if ($year !== null) {
              $year = (int) round($year);
  
              if ($this->weekYear(null, $dayOfWeek, $dayOfYear) === $year) {
                  return $this->avoidMutation();
              }
  
              $week = $this->week(null, $dayOfWeek, $dayOfYear);
              $day = $this->dayOfWeek;
              $date = $this->year($year);
              switch ($date->weekYear(null, $dayOfWeek, $dayOfYear) - $year) {
                  case 1:
                      $date = $date->subWeeks(26);
  
                      break;
                  case -1:
                      $date = $date->addWeeks(26);
  
                      break;
              }
  
              $date = $date->addWeeks($week - $date->week(null, $dayOfWeek, $dayOfYear))->startOfWeek($dayOfWeek);
  
              if ($date->dayOfWeek === $day) {
                  return $date;
              }
  
              return $date->next($day);
          }
  
          $year = $this->year;
          $day = $this->dayOfYear;
          $date = $this->avoidMutation()->dayOfYear($dayOfYear)->startOfWeek($dayOfWeek);
  
          if ($date->year === $year && $day < $date->dayOfYear) {
              return $year - 1;
          }
  
          $date = $this->avoidMutation()->addYear()->dayOfYear($dayOfYear)->startOfWeek($dayOfWeek);
  
          if ($date->year === $year && $day >= $date->dayOfYear) {
              return $year + 1;
          }
  
          return $year;
      }
  
      /**
       * Get the number of weeks of the current week-year using given first day of week and first
       * day of year included in the first week. Or use ISO format if no settings
       * given.
       *
       * @param int|null $dayOfWeek first date of week from 0 (Sunday) to 6 (Saturday)
       * @param int|null $dayOfYear first day of year included in the week #1
       *
       * @return int
       */
      public function isoWeeksInYear($dayOfWeek = null, $dayOfYear = null)
      {
          return $this->weeksInYear(
              $dayOfWeek ?? 1,
              $dayOfYear ?? 4
          );
      }
  
      /**
       * Get the number of weeks of the current week-year using given first day of week and first
       * day of year included in the first week. Or use US format if no settings
       * given (Sunday / Jan 6).
       *
       * @param int|null $dayOfWeek first date of week from 0 (Sunday) to 6 (Saturday)
       * @param int|null $dayOfYear first day of year included in the week #1
       *
       * @return int
       */
      public function weeksInYear($dayOfWeek = null, $dayOfYear = null)
      {
          $dayOfWeek = $dayOfWeek ?? $this->getTranslationMessage('first_day_of_week') ?? 0;
          $dayOfYear = $dayOfYear ?? $this->getTranslationMessage('day_of_first_week_of_year') ?? 1;
          $year = $this->year;
          $start = $this->avoidMutation()->dayOfYear($dayOfYear)->startOfWeek($dayOfWeek);
          $startDay = $start->dayOfYear;
          if ($start->year !== $year) {
              $startDay -= $start->daysInYear;
          }
          $end = $this->avoidMutation()->addYear()->dayOfYear($dayOfYear)->startOfWeek($dayOfWeek);
          $endDay = $end->dayOfYear;
          if ($end->year !== $year) {
              $endDay += $this->daysInYear;
          }
  
          return (int) round(($endDay - $startDay) / 7);
      }
  
      /**
       * Get/set the week number using given first day of week and first
       * day of year included in the first week. Or use US format if no settings
       * given (Sunday / Jan 6).
       *
       * @param int|null $week
       * @param int|null $dayOfWeek
       * @param int|null $dayOfYear
       *
       * @return int|static
       */
      public function week($week = null, $dayOfWeek = null, $dayOfYear = null)
      {
          $date = $this;
          $dayOfWeek = $dayOfWeek ?? $this->getTranslationMessage('first_day_of_week') ?? 0;
          $dayOfYear = $dayOfYear ?? $this->getTranslationMessage('day_of_first_week_of_year') ?? 1;
  
          if ($week !== null) {
              return $date->addWeeks(round($week) - $this->week(null, $dayOfWeek, $dayOfYear));
          }
  
          $start = $date->avoidMutation()->dayOfYear($dayOfYear)->startOfWeek($dayOfWeek);
          $end = $date->avoidMutation()->startOfWeek($dayOfWeek);
          if ($start > $end) {
              $start = $start->subWeeks(26)->dayOfYear($dayOfYear)->startOfWeek($dayOfWeek);
          }
          $week = (int) ($start->diffInDays($end) / 7 + 1);
  
          return $week > $end->weeksInYear($dayOfWeek, $dayOfYear) ? 1 : $week;
      }
  
      /**
       * Get/set the week number using given first day of week and first
       * day of year included in the first week. Or use ISO format if no settings
       * given.
       *
       * @param int|null $week
       * @param int|null $dayOfWeek
       * @param int|null $dayOfYear
       *
       * @return int|static
       */
      public function isoWeek($week = null, $dayOfWeek = null, $dayOfYear = null)
      {
          return $this->week(
              $week,
              $dayOfWeek ?? 1,
              $dayOfYear ?? 4
          );
      }
  }