<?php

class CalendarMonth implements ICalendarSegment
{
    private $month;
    private $year;
    private $timezone;
    private $firstDay;
    private $lastDay;

    /**
     * @var array|CalendarWeek[]
     */
    private $weeks = [];

    /**
     * @var array|CalendarReservation[]
     */
    private $reservations = [];

    public function __construct($month, $year, $timezone)
    {
        $this->month = $month;
        $this->year = $year;
        $this->timezone = $timezone;

        $this->firstDay = Date::Create($this->year, $this->month, 1, 0, 0, 0, $this->timezone);
        $this->lastDay = $this->firstDay->AddMonths(1);

        $daysInMonth = $this->lastDay->AddDays(-1)->Day();

        $weeks = floor(($daysInMonth + $this->firstDay->Weekday()-1) / 7);

        for ($week = 0; $week <= $weeks; $week++) {
            $this->weeks[$week] = new CalendarWeek($timezone);
        }

        for ($dayOffset = 0; $dayOffset < $daysInMonth; $dayOffset++) {
            $currentDay = $this->firstDay->AddDays($dayOffset);
            $currentWeek = $this->GetWeekNumber($currentDay);
            $calendarDay = new CalendarDay($currentDay);

            $this->weeks[$currentWeek]->AddDay($calendarDay);
        }
    }

    public function Weeks()
    {
        return $this->weeks;
    }

    public function FirstDay()
    {
        return $this->firstDay;
    }

    public function LastDay()
    {
        return $this->lastDay;
    }

    /**
     * @param $reservations array|CalendarReservation[]
     * @return void
     */
    public function AddReservations($reservations)
    {
        /** @var $reservation CalendarReservation */
        foreach ($reservations as $reservation) {
            $this->reservations[] = $reservation;

            /** @var $week CalendarWeek */
            foreach ($this->Weeks() as $week) {
                $week->AddReservation($reservation);
            }
        }
    }

    /**
     * @param Date $day
     * @return int
     */
    private function GetWeekNumber(Date $day)
    {
        $firstWeekday = $this->firstDay->Weekday();

        $week = floor($day->Day()/7);

        if ($day->Day()%7==0) {
            $week = ($day->Day()-1)/7;

            if ($day->Day() <= 7) {
                $week++;
            }
        } else {
            if ($day->Weekday() < $firstWeekday) {
                $week++;
            }
        }

        return intval($week);
    }


    /**
     * @return string|CalendarTypes
     */
    public function GetType()
    {
        return CalendarTypes::Month;
    }

    /**
     * @return Date
     */
    public function GetPreviousDate()
    {
        return $this->FirstDay()->AddMonths(-1);
    }

    /**
     * @return Date
     */
    public function GetNextDate()
    {
        return $this->FirstDay()->AddMonths(1);
    }

    /**
     * @return array|CalendarReservation[]
     */
    public function Reservations()
    {
        return $this->reservations;
    }
}
