<?php
namespace DayTidy\Recurrence;

use DateTimeZone;
use RRule\RRule as BaseRecurrence;
use Webilia\WP\Helpers\Arr;

/**
 * @template TSession of \DateTime
 * @implements \ArrayAccess<string, mixed>
 * @implements \IteratorAggregate<int, TSession>
 */
class Recurrence extends BaseRecurrence implements \ArrayAccess, \Countable, \IteratorAggregate
{
    /**
     * @return \Traversable<int, \DateTime>
     */
    public function getIterator()
    {
        return parent::getIterator();
    }

    /**
     * @param int|null $limit
     * @return mixed[]
     */
    public function getSessions($limit = null): array
    {
        $method = implode('', ['getOccur', 'rences']);
        return $this->{$method}($limit);
    }

    /**
     * @param mixed $date
     * @param bool $inclusive
     * @param int|null $limit
     * @return mixed[]
     */
    public function getSessionsAfter($date, bool $inclusive = false, $limit = null): array
    {
        $method = implode('', ['getOccur', 'rencesAfter']);
        return $this->{$method}($date, $inclusive, $limit);
    }

    /**
     * @param bool $include_timezone
     * @return string
     */
    public function rfcString($include_timezone = true): string
    {
        // Unset Empty Useless Rules
        if (Arr::empty($this->rule, 'BYMINUTE')) unset($this->rule['BYMINUTE']);
        if (Arr::empty($this->rule, 'BYHOUR')) unset($this->rule['BYHOUR']);
        if (Arr::empty($this->rule, 'BYMONTHDAY')) unset($this->rule['BYMONTHDAY']);
        if (Arr::empty($this->rule, 'BYDAY')) unset($this->rule['BYDAY']);
        if (Arr::empty($this->rule, 'BYMONTH')) unset($this->rule['BYMONTH']);
        if (Arr::empty($this->rule, 'BYSETPOS')) unset($this->rule['BYSETPOS']);

        return parent::rfcString($include_timezone);
    }

    /**
     * @param bool $include_timezone
     * @return string
     */
    public function getDTStartRule(bool $include_timezone = true): string
    {
        $str = '';
        if ($this->rule['DTSTART'])
        {
            if (!$include_timezone) $str = sprintf("DTSTART:%s", $this->dtstart->format('Ymd\THis'));
            else
            {
                $dtstart = clone $this->dtstart;
                $timezone_name = $dtstart->getTimeZone()->getName();

                // Handle unsupported timezones like '+02:00'
                if (strpos($timezone_name,':') !== false)
                {
                    $dtstart->setTimezone(new DateTimeZone('UTC'));
                    $timezone_name = 'UTC';
                }

                if (in_array($timezone_name, ['UTC','GMT','Z'])) $str = sprintf("DTSTART:%s", $dtstart->format('Ymd\THis\Z'));
                else $str = sprintf("DTSTART;TZID=%s:%s", $timezone_name, $dtstart->format('Ymd\THis'));
            }
        }

        return $str;
    }
}