<?php

class Studiensemester_model extends DB_Model
{
	/**
	 * Constructor
	 */
	public function __construct()
	{
		parent::__construct();
		$this->dbTable = 'public.tbl_studiensemester';
		$this->pk = 'studiensemester_kurzbz';
		$this->hasSequence = false;
	}

	// Get next study semester
	public function getNext()
    {
        $query = '
            SELECT *
            FROM
                public.tbl_studiensemester
            WHERE
                start > now()
            ORDER BY start
            LIMIT 1;
        ';

        return $this->execQuery($query);
    }

	/**
	 * getLastOrAktSemester
	 */
	public function getLastOrAktSemester($days = 60)
	{
		if (!is_numeric($days))
		{
			$days = 60;
		}

		$query = 'SELECT studiensemester_kurzbz, start, ende
					FROM public.tbl_studiensemester
				   WHERE start < NOW() - \'' . $days . ' DAYS\'::INTERVAL
				ORDER BY start DESC
				   LIMIT 1';

		return $this->execQuery($query);
	}

	/**
	 * getNextOrAktSemester
	 * 62 days - in july and august, semester after summer is returned
	 */
	public function getAktOrNextSemester($days = 62)
	{
		if (!is_numeric($days))
		{
			$days = 62;
		}

		$query = 'SELECT studiensemester_kurzbz, start, ende
					FROM public.tbl_studiensemester
					WHERE start < NOW() + \'' . $days . ' DAYS\':: INTERVAL
					ORDER BY start DESC
					LIMIT 1';

		return $this->execQuery($query);
	}

	/**
	 * getNextFrom
	 */
	public function getNextFrom($studiensemester_kurzbz)
	{
		$query = 'SELECT studiensemester_kurzbz,
						 start,
						 ende
					FROM public.tbl_studiensemester
				   WHERE start >= (
									SELECT ende
									  FROM public.tbl_studiensemester
									 WHERE studiensemester_kurzbz = ?
								)
				ORDER BY start
				   LIMIT 1';

		return $this->execQuery($query, array($studiensemester_kurzbz));
	}

	/**
	 * getPreviousFrom
	 */
	public function getPreviousFrom($studiensemester_kurzbz)
	{
		$query = 'SELECT studiensemester_kurzbz,
						 start,
						 ende
					FROM public.tbl_studiensemester
				   WHERE ende <= (
									SELECT start
									  FROM public.tbl_studiensemester
									 WHERE studiensemester_kurzbz = ?
								)
				ORDER BY start DESC
				   LIMIT 1';

		return $this->execQuery($query, array($studiensemester_kurzbz));
	}

	/**
	 * getNearest
	 */
	public function getNearest($semester = '')
	{
		$query = 'SELECT studiensemester_kurzbz,
						 start,
						 ende
					FROM public.vw_studiensemester';

		if (is_numeric($semester))
		{
			if ($semester % 2 == 0)
			{
				$ss = 'SS';
			}
			else
			{
				$ss = 'WS';
			}

			$query .= ' WHERE SUBSTRING(studiensemester_kurzbz FROM 1 FOR 2) = \'' . $ss . '\'';
		}

		$query .= ' ORDER BY delta LIMIT 1';

		return $this->execQuery($query);
	}

	/**
	 * Gets valid Ausbildungssemester of a Studiensemester with a Studiengang
	 * @param $studiensemester_kurzbz
	 * @param $studiengang_kz
	 * @return array|null
	 */
	public function getAusbildungssemesterByStudiensemesterAndStudiengang($studiensemester_kurzbz, $studiengang_kz)
	{
		$query = "SELECT DISTINCT semester
							FROM lehre.tbl_studienplan
							JOIN lehre.tbl_studienordnung USING(studienordnung_id)
							JOIN lehre.tbl_studienplan_semester USING(studienplan_id)
							WHERE tbl_studienplan_semester.studiensemester_kurzbz = ?
							AND tbl_studienordnung.studiengang_kz = ?
							ORDER BY semester";

		return $this->execQuery($query, array($studiensemester_kurzbz, $studiengang_kz));
	}

	/**
	 * Gets all Studiensemester between two dates
	 * @param $from
	 * @param $to
	 * @return array|null
	 */
	public function getByDate($from, $to)
	{
		if (date_format(date_create($from), 'Y-m-d') > (date_format(date_create($to), 'Y-m-d')))
			return success(array());

		$query = "SELECT *
							FROM public.tbl_studiensemester
							WHERE
							  (ende > ?::date AND start < ?::date)
							  OR start = ?::date
							  OR ende = ?::date
							ORDER BY start DESC";

		return $this->execQuery($query, array($from, $to, $from, $to));
	}

	/**
	 * Liefert das Studiensemester das aktuell am naehesten zu $studiensemester_kurzbz liegt
	 *
	 * @param $studiensemester_kurzbz
	 * @return array | null
	 */
	public function getNearestFrom($studiensemester_kurzbz)
	{
		$query = "SELECT studiensemester_kurzbz, start, ende FROM public.vw_studiensemester
				WHERE studiensemester_kurzbz <> ?
		        ORDER BY delta LIMIT 1";

		return $this->execQuery($query, array($studiensemester_kurzbz));
	}
}