<?php


if (! defined('BASEPATH')) exit('No direct script access allowed');

class LvPlanLib{

	private $_ci; // Code igniter instance
	

	/**
	 * fetches LvPlan events from a UID and start/end date
	 * @access public
	 *
	 */
	public function getLvPlan($start_date, $end_date, $lv_id = null){
		
		$this->_ci =& get_instance();

		$this->_ci->load->model('ressource/Mitarbeiter_model','MitarbeiterModel');
		$this->_ci->load->model('organisation/Studiensemester_model','StudiensemesterModel');
		$this->_ci->load->model('education/Studentlehrverband_model', 'StudentlehrverbandModel');
		$this->_ci->load->model('person/Benutzergruppe_model','BenutzergruppeModel');
		$this->_ci->load->model('ressource/Stundenplan_model', 'LvPlanModel');
		

		$student_uid = getAuthUID();
		if(is_null($student_uid))
		{
			return error("No UID");
		}
		
		$semester_range = $this->studienSemesterErmitteln($start_date,$end_date);
		if(isError($semester_range))
		{
			return error(getData($semester_range));
		}
		$semester_range = getData($semester_range);
		$this->sortStudienSemester($semester_range);
		$function_error = $this->applyLoadUeberSemesterHaelfte($semester_range);
		if(!is_null($function_error)){
			return $function_error;
		}
		
		if($lv_id) { // fetch LvPlan for lva, irrelevant of who is requesting it (for now)

			$lvplan_data = $this->_ci->LvPlanModel->getLvPlanLVA($start_date, $end_date, $lv_id);
			if(isError($lvplan_data))
			{
				return error(getData($lvplan_data));
			}
			$lvplan_data = getData($lvplan_data) ?? [];
			$function_error = $this->expand_object_information($lvplan_data);
			if(!is_null($function_error)){
				return $function_error;
			}

			// query lv itself in case its LvPlan is being queried and it has no entries
			$this->_ci->load->model('education/Lehrveranstaltung_model','LehrveranstaltungModel');
			$lv_result = $this->_ci->LehrveranstaltungModel->load($lv_id);
			if(isError($lv_result))
			{
				return error(getData($lv_result));
			}
			$lv = getData($lv_result)[0];
			return $lvplan_data;
			
		}
		
		$is_mitarbeiter = getData($this->_ci->MitarbeiterModel->isMitarbeiter($student_uid));
		if($is_mitarbeiter)
		{
			
			$lvplan_data = $this->_ci->LvPlanModel->getLvPlanMitarbeiter($start_date, $end_date, $student_uid);
			if(isError($lvplan_data))
			{
				return error(getData($lvplan_data));
			}
			$lvplan_data = getData($lvplan_data) ?? [];
			$function_error = $this->expand_object_information($lvplan_data);
			if(!is_null($function_error)){
				return error($function_error);
			}
			return success($lvplan_data);
		} else {
			// getting the gruppen_kurzbz of the student in the different studiensemester
			$benutzer_gruppen = $this->fetchBenutzerGruppenFromStudiensemester($semester_range);
			if(isError($benutzer_gruppen))
			{
				return error(getData($benutzer_gruppen));
			}
			$benutzer_gruppen = getData($benutzer_gruppen);

			// getting the student_lehrverbaende of the student in the different studiensemester
			$student_lehrverband = $this->fetchStudentlehrverbandFromStudiensemester($semester_range);
			if(isError($student_lehrverband))
			{
				return error(getData($student_lehrverband));
			}
			$student_lehrverband = getData($student_lehrverband);
			
			$lvplan_query = $this->_ci->LvPlanModel->getLvPlanQuery($start_date, $end_date, $semester_range, $benutzer_gruppen, $student_lehrverband);
			if(!$lvplan_query)
			{
				return error([]);
			}
			
			
			$lvplan_data = $this->_ci->LvPlanModel->lvPlanGruppierung($lvplan_query);
			if(isError($lvplan_data))
			{
				return error(getData($lvplan_data));
			}
			$lvplan_data = getData($lvplan_data) ?? [];

			$function_error = $this->expand_object_information($lvplan_data);
			if(!is_null($function_error)){
				return $function_error;
			}
			
			return success($lvplan_data);
		}
		
	}

	public function getReservierungen($start_date, $end_date, $ort_kurzbz){
		$this->_ci =& get_instance();
		$is_mitarbeiter = getData($this->_ci->MitarbeiterModel->isMitarbeiter(getAuthUID()));
		if($is_mitarbeiter)
		{
			$reservierungen = $this->_ci->ReservierungModel->getReservierungenMitarbeiter($start_date, $end_date, $ort_kurzbz);
		} else {
			// querying the reservierungen
			$reservierungen = $this->_ci->ReservierungModel->getReservierungen($start_date, $end_date, $ort_kurzbz);
		}
		if(isError($reservierungen))
		{
			return error(getData($reservierungen));
		}
		$reservierungen = getData($reservierungen) ?? [];
		$function_error = $this->expand_object_information($reservierungen);
		if(!is_null($function_error)){
			return $function_error;
		}
		return success($reservierungen);
	}

	public function getLektorenFromLehrveranstaltung($lehrveranstaltung_id, $semester, $studiengang_kz, $studiensemester_kurzbz){
		$this->_ci =& get_instance();
		$this->_ci->load->model('ressource/Stundenplan_model', 'LvPlanModel');
		$this->_ci->load->model('organisation/Studiensemester_model','StudiensemesterModel');
		
		$studiensemester = $this->_ci->StudiensemesterModel->loadWhere(["studiensemester_kurzbz"=>$studiensemester_kurzbz]);
		if(isError($studiensemester))
		{
			return error(getData($studiensemester));
		}
		$studiensemester = current(getData($studiensemester));
		$lektoren = $this->_ci->LvPlanModel->execReadOnlyQuery("
		SELECT DISTINCT uid 
		FROM campus.vw_stundenplan
		WHERE lehrveranstaltung_id = ? AND
		studiengang_kz = ? AND
		semester = ? AND
		(datum BETWEEN ? AND ?)
		",[$lehrveranstaltung_id, $studiengang_kz, $semester, $studiensemester->start, $studiensemester->ende]);
		
		if(isError($lektoren))
		{
			return error(getData($lektoren));
		}
		$lektoren = getData($lektoren);
		if(isset($lektoren)){
			$lektoren = array_map(function($lektor){
				return $lektor->uid;
			},$lektoren);

		}
		return $lektoren;
	}

	public function expand_object_information($data){
		$this->_ci =& get_instance();
		foreach ($data as $item)
		{

			$lektor_obj_array = array();
			$gruppe_obj_array = array();

			// load lektor object
			foreach ($item->lektor as $lv_lektor)
			{
				$this->_ci->LvPlanModel->addLimit(1);
				$lektor_object = $this->_ci->LvPlanModel->execReadOnlyQuery("
				SELECT mitarbeiter_uid, vorname, nachname, kurzbz
				FROM public.tbl_mitarbeiter
				JOIN public.tbl_benutzer benutzer ON benutzer.uid = mitarbeiter_uid
				JOIN public.tbl_person person ON person.person_id = benutzer.person_id
				WHERE kurzbz = ?", [$lv_lektor]);
				if (isError($lektor_object)) {
					$this->_ci->show_error(getError($lektor_object));
				}
				if(isError($lektor_object))
				{
					return error(getData($lektor_object));
				}
				$lektor_object = getData($lektor_object);
				if(count($lektor_object) == 0)
				{
					return error("No lektor object");
				}
				$lektor_object = current($lektor_object);
				// only provide needed information of the mitarbeiter object
				$lektor_obj_array[] = $lektor_object;
			}

			// load gruppe object
			foreach ($item->gruppe as $lv_gruppe)
			{
				$lv_gruppe = strtr($lv_gruppe, ['(' => '', ')' => '', '"' => '']);
				$lv_gruppe_array = explode(",", $lv_gruppe);
				list($gruppe, $verband, $semester, $studiengang_kz, $gruppen_kuerzel) = $lv_gruppe_array;

				$lv_gruppe_object = new stdClass();
				$lv_gruppe_object->gruppe = $gruppe;
				$lv_gruppe_object->verband = $verband;
				$lv_gruppe_object->semester = $semester;
				$lv_gruppe_object->studiengang_kz = $studiengang_kz;
				$lv_gruppe_object->kuerzel = $gruppen_kuerzel;

				$gruppe_obj_array[] = $lv_gruppe_object;
			}
			
			if($item->ort_kurzbz) {

				$ort_content_object = $this->_ci->LvPlanModel->execReadOnlyQuery("
				SELECT content_id
				FROM public.tbl_ort
				WHERE ort_kurzbz = ?", [$item->ort_kurzbz]);
				if (isError($ort_content_object)) {
					return error(getData($ort_content_object));
				}
				$ort_content_object = getData($ort_content_object)[0];
				if($ort_content_object) {
					$item->ort_content_id = $ort_content_object->content_id;
				}
				
				
			}

			$item->gruppe = $gruppe_obj_array;
			$item->lektor = $lektor_obj_array;

		}
	}

	// function used to sort an array of studiensemester strings
	private function sortStudienSemester(&$semester_range){
		usort(
			$semester_range,
			function($first,$second)
			{
				$sem_first = null;
				$year_first = null;
				$match_first = null;

				$sem_second = null;
				$year_second = null;
				$match_second = null;

				preg_match('/([WS]+)([0-9]+)/',$first,$match_first);
				preg_match('/([WS]+)([0-9]+)/',$second,$match_second);
				
				$sem_first = $match_first[1];
				$year_first = intval($match_first[2]);

				$sem_second = $match_second[1];
				$year_second = intval($match_second[2]);

				if($year_first < $year_second)
				{
					return -1;
				}
				else if($year_first > $year_second)
				{
					return 1;
				}
				else if($year_first == $year_second && $sem_first > $sem_second)
				{
					return 1;
				}
				else if($year_first == $year_second && $sem_first < $sem_second)
				{
					return -1;
				}
				return 0;
			} 
		);
	}

	
	private function fetchBenutzerGruppenFromStudiensemester($semester_range){
		$student_uid = getAuthUID();
		$benutzer_gruppen = [];
		// for each studiensemester fetch the benutzer gruppen and add them to an associate $bentuzer_gruppen array
		/*
		[
			['WS2023'] => [['gruppe1_SS2023','gruppe2_SS2023'],['gruppe1_WS2023','gruppe2_WS2023']],
			['SS2024'] => [['gruppe1_WS2023','gruppe2_WS2023'],['gruppe1_SS2024','gruppe2_SS2024']],
			['WS2024'] => [['gruppe1_SS2024','gruppe2_SS2024'],['gruppe1_WS2024','gruppe2_WS2024']],
		]
		*/ 
		foreach($semester_range as $semester_key => $semester_array)
		{
			$benutzer_gruppen[$semester_key] = [];
			// each semester could have ajoint semesters that need to be checked
			foreach($semester_array as $semester=>$semester_date_range)
			{
				// for each active semester query the benutzer_gruppen associated to the semester
				$benutzer_query = $this->_ci->BenutzergruppeModel->execReadOnlyQuery("
				SELECT * FROM tbl_benutzergruppe where uid = ? AND studiensemester_kurzbz = ?",[$student_uid, $semester]);
				if(isError($benutzer_query)){
					return error(getData($benutzer_query));
				}
				$benutzer_query_result = getData($benutzer_query)??[];
				
				array_push(
					$benutzer_gruppen[$semester_key],
					 array_map(
						function($item)
						{
							return "'".$item->gruppe_kurzbz. "'";
						},
						$benutzer_query_result
					)
				);
			}
		}
		
		// merge the gruppen of each studiensemester together for the original studiensemester
		/*
		[
			['WS2023'] => ['gruppe1_SS2023','gruppe2_SS2023','gruppe1_WS2023','gruppe2_WS2023'],
			['SS2024'] => ['gruppe1_WS2023','gruppe2_WS2023','gruppe1_SS2024','gruppe2_SS2024'],
			['WS2024'] => ['gruppe1_SS2024','gruppe2_SS2024','gruppe1_WS2024','gruppe2_WS2024'],
		]
		*/ 
		$benutzer_gruppen = array_map(
			function($gruppe)
			{
				$merged_gruppe = [];
				foreach($gruppe as $gruppen_array)
				{
					$merged_gruppe = array_merge($merged_gruppe, $gruppen_array);
				}
				return $merged_gruppe;
			},
			$benutzer_gruppen
		);

		return success($benutzer_gruppen);
	}

	private function fetchStudentlehrverbandFromStudiensemester($semester_range){
		$student_uid = getAuthUID();
		$student_lehrverband = [];
		// for each studiensemester fetch the studentlehrverbaende and add them to an associate $student_lehrverband array
		/*
		[
			['WS2023'] => [ [ ['stg_kz'=>298,'semester'=>1,'verband'=>"A",'gruppe'=>""] ] ],
			['SS2024'] => [ [ ['stg_kz'=>298,'semester'=>1,'verband'=>"A",'gruppe'=>""] ], [ ['stg_kz'=>298,'semester'=>2,'verband'=>"A",'gruppe'=>""] ] ],
			['WS2024'] => [ [ ['stg_kz'=>298,'semester'=>2,'verband'=>"A",'gruppe'=>""] ], [ ['stg_kz'=>298,'semester'=>3,'verband'=>"A",'gruppe'=>""] ] ],
		]
		*/ 
		foreach($semester_range as $semester_key => $semester_array)
		{
			$student_lehrverband[$semester_key] = [];
			foreach($semester_array as $semester=>$semester_date_range)
			{
				// for each active semester query the student_lehrverband associated to the semester
				$lehrverband_query = $this->_ci->BenutzergruppeModel->execReadOnlyQuery("
				SELECT * FROM tbl_studentlehrverband where student_uid = ? AND studiensemester_kurzbz = ?", [$student_uid, $semester]);
				if(isError($lehrverband_query)){
					return error(getData($lehrverband_query));
				}	
				$lehrverband_query_result = getData($lehrverband_query)??[];
				
				$converted_studentLehrverband= array_map(
					function ($item)
					{
						$result = new stdClass();
						$result->studiengang_kz = $item->studiengang_kz;
						$result->semester = $item->semester;
						$result->verband = $item->verband;
						$result->gruppe = $item->gruppe;
						return $result;
					},
					$lehrverband_query_result);
				
				array_push($student_lehrverband[$semester_key], $converted_studentLehrverband); 
				
			}
			
		}

		// merge the studentlehrverband of each studiensemester together for the original studiensemester
		/*
		[
			['WS2023'] => [ ['stg_kz'=>298,'semester'=>1,'verband'=>"A",'gruppe'=>""] ],
			['SS2024'] => [ ['stg_kz'=>298,'semester'=>1,'verband'=>"A",'gruppe'=>""], ['stg_kz'=>298,'semester'=>2,'verband'=>"A",'gruppe'=>""] ],
			['WS2024'] => [ ['stg_kz'=>298,'semester'=>2,'verband'=>"A",'gruppe'=>""], ['stg_kz'=>298,'semester'=>3,'verband'=>"A",'gruppe'=>""] ],
		]
		*/
		
		$student_lehrverband = array_map(
			function($studentlehrverband)
			{	
				$merged_studentlehrverband = [];
				foreach($studentlehrverband as $studentlehrverband_array)
				{
					$merged_studentlehrverband = array_merge($merged_studentlehrverband, $studentlehrverband_array);
				}
				return $merged_studentlehrverband;
			},
			$student_lehrverband
		);

		return success($student_lehrverband);
	}

	private function applyLoadUeberSemesterHaelfte(&$semester_range){
		/*
		@var($semester_collection)
		convert the array of studiensemester into an associative array with the studiensemester as the key 
		and the values of each key are the studiensemester needed for the query associated to that studiensemester
		example:

		#INPUT:
		['WS2023','SS2024','WS2024']
		#OUTPUT:
		[
			'WS2023' => ['SS2023','WS2023']
			'SS2024' => ['WS2023','SS2024']
			'WS2024' => ['SS2024','WS2024']
		]
		*/
		$semester_collection = [];
		foreach($semester_range as $studiensemester)
		{
			$previous_studiensemester = $this->_ci->StudiensemesterModel->getPreviousFrom($studiensemester);
			if(isError($previous_studiensemester))
			{
				return error(getData($previous_studiensemester));
			}
			$previous_studiensemester = getData($previous_studiensemester);
			if (count($previous_studiensemester) == 0) {
				return error('no previous semester');
			}
			$previous_studiensemester = current($previous_studiensemester)->studiensemester_kurzbz;
			$semester_collection[$studiensemester] = [$previous_studiensemester, $studiensemester];
		}

		/*
		@var($studienSemesterDateRanges)
		fetches for each studiensemester the start and end date, (SS) summer studiensemester are extended by 1 month to cover the summerbreak
		based on the LVPLAN_LOAD_UEBER_SEMESTERHAELFTE constant it will load both the semester and the previous semester with the full date range 
		or the semester with the full date range and the previous semester with the half date range:

		#INPUT:
		[
			'WS2023' => ['SS2023','WS2023']
			'SS2024' => ['WS2023','SS2024']
			'WS2024' => ['SS2024','WS2024']
		]
		#OUTPUT: depends whether LVPLAN_LOAD_UEBER_SEMESTERHAELFTE is true or false
		~ if LVPLAN_LOAD_UEBER_SEMESTERHAELFTE == true
		[
			"SS2024": [
				"WS2023": [
					"start"=> "2024-02-03",
					"ende"=> "2024-08-31"
				],
				"SS2024": [
					"start"=> "2024-02-03",
					"ende"=> "2024-08-31"
				]
			]
		]
		~ if LVPLAN_LOAD_UEBER_SEMESTERHAELFTE == false
		[
			"SS2024": [
				"WS2023": [
					"start"=> "2024-02-03",
					"ende"=> "2024-05-17"
				],
				"SS2024": [
					"start"=> "2024-02-03",
					"ende"=> "2024-08-31"
				]
			]
		]
		*/
		$studienSemesterDateRanges=[]; 
		foreach($semester_collection as $semester_original => $semester_adjoint)
		{
			$semester_start_ende = $this->_ci->StudiensemesterModel->getStartEndeFromStudiensemester($semester_original);
			if(isError($semester_start_ende))
			{
				return error(getData($semester_start_ende));
			}
			$semester_start_ende = current(getData($semester_start_ende)); 
				
			// initialize empty arrays to add key value pairs
			$studienSemesterDateRanges[$semester_original] = [];

			// check if the studiensemester is a summer semester and add 1 month to bridge the school summer break
			$match = null;
			preg_match("/^(SS)([0-9]+)/",$semester_original,$match);
			if(count($match) >0)
			{
				$one_month = new DateInterval('P1M');
				$one_day = DateInterval::createFromDateString('1 days');
				$summer_studiensemester_end_date = DateTime::createFromFormat('Y-m-d',$semester_start_ende->ende);
				$summer_studiensemester_end_date->add($one_month);
				$summer_studiensemester_end_date->sub($one_day);
				$semester_start_ende->ende = date_format($summer_studiensemester_end_date,'Y-m-d');
			}
			if (defined('LVPLAN_LOAD_UEBER_SEMESTERHAELFTE') && LVPLAN_LOAD_UEBER_SEMESTERHAELFTE === true)
			{
				foreach($semester_adjoint as $adjoint)
				{
					$studienSemesterDateRanges[$semester_original][$adjoint]=$semester_start_ende;
				}
			}
			else
			{
				//TODO: half of a DateInterval might not be correctly calculated
				// calculate the half of the studiensemester
				$studiensemester_start_date = DateTime::createFromFormat('Y-m-d',$semester_start_ende->start);
				$studiensemester_end_date = DateTime::createFromFormat('Y-m-d',$semester_start_ende->ende);
				$studiensemester_time_difference = $studiensemester_start_date->diff($studiensemester_end_date);
				$half_dateNumber = ceil($studiensemester_time_difference->d/2)+ceil(($studiensemester_time_difference->m*30)/2);
				$half_dateInterval = new DateInterval('P'.strval($half_dateNumber) .'D');
				$studiensemester_half = date_format($studiensemester_start_date->add($half_dateInterval),'Y-m-d');
				
				$first_half = new stdClass();
				$first_half->start = $semester_start_ende->start;
				$first_half->ende = $studiensemester_half;

				$studienSemesterDateRanges[$semester_original][$semester_adjoint[0]] = $first_half;
				$studienSemesterDateRanges[$semester_original][$semester_adjoint[1]] = $semester_start_ende;
			}
			$semester_range = $studienSemesterDateRanges;
		}
	}

	private function studienSemesterErmitteln($start_date,$end_date){
		
		// gets all studiensemester from the student from start_date to end_date
		$semester_range = $this->_ci->StudiensemesterModel->getByDateRange($start_date,$end_date);
		if(isError($semester_range))
		{
			return error(getData($semester_range));
		}
		$semester_range = array_map( 
			function($sem)
			{
				return $sem->studiensemester_kurzbz;
			},
			getData($semester_range)
		);

		// if no studiensemester is found for the given timespan, get the nearest studiensemester
		if(count($semester_range) == 0)
		{
			$aktuelle_studiensemester = $this->_ci->StudiensemesterModel->getNearest();
			if(isError($aktuelle_studiensemester))
			{
				return error(getData($aktuelle_studiensemester));
			}
			$aktuelle_studiensemester = getData($aktuelle_studiensemester);
			if (count($aktuelle_studiensemester) == 0) {
				return error("No aktuelles semester");
			}
			$aktuelle_studiensemester = current($aktuelle_studiensemester)->studiensemester_kurzbz;
			// push aktuelles semester in active semester array
			array_push($semester_range, $aktuelle_studiensemester);

		}
		return success($semester_range);
	}
}