<?php
/**
 * Copyright (C) 2024 fhcomplete.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

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

class Stundenplan extends FHCAPI_Controller
{

	/**
	 * Object initialization
	 */
	public function __construct()
	{

		parent::__construct([
			'getRoomplan' => self::PERM_LOGGED,
            'Stunden' => self::PERM_LOGGED,
            'Reservierungen' => self::PERM_LOGGED,
			'getStundenplan' => self::PERM_LOGGED,
			'getLehreinheitStudiensemester' => self::PERM_LOGGED,
			'studiensemesterDateInterval' => self::PERM_LOGGED,
		]);

        $this->load->library('LogLib');
        $this->loglib->setConfigs(array(
			'classIndex' => 5,
			'functionIndex' => 5,
			'lineIndex' => 4,
			'dbLogType' => 'API', // required
			'dbExecuteUser' => 'RESTful API'
		));

        $this->load->library('form_validation');

		//load models
		$this->load->model('ressource/Stundenplan_model', 'StundenplanModel');
		$this->load->model('ressource/Reservierung_model', 'ReservierungModel');


	}

	//------------------------------------------------------------------------------------------------------------------
	// Public methods

	//TODO: delete this function if we don't use the old calendar export endpoints anymore
	public function studiensemesterDateInterval($date){
		$this->load->model('organisation/Studiensemester_model','StudiensemesterModel');
		$studiensemester =$this->StudiensemesterModel->getByDate(date_format(date_create($date),'Y-m-d'));
		$studiensemester =current($this->getDataOrTerminateWithError($studiensemester));
		$this->terminateWithSuccess($studiensemester);
	}
		

    /**
     * fetches Stunden layout from database
     * @access public
     *
     */
    public function Stunden()
	{
		$this->load->model('ressource/Stunde_model', 'StundeModel');

		$stunden = $this->StundeModel->load();

        $stunden = $this->getDataOrTerminateWithError($stunden);

		$this->terminateWithSuccess($stunden);
	}

    /**
     * fetches room events from a certain date
     * @access public
     *
     */
	public function getRoomplan()
	{
        // form validation
        $this->load->library('form_validation');
        $this->form_validation->set_data($_GET);
        $this->form_validation->set_rules('ort_kurzbz',"Ort","required");
        $this->form_validation->set_rules('start_date',"start_date","required");
        $this->form_validation->set_rules('end_date',"end_date","required");
        if($this->form_validation->run() === FALSE) $this->terminateWithValidationErrors($this->form_validation->error_array());

        // storing the get parameter in local variables
        $ort_kurzbz = $this->input->get('ort_kurzbz', TRUE);
        $start_date = $this->input->get('start_date', TRUE);
        $end_date = $this->input->get('end_date', TRUE);

		$roomplan_data = $this->StundenplanModel->stundenplanGruppierung($this->StundenplanModel->getRoomQuery($ort_kurzbz, $start_date, $end_date));

        $roomplan_data = $this->getDataOrTerminateWithError($roomplan_data);

		$this->expand_object_information($roomplan_data);

		$this->terminateWithSuccess($roomplan_data);

	}

	/**
	 * fetches stundenplan events from a UID and start/end date
	 * @access public
	 *
	 */

	public function getStundenplan(){

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

		// form validation
		$this->load->library('form_validation');
		$this->form_validation->set_data($_GET);
		$this->form_validation->set_rules('start_date', "start_date", "required");
		$this->form_validation->set_rules('end_date', "end_date", "required");
		if ($this->form_validation->run() === FALSE)
			$this->terminateWithValidationErrors($this->form_validation->error_array());

		// storing the get parameter in local variables
		$start_date = $this->input->get('start_date', TRUE);
		$end_date = $this->input->get('end_date', TRUE);
		$lv_id = $this->input->get('lv_id', TRUE);

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

			$stundenplan_data = $this->StundenplanModel->getStundenplanLVA($start_date, $end_date, $lv_id);
			$stundenplan_data = $this->getDataOrTerminateWithError($stundenplan_data) ?? [];
			$this->expand_object_information($stundenplan_data);

			// query lv itself in case its Stundenplan is being queried and it has no entries
			$this->load->model('education/Lehrveranstaltung_model','LehrveranstaltungModel');
			$lv = getData($this->LehrveranstaltungModel->load($lv_id))[0];
			$this->addMeta('lv', $lv);
			$this->terminateWithSuccess($stundenplan_data);
			
		}
		
		$is_mitarbeiter = getData($this->MitarbeiterModel->isMitarbeiter($student_uid));
		if($is_mitarbeiter)
		{
			
			$stundenplan_data = $this->StundenplanModel->getStundenplanMitarbeiter($start_date, $end_date, $student_uid);
			$stundenplan_data = $this->getDataOrTerminateWithError($stundenplan_data) ?? [];
			$this->expand_object_information($stundenplan_data);
			$this->terminateWithSuccess($stundenplan_data);
		} else {
			// getting the gruppen_kurzbz of the student in the different studiensemester
			$benutzer_gruppen = $this->fetchBenutzerGruppenFromStudiensemester($semester_range);

			// getting the student_lehrverbaende of the student in the different studiensemester
			$student_lehrverband = $this->fetchStudentlehrverbandFromStudiensemester($semester_range);

			$stundenplan_query = $this->StundenplanModel->getStundenplanQuery($start_date, $end_date, $semester_range, $benutzer_gruppen, $student_lehrverband);
			if(!$stundenplan_query)
			{
				$this->terminateWithSuccess([]);
			}
			$stundenplan_data = $this->StundenplanModel->stundenplanGruppierung($stundenplan_query);
			$stundenplan_data = $this->getDataOrTerminateWithError($stundenplan_data) ?? [];

			$this->expand_object_information($stundenplan_data);
			
			$this->returnObj['$stundenplan_query'] = $stundenplan_query;
			$this->returnObj['$student_lehrverband'] = $student_lehrverband;
			$this->returnObj['$benutzer_gruppen'] = $benutzer_gruppen;
			$this->terminateWithSuccess($stundenplan_data);
		}
		
	}

	// gets the reservierungen of a room if the ort_kurzbz parameter is supplied otherwise gets the reservierungen of the stundenplan of a student
    public function Reservierungen($ort_kurzbz = null)
	{
		//form validation
		$this->load->library('form_validation');
		$this->form_validation->set_data($_GET);
		$this->form_validation->set_rules('start_date', "StartDate", "required");
		$this->form_validation->set_rules('end_date', "EndDate", "required");
		if($this->form_validation->run() == FALSE) $this->terminateWithValidationErrors($this->form_validation->error_array());

		$this->load->model('ressource/Mitarbeiter_model','MitarbeiterModel');

		// storing the get parameter in local variables
        $start_date = $this->input->get('start_date', TRUE);
        $end_date = $this->input->get('end_date', TRUE);

		$is_mitarbeiter = getData($this->MitarbeiterModel->isMitarbeiter(getAuthUID()));
		if($is_mitarbeiter)
		{
			$reservierungen = $this->ReservierungModel->getReservierungenMitarbeiter($start_date, $end_date, $ort_kurzbz);
		} else {
			// querying the reservierungen
			$reservierungen = $this->ReservierungModel->getReservierungen($start_date, $end_date, $ort_kurzbz);
		}
		
		$reservierungen = $this->getDataOrTerminateWithError($reservierungen) ?? [];
		$this->expand_object_information($reservierungen);
		$this->terminateWithSuccess($reservierungen);
		
	}

	public function getLehreinheitStudiensemester($lehreinheit_id){
		$this->load->model('education/Lehreinheit_model', 'LehreinheitModel');
		$this->LehreinheitModel->addSelect(["studiensemester_kurzbz"]);
		$result = $this->LehreinheitModel->load($lehreinheit_id);
		$result = current($this->getDataOrTerminateWithError($result))->studiensemester_kurzbz;
		$this->terminateWithSuccess($result);
	}

	// ################# Private Functions

	private function expand_object_information($data){

		foreach ($data as $item)
		{

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

			// load lektor object
			foreach ($item->lektor as $lv_lektor)
			{
				$this->StundenplanModel->addLimit(1);
				$lektor_object = $this->StundenplanModel->execReadOnlyQuery("
				SELECT mitarbeiter_uid, vorname, nachname, kurzbz
				FROM public.tbl_mitarbeiter
				JOIN public.tbl_benutzer benutzer ON benutzer.uid = mitarbeiter_uid
				JOIN public.tbl_person person ON person.person_id = benutzer.person_id
				WHERE kurzbz = ?", [$lv_lektor]);
				if (isError($lektor_object)) {
					$this->show_error(getError($lektor_object));
				}
				$lektor_object = $this->getDataOrTerminateWithError($lektor_object);
				if(count($lektor_object) == 0)
				{
					$this->terminateWithError("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 = $this->StundenplanModel->execReadOnlyQuery("
				SELECT content_id
				FROM public.tbl_ort
				WHERE ort_kurzbz = ?", [$item->ort_kurzbz]);
				if (isError($ort_content_object)) {
					$this->show_error(getError($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 = $this->BenutzergruppeModel->execReadOnlyQuery("
				SELECT * FROM tbl_benutzergruppe where uid = ? AND studiensemester_kurzbz = ?",[$student_uid, $semester]);
				$benutzer_query_result = $this->getDataOrTerminateWithError($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 $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 = $this->BenutzergruppeModel->execReadOnlyQuery("
				SELECT * FROM tbl_studentlehrverband where student_uid = ? AND studiensemester_kurzbz = ?", [$student_uid, $semester]);
				$lehrverband_query_result = $this->getDataOrTerminateWithError($lehrverband_query);
				array_push($student_lehrverband[$semester_key], 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)); 
			}
		}

		// 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 $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 = $this->StudiensemesterModel->getPreviousFrom($studiensemester);
			$previous_studiensemester = $this->getDataOrTerminateWithError($previous_studiensemester);
			if (count($previous_studiensemester) == 0) {
				$this->terminateWithError("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 = $this->StudiensemesterModel->getStartEndeFromStudiensemester($semester_original);
			$semester_start_ende = current($this->getDataOrTerminateWithError($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 = $this->StudiensemesterModel->getByDateRange($start_date,$end_date);
		$semester_range = array_map( 
			function($sem)
			{
				return $sem->studiensemester_kurzbz;
			},
			$this->getDataOrTerminateWithError($semester_range)
		);

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

		}
		return $semester_range;
	}

}