Checks if a student is eligible to take a course.

CourseEnrollmentEligibility.php

<?php


/**
 * CourseEnrollmentEligibility
 */

class CourseEnrollmentEligibility extends ModelService {

	/**
	 * student
	 * @var \DeltaX\Models\Student
	 */

	protected $student;

	/**
	 * curriculumItem
	 * @var \DeltaX\Models\Curriculum
	 */

	protected $curriculumItem;

	/**
	 * yearStanding
	 * @var int
	 */

	protected $yearStanding;

	/**
	 * term
	 * @var int
	 */

	protected $term;

	/**
	 * setStudent
	 * @param string $code
	 * @return self
	 */
	public function setTerm(string $code) {
		$term = $this->repoInvoker->find('school_calendar', $code);
		if (empty($student)){
			throw new InvalidTermException;
		}

		$this->term = $term;
		return $this;
	}

	/**
	 * setStudent
	 * @param string $studentNumber
	 * @return self
	 */
	public function setStudent(string $studentNumber) {
		$student = $this->repoInvoker->find('student', $studentNumber);
		if (empty($student)){
			throw new InvalidStudentNumberException;
		}

		$this->student = $student;
		return $this;
	}


	public function setCurriculumItem(string $code){
		$degree_id = $this->student->degree_id;

		$this->curriculumItem = $this->repoInvoker->entity('curricula', function() use ($code){
			return $entity->with('curriculum_term', 'course')
				->whereHas('course', function($entity) use ($code){
					$entity->where('code', $code);
				}));
		})->where([['degree_id', $degree_id]])
			->get()
			->first();	

		return $this;
	} 

	/**
	 * determineYearStandingPrerequisite
	 * @return self
	 */
	protected function determineYearStandingPrerequisite() {
		$yearLevel = $this->repoInvoker->entity('term_attendance')
			->where([['student_id', $this->student->id]])
			->max('year_level');

		$yearLevel = $this->curriculumItem->curriculum_term->year_level;

			if ($this->yearStanding > $yearLevel) {
				return [
					'available' => false,
					'message' => 'Year level is not enough'
					'year_standing' => $yearLevel,
					'required' => $requiredYearLevel
				];
			}

		return $this;
	}

	protected function determinePastEnrollment(){

		$prerequisiteItems = $this->determinePrerequisites();
		$pastEnrollment = $this->repoInvoker->entity('curricula', function($entity) use ($prerequisiteItems){
			return $entity
				->select([
					'curricula.id'
					'courses.code AS course_code',
				    'curricula.is_major',
				    'courses.name',
				    'courses.credits_in_lecture',
				    'courses.credits_in_lab',
				    'curricula.lec_contact_hrs',
				    'curricula.lab_contact_hrs',
				    'curriculum_terms.year_level',
				    'courses.code AS dependent_course',
				    'enrolled_courses.final_grade',
				    'remarks.remark', 
				])->join('courses', 'curricula.course_id', '=', 'courses.id')
				->leftJoin('enrolled_courses', 'enrolled_courses.curriculum_id', '=', 'curricula.id')
				->join('remarks', 'enrolled_courses.remark_id', '=', 'remarks.id')
				->leftJoin('term_attendance', 'enrolled_courses.term_attendance_id', '=', 'term_attendance.id')
				->leftJoin('school_calendar', 'term_attendance.school_calendar_id', '=', 'school_calendar.id')
				->whereIn('curricula.id', $prerequisiteItems->pluck('id'));
		})->where([
			['curricula.id', $this->curriculumItem->id], 
			['enrolled_courses.student_id', $this->student->id]
		], true)
		->get();

		return $pastEnrollment;
	}


	protected function determinePrerequisites(){
		return $this->repoInvoker->entity('curricula', function($entity){
			return $entity
				->select([
					'prerequisites.id', 
					'prerequisites.course_id',
					'prerequisite_courses.code',
				    'prerequisite_courses.name',
				    'prerequisite_courses.credits_in_lecture',
				    'prerequisite_courses.credits_in_lab',
				    'prerequisites.is_major',
				    'prerequisites.is_nth_year_standing',
				    'prerequisites.lec_contact_hrs',
				    'prerequisites.lab_contact_hrs'
				])->join('courses', 'curricula.course_id', '=', 'courses.id')
				->leftJoin('curriculum_prerequisites', 'curriculum_prerequisites.dependent_id', '=', 'curricula.id')
				->leftJoin('curricula AS prerequisites', 'curriculum_prerequisites.prerequisite_id', '=', 'prerequisites.id')
				->leftJoin('courses AS prerequisite_courses', 'prerequisites.course_id', '=', 'prerequisite_courses.id')
		})->where([['curricla.id', $this->curriculumItem->id]])->get();
	}

	public function checkOpenSessions(){
		$openSessions = $this->repoInvoker->entity('course_sessions', function($entity){
			return $entity
				->select([
					'course_sessions.session_alias',
					'courses.code'
				])
				->join('courses', 'course_sessions.course_id', '=', 'courses.id')
				->join('school_calendar', 'course_sessions.school_calendar_id', '=', 'courses.id')
		})->where([
			['course_sessions.course_id', $this->curriculumItem->course_id],
			['course_sessions.school_calendar_id', $this->term->id]
		])->get();

		if(empty($openSessions)){
			return [
				'available' => false,
				'message' => 'No available classes for this term'
			];
		}

	}

	/**
	 * checkEligibility
	 * @return array
	 */
	public function checkEligibility() {

		//Does the item require class standing?
		if ($this->curriculumItem['is_nth_year_standing']) {
			$yearStanding = $this->determineYearStandingPrerequisite();
			if ( ! $yearStanding['available'] ){
				return $yearStanding;
			}
		}

		$openSessions = $this->checkOpenSessions();

		//Are there any open sessions?
		if ( ! $openSessions['available'] ) {
			return $openSessions;
		}


		$prerequisiteItems = $this->determinePrerequisites();
		$pastEnrollment = $this->determinePastEnrollment();
		$prerequisiteItemsCount = $prerequisiteItems->groupBy('id')->count();
		$pastEnrollmentCount = $prerequisiteItems
			->groupBy('id')->whereIn('remark', ['PASSED','F','S','VS','O'])->count();

		//Count all the prerequisite items and the ones the student have passed.
		$result = [
			'prerequisites' => $prerequisiteItems,
			'courses_taken' => $pastEnrollment,
			'count_of_prerequisite_courses' => $prerequisiteItemsCount,
			'count_of_passed_prerequisites' => $pastEnrollmentCount,
			'availability' => $pastEnrollmentCount >= $prerequisiteItemsCount 
		];

	}