<?php

namespace App;

use Exception;
use Illuminate\Database\Eloquent\Model;

class Semester extends Model
{
    public $primaryKey = 'code';
    public $incrementing = false;
    public $timestamps = false;

    protected $keyType = 'string';
    protected $fillable = [
        'code',
        'alpha'
    ];


    public function courses() {
        return $this->belongsToMany(Course::class, 'sections');
    }

    public function sections() {
        return $this->hasMany(Section::class);
    }

    public function professors() {
        return $this->belongsToMany(Professor::class)->withPivot('admin_load', 'investigative_load');
    }

    public function getIsFutureAttribute() {
        return Semester::orderBy('code', 'desc')->take(6)->get()->contains('code', $this->code);
    }

    /**
     * Returns a clone of this semester with the provided code and alpha.
     * This functions also copies every section and professor_section
     *
     * @param string $newSemCode
     * @param string $newSemAlpha
     * @param int $dept_id
     *
     * @return Semester
     */
    public function clone(string $newSemCode, string $newSemAlpha, int $dept_id) {
        // if (Semester::find($newSemCode)) {
        //     throw new Exception('A semester with code ' . $newSemCode . ' already exists');
        // }
        $semClone = Semester::firstOrCreate(
            ['code'  => $newSemCode],
            ['alpha' => $newSemAlpha],
        );

        $this->loadMissing([
            'sections' => function ($query) use ($dept_id) {
                $query->select('sections.id', 'course_id', 'semester_code', 'sections.code', 'student_count', 'sections.syllabus', 'credits', 'quota')
                    ->join('courses', 'courses.id', '=', 'sections.course_id')
                    ->where('dept_id', '=', $dept_id);
            },
            'sections.professors',
            'sections.schedules'
        ]);
        // Copy all sections to new semester
        foreach($this->sections as $section) {
            $sectionClone = $section->replicate();
            $sectionClone->semester_code = $semClone->code;
            $existingSection = Section::where([['semester_code', '=', $sectionClone->semester_code], ['course_id', '=', $sectionClone->course_id], ['code', '=' , $sectionClone->code]])->first();
            if (!$existingSection) {
                $sectionClone->save();

                foreach($section->professors as $professor) {
                    $sectionClone->professors()->attach($professor, ['percent' => $professor->pivot->percent]);
                }

                foreach($section->schedules as $schedule) {
                    $scheduleClone = $schedule->replicate();
                    $scheduleClone->section_id = $sectionClone->id;
                    $scheduleClone->save();
                    $sectionClone->schedules()->save($scheduleClone);
                }
            }
        }

        return $semClone;
    }

}