<?php

namespace App\Database\Migrations;

use CodeIgniter\Database\Migration;

class RemoveClassAssignmentSemester extends Migration
{
    public function up()
    {
        if ($this->db->tableExists('teacher_class') && $this->db->fieldExists('semester', 'teacher_class')) {
            if ($this->indexExists('teacher_class', 'unique_teacher_assignment')) {
                $this->db->query('ALTER TABLE `teacher_class` DROP INDEX `unique_teacher_assignment`');
            }

            $this->forge->dropColumn('teacher_class', 'semester');

            $this->db->query(
                'ALTER TABLE `teacher_class` ADD UNIQUE KEY `unique_teacher_assignment` (`teacher_id`, `class_section_id`, `school_year`)'
            );
        }
        if ($this->db->tableExists('student_class') && $this->db->fieldExists('semester', 'student_class')) {
            $this->forge->dropColumn('student_class', 'semester');
        }
    }

    public function down()
    {
        if ($this->db->tableExists('teacher_class')) {
            $this->forge->addColumn('teacher_class', [
                'semester' => [
                    'type'       => 'VARCHAR',
                    'constraint' => 25,
                    'null'       => false,
                    'default'    => '',
                ],
            ]);
        }
        if ($this->db->tableExists('student_class')) {
            $this->forge->addColumn('student_class', [
                'semester' => [
                    'type'       => 'VARCHAR',
                    'constraint' => 255,
                    'null'       => false,
                    'default'    => '',
                ],
            ]);
        }
    }

    private function indexExists(string $table, string $index): bool
    {
        $result = $this->db->query(
            'SHOW INDEX FROM `' . str_replace('`', '``', $table) . '` WHERE Key_name = ' . $this->db->escape($index)
        );

        return $result->getNumRows() > 0;
    }
}