<?php

namespace App\Database\Migrations;

use CodeIgniter\Database\Migration;

class AddYearlyBatchNumberToReimbursementBatches extends Migration
{
    public function up()
    {
        if (! $this->db->tableExists('reimbursement_batches') || $this->db->fieldExists('yearly_batch_number', 'reimbursement_batches')) {
            return;
        }

        $fields = [
            'yearly_batch_number' => [
                'type'       => 'INT',
                'constraint' => 11,
                'unsigned'   => true,
                'default'    => 0,
                'null'       => false,
                'after'      => 'title',
            ],
        ];

        $this->forge->addColumn('reimbursement_batches', $fields);

        $this->fillExistingBatchNumbers();
    }

    public function down()
    {
        if (! $this->db->tableExists('reimbursement_batches') || ! $this->db->fieldExists('yearly_batch_number', 'reimbursement_batches')) {
            return;
        }

        $this->forge->dropColumn('reimbursement_batches', 'yearly_batch_number');
    }

    private function fillExistingBatchNumbers(): void
    {
        $this->db->query("SET @prev_school_year := '', @row_number := 0");
        $this->db->query(
            'UPDATE reimbursement_batches b
             JOIN (
                 SELECT id,
                        (@row_number := IF(@prev_school_year = COALESCE(school_year, \'\'), @row_number + 1, 1)) AS seq,
                        @prev_school_year := COALESCE(school_year, \'\') AS school_year_marker
                 FROM reimbursement_batches
                 ORDER BY COALESCE(school_year, \'\'), COALESCE(opened_at, \'1970-01-01 00:00:00\'), id
             ) ranks ON b.id = ranks.id
             SET b.yearly_batch_number = ranks.seq'
        );
    }
}