<?php

namespace App\Database\Schema;

use Illuminate\Database\Schema\Blueprint as BaseBlueprint;

class Blueprint extends BaseBlueprint
{
    private const MAX_INDEX_NAME_LENGTH = 64;
    private const MAX_FRAGMENT_INDEX_LEGNTH = 4;
    private const MIN_FRAGMENT_INDEX_LEGNTH = 3;

    /**
     * Create a default index name for the table.
     *
     * @param  string  $type
     * @param  array  $columns
     * @return string
     */
    protected function createIndexName($type, array $columns)
    {
        $index = $this->getReducedIndexName($type, $columns, self::MAX_FRAGMENT_INDEX_LEGNTH);

        return str_replace(['-', '.'], '_', $index);
    }

    private function getReducedIndexName($type, array $columns, int $fragmentLength)
    {
        $table = null;

        foreach($columns as $key => $value) {
            $column = null;

            foreach(explode('_', $value) as $explode) {
                $column .= substr($explode, 0, $fragmentLength) . '_';
            }

            $columns[$key] = rtrim($column, '_');
        }

        foreach(explode('_', $this->table) as $explode) {
            $table .= substr($explode, 0, $fragmentLength) . '_';
        }

        $index = strtolower($this->prefix.rtrim($table, '_').'_'.implode('_', $columns).'_'.$type);

        if (strlen($index) > self::MAX_INDEX_NAME_LENGTH) {

            $newFragmentLength = $fragmentLength - 1;

            if ($newFragmentLength < self::MIN_FRAGMENT_INDEX_LEGNTH) {

                throw new \Exception("An error has occurred while reducing the length of the index. "
                    . "Please, name it manually.\nThe last try result in: {$index}.");
            }

            return $this->getReducedIndexName($type, $columns, $newFragmentLength);
        }

        return $index;
    }
}