<?php

namespace App\Services\Asteria;

use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Schema;

/**
 * Schema helpers that work against Magento 1's MySQL 5.6.
 *
 * Laravel's Schema::hasColumn() reads information_schema.columns.generation_expression,
 * which does not exist until MySQL 5.7.
 */
class Magento1Schema
{
    /** @var array<string, array<int, string>> */
    private array $columns = [];

    /** @var array<string, bool> */
    private array $tables = [];

    public function __construct(private string $connection = 'asteria') {}

    public function hasTable(string $table): bool
    {
        return $this->tables[$table] ??= Schema::connection($this->connection)->hasTable($table);
    }

    /**
     * @param  array<int, string>  $candidates
     * @return array<int, string>
     */
    public function existingColumns(string $table, array $candidates): array
    {
        if (! $this->hasTable($table)) {
            return [];
        }

        $listing = array_fill_keys(array_map('strtolower', $this->columnListing($table)), true);

        return array_values(array_filter(
            $candidates,
            fn (string $column) => isset($listing[strtolower($column)])
        ));
    }

    /**
     * @return array<int, string>
     */
    public function columnListing(string $table): array
    {
        if (isset($this->columns[$table])) {
            return $this->columns[$table];
        }

        $connection = DB::connection($this->connection);

        if ($connection->getDriverName() === 'mysql') {
            $wrapped = $connection->getQueryGrammar()->wrapTable($table);
            $rows = $connection->select('show columns from '.$wrapped);
            $names = [];

            foreach ($rows as $row) {
                $row = (array) $row;
                $name = $row['Field'] ?? $row['field'] ?? null;

                if (is_string($name) && $name !== '') {
                    $names[] = $name;
                }
            }

            return $this->columns[$table] = $names;
        }

        return $this->columns[$table] = Schema::connection($this->connection)->getColumnListing($table);
    }
}