SystemVariableGrammar.php

<?php

declare(strict_types=1);

namespace Mpyw\LaravelMySqlSystemVariableManager;

use function implode;
use function sprintf;
use function str_replace;

class SystemVariableGrammar
{
    /**
     * @param string[] $variables
     */
    public static function selectStatement(array $variables): string
    {
        return 'select ' . implode(', ', static::variableExpressions($variables));
    }

    /**
     * @param  string[] $variables
     * @return string[]
     */
    public static function variableExpressions(array $variables): array
    {
        $expressions = [];
        foreach ($variables as $variable) {
            $expressions[] = sprintf('@@%1$s as %1$s', static::escapeIdentifier($variable));
        }

        return $expressions;
    }

    /**
     * @param array<array-key, mixed> $values
     */
    public static function assignmentStatement(array $values): string
    {
        return 'set session ' . implode(', ', static::assignmentExpressions($values));
    }

    /**
     * @param  array<array-key, mixed> $values
     * @return string[]
     */
    public static function assignmentExpressions(array $values): array
    {
        $expressions = [];
        foreach ($values as $name => $value) {
            $expressions[] = static::escapeIdentifier($name) . '=' . Value::wrap($value)->getPlaceholder();
        }

        return $expressions;
    }

    public static function escapeIdentifier(string $identifier): string
    {
        return '`' . str_replace('`', '``', $identifier) . '`';
    }
}