<?php

declare(strict_types=1);

namespace GraphQL\Type\Definition;

use Exception;
use GraphQL\Error\Error;
use GraphQL\Language\AST\Node;
use GraphQL\Language\AST\StringValueNode;
use GraphQL\Utils\Utils;
use function is_array;
use function is_object;
use function is_scalar;
use function method_exists;

class StringType extends ScalarType
{
    /** @var string */
    public $name = Type::STRING;

    /** @var string */
    public $description =
        'The `String` scalar type represents textual data, represented as UTF-8
character sequences. The String type is most often used by GraphQL to
represent free-form human-readable text.';

    /**
     * @param mixed $value
     *
     * @return mixed|string
     *
     * @throws Error
     */
    public function serialize($value)
    {
        if ($value === true) {
            return 'true';
        }
        if ($value === false) {
            return 'false';
        }
        if ($value === null) {
            return 'null';
        }
        if (is_object($value) && method_exists($value, '__toString')) {
            return (string) $value;
        }
        if (! is_scalar($value)) {
            throw new Error('String cannot represent non scalar value: ' . Utils::printSafe($value));
        }

        return $this->coerceString($value);
    }

    private function coerceString($value)
    {
        if (is_array($value)) {
            throw new Error(
                'String cannot represent an array value: ' .
                Utils::printSafe($value)
            );
        }

        return (string) $value;
    }

    /**
     * @param mixed $value
     *
     * @return string
     *
     * @throws Error
     */
    public function parseValue($value)
    {
        return $this->coerceString($value);
    }

    /**
     * @param Node         $valueNode
     * @param mixed[]|null $variables
     *
     * @return string|null
     *
     * @throws Exception
     */
    public function parseLiteral($valueNode, ?array $variables = null)
    {
        if ($valueNode instanceof StringValueNode) {
            return $valueNode->value;
        }

        // Intentionally without message, as all information already in wrapped Exception
        throw new Exception();
    }
}