class EmailHeaderSame

final class EmailHeaderSame extends Constraint {
    public function __construct(string $headerName, string $expectedValue) {
    }
    public function toString() : string {
        return \sprintf('has header "%s" with value "%s"', $this->headerName, $this->expectedValue);
    }
    
    /**
     * @param RawMessage $message
     */
    protected function matches($message) : bool {
        if (RawMessage::class === $message::class) {
            throw new \LogicException('Unable to test a message header on a RawMessage instance.');
        }
        return $this->expectedValue === $this->getHeaderValue($message);
    }
    
    /**
     * @param RawMessage $message
     */
    protected function failureDescription($message) : string {
        return \sprintf('the Email %s (value is %s)', $this->toString(), $this->getHeaderValue($message) ?? 'null');
    }
    private function getHeaderValue($message) : ?string {
        if (null === ($header = $message->getHeaders()
            ->get($this->headerName))) {
            return null;
        }
        return $header instanceof UnstructuredHeader ? $header->getValue() : $header->getBodyAsString();
    }

}