Captcha::sanitize()

	public function sanitize() {
		if ( true === $this->sanitized ) {
			return $this->sanitized_value;
		}

		require_once ANSPRESS_ADDONS_DIR . '/recaptcha/recaptcha/autoload.php';

		if ( ap_opt( 'recaptcha_method' ) === 'curl' ) {
			$method = new \ReCaptcha\RequestMethod\CurlPost();
		} else {
			$method = new \ReCaptcha\RequestMethod\Post();
		}

		$recaptcha = new \ReCaptcha\ReCaptcha(
			trim( ap_opt( 'recaptcha_secret_key' ) ),
			$method
		);

		$ip = filter_var( $_SERVER['REMOTE_ADDR'], FILTER_VALIDATE_IP ); //@codingStandardsIgnoreLine.
		$captcha_response = ap_sanitize_unslash( 'g-recaptcha-response', 'r' );
		$this->response   = $recaptcha->verify( $captcha_response, $ip );

		$this->sanitized = true;

		if ( $this->response->isSuccess() ) {
			$this->sanitized_value = true;
		} else {
			$this->add_error( 'captcha', __( 'Failed to verify captcha. Please try again.', 'anspress-question-answer' ) );
			$this->sanitized_value = false;
		}
	}