<?php

if ( ! class_exists( 'Jetpack_Protect_Math_Authenticate' ) ) {
	/*
	 * The math captcha fallback if we can't talk to the Protect API
	 */
	class Jetpack_Protect_Math_Authenticate {

		static $loaded;

		function __construct() {

			if ( self::$loaded ) {
				return;
			}

			self::$loaded = 1;

			add_action( 'login_form', array( $this, 'math_form' ) );

			if( isset( $_POST[ 'jetpack_protect_process_math_form' ] ) ) {
				add_action( 'init', array( $this, 'process_generate_math_page' ) );
			}
		}

		/**
		 * Verifies that a user answered the math problem correctly while logging in.
		 *
		 * @return bool Returns true if the math is correct
		 * @throws Error if insuffient $_POST variables are present.
		 * @throws Error message if the math is wrong
		 */
		static function math_authenticate() {
			$salt        = get_site_option( 'jetpack_protect_key' ) . get_site_option( 'admin_email' );
			$ans         = isset( $_POST['jetpack_protect_num'] ) ? (int) $_POST['jetpack_protect_num'] : '' ;
			$salted_ans  = sha1( $salt . $ans );
			$correct_ans = isset( $_POST[ 'jetpack_protect_answer' ] ) ? $_POST[ 'jetpack_protect_answer' ] : '' ;

			if( isset( $_COOKIE[ 'jpp_math_pass' ] ) ) {
				$jetpack_protect = Jetpack_Protect_Module::instance();
				$transient = $jetpack_protect->get_transient( 'jpp_math_pass_' . $_COOKIE[ 'jpp_math_pass' ] );

				if( !$transient || $transient < 1 ) {
					Jetpack_Protect_Math_Authenticate::generate_math_page();
				}
				return true;
			}

			if ( ! $correct_ans || !$_POST['jetpack_protect_num'] ) {
				Jetpack_Protect_Math_Authenticate::generate_math_page();
			} elseif ( $salted_ans != $correct_ans ) {
				wp_die(
				__( '<strong>You failed to correctly answer the math problem.</strong>  This is used to combat spam when the Protect API is unavailable.  Please use your browser\'s back button to return to the login form, press the "refresh" button to generate a new math problem, and try to log in again.', 'jetpack' ),
				'',
				array ( 'response' => 401 )
				);
			} else {
				return true;
			}
		}

		/**
		 * Creates an interim page to collect answers to a math captcha
		 *
		 * @return none, execution stopped
		 */
		static function generate_math_page( $error = false ) {
			$salt = get_site_option( 'jetpack_protect_key' ) . get_site_option( 'admin_email' );
			$num1 = rand( 0, 10 );
			$num2 = rand( 1, 10 );
			$sum  = $num1 + $num2;
			$ans  = sha1( $salt . $sum );
			ob_start();
			?>
			<h2><?php _e( 'Please solve this math problem to prove that you are not a bot.  Once you solve it, you will need to log in again.', 'jetpack' ); ?></h2>
			<?php if ($error): ?>
				<h3><?php _e( 'Your answer was incorrect, please try again.', 'jetpack' ); ?></h3>
			<?php endif ?>

			<form action="<?php echo wp_login_url(); ?>" method="post" accept-charset="utf-8">
				<?php Jetpack_Protect_Math_Authenticate::math_form(); ?>
				<input type="hidden" name="jetpack_protect_process_math_form" value="1" id="jetpack_protect_process_math_form" />
				<p><input type="submit" value="<?php esc_html_e( 'Continue &rarr;', 'jetpack' ); ?>"></p>
			</form>
		<?php
			$mathpage = ob_get_contents();
			ob_end_clean();
			wp_die(
				$mathpage,
				'',
				array ( 'response' => 401 )
			);
		}

		public function process_generate_math_page() {
			$salt        = get_site_option( 'jetpack_protect_key' ) . get_site_option( 'admin_email' );
			$ans         = (int)$_POST['jetpack_protect_num'];
			$salted_ans  = sha1( $salt . $ans );
			$correct_ans = $_POST[ 'jetpack_protect_answer' ];

			if ( $salted_ans != $correct_ans ) {
				Jetpack_Protect_Math_Authenticate::generate_math_page(true);
			} else {
				$temp_pass = substr( sha1( rand( 1, 100000000 ) . get_site_option( 'jetpack_protect_key' ) ), 5, 25 );

				$jetpack_protect = Jetpack_Protect_Module::instance();
				$jetpack_protect->set_transient( 'jpp_math_pass_' . $temp_pass, 3, DAY_IN_SECONDS );
				setcookie('jpp_math_pass', $temp_pass, time() + DAY_IN_SECONDS, COOKIEPATH, COOKIE_DOMAIN, false);
				return true;
			}
		}

		/**
		 * Requires a user to solve a simple equation. Added to any WordPress login form.
		 *
		 * @return VOID outputs html
		 */
		static function math_form() {
			$salt = get_site_option( 'jetpack_protect_key' ) . get_site_option( 'admin_email' );
			$num1 = rand( 0, 10 );
			$num2 = rand( 1, 10 );
			$sum  = $num1 + $num2;
			$ans  = sha1( $salt . $sum );
			?>
			<div style="margin: 5px 0 20px;">
				<strong><?php esc_html_e( 'Prove your humanity:', 'jetpack' ); ?> </strong>
				<?php echo $num1 ?> &nbsp; + &nbsp; <?php echo $num2 ?> &nbsp; = &nbsp;
				<input type="input" name="jetpack_protect_num" value="" size="2" />
				<input type="hidden" name="jetpack_protect_answer" value="<?php echo $ans; ?>" />
			</div>
		<?php
		}

	}
}