/**
 * License: Public domain.
 *
 * Description: This snippet integrates the OIDC connect button with WooCommerce
 *              to allow importing the customer's shopping details via OIDC.
 * Author Christian Grothoff <grothoff@taler.net>
 */

// Add OIDC login form to checkout page.
add_action(
	'openid-connect-generic-register-login-form',
	function ( $login_form ) {

		// If WooCommerce is inactive, do nothing.
		if ( ! in_array(
			'woocommerce/woocommerce.php',
			apply_filters(
				'active_plugins',
				get_option( 'active_plugins' )
			),
			true
		) ) {
			return;
		}

		// Show login form at the shopping cart (if not logged in).
		add_action(
			'woocommerce_before_checkout_billing_form',
			function ( $checkout ) use ( $login_form ) {
				$user = wp_get_current_user();
				if ( 0 === $user->ID ) {
					// ID 0 is used to indicate user is not logged in.
					// Re-use filter logic to generate login page.
					print ( $login_form->handle_login_page( '' ) );
				}
			}
		);

		// Add action to set cookie to redirect back to current
		// (checkout) page after OIDC provided the data.
		add_action(
			'woocommerce_before_checkout_billing_form',
			function ( $checkout ) use ( $login_form ) {
                                 $login_form->handle_redirect_cookie ( );
                        }
		);

	}
);


// Hook to convert OIDC fields to WC checkout fields if logged in.
add_filter(
	'woocommerce_checkout_fields',
	'filter_checkout_get_value'
);


/**
 * Checks if $claimname is in the body or _claim_names of the userinfo.
 * If yes, returns the claim value. Otherwise, returns false.
 *
 * @param string $claimname the claim name to look for
 * @param array $userinfo the JSON to look in
 * @param string $claimvalue the source claim value ( from the body of the JWT of the claim source)
 * @return True if a reference was found
 */
function get_claim( $claimname, $userinfo, &$claimvalue ) {
  if ( ! isset( $userinfo ) ) {
    return False;
  }
  /**
   * If we find a simple claim, return it.
   */
  if ( array_keys_exists( $claimname, $userinfo ) ) {
    $claimvalue = $userinfo[$claimname];
    return True;
  }
  /**
   * If there are not aggregated claims, it is over.
   */
  if  ( ! array_key_exists( '_claim_names', $userinfo ) ||
        ! array_key_exists( '_claim_sources', $userinfo ) ) {
    return False;
  }
  $claim_src_ptr = $userinfo['_claim_names'];
  if ( ! isset( $claim_src_ptr ) ) {
    return False;
  }
  /**
   * No reference found
   */
  if ( ! array_key_exists( $claimname, $claim_src_ptr ) ) {
    return False;
  }
  $src = $claim_src_ptr[$claimname];
  //Reference found, but no corresponding JWT. This is a malformed userinfo
  if ( ! array_key_exists( $src, $userinfo['_claim_sources']) ) {
    return False;
  }
  //Source claim is not a JWT. Abort.
  if ( ! array_key_exists( 'JWT',  $src ) ) {
    return False;
  }
  /**
   * Extract claim from JWT.
   * FIXME: We probably want to verify the JWT signature/issuer here!
   */
  $jwt = $src['JWT'];
  list ($header, $body, $rest) = split('.', $jwt, 3);
  $body_decoded = base64_decode ( $body, false );
  if ( ( isset ( $body_decoded ) ) &&
    ( array_key_exists( $claimname, $body_decoded ) ) ) {
    $claimvalue = $body_decoded[$claimname];
    return True;
  }
  return False;
}

/**
 * Filter to transform (defaults) for the Billing details according to
 * the information obtained from OpenID Connect (OIDC).  WooCommerce
 * already grabs many of the values properly, but there are some fields
 * which we have to convert manually.
 *
 * @param array $in Data structure with shipping details to extend and return.
 *
 * @return array Enhanced shipping details.
 */
function filter_checkout_get_value( $in = array() ) {
	$user = wp_get_current_user();
	if ( 0 !== $user->ID ) {
    $token_response = $user->get( 'openid-connect-generic-last-user-claim' );
    $src = '';
    if ( get_claim( 'given_name', $token_response, $given_name ) ) {
			$in['billing']['billing_first_name']['default']   = $given_name;
			$in['shipping']['shipping_first_name']['default'] = $given_name;
		}
		if ( get_claim( 'family_name', $token_response, $family_name ) ) {
			$in['billing']['billing_last_name']['default']   = $family_name;
			$in['shipping']['shipping_last_name']['default'] = $family_name;
		}
		if ( get_claim( 'phone_number', $token_response, $phone_number ) ) {
			$in['billing']['billing_phone']['default']   = $phone_number;
			$in['shipping']['shipping_phone']['default'] = $phone_number;
    }
    if ( get_claim( 'address', $token_response, $address ) ) {
			if ( array_key_exists( 'postal_code', $address ) ) {
				$postal_code                                    = $address ['postal_code'];
				$in['billing']['billing_postcode']['default']   = $postal_code;
				$in['shipping']['shipping_postcode']['default'] = $postal_code;
			}
			if ( array_key_exists( 'country', $address ) ) {
				$country                                       = $address ['country'];
				$in['billing']['billing_country']['default']   = $country;
				$in['shipping']['shipping_country']['default'] = $country;
			}
			if ( array_key_exists( 'locality', $address ) ) {
				$locality                                   = $address ['locality'];
				$in['billing']['billing_city']['default']   = $locality;
				$in['shipping']['shipping_city']['default'] = $locality;
			}
			if ( array_key_exists( 'region', $address ) ) {
				$region                                      = $address ['region'];
				$in['billing']['billing_state']['default']   = $region;
				$in['shipping']['shipping_state']['default'] = $region;
			}
			if ( array_key_exists( 'formatted', $address ) ) {
				$formatted = $address ['formatted'];
				$lines     = explode( '\r\n', $formatted );
				if ( count( $lines ) > 0 ) {
					$in['billing']['billing_address_1']['default']   = $lines[0];
					$in['shipping']['shipping_address_1']['default'] = $lines[0];
				}
				if ( count( $lines ) > 1 ) {
					$in['billing']['billing_address_2']['default']   = $lines[1];
					$in['shipping']['shipping_address_2']['default'] = $lines[1];
				}
			}
			if ( array_key_exists( 'street_address', $address ) ) {
				$street_address = $address ['street_address'];
				if ( ! array_key_exists( 'formatted', $address ) ) {
					$in['billing']['billing_address_1']['default']   = $street_address;
					$in['shipping']['shipping_address_1']['default'] = $street_address;
				}
			}
		}
	}
	return $in;
}