felixarntz/site-icon-extended

<?php
/**
 * WPSIE\XMLHandler class
 *
 * @package WPSIE
 * @author Felix Arntz <felix-arntz@leaves-and-love.net>
 * @since 0.1.0
 */

namespace WPSIE;

if ( ! defined( 'ABSPATH' ) ) {
    die();
}

if ( ! class_exists( 'WPSIE\XMLHandler' ) ) {
    /**
     * This class is responsible for everything related to generating the browserconfig.xml file.
     *
     * @since 0.1.0
     */
    class XMLHandler {

        /**
         * @since 0.1.0
         * @var WPSIE\XMLHandler|null Holds the singleton instance of the class.
         */
        private static $instance = null;

        /**
         * Returns the singleton instance of the class.
         *
         * @since 0.1.0
         * @return WPSIE\XMLHandler
         */
        public static function instance() {
            if ( null === self::$instance ) {
                self::$instance = new self();
            }
            return self::$instance;
        }

        /**
         * @since 0.1.0
         * @var array Holds the icon sizes for the browserconfig.xml file.
         */
        private $sizes = array();

        /**
         * Class constructor.
         *
         * @since 0.1.0
         */
        private function __construct() {
        }

        /**
         * Sets the icon sizes.
         *
         * @since 0.1.0
         * @param array $sizes an array of integers for the icon sizes
         */
        public function set_sizes( $sizes ) {
            $this->sizes = $sizes;
        }

        /**
         * Adds actions and filters to integrate the class functionality into WordPress.
         *
         * @since 0.1.0
         */
        public function add_hooks() {
            add_action( 'after_setup_theme', array( $this, 'reduce_query_load' ), 99 );
            add_action( 'init', array( $this, 'add_query_var' ), 1 );
            add_action( 'init', array( $this, 'add_rewrite_rule' ), 1 );
            add_action( 'pre_get_posts', array( $this, 'maybe_show_browserconfig' ), 1, 1 );

            add_filter( 'redirect_canonical', array( $this, 'fix_canonical' ), 10, 1 );
        }

        /**
         * Gets the URL to the browserconfig.xml file.
         *
         * @since 0.1.0
         * @return string|false URL to the file or false if no icon is set
         */
        public function get_browserconfig_url() {
            global $wp_rewrite;

            if ( ! has_site_icon() ) {
                return false;
            }

            $base = $wp_rewrite->using_index_permalinks() ? 'index.php/' : '/';

            return home_url( $base . 'browserconfig.xml' );
        }

        /**
         * Reduces query load on a browserconfig.xml request by removing unnecessary actions.
         *
         * This function was basically taken from the Yoast SEO plugin.
         *
         * @since 0.1.0
         */
        public function reduce_query_load() {
            if ( ! isset( $_SERVER['REQUEST_URI'] ) ) {
                return;
            }

            $extension = substr( $_SERVER['REQUEST_URI'], -4 );

            if ( false !== stripos( $_SERVER['REQUEST_URI'], 'browserconfig' ) && '.xml' === $extension ) {
                remove_all_actions( 'widgets_init' );
            }
        }

        /**
         * Adds a query var to check for the browserconfig.xml file.
         *
         * @since 0.1.0
         */
        public function add_query_var() {
            global $wp;

            if ( ! is_object( $wp ) ) {
                return;
            }

            $wp->add_query_var( 'wpsie_browserconfig' );
        }

        /**
         * Adds a rewrite rule for the browserconfig.xml file.
         *
         * @since 0.1.0
         */
        public function add_rewrite_rule() {
            add_rewrite_rule( 'browserconfig\.xml$', 'index.php?wpsie_browserconfig=1', 'top' );
        }

        /**
         * Fixes the canonical redirect for the browserconfig.xml file by preventing a trailing slash.
         *
         * @since 0.1.0
         * @param mixed $redirect argument passed by WordPress
         * @return mixed returns false on a browserconfig.xml request
         */
        public function fix_canonical( $redirect ) {
            $browserconfig = get_query_var( 'wpsie_browserconfig' );
            if ( empty( $browserconfig ) ) {
                return $redirect;
            }

            return false;
        }

        /**
         * Shows the browserconfig.xml file if the query var is set.
         *
         * @since 0.1.0
         * @param WP_Query $query the query object to check
         */
        public function maybe_show_browserconfig( $query ) {
            if ( ! $query->is_main_query() ) {
                return;
            }

            $browserconfig = get_query_var( 'wpsie_browserconfig' );
            if ( empty( $browserconfig ) ) {
                return;
            }

            $this->show_browserconfig();
        }

        /**
         * Sets the necessary headers and shows the browserconfig.xml file.
         *
         * @since 0.1.0
         */
        private function show_browserconfig() {
            if ( ! headers_sent() ) {
                header( ( ( isset( $_SERVER['SERVER_PROTOCOL'] ) && $_SERVER['SERVER_PROTOCOL'] !== '' ) ? sanitize_text_field( $_SERVER['SERVER_PROTOCOL'] ) : 'HTTP/1.1' ) . ' 200 OK', true, 200 );
                header( 'X-Robots-Tag: noindex, follow', true );
                header( 'Content-Type: text/xml' );
                header( 'Content-Disposition: inline; filename="browserconfig.xml"' );
            }

            echo '<?xml version="1.0" encoding="' . get_bloginfo( 'charset' ) . '"?>' . "\n";
            echo $this->get_browserconfig();

            remove_all_actions( 'wp_footer' );
            die();
        }

        /**
         * Gets the content of the browserconfig.xml file.
         *
         * @since 0.1.0
         * @return string the content as valid XML
         */
        private function get_browserconfig() {
            $content = '<browserconfig>' . "\n";
            $content .= '<msapplication>' . "\n";
            $content .= '<tile>' . "\n";

            if ( has_site_icon() ) {
                foreach ( $this->sizes as $size ) {
                    $content .= sprintf( '<square%1$slogo src="%2$s"/>', sprintf( '%1$dx%1$d', $size ), esc_url( get_site_icon_url( $size ) ) ) . "\n";
                }
            }

            $background_color = BackgroundHandler::instance()->get_background_color();
            if ( $background_color ) {
                $content .= sprintf( '<TileColor>%s</TileColor>', esc_html( '#' . ltrim( $background_color, '#' ) ) ) . "\n";
            }

            $content .= '</tile>' . "\n";
            $content .= '</msapplication>' . "\n";
            $content .= '</browserconfig>' . "\n";

            return $content;
        }
    }
}