<?php

/**
 * The public-facing functionality of the plugin.
 *
 * @link       http://pixelative.co
 * @since      1.0.0
 *
 * @package    Amp_WP
 * @subpackage Amp_WP/public
 */

/**
 * The public-facing functionality of the plugin.
 *
 * Defines the plugin name, version, and two examples hooks for how to
 * enqueue the public-facing stylesheet and JavaScript.
 *
 * @package    Amp_WP
 * @subpackage Amp_WP/public
 * @author     Pixelative <mohsin@pixelative.co>
 */
class Amp_WP_Public {
    /**
     * The ID of this plugin.
     *
     * @since    1.0.0
     * @access   private
     * @var      string    $plugin_name    The ID of this plugin.
     */
    private $plugin_name;

    /**
     * The version of this plugin.
     *
     * @since    1.0.0
     * @access   private
     * @var      string    $version    The current version of this plugin.
     */
    private $version;
    
    /**
     * Default Endpoint for AMP URL of Site.
     * This cna Can Be Overridden by Filter
     * 
     * @var      string
     * 
     * @since   1.0.0
     * 
     */
    const AMP_WP_STARTPOINT = 'amp';
    
    /**
     * pre_get_posts hook priority
     *
     * @var      int
     * 
     * @since   1.0.0
     */
    const AMP_WP_ISOLATE_QUERY_HOOK_PRIORITY = 100;
    
    /**
     * Store amp_wp_head action callbacks
     *
     * @see amp_wp_collect_and_remove_head_actions
     * 
     * @var     array
     *
     * @since   1.0.0
     */
    private $head_actions;

    /**
     * Store Array of Posts Id to Exlucde Transform Permalinks to Amp
     *
     * Array structure: array {
     *      'post id' => dont care,
     *      ...
     * }
     *
     * @see amp_wp_transform_post_link_to_amp
     *
     * @var     array
     * 
     * @since   1.0.0
     */
    public $excluded_posts_id = array();
    
    /**
     * Initialize the class and set its properties.
     *
     * @param   string  $plugin_name    The name of the plugin.
     * @param   string  $version        The version of this plugin.
     * @since   1.0.0
     * 
     */
    public function __construct($plugin_name, $version) {

        $this->plugin_name = $plugin_name;
        $this->version = $version;
        
        // Registers the AMP Rewrite Rules
        add_filter( 'init', array( $this, 'amp_wp_add_rewrite' ) );
        add_filter( 'init', array( $this, 'amp_wp_append_index_rewrite_rule' ) );
        
        // Check Plugin Compatibility
        add_filter( 'template_redirect', array( $this, 'amp_wp_plugins_compatibility' ) );
        
        // Initialize AMP Components
        add_filter( 'init', array( $this, 'amp_wp_include_components' ) );
        
        // Changes Page Template File With AMP Template File
        add_action('template_include', array($this, 'amp_wp_include_template_file'), 9999);
        
        // Override Template File
        add_filter( 'comments_template', array( $this, 'amp_wp_override_comments_template' ), 9999 );
        
        // Initialize AMP Theme and It’s Functionality
        add_action( 'after_setup_theme', array( $this, 'amp_wp_template_functions' ), 1 );
        
        // Replace All Links Inside Contents to AMP Version.
        // Stops User to Go Outside of AMP Version.
        add_action( 'wp', array( $this, 'amp_wp_replace_internal_links_with_amp_version' ) );
        
        // Registers All Components Scripts Into the Header Style and Scripts
        add_action( 'amp_wp_template_enqueue_scripts', array( $this, 'amp_wp_enqueue_components_scripts' ) );
        
        // Let the Components to Do Their Functionality in Head
        add_action( 'amp_wp_template_head', array( $this, 'amp_wp_trigger_component_head' ), 0 );
        
        // Collect All Output to Can Enqueue Only Needed Scripts and Styles in Pages.
        add_action( 'amp_wp_template_head', array( $this, 'amp_wp_buffer_head_start' ), 1 );
        add_action( 'amp_wp_template_footer', array( $this, 'amp_wp_buffer_head_end' ), 999 );
        
        // Collect and Rollback All Main Query Posts to Disable Thirdparty Codes to Change Main Query!
        // Action After 1000 Priority Can Work
        add_action( 'pre_get_posts', array( $this, 'amp_wp_isolate_pre_get_posts_start' ), 1 );
        add_action( 'pre_get_posts', array( $this, 'amp_wp_isolate_pre_get_posts_end' ), self::AMP_WP_ISOLATE_QUERY_HOOK_PRIORITY );
        
        add_action( 'template_redirect', array( $this, 'amp_wp_redirect_endpoint_url' ) );
        add_filter( 'redirect_canonical', array( $this, 'amp_wp_fix_prevent_extra_redirect_single_pagination' ) );
        
        add_action( 'request', array( $this, 'amp_wp_fix_search_page_queries' ) );
        add_filter( 'request', array( $this, 'amp_wp_force_query_var_value' ) );
        add_action( 'parse_query', array( $this, 'amp_wp_correct_query_when_is_front_page' ) );
        
        // Auto Redirect Mobile Users
        add_action( 'template_redirect', array( $this, 'amp_wp_auto_redirect_to_amp' ), 1 );
        
        // Init AMPWP JSON-LD
        add_action('template_redirect', 'Amp_WP_Public::amp_wp_init_json_ld', 1);
        
        $this->amp_wp_fix_front_page_display_options();
    }
    
    /**
     * Register the stylesheets for the admin area.
     *
     * @since    1.0.0
     */
    public function enqueue_styles() {}

    /**
     * Register the JavaScript for the admin area.
     *
     * @since    1.0.0
     */
    public function enqueue_scripts() {}
    
    /**
     * Callback: Add rewrite rules
     * Action: init
     *
     * @version 1.0.0
     * @since   1.0.0
    */
    public function amp_wp_add_rewrite() {
        amp_wp_add_rewrite_startpoint( self::AMP_WP_STARTPOINT, EP_ALL );
        
        /**
         * "Automattic AMP" Plugin Compatibility
         */
        $amp_qv = defined( 'AMP_WP_QUERY_VAR' ) ? AMP_WP_QUERY_VAR : 'amp';
        add_rewrite_endpoint( $amp_qv, EP_PERMALINK );
    }
    
    /**
     * Add a Rewrite Rule to Detect site.com/amp/ Requests
     *
     * @version 1.0.0
     * @since   1.0.0
     *
     * @return  array
     */
    public function amp_wp_append_index_rewrite_rule() {
        add_rewrite_rule( self::AMP_WP_STARTPOINT . '/?$', "index.php?amp=index", 'top' );
    }
    
    /**
     * Change most popular cache plugins in amp version to compatible with it
     *
     * @since 1.0.0
     */
    public function amp_wp_plugins_compatibility() {
        if( !is_amp_wp() ) {
            return;
        }

        /**
         * W3 total cache
         */
        add_filter( 'w3tc_minify_js_enable', '__return_false' );
        add_filter( 'w3tc_minify_css_enable', '__return_false' );

        /**
         * WP Rocket
         */
        if( defined( 'WP_ROCKET_VERSION' ) ) {
            if( !defined( 'DONOTMINIFYCSS' ) ) {
                define( 'DONOTMINIFYCSS', TRUE );
            }

            if( !defined( 'DONOTMINIFYJS' ) ) {
                define( 'DONOTMINIFYJS', TRUE );
            }

            // Disable WP Rocket lazy load
            add_filter( 'do_rocket_lazyload', '__return_false', PHP_INT_MAX );
            add_filter( 'do_rocket_lazyload_iframes', '__return_false', PHP_INT_MAX );

            // Disable HTTP protocol removing on script, link, img, srcset and form tags.
            remove_filter( 'rocket_buffer', '__rocket_protocol_rewrite', PHP_INT_MAX );
            remove_filter( 'wp_calculate_image_srcset', '__rocket_protocol_rewrite_srcset', PHP_INT_MAX );

            // Disable Concatenate Google Fonts
            add_filter( 'get_rocket_option_minify_google_fonts', '__return_false', PHP_INT_MAX );

            // Disable CSS & JS magnification
            add_filter( 'get_rocket_option_minify_js', '__return_false', PHP_INT_MAX );
            add_filter( 'get_rocket_option_minify_css', '__return_false', PHP_INT_MAX );
        }

        /**
         * WP Speed of Light
         *
         * https://wordpress.org/plugins-wp/wp-speed-of-light/
         */
        if( defined( 'WPSOL_VERSION' ) ) {
            add_filter( 'wpsol_filter_js_noptimize', '__return_true', PHP_INT_MAX );
            add_filter( 'wpsol_filter_css_noptimize', '__return_true', PHP_INT_MAX );
        }

        /**
         * Lazy Load
         * https://wordpress.org/plugins/lazy-load/
         */
        if( class_exists( 'LazyLoad_Images' ) ) {
            add_filter( 'lazyload_is_enabled', '__return_false', PHP_INT_MAX );
        }

        /**
         * Lazy Load XT
         * https://wordpress.org/plugins/lazy-load-xt/
         */
        if( class_exists( 'Image_Lazy_Load' ) ) {
            global $lazyloadxt;
            if( is_object( $lazyloadxt ) ) {
                remove_filter( 'the_content', array( $lazyloadxt, 'filter_html' ) );
                remove_filter( 'widget_text', array( $lazyloadxt, 'filter_html' ) );
                remove_filter( 'post_thumbnail_html', array( $lazyloadxt, 'filter_html' ) );
                remove_filter( 'get_avatar', array( $lazyloadxt, 'filter_html' ) );
            }
        }

        /***
         * Facebook Comments Plugin
         * https://wordpress.org/plugins/facebook-comments-plugin/
         */
        if( function_exists( 'fbcommentshortcode' ) ) {
            remove_action( 'wp_footer', 'fbmlsetup', 100 );
            remove_filter( 'the_content', 'fbcommentbox', 100 );
            remove_filter( 'widget_text', 'do_shortcode' );
        }

        /***
         * Yoast SEO
         * https://wordpress.org/plugins/wordpress-seo/
         */
        if( defined( 'WPSEO_VERSION' ) ) {
            if( class_exists( 'WPSEO_OpenGraph' ) ) {
                add_action( 'amp_wp_template_head', array( $this, 'amp_wp_yoast_seo_metatags_compatibility' ) );
            }

            if( is_home() && ! amp_wp_is_static_home_page() && self::amp_wp_get_option( 'show_on_front' ) === 'page' ) {
                add_filter( 'pre_get_document_title', 'Amp_WP_Public::amp_wp_yoast_seo_homepage_title', 99 );
            }

            if( is_home() ) {
                add_filter( 'amp_wp_json_ld_website', 'Amp_WP_Public::amp_wp_yoast_seo_homepage_json_ld' );
            }
        }

        /***
         * Ultimate Tweaker
         * https://ultimate-tweaker.com/
         */
        if( class_exists( 'ultimate_tweaker_Plugin_File' ) && defined( 'UT_VERSION' ) ) {
            amp_wp_remove_class_filter( 'post_thumbnail_html', 'OT_media_image_no_width_height_Tweak', '_do', 10 );
            amp_wp_remove_class_filter( 'image_send_to_editor', 'OT_media_image_no_width_height_Tweak', '_do', 10 );
        }

        /**
         * WPO Tweaks
         *
         * https://servicios.ayudawp.com/
         */
        if( function_exists( 'wpo_tweaks_init' ) ) {
            remove_filter( 'script_loader_tag', 'wpo_defer_parsing_of_js' );
        }
    }
    
    /**
     * Include Active Template functions.php File If Exits
     *
     * Callback: include
     * action: after_setup_theme
     *
     * @since   1.0.0
     */
    public function amp_wp_template_functions() {
        if( file_exists( AMPWP_TEMPLATE_DIR_PATH . 'includes/functions/amp-wp-template-functions.php' ) ) {
            require_once AMPWP_TEMPLATE_DIR_PATH . 'includes/functions/amp-wp-template-functions.php';
        }
    }
    
    /**
     * Callback: Include registered AMP components
     * Action: init
     *
     * @since 1.0.0
     */
    public function amp_wp_include_components() {
        include AMPWP_TEMPLATE_DIR_PATH . 'includes/components/class-amp-wp-img-component.php';
        include AMPWP_TEMPLATE_DIR_PATH . 'includes/components/class-amp-wp-iframe-component.php';
        include AMPWP_TEMPLATE_DIR_PATH . 'includes/components/class-amp-wp-carousel-component.php';
    }
    
    /**
     * Callback: Include AMP template file in AMP pages
     * Action: template_include
     *
     * @param   string $template_file_path Original Template File Path
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     *
     * @return  string
     */
    public function amp_wp_include_template_file( $template_file_path ) {
        if( !is_amp_wp() ) {
            return $template_file_path;
        }

        $include = $this->amp_wp_template_loader();
        if( $include ) {
            return $include;
        }
    }
    
    /**
     * Load a Template
     *
     * Handles Template Usage so That We Can Use Our Own Templates Instead of the Themes
     *
     * Templates are in the 'templates' folder. amp-wp looks for theme.
     * overrides in /yourtheme/amp-wp/ by default.
     *
     * @see Template Hierarchy Reference https://developer.wordpress.org/files/2014/10/wp-hierarchy.png
     * @param   mixed   $template
     * @return  string
     */
    public function amp_wp_template_loader() {
        if( amp_wp_is_static_home_page() ) {
            $template = amp_wp_static_home_page_template();
            $this->amp_wp_set_page_query( apply_filters( 'amp_wp_template_page_on_front', 0 ) );
        } elseif ( is_home() ) {
            $template = amp_wp_home_template();
        } elseif ( is_post_type_archive() ) {
            $template = amp_wp_archive_post_type_template();
        } elseif ( is_archive() ){
            $template = amp_wp_archive_template();
        } elseif ( is_attachment() ){
            $template = amp_wp_attachment_template();
            remove_filter( 'the_content', 'prepend_attachment' );
        } elseif ( is_single() ) {
            $template = amp_wp_single_template();
        } elseif ( is_page() ) {
            $template = amp_wp_page_template();
        } elseif ( is_404() ) {
            $template = amp_wp_404_template();
        } elseif ( is_search() ) {
            $template = amp_wp_search_template();
        } elseif ( is_embed() ) {
            return $template;
        } else {
            $template = amp_wp_index_template();
        }
        return $template;
    }
    
    /**
     * Replace amp comment file with theme file
     *
     * @param string $file
     *
     * @since 1.0.0
     * @return string
     */
    public function amp_wp_override_comments_template( $file ) {
        if( is_amp_wp() ) {
            if( $path = amp_wp_locate_template( basename( $file ) ) ) {
                return $path;
            }
        }
        return $file;
    }
    
    /**
     * Replaces All Website Internal Links With AMP Version
     *
     * @hooked wp
     *
     * @param WP $wp
     *
     * @since  1.0.0
     * @return string
     */
    public function amp_wp_replace_internal_links_with_amp_version( $wp ) {
        if( empty( $wp->query_vars['amp'] ) ) { return; }

        add_filter( 'nav_menu_link_attributes', array( 'Amp_WP_Content_Sanitizer', 'replace_href_with_amp' ) );
        add_filter( 'the_content', array( 'Amp_WP_Content_Sanitizer', 'transform_all_links_to_amp' ) );

        add_filter( 'author_link', array( 'Amp_WP_Content_Sanitizer', 'transform_to_amp_url' ) );
        add_filter( 'term_link', array( 'Amp_WP_Content_Sanitizer', 'transform_to_amp_url' ) );

        add_filter( 'post_link', array( $this, 'amp_wp_transform_post_link_to_amp' ), 20, 2 );
        add_filter( 'page_link', array( $this, 'amp_wp_transform_post_link_to_amp' ), 20, 2 );
        add_filter( 'attachment_link', array( 'Amp_WP_Content_Sanitizer', 'transform_to_amp_url' ) );
        add_filter( 'post_type_link', array( 'Amp_WP_Content_Sanitizer', 'transform_to_amp_url' ) );
    }
    
    /**
     * Transform allowed posts URL to AMP
     *
     * @param   string      $url  The Post’s Permalink
     * @param   WP_Post|int $post The post object/id  of the post.
     *
     * @since   1.0.0
     * @return  string
     */
    public function amp_wp_transform_post_link_to_amp( $url, $post ) {
        $post_id = isset( $post->ID ) ? $post->ID : $post;

        if( isset( $this->excluded_posts_id[ $post_id ] ) ) {
            return $url;
        }
        return Amp_WP_Content_Sanitizer::transform_to_amp_url( $url );
    }
    
    /**
     * Append AMP Components JavaScript If AMP Version Requested
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_enqueue_components_scripts() {
        $deps = array( 'ampproject' );
        amp_wp_enqueue_script( $deps[0], 'https://cdn.ampproject.org/v0.js' );
        
        // Enqueues all needed scripts of components with 'ampproject' dependency
        $this->amp_wp_call_components_method( 'enqueue_amp_scripts', $deps );

        if( current_theme_supports( 'amp-wp-navigation' ) && current_theme_supports( 'amp-wp-has-nav-child' ) ) {
            amp_wp_enqueue_script( 'amp-accordion', 'https://cdn.ampproject.org/v0/amp-accordion-0.1.js' );
        }
        if( current_theme_supports( 'amp-wp-form' ) ) {
            amp_wp_enqueue_script( 'amp-form', 'https://cdn.ampproject.org/v0/amp-form-0.1.js' );
        }
    }
    
    /**
     * Callback: Fire head method of component for following purpose:
     * 1) Component able to add_filter or add_action if needed
     * 2) Create fresh instance of each component and cache
     *
     * Action:  amp_wp_template_head
     *
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_trigger_component_head() {
        $this->amp_wp_call_components_method( 'head' );
    }
    
    /**
     * Callback: Starts the Collecting Output to Enable Components to Add Style Into Head
     * Print Theme Completely Then Fire amp_wp_head() Callbacks and Append It Before </head>
     *
     * Action:  amp_wp_template_head
     *
     * @see     amp_wp_buffer_head_end
     *
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_buffer_head_start() {
        remove_action( current_action(), array( $this, __FUNCTION__ ), 1 );
        $this->amp_wp_collect_and_remove_head_actions();
        ob_start();
    }

    /**
     * Collect amp_wp_head actions and remove those actions
     *
     * @see   amp_wp_head
     *
     * @since 1.0.0
     */
    public function amp_wp_collect_and_remove_head_actions() {
        $actions = &$GLOBALS['wp_filter']['amp_wp_template_head'];
        $this->head_actions = $actions;
        $actions = array();
    }
    
    /**
     * Callback: Fire amp_wp_head() and print buffered output
     * Action:  amp_wp_template_head
     *
     * @see amp_wp_buffer_head_start
     *
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_buffer_head_end() {

        $content = ob_get_clean();
        $prepend = '';

        if( !amp_wp_is_customize_preview() ) {
            $prepend .= '</head>';

            /**
             * Convert Output to Valid AMP HTML
             */
            $instance = new Amp_WP_Html_Util();
            $instance->loadHTML( '<!DOCTYPE html><html><head><meta http-equiv="content-type" content="text/html; charset=utf-8">' . $content . '</body></html>', NULL, FALSE );

            preg_match( '#(<\s*body[^>]*>)#isx', $content, $match );
            $prepend .= isset( $match[1] ) ? $match[1] : '<body>'; // open body tag

            $this->amp_wp_render_content( $instance, TRUE ); // Convert HTML top amp html

            // @see Amp_WP_Component::enqueue_amp_tags_script
            $this->amp_wp_call_components_method( 'enqueue_amp_tags_script', $instance );

            $content = $instance->get_content( TRUE );
            // End convert output to valid amp html
        }

        $GLOBALS['wp_filter']['amp_wp_template_head'] = $this->head_actions;
        $this->head_actions = array();
        do_action( 'amp_wp_template_head' );
        echo $prepend, $content;
    }
    
    /**
     * Transforms HTML Content to AMP Content
     *
     * todo: Add File Caching
     *
     * @param   Amp_WP_Html_Util    $instance
     * @param   boolean             $sanitize
     *
     * @since   1.0.0
     */
    public function amp_wp_render_content( Amp_WP_Html_Util $instance, $sanitize = FALSE ) {
        $this->amp_wp_call_components_method( 'render', $instance );
        if( $sanitize ) {
            $sanitizer = new Amp_WP_Content_Sanitizer( $instance );
            $sanitizer->sanitize();
        }
    }
    
    /**
     * Fire specific method of all components
     *
     * @param string $method_name component method
     *
     * @param mixed  $param
     *
     * @return mixed
     * @since 1.0.0
     *
     */
    public function amp_wp_call_components_method( $method_name, $param = NULL ) {
        global $amp_wp_registered_components;

        if( !$amp_wp_registered_components ) {
            return $param;
        }

        // collect and prepare method arguments
        $args = func_get_args();
        $args = array_slice( $args, 1 );
        if ( ! isset( $args[0] ) ) {
                $args[0] = NULL;
        }

        // iterate registered components and call method on them
        foreach( $amp_wp_registered_components as $component ) {
            $instance = Amp_WP_Component::instance( $component['component_class'] );
            if( $this->_amp_wp_can_call_component_method( $instance, $method_name, $args ) ) {
                $args[0] = call_user_func_array( array( $instance, $method_name ), $args );
            }
        }
        return $args[0];
    }
    
    /**
     * Determines that method exists and is callable on object instance
     *
     * @param   Amp_WP_Component $instance    Live object of Amp_WP_Component
     * @param   string               $method_name Method of object
     * @param   array                $args
     *
     * @access  private
     * @since   1.0.0
     *
     * @return bool
     */
    private function _amp_wp_can_call_component_method( &$instance, &$method_name, &$args ) {
        $return = is_callable( array( $instance, $method_name ) );
        switch ( $method_name ) {
            case 'enqueue_amp_scripts':
                $return = $return && $instance->can_enqueue_scripts();
            break;
        }
        return $return;
    }
    
    /**
     * Callback: Prevent Third Party Codes to Change the Main Query on AMP Version
     *
     * You Can Add Action To 'pre_get_posts' With Priority Grater Than 1000 to Change It.
     *
     * Action:  pre_get_posts
     *
     * @see     amp_wp_isolate_pre_get_posts_end
     *
     * @param   WP_Query    $wp_query
     * 
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_isolate_pre_get_posts_start( $wp_query ) {
        global $amp_wp_isolate_pre_get_posts;
        if( is_amp_wp( $wp_query ) && !is_admin() && $wp_query->is_main_query() ) {
            $amp_wp_isolate_pre_get_posts = $wp_query->query_vars;
        }
    }
    
    /**
     * Rollback the Main Query Vars.
     *
     * @see 'amp_wp_isolate_pre_get_posts_end' for more documentation
     *
     * Action:  pre_get_posts
     * @version 1.0.0
     * @since   1.0.0
     *
     * @param WP_Query $wp_query
     */
    public function amp_wp_isolate_pre_get_posts_end( &$wp_query ) {
        global $amp_wp_isolate_pre_get_posts;
        if( is_amp_wp( $wp_query ) && !is_admin() && $wp_query->is_main_query() ) {
            if( $amp_wp_isolate_pre_get_posts ) {
                $wp_query->query_vars = $amp_wp_isolate_pre_get_posts;
                unset( $amp_wp_isolate_pre_get_posts );
            }
        }
    }
    
    /**
     * Handy fix for changing search query
     *
     * @param   mixed $q
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     * 
     * @return  mixed
     */
    public function amp_wp_fix_search_page_queries( $q ) {
        if( !empty( $q['amp'] ) && !empty( $q['s'] ) ) {
            $q['post_type'] = array( 'post' );
        }
        return $q;
    }
    
    /**
     * Make sure the `amp` query var has an explicit value.
     * 
     * @param   int     $query_vars
     * @since   1.0.0
     * 
     * @return  int
     */
    public function amp_wp_force_query_var_value( $query_vars ) {
        if( isset( $query_vars[ self::AMP_WP_STARTPOINT ] ) && '' === $query_vars[ self::AMP_WP_STARTPOINT ] ) {
            $query_vars[ self::AMP_WP_STARTPOINT ] = 1;
	}
	return $query_vars;
    }
    
    /**
     * Fix up WP_Query for front page when amp query var is present.
     *
     * Normally the front page would not get served if a query var is present other than preview, page, paged, and cpage.
     *
     * @since 1.0.0
     * @see WP_Query::parse_query()
     * @link https://github.com/WordPress/wordpress-develop/blob/0baa8ae85c670d338e78e408f8d6e301c6410c86/src/wp-includes/class-wp-query.php#L951-L971
     *
     * @param WP_Query $query Query.
     */
    public function amp_wp_correct_query_when_is_front_page( WP_Query $query ) {
            $is_front_page_query = (
                    $query->is_main_query()
                    &&
                    $query->is_home()
                    &&
                    // Is AMP endpoint.
                    false !== $query->get( self::AMP_WP_STARTPOINT, false )
                    &&
                    // Is query not yet fixed uo up to be front page.
                    ! $query->is_front_page()
                    &&
                    // Is showing pages on front.
                    'page' === get_option( 'show_on_front' )
                    &&
                    // Has page on front set.
                    get_option( 'page_on_front' )
                    &&
                    // See line in WP_Query::parse_query() at <https://github.com/WordPress/wordpress-develop/blob/0baa8ae/src/wp-includes/class-wp-query.php#L961>.
                    0 === count( array_diff( array_keys( wp_parse_args( $query->query ) ), array( self::AMP_WP_STARTPOINT, 'preview', 'page', 'paged', 'cpage' ) ) )
            );
            if( $is_front_page_query ) {
                $query->is_home = false;
                $query->is_page = true;
                $query->is_singular = true;
                $query->set( 'page_id', get_option( 'page_on_front' ) );
            }
    }
    
    /**
     * "Automattic AMP" Plugin Compatibility
     *
     * Redirect AMP URLs With AMP Endpoint to New AMP URL
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_redirect_endpoint_url() {
        $amp_qv = defined( 'AMP_WP_QUERY_VAR' ) ? AMP_WP_QUERY_VAR : 'amp';
        if( get_query_var( $amp_qv, FALSE ) === FALSE ) {
            if( !is_404() ) { # /amp at the end of some urls cause 404 error
                return;
            }
        }

        $path = amp_wp_get_wp_installation_slug();
        $request_url = str_replace( $path, '', $_SERVER['REQUEST_URI'] );
        preg_match( "#^/*(.*?)/$amp_qv/*$#", $request_url, $automattic_amp_match );
        
        if( !$this->amp_version_exists() ) {
            if( !empty( $automattic_amp_match[1] ) ) {
                $redirect_url = home_url( $automattic_amp_match[1] );
            } elseif ( preg_match( "#^/*$amp_qv/+(.*?)/*$#", $request_url, $matched ) ) {
                $redirect_url = home_url( $matched[1] );
            } else {
                $redirect_url = amp_wp_get_canonical_url();
            }
            if( $redirect_url ) {
                wp_redirect( $redirect_url );
                exit;
            }
        }

        if( !empty( $automattic_amp_match[1] ) ) {
            $new_amp_url = Amp_WP_Content_Sanitizer::transform_to_amp_url( site_url( $automattic_amp_match[1] ) );
            $new_amp_url = trailingslashit( $new_amp_url );

            if( $new_amp_url && trim( str_replace( site_url(), '', $new_amp_url ), '/' ) !== trim( $request_url, '/' ) ) {
                wp_redirect( $new_amp_url, 301 );
                exit;
            }
        }
    }
    
    /**
     * Prevent Redirect Pages Within Single Post
     *
     * @param   bool $redirect
     *
     * @access  public
     * @since   1.0.0
     * 
     * @return  bool
     */
    public function amp_wp_fix_prevent_extra_redirect_single_pagination( $redirect ) {
        if( $redirect && is_amp_wp() && get_query_var( 'page' ) > 1 ) {
            return FALSE;
        }
        return $redirect;
    }
    
    /**
     * Get Requested Page URL
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     * 
     * @return  string
     */
    public static function amp_wp_get_requested_page_url() {
        if( isset( $_SERVER['HTTP_HOST'] ) ) {
            $requested_url = is_ssl() ? 'https://' : 'http://';
            $requested_url .= $_SERVER['HTTP_HOST'];
            $requested_url .= $_SERVER['REQUEST_URI'];

            return $requested_url;
        }
        return '';
    }
    
    /**
     * Redirect Users to AMP Version of the Page Automatically
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_auto_redirect_to_amp() {
        if( is_amp_wp() ) {
            return;
        }
        if( !apply_filters( 'amp_wp_template_auto_redirect', FALSE ) ) {
            return;
        }

        if( !empty( $_GET['amp-wp-skip-redirect'] ) || !empty( $_COOKIE['amp-wp-skip-redirect'] ) ) {
            if( !isset( $_COOKIE['amp-wp-skip-redirect'] ) ) {
                setcookie( 'amp-wp-skip-redirect', TRUE, time() + DAY_IN_SECONDS, '/' );
            }
            return;
        } else {
            if( isset( $_COOKIE['amp-wp-skip-redirect'] ) ) {
                unset( $_COOKIE['amp-wp-skip-redirect'] );
            }
        }
        
        // if post have not AMP version
        if( !$this->amp_version_exists() ) {
            return;
        }

        if( wp_is_mobile() ) {
            $requested_url = self::amp_wp_get_requested_page_url();
            $amp_permalink = Amp_WP_Content_Sanitizer::transform_to_amp_url( $requested_url );

            if( $requested_url && $amp_permalink && $amp_permalink !== $requested_url ) {
                wp_redirect( $amp_permalink );
                exit;
            }
        } elseif ( Amp_WP_Public::amp_wp_have_cache_plugin() ) {
            // Adds advanced javascript code to page to redirect page in front end!
            // Last and safest way to redirect but it will have a little delay!
            add_action( 'wp_print_scripts', array( $this, 'amp_wp_print_mobile_redirect_script' ) );
        }
    }
    
    /**
     * Is Any Caching Plugin Install on This WordPress Installation
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     * 
     * @return bool
     */
    public function amp_wp_have_cache_plugin() {
        if( defined( 'WP_CACHE' ) && WP_CACHE ) { return TRUE; }

        // Fix for "WP Fastest Cache" plugin
        if( $plugins = array_flip( wp_get_active_and_valid_plugins() ) ) {
            return isset( $plugins[ WP_PLUGIN_DIR . '/wp-fastest-cache/wpFastestCache.php' ] );
        }

        return FALSE;
    }
    
    /**
     * Print Script to Redirect Mobile Devices to AMP Version
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_print_mobile_redirect_script() {
        $requested_url = self::amp_wp_get_requested_page_url();
        $amp_permalink = Amp_WP_Content_Sanitizer::transform_to_amp_url( $requested_url );

        if( !$requested_url || !$amp_permalink || $amp_permalink === $requested_url ) {
            return;
        }
    ?>
        <script><?php echo include AMPWP_PATH . 'public/js/mobile_redirect.js'; ?></script>
    <?php
    }
    
    /**
     * Initialize AMPWP JSON-LD
     */
    public static function amp_wp_init_json_ld() {
        if( !is_amp_wp() ) {
            return;
        }
        
        if( !class_exists('Amp_WP_Json_Ld_Generator') ) {
            include AMPWP_PATH . 'includes/class-amp-wp-json-ld-generator.php';
        }
        
        // Config AMPWP JSON-LD
        add_filter('amp_wp_json_ld_config', 'Amp_WP_Public::config_json_ld', 15);
    }
    
    /**
     * Configurations of JSON-LD
     *
     * @param   $config
     * @since   1.0.0
     *
     * @return  mixed
     */
    public static function config_json_ld($config) {
        $branding = amp_wp_get_branding_info();
        if( !empty( $branding['logo']['src'] ) ) {
            $config['logo'] = $branding['logo']['src'];
        }
        return $config;
    }
    
    /**
     * Fix Front Page Display Option to Detect Homepage
     * 
     * @access  1.0.0
     * @version 1.0.0
     * @since   1.0.0
     */
    public function amp_wp_fix_front_page_display_options() {
        add_action( 'pre_option_page_on_front', array( $this, 'amp_wp_return_zero_in_amp' ) );
        add_action( 'pre_option_show_on_front', array( $this, 'amp_wp_fix_show_on_front' ) );
    }
    
    /**
     * Just Return Zero in AMP Version
     *
     * @param mixed $current
     *
     * @access  1.0.0
     * @version 1.0.0
     * @since   1.0.0
     * 
     * @return mixed
     */
    public function amp_wp_return_zero_in_amp( $current ) {
        if( is_amp_wp() && empty( $GLOBALS['_amp_bypass_option'] ) ) {
            return 0;
        }
        return $current;
    }
    
    /**
     * Just Return ‘Posts’ String in AMP Version
     *
     * @param mixed $current
     * 
     * @access  1.0.0
     * @version 1.0.0
     * @since   1.0.0
     * 
     * @return mixed
     */
    public function amp_wp_fix_show_on_front( $current ) {
        if( is_amp_wp() && empty( $GLOBALS['_amp_bypass_option'] ) ) {
            return 'posts';
        }
        return $current;
    }
    
    /**
     * Setup page query
     *
     * @param $page_id
     * 
     * @access  1.0.0
     * @version 1.0.0
     * @since   1.0.0
     * 
     */
    public function amp_wp_set_page_query( $page_id ) {
        query_posts('page_id=' . $page_id . '&amp=' . get_query_var('amp'));
    }
    
    /**
     * Check AMP version of the posts exists
     *
     * @since 1.0.0
     * @return bool of exists
     */
    public static function amp_version_exists() {
        
        static $filters;

        if( !isset( $filters ) ) {
            $filters = wp_parse_args(
                apply_filters('amp_wp_filter_config_list', array()), array(
                    'disabled_post_types' => array(),
                    'disabled_taxonomies' => array(),
                    'disabled_homepage' => FALSE,
                    'disabled_search' => FALSE,
                )
            );
        }
        
        if( is_singular() ) {
            $post_id = get_queried_object_id();
        } elseif ( is_home() && amp_wp_is_static_home_page() ) {
            $post_id = intval( apply_filters('amp_wp_template_page_on_front', 0) );
        } else {
            $post_id = 0;
        }
        
        if( $post_id ) {
            //if( get_post_meta( $post_id, 'disable-amp-wp', TRUE ) || isset( $this->excluded_posts_id[$post_id] ) ) {
            if( get_post_meta( $post_id, 'disable-amp-wp', TRUE ) ) {
                return FALSE;
            }
        }
        
        if( empty( $filters ) ) { return TRUE; }
        if( is_home() ) { return !$filters['disabled_homepage']; }
        if( is_search() ) { return !$filters['disabled_search']; }
        if( is_singular() ) { return !in_array(get_queried_object()->post_type, $filters['disabled_post_types']); }
        if( is_post_type_archive() ) {
            $queried_object = get_queried_object();
            if( $queried_object instanceof WP_Post_Type ) { #  WP >= 4.6.0
                $post_type = $queried_object->name;
            } elseif ( $queried_object instanceof WP_Post) { #  WP < 4.6.0
                $post_type = $queried_object->post_type;
            } else {
                return FALSE;
            }
            return !in_array($post_type, $filters['disabled_post_types']);
        }
        if( is_tax() || is_category() || is_tag() ) { return !in_array( get_queried_object()->taxonomy, $filters['disabled_taxonomies'] ); }
        return TRUE;
    }
    
    /**
     * Prints meta tags with using Yoast SEO Open Graph feature.
     */
    public function amp_wp_yoast_seo_metatags_compatibility() {
        
        // Remove canonical from in Yoast to generate correct canonical
	amp_wp_remove_class_action( 'wpseo_head', 'WPSEO_Frontend', 'canonical', 20 );
                
        do_action( 'wpseo_opengraph' );
    }
    
    /**
     * Sync non-amp Homepage Title With AMP Version
     *
     * @param   string  $title
     *
     * @access  public
     * @version 1.0.0
     * @since   1.0.0
     * 
     * @return string
     */
    public static function amp_wp_yoast_seo_homepage_title( $title ) {
        if( ( $post_id = self::amp_wp_get_option( 'page_on_front' ) ) && is_callable( 'WPSEO_Frontend::get_instance' ) ) {
            $post = get_post( $post_id );
            if( $post instanceof WP_Post ) {
                $wp_seo = WPSEO_Frontend::get_instance();
                if( $new_title = $wp_seo->get_content_title( $post ) ) {
                    return $new_title;
                }
            }
        }
        return $title;
    }
    
    /**
     * Sync json-ld Data With Yoast SEO Plugin
     *
     * @param array $data
     *
     * @since 1.0.0
     * @return array
     */
    public static function amp_wp_yoast_seo_homepage_json_ld( $data ) {
        if( is_callable( 'WPSEO_Options::get_options' ) ) {
            $options = WPSEO_Options::get_options( array( 'wpseo', 'wpseo_social' ) );

            if( !empty( $options['website_name'] ) ) {
                $data['name'] = $options['website_name'];
            }
            if( !empty( $options['alternate_website_name'] ) ) {
                $data['alternateName'] = $options['alternate_website_name'];
                unset( $data['description'] );
            }
        }
        return $data;
    }
    
    /**
     * Get WordPress option
     *
     * @param string $option
     * @param mixed  $default
     *
     * @since 1.0.0
     * @return mixed
     */
    public static function amp_wp_get_option( $option, $default = FALSE ) {
        $tmp = isset( $GLOBALS['_amp_bypass_option'] ) ? $GLOBALS['_amp_bypass_option'] : FALSE;
        $GLOBALS['_amp_bypass_option'] = TRUE;
        $results = get_option( $option, $default );
        $GLOBALS['_amp_bypass_option'] = $tmp;

        return $results;
    }
}