<?php 
/** 
 * Server-side rendering of the `core/post-navigation-link` block. 
 * 
 * @package WordPress 
 */ 
 
/** 
 * Renders the `core/post-navigation-link` block on the server. 
 * 
 * @since 5.9.0 
 * 
 * @param array  $attributes Block attributes. 
 * @param string $content    Block default content. 
 * 
 * @return string Returns the next or previous post link that is adjacent to the current post. 
 */ 
function render_block_core_post_navigation_link( $attributes, $content ) { 
    if ( ! is_singular() ) { 
        return ''; 
    } 
 
    // Get the navigation type to show the proper link. Available options are `next|previous`. 
    $navigation_type = isset( $attributes['type'] ) ? $attributes['type'] : 'next'; 
    // Allow only `next` and `previous` in `$navigation_type`. 
    if ( ! in_array( $navigation_type, array( 'next', 'previous' ), true ) ) { 
        return ''; 
    } 
    $classes = "post-navigation-link-$navigation_type"; 
    if ( isset( $attributes['textAlign'] ) ) { 
        $classes .= " has-text-align-{$attributes['textAlign']}"; 
    } 
    $wrapper_attributes = get_block_wrapper_attributes( 
        array( 
            'class' => $classes, 
        ) 
    ); 
    // Set default values. 
    $format = '%link'; 
    $link   = 'next' === $navigation_type ? _x( 'Next', 'label for next post link' ) : _x( 'Previous', 'label for previous post link' ); 
    $label  = ''; 
 
    // Only use hardcoded values here, otherwise we need to add escaping where these values are used. 
    $arrow_map = array( 
        'none'    => '', 
        'arrow'   => array( 
            'next'     => '?', 
            'previous' => '?', 
        ), 
        'chevron' => array( 
            'next'     => '»', 
            'previous' => '«', 
        ), 
    ); 
 
    // If a custom label is provided, make this a link. 
    // `$label` is used to prepend the provided label, if we want to show the page title as well. 
    if ( isset( $attributes['label'] ) && ! empty( $attributes['label'] ) ) { 
        $label = "{$attributes['label']}"; 
        $link  = $label; 
    } 
 
    // If we want to also show the page title, make the page title a link and prepend the label. 
    if ( isset( $attributes['showTitle'] ) && $attributes['showTitle'] ) { 
        /* 
         * If the label link option is not enabled but there is a custom label, 
         * display the custom label as text before the linked title. 
         */ 
        if ( ! $attributes['linkLabel'] ) { 
            if ( $label ) { 
                $format = '<span class="post-navigation-link__label">' . wp_kses_post( $label ) . '</span> %link'; 
            } 
            $link = '%title'; 
        } elseif ( isset( $attributes['linkLabel'] ) && $attributes['linkLabel'] ) { 
            // If the label link option is enabled and there is a custom label, display it before the title. 
            if ( $label ) { 
                $link = '<span class="post-navigation-link__label">' . wp_kses_post( $label ) . '</span> <span class="post-navigation-link__title">%title</span>'; 
            } else { 
                /* 
                 * If the label link option is enabled and there is no custom label, 
                 * add a colon between the label and the post title. 
                 */ 
                $label = 'next' === $navigation_type ? _x( 'Next:', 'label before the title of the next post' ) : _x( 'Previous:', 'label before the title of the previous post' ); 
                $link  = sprintf( 
                    '<span class="post-navigation-link__label">%1$s</span> <span class="post-navigation-link__title">%2$s</span>', 
                    wp_kses_post( $label ), 
                    '%title' 
                ); 
            } 
        } 
    } 
 
    // Display arrows. 
    if ( isset( $attributes['arrow'] ) && 'none' !== $attributes['arrow'] && isset( $arrow_map[ $attributes['arrow'] ] ) ) { 
        $arrow = $arrow_map[ $attributes['arrow'] ][ $navigation_type ]; 
 
        if ( 'next' === $navigation_type ) { 
            $format = '%link<span class="wp-block-post-navigation-link__arrow-next is-arrow-' . $attributes['arrow'] . '" aria-hidden="true">' . $arrow . '</span>'; 
        } else { 
            $format = '<span class="wp-block-post-navigation-link__arrow-previous is-arrow-' . $attributes['arrow'] . '" aria-hidden="true">' . $arrow . '</span>%link'; 
        } 
    } 
 
    /* 
     * The dynamic portion of the function name, `$navigation_type`, 
     * Refers to the type of adjacency, 'next' or 'previous'. 
     * 
     * @see https://developer.wordpress.org/reference/functions/get_previous_post_link/ 
     * @see https://developer.wordpress.org/reference/functions/get_next_post_link/ 
     */ 
    $get_link_function = "get_{$navigation_type}_post_link"; 
 
    if ( ! empty( $attributes['taxonomy'] ) ) { 
        $content = $get_link_function( $format, $link, true, '', $attributes['taxonomy'] ); 
    } else { 
        $content = $get_link_function( $format, $link ); 
    } 
 
    return sprintf( 
        '<div %1$s>%2$s</div>', 
        $wrapper_attributes, 
        $content 
    ); 
} 
 
/** 
 * Registers the `core/post-navigation-link` block on the server. 
 * 
 * @since 5.9.0 
 */ 
function register_block_core_post_navigation_link() { 
    register_block_type_from_metadata( 
        __DIR__ . '/post-navigation-link', 
        array( 
            'render_callback' => 'render_block_core_post_navigation_link', 
        ) 
    ); 
} 
add_action( 'init', 'register_block_core_post_navigation_link' ); 
 
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