1<?php
  2/**
  3 * Server-side rendering of the `core/post-navigation-link` block.
  4 *
  5 * @package WordPress
  6 */
  7
  8/**
  9 * Renders the `core/post-navigation-link` block on the server.
 10 *
 11 * @since 5.9.0
 12 *
 13 * @param array  $attributes Block attributes.
 14 * @param string $content    Block default content.
 15 *
 16 * @return string Returns the next or previous post link that is adjacent to the current post.
 17 */
 18function render_block_core_post_navigation_link( $attributes, $content ) {
 19	if ( ! is_singular() ) {
 20		return '';
 21	}
 22
 23	// Get the navigation type to show the proper link. Available options are `next|previous`.
 24	$navigation_type = isset( $attributes['type'] ) ? $attributes['type'] : 'next';
 25	// Allow only `next` and `previous` in `$navigation_type`.
 26	if ( ! in_array( $navigation_type, array( 'next', 'previous' ), true ) ) {
 27		return '';
 28	}
 29	$classes = "post-navigation-link-$navigation_type";
 30	if ( isset( $attributes['textAlign'] ) ) {
 31		$classes .= " has-text-align-{$attributes['textAlign']}";
 32	}
 33	$wrapper_attributes = get_block_wrapper_attributes(
 34		array(
 35			'class' => $classes,
 36		)
 37	);
 38	// Set default values.
 39	$format = '%link';
 40	$link   = 'next' === $navigation_type ? _x( 'Next', 'label for next post link' ) : _x( 'Previous', 'label for previous post link' );
 41	$label  = '';
 42
 43	// Only use hardcoded values here, otherwise we need to add escaping where these values are used.
 44	$arrow_map = array(
 45		'none'    => '',
 46		'arrow'   => array(
 47			'next'     => '→',
 48			'previous' => '←',
 49		),
 50		'chevron' => array(
 51			'next'     => '»',
 52			'previous' => '«',
 53		),
 54	);
 55
 56	// If a custom label is provided, make this a link.
 57	// `$label` is used to prepend the provided label, if we want to show the page title as well.
 58	if ( isset( $attributes['label'] ) && ! empty( $attributes['label'] ) ) {
 59		$label = "{$attributes['label']}";
 60		$link  = $label;
 61	}
 62
 63	// If we want to also show the page title, make the page title a link and prepend the label.
 64	if ( isset( $attributes['showTitle'] ) && $attributes['showTitle'] ) {
 65		/*
 66		 * If the label link option is not enabled but there is a custom label,
 67		 * display the custom label as text before the linked title.
 68		 */
 69		if ( ! $attributes['linkLabel'] ) {
 70			if ( $label ) {
 71				$format = '<span class="post-navigation-link__label">' . wp_kses_post( $label ) . '</span> %link';
 72			}
 73			$link = '%title';
 74		} elseif ( isset( $attributes['linkLabel'] ) && $attributes['linkLabel'] ) {
 75			// If the label link option is enabled and there is a custom label, display it before the title.
 76			if ( $label ) {
 77				$link = '<span class="post-navigation-link__label">' . wp_kses_post( $label ) . '</span> <span class="post-navigation-link__title">%title</span>';
 78			} else {
 79				/*
 80				 * If the label link option is enabled and there is no custom label,
 81				 * add a colon between the label and the post title.
 82				 */
 83				$label = 'next' === $navigation_type ? _x( 'Next:', 'label before the title of the next post' ) : _x( 'Previous:', 'label before the title of the previous post' );
 84				$link  = sprintf(
 85					'<span class="post-navigation-link__label">%1$s</span> <span class="post-navigation-link__title">%2$s</span>',
 86					wp_kses_post( $label ),
 87					'%title'
 88				);
 89			}
 90		}
 91	}
 92
 93	// Display arrows.
 94	if ( isset( $attributes['arrow'] ) && 'none' !== $attributes['arrow'] && isset( $arrow_map[ $attributes['arrow'] ] ) ) {
 95		$arrow = $arrow_map[ $attributes['arrow'] ][ $navigation_type ];
 96
 97		if ( 'next' === $navigation_type ) {
 98			$format = '%link<span class="wp-block-post-navigation-link__arrow-next is-arrow-' . $attributes['arrow'] . '" aria-hidden="true">' . $arrow . '</span>';
 99		} else {
100			$format = '<span class="wp-block-post-navigation-link__arrow-previous is-arrow-' . $attributes['arrow'] . '" aria-hidden="true">' . $arrow . '</span>%link';
101		}
102	}
103
104	/*
105	 * The dynamic portion of the function name, `$navigation_type`,
106	 * Refers to the type of adjacency, 'next' or 'previous'.
107	 *
108	 * @see https://developer.wordpress.org/reference/functions/get_previous_post_link/
109	 * @see https://developer.wordpress.org/reference/functions/get_next_post_link/
110	 */
111	$get_link_function = "get_{$navigation_type}_post_link";
112
113	if ( ! empty( $attributes['taxonomy'] ) ) {
114		$content = $get_link_function( $format, $link, true, '', $attributes['taxonomy'] );
115	} else {
116		$content = $get_link_function( $format, $link );
117	}
118
119	return sprintf(
120		'<div %1$s>%2$s</div>',
121		$wrapper_attributes,
122		$content
123	);
124}
125
126/**
127 * Registers the `core/post-navigation-link` block on the server.
128 *
129 * @since 5.9.0
130 */
131function register_block_core_post_navigation_link() {
132	register_block_type_from_metadata(
133		__DIR__ . '/post-navigation-link',
134		array(
135			'render_callback' => 'render_block_core_post_navigation_link',
136		)
137	);
138}
139add_action( 'init', 'register_block_core_post_navigation_link' );
140