1 files changed, 124 insertions, 0 deletions
diff --git a/wp-includes/blocks/post-navigation-link.php b/wp-includes/blocks/post-navigation-link.php
new file mode 100644
index 0000000..add112c
--- /dev/null
+++ b/wp-includes/blocks/post-navigation-link.php
@@ -0,0 +1,124 @@
+<?php
+/**
+ * Server-side rendering of the `core/post-navigation-link` block.
+ *
+ * @package WordPress
+ */
+
+/**
+ * Renders the `core/post-navigation-link` block on the server.
+ *
+ * @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'.
+	$get_link_function = "get_{$navigation_type}_post_link";
+	$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.
+ */
+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' );