WordPress/wp-admin/edit-link-form.php

<?php
/**
 * Edit links form for inclusion in administration panels.
 *
 * @package WordPress
 * @subpackage Administration
 */

// don't load directly
if ( ! defined( 'ABSPATH' ) ) {
	die( '-1' );
}

if ( ! empty( $link_id ) ) {
	$heading      = sprintf( __( '<a href="%s">Links</a> / Edit Link' ), 'link-manager.php' );
	$submit_text  = __( 'Update Link' );
	$form_name    = 'editlink';
	$nonce_action = 'update-bookmark_' . $link_id;
} else {
	$heading      = sprintf( __( '<a href="%s">Links</a> / Add New Link' ), 'link-manager.php' );
	$submit_text  = __( 'Add Link' );
	$form_name    = 'addlink';
	$nonce_action = 'add-bookmark';
}

require_once( ABSPATH . 'wp-admin/includes/meta-boxes.php' );

add_meta_box( 'linksubmitdiv', __( 'Save' ), 'link_submit_meta_box', null, 'side', 'core' );
add_meta_box( 'linkcategorydiv', __( 'Categories' ), 'link_categories_meta_box', null, 'normal', 'core' );
add_meta_box( 'linktargetdiv', __( 'Target' ), 'link_target_meta_box', null, 'normal', 'core' );
add_meta_box( 'linkxfndiv', __( 'Link Relationship (XFN)' ), 'link_xfn_meta_box', null, 'normal', 'core' );
add_meta_box( 'linkadvanceddiv', __( 'Advanced' ), 'link_advanced_meta_box', null, 'normal', 'core' );

/** This action is documented in wp-admin/includes/meta-boxes.php */
do_action( 'add_meta_boxes', 'link', $link );

/**
 * Fires when link-specific meta boxes are added.
 *
 * @since 3.0.0
 *
 * @param object $link Link object.
 */
do_action( 'add_meta_boxes_link', $link );

/** This action is documented in wp-admin/includes/meta-boxes.php */
do_action( 'do_meta_boxes', 'link', 'normal', $link );
/** This action is documented in wp-admin/includes/meta-boxes.php */
do_action( 'do_meta_boxes', 'link', 'advanced', $link );
/** This action is documented in wp-admin/includes/meta-boxes.php */
do_action( 'do_meta_boxes', 'link', 'side', $link );

add_screen_option(
	'layout_columns',
	array(
		'max'     => 2,
		'default' => 2,
	)
);

get_current_screen()->add_help_tab(
	array(
		'id'      => 'overview',
		'title'   => __( 'Overview' ),
		'content' =>
		'<p>' . __( 'You can add or edit links on this screen by entering information in each of the boxes. Only the link&#8217;s web address and name (the text you want to display on your site as the link) are required fields.' ) . '</p>' .
		'<p>' . __( 'The boxes for link name, web address, and description have fixed positions, while the others may be repositioned using drag and drop. You can also hide boxes you don&#8217;t use in the Screen Options tab, or minimize boxes by clicking on the title bar of the box.' ) . '</p>' .
		'<p>' . __( 'XFN stands for <a href="http://gmpg.org/xfn/">XHTML Friends Network</a>, which is optional. WordPress allows the generation of XFN attributes to show how you are related to the authors/owners of the site to which you are linking.' ) . '</p>',
	)
);

get_current_screen()->set_help_sidebar(
	'<p><strong>' . __( 'For more information:' ) . '</strong></p>' .
	'<p>' . __( '<a href="https://codex.wordpress.org/Links_Add_New_Screen">Documentation on Creating Links</a>' ) . '</p>' .
	'<p>' . __( '<a href="https://wordpress.org/support/">Support</a>' ) . '</p>'
);

require_once( ABSPATH . 'wp-admin/admin-header.php' );
?>

<div class="wrap">
<h1 class="wp-heading-inline">
<?php
echo esc_html( $title );
?>
</h1>

<a href="link-add.php" class="page-title-action"><?php echo esc_html_x( 'Add New', 'link' ); ?></a>

<hr class="wp-header-end">

<?php if ( isset( $_GET['added'] ) ) : ?>
<div id="message" class="updated notice is-dismissible"><p><?php _e( 'Link added.' ); ?></p></div>
<?php endif; ?>

<form name="<?php echo esc_attr( $form_name ); ?>" id="<?php echo esc_attr( $form_name ); ?>" method="post" action="link.php">
<?php
if ( ! empty( $link_added ) ) {
	echo $link_added;
}

wp_nonce_field( $nonce_action );
wp_nonce_field( 'closedpostboxes', 'closedpostboxesnonce', false );
wp_nonce_field( 'meta-box-order', 'meta-box-order-nonce', false );
?>

<div id="poststuff">

<div id="post-body" class="metabox-holder columns-<?php echo 1 == get_current_screen()->get_columns() ? '1' : '2'; ?>">
<div id="post-body-content">
<div id="namediv" class="stuffbox">
<h2><label for="link_name"><?php _ex( 'Name', 'link name' ); ?></label></h2>
<div class="inside">
	<input type="text" name="link_name" size="30" maxlength="255" value="<?php echo esc_attr( $link->link_name ); ?>" id="link_name" />
	<p><?php _e( 'Example: Nifty blogging software' ); ?></p>
</div>
</div>

<div id="addressdiv" class="stuffbox">
<h2><label for="link_url"><?php _e( 'Web Address' ); ?></label></h2>
<div class="inside">
	<input type="text" name="link_url" size="30" maxlength="255" class="code" value="<?php echo esc_attr( $link->link_url ); ?>" id="link_url" />
	<p><?php _e( 'Example: <code>http://wordpress.org/</code> &#8212; don&#8217;t forget the <code>http://</code>' ); ?></p>
</div>
</div>

<div id="descriptiondiv" class="stuffbox">
<h2><label for="link_description"><?php _e( 'Description' ); ?></label></h2>
<div class="inside">
	<input type="text" name="link_description" size="30" maxlength="255" value="<?php echo isset( $link->link_description ) ? esc_attr( $link->link_description ) : ''; ?>" id="link_description" />
	<p><?php _e( 'This will be shown when someone hovers over the link in the blogroll, or optionally below the link.' ); ?></p>
</div>
</div>
</div><!-- /post-body-content -->

<div id="postbox-container-1" class="postbox-container">
<?php

/** This action is documented in wp-admin/includes/meta-boxes.php */
do_action( 'submitlink_box' );
$side_meta_boxes = do_meta_boxes( 'link', 'side', $link );

?>
</div>
<div id="postbox-container-2" class="postbox-container">
<?php

do_meta_boxes( null, 'normal', $link );

do_meta_boxes( null, 'advanced', $link );

?>
</div>
<?php

if ( $link_id ) :
	?>
<input type="hidden" name="action" value="save" />
<input type="hidden" name="link_id" value="<?php echo (int) $link_id; ?>" />
<input type="hidden" name="cat_id" value="<?php echo (int) $cat_id; ?>" />
<?php else : ?>
<input type="hidden" name="action" value="add" />
<?php endif; ?>

</div>
</div>

</form>
</div>