dwp-guten/dwp-metaboxes.php

<?php

/***********************************************************
############ Media URL (dwp23_media_url_meta) ##############
************************************************************/

add_action('init', 'dwp23_guten_register_media_meta');
function dwp23_guten_register_media_meta() {
	register_meta('post', 'dwp23_media_url_meta', array(
		'show_in_rest' => true,
		'type' => 'string',
		'single' => true,
		'sanitize_callback' => 'sanitize_text_field',
		'auth_callback' => function() {
			return current_user_can('edit_posts');
		}
	));
}

add_action( 'add_meta_boxes', 'dwp23_guten_add_media_meta_box' );
function dwp23_guten_add_media_meta_box() {
	add_meta_box(
		'dwp23_guten_post_options_metabox',
		'Post Options',
		'dwp23_guten_post_options_metabox_callback',
		'post',
		'normal',
		'default',
		array('__back_compat_meta_box' => true)
	);
}

add_action( 'save_post', 'dwp23_guten_save_post_metabox', 10, 2 );
function dwp23_guten_post_options_metabox_callback($post) {
	$field_value = get_post_meta($post->ID, 'dwp23_media_url_meta', true);
	wp_nonce_field( 'dwp23_guten_update_post_metabox', 'dwp23_guten_update_post_nonce' );
	?>
	<p>
    <label for="dwp23_guten_media_metafield"><?php esc_html_e( 'Media URL', 'textdomain' ); ?></label>
    <br />
    <input class="widefat" type="text" name="dwp23_guten_media_metafield" id="dwp23_guten_media_metafield" value="<?php echo esc_attr( $field_value ); ?>" />
	</p>
	<?php
}

function dwp23_guten_save_post_metabox($post_id, $post) {
  $edit_cap = get_post_type_object( $post->post_type )->cap->edit_post;
  if( !current_user_can( $edit_cap, $post_id )) {
     return;
  }
  if( !isset( $_POST['dwp23_guten_update_post_nonce']) || !wp_verify_nonce( $_POST['dwp23_guten_update_post_nonce'], 'dwp23_guten_update_post_metabox' )) {
     return;
  }
  if(array_key_exists('dwp23_guten_media_metafield', $_POST)) {
    update_post_meta(
      $post_id,
      'dwp23_media_url_meta',
      sanitize_text_field($_POST['dwp23_guten_media_metafield'])
    );
  }
}


/***********************************************************
########## Media Poster URL (dwp23_poster_url_meta) ##########
************************************************************/

add_action('init', 'dwp23_guten_register_poster_url_meta');
function dwp23_guten_register_poster_url_meta() {
	register_meta('post', 'dwp23_poster_url_meta', array(
		'show_in_rest' => true,
		'type' => 'string',
		'single' => true,
		'sanitize_callback' => 'sanitize_text_field',
		'auth_callback' => function() {
			return current_user_can('edit_posts');
		}
	));
}

add_action( 'add_meta_boxes', 'dwp23_guten_add_poster_url_meta_box' );
function dwp23_guten_add_poster_url_meta_box() {
	add_meta_box(
		'dwp23_guten_post_options_metabox',
		'Post Options',
		'dwp23_guten_post_options_metabox_poster_url',
		'post',
		'normal',
		'default',
		array('__back_compat_meta_box' => true)
	);
}

function dwp23_guten_post_options_metabox_poster_url($post) {
  $field_value = get_post_meta($post->ID, 'dwp23_image_meta_url', true);
  wp_nonce_field( 'dwp23_guten_update_post_metabox_poster_url', 'dwp23_guten_update_post_nonce' );
  ?>
  <p>
    <label for="dwp23_guten_poster_url_metafield"><?php esc_html_e( 'Poster Image URL', 'textdomain' ); ?></label>
    <br />
    <input class="widefat" type="text" name="dwp23_guten_poster_url_metafield" id="dwp23_guten_poster_url_metafield" value="<?php echo esc_attr( $field_value ); ?>" />
  </p>
  <?php
}

add_action( 'save_post', 'dwp23_guten_save_post_metabox_poster_image_url', 10, 2 );
function dwp23_guten_save_post_metabox_poster_image_url($post_id, $post) {
  $edit_cap = get_post_type_object( $post->post_type )->cap->edit_post;
  if( !current_user_can( $edit_cap, $post_id )) {
		return;
  }
  if( !isset( $_POST['dwp23_guten_update_post_nonce_featured_image_url']) || !wp_verify_nonce( $_POST['dwp23_guten_update_post_nonce_featured_image_url'], 'dwp23_guten_update_post_metabox_featured_image_url' )) {
		return;
  }
  if(array_key_exists('dwp23_guten_media_metafield', $_POST)) {
    update_post_meta(
			$post_id,
			'dwp23_image_meta_url',
			sanitize_text_field($_POST['dwp23_guten_featured_image_url_metafield'])
    );
  }
}