Adds a metabox to define a custom tab title and content on woocommerce product pages.

woocommerce-custom-extra-tab.php

<?php
/**
 * Woocommerce custom extra tab
 *
 * Adds a metabox to define a custom tab label and content on woocommerce product pages. Also remove predifined
 * description tab title so we can define our own directly inside tab content.
 *
 * @link              https://gist.github.com/smeric/ff09b2f993dc8378a04a
 * @version           1.0.1
 * @package           woocommerce_custom_extra_tab
 * @credits           Brad Dalton
 * @see               http://wpsites.net/wordpress-admin/custom-meta-box-functions-code/
 *
 * @wordpress-plugin
 * Plugin Name:       Woocommerce custom extra tab
 * Plugin URI:        https://gist.github.com/smeric/ff09b2f993dc8378a04a
 * Description:       Adds a metabox to define a custom tab label and content on woocommerce product pages. Also remove predifined description tab title so we can define our own directly inside tab content.
 * Version:           1.0.1
 * Author:            Sébastien Méric <[email protected]>
 * Author URI:        http://www.sebastien-meric.com/
 * License:           GPL-2.0+
 * License URI:       http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain:       woocommerce_custom_extra_tab
 * Domain Path:       /languages
 * 
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU
 * General Public License as published by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
 * even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write
 * to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

/**
 * Define the internationalization functionality.
 *
 * Loads and defines the internationalization files for this plugin
 * so that its ready for translation.
 * 
 * @since      1.0.0
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 **/
add_action( 'after_setup_theme', 'woocommerce_custom_extra_tab_after_setup_theme' );
function woocommerce_custom_extra_tab_after_setup_theme() {
	// Load the plugin text domain for translation.
	$locale = apply_filters( 'woocommerce_custom_extra_tab_locale', get_locale(), 'woocommerce_custom_extra_tab' );
	load_textdomain( 'woocommerce_custom_extra_tab', trailingslashit( WP_LANG_DIR ) . 'woocommerce_custom_extra_tab/woocommerce_custom_extra_tab-' . $locale . '.mo' );
	load_plugin_textdomain( 'woocommerce_custom_extra_tab', false, dirname( plugin_basename( __FILE__ ) ) . '/languages' );
}

/**
 * Remove default description tab title so we may specify a custom one directly inside content.
 *
 * @since      1.0.1
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 */
add_filter( 'woocommerce_product_description_heading', '__return_empty_string', 100 );

/**
 * Add the new tab to product page.
 *
 * @since      1.0.0
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 */
add_filter( 'woocommerce_product_tabs', 'woocommerce_custom_extra_tab' );
function woocommerce_custom_extra_tab( $tabs ) {
	global $post;

	$custom_tab_label = get_post_meta( $post->ID, 'custom_tab_label', true );
	if ( $custom_tab_label ) {
		// Adds the new tab
		$tabs['custom_tab'] = array(
			'title' 	=> $custom_tab_label,
			'priority' 	=> 29,
			'callback' 	=> 'woocommerce_custom_extra_tab_content'
		);
	}

	return $tabs;
}

/**
 * Display custom tab content.
 * 
 * @since      1.0.0
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 **/
function woocommerce_custom_extra_tab_content() {
	global $post;

	$custom_tab_content = get_post_meta( $post->ID, 'custom_tab_content', true );
	// The new tab formated content with shortcodes support
	echo wpautop( do_shortcode( $custom_tab_content ) );
}

/**
 * Meta box parameters.
 *
 * @since      1.0.0
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 */
add_action( 'add_meta_boxes', 'woocommerce_custom_extra_tab_register_metabox' );
function woocommerce_custom_extra_tab_register_metabox() {
	add_meta_box(
		'custom_tab_meta_box',
		__( 'Custom tab', 'woocommerce_custom_extra_tab' ),
		'woocommerce_custom_extra_tab_meta_box',
		'product',
		'normal',
		'low'
	);
}

/**
 * Create nonce, output tab label field and mini editor on edit product screen.
 *
 * @since      1.0.0
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 */
function woocommerce_custom_extra_tab_meta_box( $post ) {
	$nonce = wp_create_nonce( 'woocommerce_custom_extra_tab_meta_box_nonce' );
	$value = get_post_meta( $post->ID, 'custom_tab_label', true );
?>
	<input type="hidden" name="woocommerce_custom_extra_tab_meta_box_nonce" value="<?php echo $nonce ?>" />
	<p>
		<label for="custom_tab_label"><?php _e( 'Tab label', 'woocommerce_custom_extra_tab' ) ?></label><br />
		<input type="text" name="custom_tab_label" id="custom_tab_label" value="<?php echo( $value ? $value : '' ) ?>" class="regular-text" />
	</p>
	<p>
		<label for="custom_tab_content"><?php _e( 'Tab content', 'woocommerce_custom_extra_tab' ) ?></label>
	</p>
<?php
	$value = get_post_meta( $post->ID, 'custom_tab_content', true );
	wp_editor( $value, 'custom_tab_content', array( 'textarea_rows' => 10 ) );
}

/**
 * Run checks before saving tab label and content to database.
 *
 * @since      1.0.0
 * @package    woocommerce_custom_extra_tab
 * @author     Sébastien Méric <[email protected]>
 */
add_action( 'save_post', 'woocommerce_custom_extra_tab_save_meta_box_content', 10, 2 );
function woocommerce_custom_extra_tab_save_meta_box_content( $post_id ) {
	// If this is an autosave, our form has not been submitted, don't want to do anything.
	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE
		|| ! isset ( $_POST['post_type'] )
		|| 'product' !== $_POST['post_type']
		|| ! current_user_can( 'edit_products', $post_id ) // Check the user's permissions.
		|| ! wp_verify_nonce( $_POST['woocommerce_custom_extra_tab_meta_box_nonce'], 'woocommerce_custom_extra_tab_meta_box_nonce' ) ) {
		return $post_id;
	}

	if ( isset ( $_POST['custom_tab_label'] ) ) {
		update_post_meta( $post_id, 'custom_tab_label', $_POST['custom_tab_label'] );
	}
	else {
		delete_post_meta( $post_id, 'custom_tab_label' );
	}

	if ( isset ( $_POST['custom_tab_content'] ) ) {
		update_post_meta( $post_id, 'custom_tab_content', $_POST['custom_tab_content'] );
	}
	else {
		delete_post_meta( $post_id, 'custom_tab_content' );
	}
}