functions.php

<?php
/*
	Seperate Woocommerce reviews from comments and make a reviews moderation panel.
*/
class PL_Woo_Review_Mods {
	function __construct() {
		add_action( 'current_screen', array( $this, 'check_current_page' ), 10, 2 );
		add_action( 'admin_menu', array( $this, 'add_product_reviews' ) );
	}
	function check_current_page( $screen ) {
		if ( $screen->id == 'edit-comments' ) {
			add_filter( 'comments_clauses', array( $this, 'separate_comments_and_review' ), 10, 2 );
			add_filter( 'comment_status_links', array( $this, 'change_comment_status_link' ) );
			if( isset( $_GET['post_type'] ) && $_GET['post_type'] == 'product' ) {
				add_filter( 'manage_edit-comments_columns', array( $this, 'comment_columns' ) );
				add_filter( 'manage_comments_custom_column', array( $this, 'comment_column' ), 10, 2 );
			}
		}
	}

	function comment_column( $column, $comment_ID ) {
	if ( 'review_custom_column' == $column ) {
		$rating = get_comment_meta( $comment_ID, 'rating', true );
		echo $rating;
	}
}

function comment_columns( $columns ) {
	$columns['review_custom_column'] = __( 'Rating' );
	return $columns;
}

	function change_comment_status_link( $status_links ) {
		if( isset( $_GET['post_type'] ) ) {
			$status_links['all'] = '<a href="edit-comments.php?post_type=product&comment_status=all">All</a>';
			$status_links['moderated'] = '<a href="edit-comments.php?post_type=product&comment_status=moderated">Pending</a>';
			$status_links['approved'] = '<a href="edit-comments.php?post_type=product&comment_status=approved">Approved</a>';
			$status_links['spam'] = '<a href="edit-comments.php?post_type=product&comment_status=spam">Spam</a>';
			$status_links['trash'] = '<a href="edit-comments.php?post_type=product&comment_status=trash">Trash</a>';
		}
	return $status_links;
	}
	function separate_comments_and_review( $clauses, $wp_comment_query ) {

		global $wpdb;
		if ( ! $clauses['join'] ) {
			$clauses['join'] = "JOIN $wpdb->posts ON $wpdb->posts.ID = $wpdb->comments.comment_post_ID";
		}
		if( ! empty( $_GET['post_type'] ) && $_GET['post_type'] == 'product' ) {
			if ( ! $wp_comment_query->query_vars['post_type'] ) {}
				$clauses['where'] .= $wpdb->prepare( " AND {$wpdb->posts}.post_type = %s", 'product' );

		} else {
			if ( ! $wp_comment_query->query_vars['post_type' ] )
				$clauses['where'] .= $wpdb->prepare( " AND {$wpdb->posts}.post_type != %s", 'product' );
		}
	return $clauses;
	}
	function add_product_reviews() {
		global $wpdb;
		$query = "SELECT *
			FROM wp_comments
			INNER JOIN wp_posts ON ( wp_posts.ID = wp_comments.comment_post_ID )
			WHERE wp_posts.post_type = 'product'
			AND wp_comments.comment_approved = '0'";
		$result = $wpdb->get_row($query);
		$count = $wpdb->num_rows;
		if( $count > 0 ) {
			$alert = sprintf( ' <span class="awaiting-mod count-%s"><span class="pending-count">%s</span></span>',
			$count,
			$count
			);
		} else {
			$alert = '';
		}
		$post_type = 'product';
		$text = sprintf( 'Reviews%s', $alert );
		add_menu_page( $text,$text,'manage_options',"edit-comments.php?post_type={$post_type}",'','',59);
	}
}
if( is_admin() )
	new PL_Woo_Review_Mods;