Pre-populate Woocommerce checkout fields

functions.php

<?php
/**
 * Pre-populate Woocommerce checkout fields
 */
add_filter('woocommerce_checkout_get_value', function($input, $field ) {
	global $current_user;
	switch ($field) :
		case 'billing_first_name':
		case 'shipping_first_name':
			return $current_user->first_name;
		break;
		
		case 'billing_last_name':
		case 'shipping_last_name':
			return $current_user->last_name;
		break;
		case 'billing_email':
			return $current_user->user_email;
		break;
		case 'billing_phone':
			return $current_user->phone;
		break;
	endswitch;
}, 10, 2);