How to add multiple images in _product_image_gallary using php

I need to copy images from a remote server and add multiple values to _product_gallary_image post meta in wordpress. For example it should be like that;

_product_image_gallary | 123,456,124,786,653

Everything is working fine except all image ids are not added only last image is added. When i use add_post_meta in foreach loop its adding all images in seperate row like; 205 _product_image_gallary 234 205 _product_image_gallary 235 205 _product_image_gallary 236

Please check code here http://ift.tt/1VDdHA9.

via Chebli Mohamed