anyone has the code of or something like bitpay?
Bitpay is simple , no programming knowledge or big skills required to use it =>
https://bitpay.com/bitcoin-payment-gateway-api they also have samples for PHP , NodeJS & Ruby (the widely used languages) :
https://bitpay.com/bitcoin-for-ecommerce#code-libraries and they also support WordPress , Shopify ,Foxycart , 3dcart etc...
Basically , the above apply on most of payment gateways like Coinbase.com and many others...