How I stopped hardcoding business rules in PHP - and built a rule engine to fix it

Every PHP developer knows this situation: a client calls and says "I want free shipping for VIP customers on weekends, but only if the cart total is above €100."

You open your code. You find the shipping module. You add an if. You deploy.

Three weeks later: "Actually, make it €80. And also for the 'Premium' group."

You open your code again.

This loop : client request -> find logic in code -> modify -> deploy, was costing me a lot of time. And it's not just shipping. I build custom ecommerce solutions: payment modules, synchronization systems, pricing calculators. Business rules are everywhere, and they change constantly.