PremiumBuy

PremiumBuy is a Payment, Checkout & Rewards all in one service, that serves any in-store & on-chain payment needs. We rewards consumers with premium offers when they hit a minimum purchasing amount. And we gamify the entire in-store on-chain payment experience to encourage more adoption, by providing monetary benefits, entertainment and full transparency and fairness.

Entities:

• Point of Sale machine that does checkout and displays on-chain QR codes. This POS machine prints a lottery ticket after user makes a successful in-store payment. (Merchant)
• A smart contract that records and verifies the authenticity of a lottery ticket, and opens up claiming to the address that won the ticket with on-chain spending proof. (Contract)
• A backend server that does additional metadata recording (Backend)
• A UI/UX friendly lottery claiming site (consumer)

There are 4 repos: First, Point-of-sale application. This project builds on android system with Java.User can select the item what they want, and then use their mobile wallet to scan QR code payment, machine will automatically print the receipt, scan the QR code on the receipt to view consumption records/merchant activities/consumption chain verification.

Second, a Smart contract build using foundry.

Third, a Backend service that records metadata. The Service provides three main components: Index Service: Monitors merchant's receipt transactions and records lottery details off-chain in database API Service: Handles requests from merchant's Android app and user's lottery redemption endpoints Sign Protocol: Enables merchants to call Sign Protocol for on-chain verification of transaction and lottery details

Lastly, a consumer facing reward claiming site. This project utilizes celo-composer starter kit to kick start the coding, with wagmi, viem, nextjs, tailwindcss, shadcn and so on. We support 4 chains: Celo, Base, Flow and Morph as we deem them as consumer friendly chains. We record every payment receipt on-chain, together with the receipt items. And since each receipt is bind to a lottery ticket, we utilize Sign Protocol to verify the authenticity of the receipt as well as the authenticity of the lottery ticket.