E-commerce Order Purchasing Smart Contract

Purposes of the smart contract

This smart contract is an enhanced version of a traditional e-commerce order purchase contract. The major purpose of the smart contract is to avoid fraudulent transactions resulting from traditional credit card purchases. The second purpose is to eliminate the need for payment processors, which validate and transport transactions between customers and retailers. As a result, retailers may focus on product development rather than incurring losses from fraudulent transactions or paying fees to payment processors to ensure the payment process operates properly.

Parties will participate in the smart contract

Retailer: the agent produces the products for sale.
Customer: someone who needs to purchase a product for a certain purpose.

Functionalities of the smart contract

Get a list of the retailer’s products. We assumed that the retailer had already created products, so all we needed to do was list them.
Place an order for the product that the customer desires.
The customer cancels a placed order.
Issue a refund to the customer.

We can determine whether a refund is partial or full based on the amount.

Pseudo code of functionality

Before describing the pseudo code for each function, we define two structures that will be utilized in several functions. The common functions such as getProductFromListProducts, generateOrderId, and getOrder will be defined according to the programming language. Therefore, the pseudo code for these functions will not be declared in this document.

CONTRACT: EcommercePurchasing
BEGIN
  # The order status enum represents the status of an order.
  ENUM OrderStatus {
    PaymentPending,
    PaymentFailed,
    New,
    Canceled,
    PartialRefunded
  }

  # The order structure represents an order.
  STRUCT Order {
    STRING id;
    STRING product_id;
    DOUBLE amount;
    STRING customer_address;
    UINT status;
    DOUBLE refunded_amount;
  }

  # The product structure represents a product.
  STRUCT Product {
    STRING id;
    STRING name;
    STRING description;
    STRING image;
    DOUBLE price;
  }

  # The listProducts is an array of Product with a fixed size of 3.
  DECLARE CONSTANT Product[3] listProducts;
END

Get a list of the retailer’s products

Function: getProducts
 RETURNS Product[3]
 BEGIN
   RETURN listProducts;
 END

Place an order for the product that the customer desires

Function: placeOrder
    PARAMS (STRING product_id, DOUBLE amount)
    BEGIN
      # Step 1: Check if the product is valid.
      Product product = getProductFromListProducts(product_id);
      if product is not found THEN
        PRINT "Product is invalid";
        EXIT;
      ENDIF

      # Step 2: Check if the customer has enough balance.
      SET customer_address = owner.address
      if customer balance is less than amount THEN
        PRINT "Not enough balance";
        EXIT;
      ENDIF

      # Step 3: Create an order.
      Order order = NEW Order();
      order.id = generateOrderId();
      order.product_id = product_id;
      order.amount = amount;
      order.customer_address = customer_address;
      order.status = OrderStatus.PaymentPending;
      order.refunded_amount = 0;

      # Step 4: Issue a transaction from customer to retailer.
      IF transfer transaction is failed THEN
        order.status = OrderStatus.PaymentFailed;
        PRINT "Transaction failed";
      ELSE
        order.status = OrderStatus.New;
        PRINT "You have successfully purchased an order with id" +      order.id;
      ENDIF
    END

The customer cancels a placed order

Function: cancelOrder
    PARAMS (STRING order_id)
    BEGIN
      # Step 1: Get Order info from order id.
      Order order = getOrder(order_id);

      # Step 2: Check if the order is already canceled.
      IF order.status == OrderStatus.Canceled THEN
        PRINT "This order is already canceled";
        EXIT;

      # Step 3: Proceed to cancel the order.
      ELSE IF order.status == OrderStatus.New
           OR order.status == OrderStatus.PartialRefunded THEN

        # Step 3.1: Calculate the refund amount.
        DOUBLE refund_amount = order.amount - order.refunded_amount;

        # Step 3.2: Check if the refund amount is 0 then update the order status to canceled.
        IF refund_amount == 0 THEN
          order.status = OrderStatus.Canceled;
          PRINT "You successfully canceled your order";
          EXIT;

        # Step 3.3: Issue a refund and update the order status to canceled.
        ELSE
          IF issueRefund(order_id, refund_amount) THEN
            order.status = OrderStatus.Canceled;
            PRINT "You successfully canceled your order";
          ELSE
            PRINT "Error occurred while refunding";
          ENDIF
        ENDIF
      ELSE
        PRINT "The order status is invalid";
      ENDIF
    END

Issue a refund to the customer

Function: issueRefund
    PARAMS (STRING order_id, DOUBLE refund_amount)
    BEGIN
      # Step 1: Get order info from order id.
      Order order = getOrder(order_id);

      # Step 2: Calculate max refund amount.
      DOUBLE max_refund_amount = order.amount - order.refunded_amount;

      # Step 3: Compare max refund amount with refund amount
      IF refund_amount > max_refund_amount THEN
        PRINT "Refund amount is greater than " + max_refund_amount;
        EXIT;

      ELSE
        # Step 4: Issue a refund transaction.
        IF refund transaction is failed THEN
          PRINT "Transaction failed";
        ELSE
          PRINT "You successfully refunded your payment";
        ENDIF
      ENDIF
    END

References

Just a moment... (n.d.). Just a moment... https://ca.indeed.com/career-advice/career-development/what-is-pseudocode

Pseudocode guidelines. (n.d.). courses.cs.washington.edu. https://courses.cs.washington.edu/courses/cse326/02wi/pseudocode.htm