Receiving request to remove a pharmaceutical item from an active order and sending the updated order with refund terms (Node.js)

In this use case, the user removes one or more items after the order has been confirmed. If the user has already made the payment, the pharmacy sends refund terms that the user needs to agree to before the item(s) is removed. In case the order is postpaid, the pharmacy can update the total amount to be paid after the fulfillment of the order.

Code snippets

BPP receives protocol update

/*
Example Request JSON:
{
    "context": {
        "domain": "nic2004:52311",
        "country": "IND",
        "city": "std:080",
        "action": "update",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "transaction_id": "1239890342",
        "message_id": "123793824",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "update_target": "items",
        "order": {
            "id": "order_1",
            "state": "Active",
            "items": [
                {
                    "id": "a_500",
                    "price" : {
                        "currency": "INR",
                        "value": "500"
                    },
                    "quantity": {
                        "selected": {
                            "count": 1
                        }
                    }
                }
            ],
            "billing": {
                "name": "Jane Doe",
                "address": {
                    "door": "21A",
                    "name": "ABC Apartments",
                    "locality": "HSR Layout",
                    "city": "Bengaluru",
                    "state": "Karnataka",
                    "country": "India",
                    "area_code": "560102"
                },
                "email": "[email protected]",
                "phone": "+919876523210"
            },
            "fulfillment": {
                "type": "HOME-DELIVERY",
                "start": {
                    "location": {
                        "id": "abc_medicines_koramangala",
                        "descriptor": {
                            "name": "ABC Medicines"
                        },
                        "gps": "12.9349377,77.6055586"
                    },
                    "contact": {
                        "phone": "+919999999999",
                        "email": "[email protected]"
                    }
                },
                "end": {
                    "location": {
                        "gps": "12.914028, 77.638698",
                        "address": {
                            "door": "21A",
                            "name": "ABC Apartments",
                            "locality": "HSR Layout",
                            "city": "Bengaluru",
                            "state": "Karnataka",
                            "country": "India",
                            "area_code": "560102"
                        }
                    },
                    "time": {
                        "range": {
                            "start": "2021-06-15T07:11:36.212Z",
                            "end": "2021-06-15T07:12:36.212Z"
                        }
                    },
                    "instructions": {
                        "name": "drop off instructions",
                        "short_desc": "Leave at door step"
                    },
                    "contact": {
                        "phone": "+919876543210",
                        "email": "[email protected]"
                    }
                },
                "customer": {
                    "person":{
                        "name": "John Doe",
                        "image": "https://mock_bap.com/prescription1.jpg",
                        "dob": "1991-08-12"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "1100"
                },
                "breakup": [
                    {
                        "title": "Vitamin C",
                        "price": {
                            "currency": "INR",
                            "value": "500"
                        }
                    }, 
                   {
                        "title": "Antibiotics",
                        "price": {
                            "currency": "INR",
                            "value": "500"
                        }
                    },
                    {
                        "title": "Delivery Charge",
                        "price": {
                            "currency": "INR",
                            "value": "100"
                        }
                    }
                ],
                "ttl": "P1H"
            },
            "payment": {
                "uri": "https://api.bpp.com/pay?amt=$amount&txn_id=ksh87yriuro34iyr3p4&mode=upi&vpa=bpp@upi",
                "tl_method": "http/get",
                "params": {
                    "transaction_id": "ksh87yriuro34iyr3p4",
                    "amount": "1100",
                    "mode": "upi",
                    "vpa": "bpp@upi"
                },
                "type": "ON-FULFILLMENT",
                "status": "NOT-PAID"
            }
        }
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/health_pharmacy/update', auth, update);

    function update({ headers, body }, res) {
        try {
            const message = _.get(body, "message");
            const context = _.get(body, "context");
            if (!context) {
                return res.status(400).send(httpResponse("NACK", "Missing Context"));
            }
            if (!message) {
                return res.status(400).send(httpResponse("NACK", "Missing Message"));
            }
            // ... Returns the ack immediately and continue the processing after validation
            res.status(200).send(httpResponse("ACK"));
            processUpdate(headers, body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BPP processes the status

function processUpdate(requestHeaders, updateRequestBody) {
    // Execute business logic here
    let updateResponse = {}
    generateResponse(requestHeaders, updateResponse)
}

BPP generates response

    async function generateResponse(){
/*
Example Request JSON :
{
    "context": {
        "domain": "nic2004:52311",
        "country": "IND",
        "city": "std:080",
        "action": "on_update",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "transaction_id": "1239890342",
        "message_id": "123793824",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order": {
            "id": "order_1",
            "state": "Active",
            "items": [
                {
                    "id": "a_500",
                    "price" : {
                        "currency": "INR",
                        "value": "500"
                    },
                    "quantity": {
                        "selected": {
                            "count": 1
                        }
                    }
                }
            ],
            "billing": {
                "name": "Jane Doe",
                "address": {
                    "door": "21A",
                    "name": "ABC Apartments",
                    "locality": "HSR Layout",
                    "city": "Bengaluru",
                    "state": "Karnataka",
                    "country": "India",
                    "area_code": "560102"
                },
                "email": "[email protected]",
                "phone": "+919876523210"
            },
            "fulfillment": {
                "type": "HOME-DELIVERY",
                "start": {
                    "location": {
                        "id": "abc_medicines_koramangala",
                        "descriptor": {
                            "name": "ABC Medicines"
                        },
                        "gps": "12.9349377,77.6055586"
                    },
                    "contact": {
                        "phone": "+919999999999",
                        "email": "[email protected]"
                    }
                },
                "end": {
                    "location": {
                        "gps": "12.914028, 77.638698",
                        "address": {
                            "door": "21A",
                            "name": "ABC Apartments",
                            "locality": "HSR Layout",
                            "city": "Bengaluru",
                            "state": "Karnataka",
                            "country": "India",
                            "area_code": "560102"
                        }
                    },
                    "time": {
                        "range": {
                            "start": "2021-06-15T07:11:36.212Z",
                            "end": "2021-06-15T07:12:36.212Z"
                        }
                    },
                    "instructions": {
                        "name": "drop off instructions",
                        "short_desc": "Leave at door step"
                    },
                    "contact": {
                        "phone": "+919876543210",
                        "email": "[email protected]"
                    }
                },
                "customer": {
                    "person":{
                        "name": "John Doe",
                        "image": "https://mock_bap.com/prescription1.jpg",
                        "dob": "1991-08-12"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "600"
                },
                "breakup": [
                   {
                        "title": "Antibiotics",
                        "price": {
                            "currency": "INR",
                            "value": "500"
                        }
                    },
                    {
                        "title": "Delivery Charge",
                        "price": {
                            "currency": "INR",
                            "value": "100"
                        }
                    }
                ],
                "ttl": "P1H"
            },
            "payment": {
                "uri": "https://api.bpp.com/pay?amt=$amount&txn_id=ksh87yriuro34iyr3p4&mode=upi&vpa=bpp@upi",
                "tl_method": "http/get",
                "params": {
                    "transaction_id": "ksh87yriuro34iyr3p4",
                    "amount": "600",
                    "mode": "upi",
                    "vpa": "bpp@upi"
                },
                "type": "ON-FULFILLMENT",
                "status": "NOT-PAID"
            }
        }
    }
}
*/
        //The below code generates the above example JSON.
        let onUpdateResponseBody = {}
        //call protocol on_update
        await callOnUpdate(requestHeaders, onUpdateResponseBody);
    }

BPP calls protocol on_update

    async function callOnUpdate(requestHeaders, onUpdateResponseBody) {
        // Take the subscriber Id from the header and calls the registry to get the url. If already cached it need not to call again
        const uri = await lookup(requestHeaders);
        // Construct Header
        const headers = constructAuthHeader(); // Auth Header with digital Signature
        return axios({ url: `${uri}/health_pharmacy/on_track`, method: "POST", headers, data: onUpdateResponseBody })
    }