Cancellation of a consultation appointment with reason for cancellation (Node.js)

In this use case, the user or the healthcare service provider (doctor, clinic, hospital etc) cancels an appointment from either end

Code snippets

BPP receives protocol cancel

/*
Example Request JSON:
{
    "context": {
        "domain": "nic2004:85121",
        "country": "IND",
        "city": "std:080",
        "action": "cancel",
        "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",
        "cancellation_reason_id": "reason_3"
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/healthcare_consultation/cancel', auth, cancel);

    function cancel({ 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"));
            processCancel(headers, body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BPP processes the cancel

    function processCancel(requestHeaders, cancelRequestBody) {
        // Execute business logic here
        let cancelResponse = {}
        generateResponse(requestHeaders, cancelResponse)
    }

BPP generates response

    async function generateResponse(requestHeaders, rawResponse){
/*
Example Request JSON :
{
    "context": {
        "domain": "nic2004:85121",
        "country": "IND",
        "city": "std:080",
        "action": "on_status",
        "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": "Cancelled",
            "items": [
                {
                    "id": "dr_veena_slot_1",
                    "quantity": {
                        "count": 1
                    }
                }
            ],
            "billing": {
                "name": "John Doe",
                "address": {
                    "door": "21A",
                    "name": "ABC Apartments",
                    "locality": "HSR Layout",
                    "city": "Bengaluru",
                    "state": "Karnataka",
                    "country": "India",
                    "area_code": "560102"
                },
                "email": "[email protected]",
                "phone": "+919876543210"
            },
            "fulfillment": {
                "type": "IN-PERSON",
                "end": {
                    "location": {
                        "id": "good-health-koramangala",
                        "gps": "12.9349377,77.6055586"
                    },
                    "time": {
                        "range": {
                            "start": "2021-08-11T04:30:00.000Z",
                            "end": "2021-08-11T05:30:00.000Z"
                        }
                    },
                    "contact": {
                        "phone": "+919876543210",
                        "email": "[email protected]"
                    }
                },
                "agent": {
                    "name": "Dr. Veena H",
                    "dob": "1989-08-12",
                    "gender": "Female",
                    "tags": {
                        "doctor_registration_no": "12345"
                    },
                    "phone": "+919876543210",
                    "email": "[email protected]"
                },
                "customer": {
                    "person": {
                        "name": "Remya C",
                        "dob": "1989-08-12",
                        "gender": "Female"
                    },
                    "contact": {
                        "phone": "+919898987676",
                        "email": "[email protected]"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "1100"
                },
                "breakup": [
                    {
                        "title": "Consultation Charges",
                        "price": {
                            "currency": "INR",
                            "value": "1000"
                        }
                    },
                    {
                        "title": "Service 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"
            }
        }
    }
}
*/
        // The below code generates the above example JSON.
        let onCancelResponseBody = {}
        // call protocol on_cancel
        await callOnCancel(headers, onCancelResponseBody);
    }

BPP calls protocol on_cancel

    async function callOnCancel(requestHeaders, onCancelResponseBody) {
        // 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}/healthcare_consultation/on_cancel`, method: "POST", headers, data: onCancelResponseBody });
    }