Receiving billing and shipping details during checkout and sending the final quote and payment terms (Node.js)

In this use case, the user provides all the information required by the diagnostic center to book an appointment and receives the final invoice with payment terms

Code snippets

BPP receives protocol init

/*
Example Request JSON:
{
    "context": {
        "domain": "nic2004:85195",
        "country": "IND",
        "city": "std:080",
        "action": "init",
        "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": {
            "items": [
                {
                    "id": "health_checkup",
                    "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": "srs-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]"
                    }
                }
            }
        }
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/healthcare_diagnostics/init', auth, init);

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

BPP processes the init

    function processInit(requestHeaders, initRequestBody) {
        // Execute business logic here
        let initResponse = {}
        generateResponse(requestHeaders, initResponse)
    }

BPP generates response

    async function generateResponse(requestHeaders, rawResponse){
/*
Example Request JSON :
{
    "context": {
        "domain": "nic2004:85195",
        "country": "IND",
        "city": "std:080",
        "action": "on_init",
        "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": {
            "items": [
                {
                    "id": "health_checkup",
                    "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": {
                "end": {
                    "location": {
                        "id": "srs-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]"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "1100"
                },
                "breakup": [
                    {
                        "title": "Lab 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"
            }
        }
    }
}
*/
        let onInitResponseBody = {

        }
        //call protocol on_init
        await callOnInit(requestHeaders, onInitResponseBody);
    }

BPP calls protocol on_init

    async function callOnInit(requestHeaders, onInitResponseBody) {
        // 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_diagnostics/on_init`, method: "POST", headers, data: onInitResponseBody });
    }