Snipcart custom shipping method built with Firebase Cloud functions

shipping-rates-example.json

{
    "rates": [
        [
            {
                "label": {
                    "en": "Free Shipping",
                    "de": "Kostenloser Versand"
                },
                "minTotoal": 29.0,
                "shippingCost": 0.0,
                "countries": ["AT"]
            },
            {
                "label": {
                    "en": "Standard Shipping",
                    "de": "Standard Versand"
                },
                "shippingCost": 3.0,
                "countries": ["AT"]
            },
            {
                "label": {
                    "en": "Free Shipping (EU)",
                    "de": "Kostenloser Versand (EU)"
                },
                "minTotoal": 29.0,
                "shippingCost": 0.0,
                "countries": ["BE","BG","HR","CY","CZ","DK","EE","FI","FR","DE","GR","HU","IE","IT","LV","LT","LU","MT","NL","PL","PT","RO","SK","SI","ES","SE","GB"]
            },
            {
                "label": {
                    "en": "Standard Shipping (EU)",
                    "de": "Standard Versand (EU)"
                },
                "shippingCost": 8.0,
                "countries": ["BE","BG","HR","CY","CZ","DK","EE","FI","FR","DE","GR","HU","IE","IT","LV","LT","LU","MT","NL","PL","PT","RO","SK","SI","ES","SE","GB"]
            },
            {
                "label": {
                    "en": "Free Shipping (Global)",
                    "de": "Kostenloser Versand (Global)"
                },
                "minTotoal": 59.0,
                "shippingCost": 0.0
            },
            {
                "label": {
                    "en": "Standard Shipping (Global)",
                    "de": "Standard Versand (Global)"
                },
                "shippingCost": 15.0
            }
        ]
    ]
}

snipcart-custom-shipping.ts

/* How to use: 
1. create firebase project and add cloud function from below
2. copy shipping-rates-example.json file, modify it and host it somewhere public (some web hosting)
3. in snipcart settings enable shipping webhook with following webhook url: https://[yourfirebaseurl].cloudfunctions.net/shippingcalculator?rates_url=[url of publicly hosted shipping-rates.json file]
*/

import * as functions from "firebase-functions";
import fetch from "node-fetch";

import * as shippingRatesExample from "./shipping-rates-example.json";

type ShippingRates = typeof shippingRatesExample;

interface ResponseShippingMethodes {
    description: string;
    cost: number;
}

const getShippingRate = (
    countryCode: string,
    orderAmount: number,
    lang: string,
    rateData: any
): undefined | ResponseShippingMethodes => {
    const foundRate = rateData.find((currentRate: any): any => {
        let minimum = 0;
        if (currentRate.minTotoal) {
            minimum = currentRate.minTotoal;
        }
        const passesMinimum = minimum < orderAmount;

        if (!currentRate.countries && passesMinimum) {
            return true;
        }

        if (passesMinimum) {
            const hasCountry = currentRate.countries.find((country: string) => country === countryCode);

            if (hasCountry) {
                return true;
            }
        }

        return false;
    });

    if (foundRate) {
        return {
            description: foundRate.label[lang],
            cost: foundRate.shippingCost,
        };
    }

    return undefined;
};

const getShippingRates = async (url: string): Promise<any> => {
    const response = await fetch(url);

    if (!response.ok) {
        return response.statusText;
    }
    return await response.json();
};

exports.shippingCalculator = functions.https.onRequest(async (req: functions.Request, res: functions.Response) => {
    // Grab the text parameter.
    const ratesUrl = req.query.rates_url as string;

    if (!ratesUrl) {
        res.status(400).send("Please provide correct url paramenter");
    }

    const responseShippingMethodes: ResponseShippingMethodes[] = [];

    if (req.body.eventName === "shippingrates.fetch") {
        try {
            const shippingRates: ShippingRates = await getShippingRates(ratesUrl);

            if (!shippingRates) {
                res.status(500).send("Error: no shipping config.");
            }

            shippingRates.rates.forEach((rateData) => {
                const rate = getShippingRate(
                    req.body.content.shippingAddressCountry,
                    req.body.content.finalGrandTotal,
                    req.body.content.lang,
                    rateData
                );

                if (rate) {
                    responseShippingMethodes.push(rate);
                }
            });
        } catch (e) {
            res.status(500).send("Error: with shipping config request.");
        }
    }

    console.log(JSON.stringify(responseShippingMethodes));

    if (responseShippingMethodes.length > 0) {
        const formattedDate = {
            rates: responseShippingMethodes,
        };

        res.status(200).send(formattedDate);
    } else {
        res.status(404).send("Error: Could not find any shipping methode");
    }
});