Downloading, storing, and updating the rule artifact via JSON payload

//... Code removed for brevity

function onArtifactDownloadSucceeded(event) {
    const jsonPath = 'src/config/target-rules.json'
    fs.writeFile(jsonPath, JSON.stringify(event.artifactPayload), 'utf8', (err) => {
        if (err) {
            throw err;
        };
        console.log(`The artifact from '${event.artifactLocation}' is now saved to '${jsonPath}'`);
    });
}


function onArtifactDownloadFailed(event) {
  console.log(`The local decisioning artifact failed to download from '${event.artifactLocation}' with the following error message: ${event.error.message}`);
}

//... Code removed for brevity

const express = require("express");
const cookieParser = require("cookie-parser");
const TargetClient = require("@adobe/target-nodejs-sdk");
const CONFIG = {
    client: "<your target client code>",
    organizationId: "your EC org id",
    decisioningMethod: "on-device",
    pollingInterval : 300000,
    events: {
        clientReady : startWebServer,
        artifactDownloadSucceeded : onArtifactDownloadSucceeded,
        artifactDownloadFailed : onArtifactDownloadFailed
    },
};

function onArtifactDownloadSucceeded(event) {
    const jsonPath = 'src/config/target-rules.json'
    fs.writeFile(jsonPath, JSON.stringify(event.artifactPayload), 'utf8', (err) => {
        if (err) {
            throw err;
        };
        console.log(`The artifact from '${event.artifactLocation}' is now saved to '${jsonPath}'`);
    });
}

function onArtifactDownloadFailed(event) {
  console.log(`The on-device decisioning artifact failed to download from '${event.artifactLocation}' with the following error message: ${event.error.message}`);
}

const app = express();
const targetClient = TargetClient.create(CONFIG);

app.use(cookieParser());

function saveCookie(res, cookie) {
  if (!cookie) {
    return;
  }

  res.cookie(cookie.name, cookie.value, {maxAge: cookie.maxAge * 1000});
}

const getResponseHeaders = () => ({
  "Content-Type": "text/html",
  "Expires": new Date().toUTCString()
});

function sendSuccessResponse(res, response) {
  res.set(getResponseHeaders());
  saveCookie(res, response.targetCookie);
  res.status(200).send(response);
}

function sendErrorResponse(res, error) {
  res.set(getResponseHeaders());
  res.status(500).send(error);
}

function startWebServer() {
    app.get('/*', async (req, res) => {
    const targetCookie = req.cookies[TargetClient.TargetCookieName];
    const request = {
        execute: {
        mboxes: [{
            address: { url: req.headers.host + req.originalUrl },
            name: "on-device-homepage-banner" // Ensure that you have a LIVE Activity running on this location
        }]
        }};

    try {
        const response = await targetClient.getOffers({ request, targetCookie });
        sendSuccessResponse(res, response);
    } catch (error) {
        console.error("Target:", error);
        sendErrorResponse(res, error);
    }
    });

    app.listen(3000, function () {
    console.log("Listening on port 3000 and watching!");
    });
}