This script is used to send ethereum based push notifications.

sendNotifications.js

require("dotenv").config();
const Ipfs = require("nano-ipfs-store"); // Used to spin up local ipfs node
const  ethers  = require("ethers");
const epnsAbi = require("../abis/epnsAbi.json");
const { EPNS_PROXY_ADDRESS, PROVIDER } = require("../constants");

async function newMessage(newsTitle, description) {
  return await new Promise((resolve, reject) => {
    const title = newsTitle;
    const message = description;
    const payloadTitle = newsTitle;
    const payloadMsg = description;

    const payload = {
      notification: {
        title: title,
        body: message,
      },
      data: {
        type: "1", // Group Message
        secret: "",
        asub: payloadTitle,
        amsg: payloadMsg,
        acta: "https://medium.com",
        aimg: "",
      },
    };

    resolve(payload);
  });
}

async function sendMessage(title, description) {
  return new Promise((resolve, reject) => {
    let EPNS_CONTRACT_ABI = epnsAbi;
    let EPNS_CONTRACT_ADDR = EPNS_PROXY_ADDRESS;
    let channelPK = process.env.PRIVATE_KEY;

    //Initialize the EPNS Contract
    const contract = new ethers.Contract(
      EPNS_CONTRACT_ADDR,
      EPNS_CONTRACT_ABI,
      PROVIDER // Ropsten Provider
    );
    const wallet = new ethers.Wallet(channelPK, PROVIDER);
    contractWithSigner = contract.connect(wallet); //Connect the signer

    newMessage(title, description).then((payload) => {
      const jsonizedPayload = JSON.stringify(payload);
      const ipfs = Ipfs.at("https://ipfs.infura.io:5001");

      // Upload the IPFS payload
      ipfs.add(jsonizedPayload).then((ipfshash) => {
        const notificationType = parseInt(payload.data.type);
        const identity = notificationType + "+" + ipfshash;
        const identityBytes = ethers.utils.toUtf8Bytes(identity);
        const channelAddress = "YOUR_CHANNEL_ADDR";

        //Send the notification
        const txPromise = contractWithSigner.sendNotification(
          channelAddress,
          identityBytes
        );

        txPromise
          .then(async function (tx) {
            console.log("News update sent", tx.hash);
            resolve(tx);
          })
          .catch((err) => {
            console.log("failed");
            reject("Unable to complete transaction, error: %o", err);
          });
      });
    });
  });
}
module.exports = { sendMessage };