index.js

const simpleParser = require("mailparser").simpleParser;
const cheerio = require("cheerio");
const AWS = require("aws-sdk");
const Twitter = require("twitter");
AWS.config.update({ region: "us-west-2" });
const s3 = new AWS.S3();
let $ = null;

const twitter = new Twitter({
  consumer_key: process.env.TWITTER_CONSUMER_KEY,
  consumer_secret: process.env.TWITTER_CONSUMER_SECRET,
  access_token_key: process.env.TWITTER_ACCESS_TOKEN_KEY,
  access_token_secret: process.env.TWITTER_ACCESS_TOKEN_SECRET,
});

const amex = (jq) => {
  const words = [];
  let startIndex = null;

  jq("b").each(function (i, elem) {
    const text = jq(this).text();
    if (text.indexOf("your Card") > -1) {
      startIndex = i + 1;
    }
    words[i] = text;
  });

  if (startIndex !== null) {
    const merchant = words[startIndex];
    const amount = words[startIndex + 1].replace("*", "");
    return `${merchant} — ${amount}`;
  } else {
    return null;
  }
};

const citibank = (jq) => {
  const merchant = jq("td")
    .filter((i, el) => jq(el).text().startsWith("Merchant"))
    .closest("table")
    .closest("td")
    .next("td")
    .text()
    .trim();

  const amount = jq("span")
    .filter((i, el) => jq(el).text().startsWith("Amount:"))
    .text()
    .replace("Amount: ", "")
    .trim();

  return `${merchant} — ${amount}`;
};

const square = ($, subject) => {
  let merchant = null;
  const matches = subject.match(/(?<=Receipt from).*/);
  if (matches && matches[0]) {
    merchant = matches[0].trim();
  }
  const amount = $("span")
    .filter((i, el) => $(el).text() === "$")
    .parent()
    .text()
    .trim();
  return `${merchant} — ${amount}`;
};

const chase = (text) => {
  let merchant = null;

  const regex = /(A charge of)(.+)(at)(.+) (has)/;
  const results = regex.exec(text);

  if (results.length == 6) {
    // we remove USD so that way non US currencies will render the type
    const amount = results[2]
      .replace(" (", "")
      .replace(") ", "")
      .replace(/USD/, "")
      .trim();
    merchant = results[4].trim();
    return `${merchant} — ${amount}`;
  } else {
    console.log("Regex didn't match");
    return null;
  }
};

const main = async (message) => {
  const { html, subject, text } = await simpleParser(message);
  $ = cheerio.load(html);
  let response = null;

  if (subject.indexOf("Transaction Alert from Chase") > -1) {
    console.log("Chase");
    response = chase(text);
  } else if (html !== false) {
    if (html.indexOf("American Express") > -1) {
      console.log("American Express");
      response = amex($);
    } else if (html.indexOf("Citibank") > -1) {
      console.log("Citibank");
      response = citibank($);
    } else if (html.indexOf("Square") > -1) {
      console.log("Square");
      response = square($, subject);
    } else {
      console.log("Couldn't determine bank");
    }
  } else {
    console.log("Couldn't find HTML in email. Can't parse.");
  }

  console.log(response);
  if (response !== null) {
    return new Promise((resolve) => {
      twitter.post("statuses/update", { status: response }, (err, data) => {
        if (err) {
          console.error(err);
        }
        resolve(response);
      });
    });
  }
  return response;
};

exports.handler = async (event) => {
  const messageId = event["Records"][0].ses.mail.messageId;
  const params = {
    Bucket: "transaction-emails",
    Key: messageId,
  };

  console.log("Message ID", messageId);
  return new Promise((resolve) => {
    s3.getObject(params, async function (err, data) {
      if (err) {
        console.log(err, err.stack);
      } else {
        const res = await main(data.Body);
        resolve(res);
      }
    });
  });
};