custom_mail_cognito.js

var AES = require('crypto-js/aes');

const password = process.env.PASSWORD;

function toHex(encrypted) {
    var hex = "";
    for (var i = 0; i < encrypted.length; i++) {
        hex += encrypted.charCodeAt(i).toString(16)
    }
    return hex;
}

exports.handler = function(event, context, cb) {
    var encrypted = AES.encrypt(`${ event.userName }::${ Date.now() }`, password);
    var hexEncrypted = toHex(encrypted.toString());
    var link = `https://www.example.com/recover-password/${ hexEncrypted }`;

    var msj = "<p>" + 
        event.request.codeParameter +
        "</p>";
        
    var msjConfirm = "<p>" +
        event.request.codeParameter + 
        "</p>";

    console.log('userPoolId', event.userPoolId);
    console.log('triggerSource', event.triggerSource);
    console.log('userName', event.userName);
    console.log('response', msj);

    if (event.userPoolId === "poolId") {
        // Identify why was this function invoked
        if (event.triggerSource === "CustomMessage_ForgotPassword") {
            // Ensure that your message contains event.request.codeParameter. This is the placeholder for code that will be sent
            event.response.smsMessage = "Your confirmation code is " + event.request.codeParameter;
            event.response.emailSubject = "Recover your password";
            event.response.emailMessage = msj;
        }
        if (event.triggerSource === "CustomMessage_SignUp" || event.triggerSource === "CustomMessage_ResendCode") {
            event.response.smsMessage = "Your confirmation code is " + event.request.codeParameter;
            event.response.emailSubject = "Confirm your account";
            event.response.emailMessage = msjConfirm;
        }
        // Create custom message for other events
    }
    
    console.log('response',event.response);

    // Return result to Cognito
    cb(null, event);
};