handler.js

const fs = require('fs')
const path = require('path')

const files = {
  '/public/index.css': {
    content: fs.readFileSync(path.join(__dirname, 'public', 'index.css'), 'utf8'),
    type: 'text/css'
  },
  '/public/main.js': {
    content: fs.readFileSync(path.join(__dirname, 'public', 'main.js'), 'utf8'),
    type: 'text/javascript'
  },
  '/': {
    content: fs.readFileSync(path.join(__dirname, 'index.html'), 'utf8'),
    type: 'text/html'
  }
}

/**
 *
 * Event doc: https://docs.aws.amazon.com/apigateway/latest/developerguide/set-up-lambda-proxy-integrations.html#api-gateway-simple-proxy-for-lambda-input-format
 * @param {Object} event - API Gateway Lambda Proxy Input Format
 *
 * Context doc: https://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-context.html
 * @param {Object} context
 *
 * Return doc: https://docs.aws.amazon.com/apigateway/latest/developerguide/set-up-lambda-proxy-integrations.html
 * @returns {Object} object - API Gateway Lambda Proxy Output Format
 *
 */
exports.lambdaHandler = async (event, context) => {
  // This will either be /, /public/index.css, or /public/main.js
  const requestPath = event.path
  const { content, type } = files[requestPath]

  return {
    headers: { 'content-type': type },
    statusCode: 200,
    body: content
  }
}