Middy.js Middleware Engine for AWS Lambda

import middy from '@middy/core';
import jsonBodyParser from '@middy/http-json-body-parser';
import httpErrorHandler from '@middy/http-error-handler';
import validator from '@middy/validator';

// Define your AWS Lambda handler function
const paymentHandler = async (event, context) => {
  // Assume event.body is already parsed by jsonBodyParser
  const { amount, currency, token } = event.body;

  if (!amount || !currency || !token) {
    throw new Error('Missing required payment details.');
  }

  // Simulate payment processing
  console.log(`Processing payment for ${amount} ${currency} with token ${token}`);
  const paymentId = `pay_${Date.now()}`;

  return {
    statusCode: 200,
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ message: 'Payment processed successfully', paymentId })
  };
};

const inputSchema = {
  type: 'object',
  properties: {
    body: {
      type: 'object',
      properties: {
        amount: { type: 'number', minimum: 0.01 },
        currency: { type: 'string', pattern: '^[A-Z]{3}$' },
        token: { type: 'string' }
      },
      required: ['amount', 'currency', 'token']
    }
  },
  required: ['body']
};

// Wrap your handler with middy and apply middlewares
export const handler = middy(paymentHandler)
  .use(jsonBodyParser())
  .use(validator({ inputSchema }))
  .use(httpErrorHandler()); // Must be the last middleware for error catching