Stripe (customer pays)
  ↓
Stripe sends webhook event to your server
  ↓
Your webhook handler receives the event
  ↓
Validate the signature (critical — verify it's really from Stripe)
  ↓
Check if it's a successful charge
  ↓
Extract customer email + product ID
  ↓
Send email with download link using Resend/SendGrid/SES
  ↓
Log the delivery (database or spreadsheet)
  ↓
Done

# Install Stripe CLI
brew install stripe/stripe-cli/stripe

# Login to your Stripe account
stripe login

# Forward webhook events to your local server
stripe listen --forward-to localhost:3000/api/stripe/webhook

# In another terminal, trigger a test event
stripe trigger charge.succeeded

npm install stripe resend dotenv

# .env
STRIPE_WEBHOOK_SECRET=whsec_test_xxxxx
RESEND_API_KEY=re_xxxxx
PRODUCT_ID_TO_FILE_MAP={...}  # JSON mapping products to file URLs

import Stripe from 'stripe'
import { Resend } from 'resend'
import dotenv from 'dotenv'

dotenv.config()

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY)
const resend = new Resend(process.env.RESEND_API_KEY)

// Map product IDs to download URLs
const PRODUCTS = {
  'price_xxxxx': { name: 'AI Agent Manual', url: 'https://cdn.example.com/ai-manual.pdf' },
  'price_yyyyy': { name: 'Claude Workflow Pack', url: 'https://cdn.example.com/workflows.zip' },
}

export default async function handler(req, res) {
  if (req.method !== 'POST') {
    return res.status(405).json({ error: 'Method not allowed' })
  }

  const sig = req.headers['stripe-signature']
  let event

  try {
    // Verify the signature
    event = stripe.webhooks.constructEvent(
      req.body,
      sig,
      process.env.STRIPE_WEBHOOK_SECRET
    )
  } catch (err) {
    console.error('❌ Signature verification failed:', err.message)
    return res.status(400).json({ error: 'Invalid signature' })
  }

  // Handle the charge.succeeded event
  if (event.type === 'charge.succeeded') {
    const charge = event.data.object
    const priceId = charge.metadata?.price_id // You set this when creating the charge
    const product = PRODUCTS[priceId]

    if (!product) {
      console.error(`❌ Unknown product: ${priceId}`)
      return res.status(400).json({ error: 'Product not found' })
    }

    // Send the download email
    try {
      const emailResponse = await resend.emails.send({
        from: 'you@example.com',
        to: charge.billing_details.email,
        subject: `Your ${product.name} is ready to download`,
        html: `
          <h2>Thanks for your purchase!</h2>
          <p>Here's your download link:</p>
          <a href="${product.url}">Download ${product.name}</a>
          <p style="color:#999;font-size:12px;margin-top:20px">
            This link expires in 7 days.
          </p>
        `,
      })

      console.log(`✅ Email sent to ${charge.billing_details.email}`)

      // Log to database (optional but recommended)
      // await db.deliveries.create({
      //   email: charge.billing_details.email,
      //   productId: priceId,
      //   chargeId: charge.id,
      //   sentAt: new Date(),
      // })

      return res.status(200).json({ success: true })
    } catch (error) {
      console.error('❌ Failed to send email:', error)
      return res.status(500).json({ error: 'Email delivery failed' })
    }
  }

  // Ignore other event types
  return res.status(200).json({ received: true })
}

// Example: Checkout with Stripe.js
const response = await fetch('/api/create-charge', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    amount: 1999, // $19.99
    productId: 'price_xxxxx', // The product being purchased
    email: customerEmail,
  }),
})

const charge = await stripe.charges.create({
  amount: 1999,
  currency: 'usd',
  source: paymentToken,
  receipt_email: email,
  metadata: {
    price_id: productId, // This is what the webhook looks for
  },
})

// Before sending email
await db.webhookEvents.create({
  stripeEventId: event.id,
  type: event.type,
  status: 'pending',
})

// After sending email
await db.webhookEvents.update(stripeEventId, {
  status: 'delivered',
  sentAt: new Date(),
})

const existing = await db.webhookEvents.findOne({ stripeEventId: event.id })
if (existing) {
  return res.status(200).json({ skipped: true })
}