// Environment variables (never commit API keys)
const API_KEY = process.env.CREEM_API_KEY;
const BASE_URL = process.env.NODE_ENV === 'production'
  ? 'https://api.creem.io'
  : 'https://test-api.creem.io';

// All requests require the x-api-key header
const headers = {
  'x-api-key': API_KEY,
  'Content-Type': 'application/json'
};

// POST /v1/checkouts
const createCheckout = async (productId: string, options?: {
  requestId?: string;
  successUrl?: string;
  customerEmail?: string;
  discountCode?: string;
  units?: number;
  metadata?: Record<string, any>;
}) => {
  const response = await fetch(`${BASE_URL}/v1/checkouts`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      product_id: productId,
      request_id: options?.requestId,
      success_url: options?.successUrl,
      customer: options?.customerEmail ? { email: options.customerEmail } : undefined,
      discount_code: options?.discountCode,
      units: options?.units,
      metadata: options?.metadata
    })
  });

  const checkout = await response.json();
  // Redirect user to: checkout.checkout_url
  return checkout;
};

import crypto from 'crypto';

// Signature verification
function verifyWebhookSignature(payload: string, signature: string, secret: string): boolean {
  const computed = crypto
    .createHmac('sha256', secret)
    .update(payload)
    .digest('hex');
  return computed === signature;
}

// Webhook handler
export async function handleWebhook(req: Request) {
  const signature = req.headers.get('creem-signature');
  const rawBody = await req.text();

  if (!verifyWebhookSignature(rawBody, signature!, process.env.CREEM_WEBHOOK_SECRET!)) {
    return new Response('Invalid signature', { status: 401 });
  }

  const event = JSON.parse(rawBody);

  switch (event.eventType) {
    case 'checkout.completed':
      // Payment successful - grant access
      await handleCheckoutCompleted(event.object);
      break;
    case 'subscription.paid':
      // Recurring payment - extend access
      await handleSubscriptionPaid(event.object);
      break;
    case 'subscription.canceled':
      // Subscription ended - revoke access at period end
      await handleSubscriptionCanceled(event.object);
      break;
    case 'subscription.expired':
      // Subscription expired - payment retries may happen
      await handleSubscriptionExpired(event.object);
      break;
    case 'refund.created':
      // Refund processed - may need to revoke access
      await handleRefund(event.object);
      break;
  }

  return new Response('OK', { status: 200 });
}

// Activate on first use
const activateLicense = async (licenseKey: string, instanceName: string) => {
  const response = await fetch(`${BASE_URL}/v1/licenses/activate`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      key: licenseKey,
      instance_name: instanceName // e.g., "johns-macbook-pro"
    })
  });

  const result = await response.json();
  // Store result.instance.id locally for future validation
  return result;
};

// Validate on app startup
const validateLicense = async (licenseKey: string, instanceId: string) => {
  const response = await fetch(`${BASE_URL}/v1/licenses/validate`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      key: licenseKey,
      instance_id: instanceId
    })
  });

  const result = await response.json();
  // result.status: "active" | "inactive" | "expired" | "disabled"
  return result;
};

// Deactivate when user switches device
const deactivateLicense = async (licenseKey: string, instanceId: string) => {
  const response = await fetch(`${BASE_URL}/v1/licenses/deactivate`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      key: licenseKey,
      instance_id: instanceId
    })
  });
  return response.json();
};

// Update seat count
const updateSubscriptionSeats = async (subscriptionId: string, itemId: string, newUnits: number) => {
  const response = await fetch(`${BASE_URL}/v1/subscriptions/${subscriptionId}`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      items: [{ id: itemId, units: newUnits }],
      update_behavior: 'proration-charge-immediately' // or 'proration-charge', 'proration-none'
    })
  });
  return response.json();
};

// Upgrade to different plan
const upgradeSubscription = async (subscriptionId: string, newProductId: string) => {
  const response = await fetch(`${BASE_URL}/v1/subscriptions/${subscriptionId}/upgrade`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      product_id: newProductId,
      update_behavior: 'proration-charge-immediately'
    })
  });
  return response.json();
};

// Cancel subscription
const cancelSubscription = async (subscriptionId: string, immediate: boolean = false) => {
  const response = await fetch(`${BASE_URL}/v1/subscriptions/${subscriptionId}/cancel`, {
    method: 'POST',
    headers,
    body: JSON.stringify({
      mode: immediate ? 'immediate' : 'scheduled' // scheduled = at period end
    })
  });
  return response.json();
};

const getCustomerPortalLink = async (customerId: string) => {
  const response = await fetch(`${BASE_URL}/v1/customers/billing`, {
    method: 'POST',
    headers,
    body: JSON.stringify({ customer_id: customerId })
  });

  const { customer_portal_link } = await response.json();
  return customer_portal_link;
};

const handleApiResponse = async (response: Response) => {
  if (response.ok) {
    return response.json();
  }

  switch (response.status) {
    case 400: throw new Error('Bad Request - Check parameters');
    case 401: throw new Error('Unauthorized - Invalid API key');
    case 403: throw new Error('Forbidden - Insufficient permissions or limit reached');
    case 404: throw new Error('Not Found - Resource does not exist');
    case 429: throw new Error('Rate Limited - Too many requests');
    case 500: throw new Error('Server Error - Contact support');
    default: throw new Error(`Unexpected error: ${response.status}`);
  }
};