import type { VercelRequest, VercelResponse } from '@vercel/node';
import type Order from './_Order';
import { paypalCaptureOrder, paypalCreateOrder } from './_paypal';

export default async function handler(request: VercelRequest, response: VercelResponse) {
  if (request.method === 'POST') {
    await handlePost(request, response);
  } else if (request.method === 'PATCH') {
    await handlePatch(request, response);
  } else {
    console.warn('Method was not POST. Method was ' + request.method);
    response.status(404);
    return;
  }
}

async function handlePost(request: VercelRequest, response: VercelResponse) {
  const { productDescription, shortDescription, totalPrice }: Partial<Order> = request.body;
  
  if (!productDescription) {
    response.status(400).send('Expected body to contain productDescription, but none provided.');
  } else if (!shortDescription) {
    response.status(400).send('Expected body to contain shortDescription, but none provided.');
  } else if (!totalPrice) {
    response.status(400).send('Expected body to contain totalPrice, but none provided.');
  } else {
    try {
      const paypalResponse = await paypalCreateOrder({ productDescription, shortDescription, totalPrice });

      const { id, links } = paypalResponse;
      const isApprovalLink = (o: object) => (
        'rel' in o &&
        o.rel === 'approve' &&
        'href' in o &&
        typeof(o.href) === 'string' &&
        o.href.length > 0
      );

      if (!id || typeof(id) !== 'string' || id.length === 0) {
        throw new Error(`
          PayPal did not return the created order ID
          in an expected format. PayPal returned: ${paypalResponse}
        `);
      }
      if (!links || !('length' in links) || !links.some(isApprovalLink)) {
        throw new Error(`
          PayPal did not return the order approval link in
          an expected format. PayPal returned: ${paypalResponse}
        `);
      }

      response.status(201).json({
        orderId: id,
        approvalLink: links.find(isApprovalLink).href,
      });
    } catch (err) {
      response.status(500).send(`Internal server error. ${err}`);
    }
  }
}

async function handlePatch(request: VercelRequest, response: VercelResponse) {
  const { id, isApproved }: Partial<PatchRequestBody> = request.body;
  
  if (!id) {
    response.status(400).send('Expected body to contain id, but none provided.');
  } else if (!isApproved) {
    response.status(400).send('Expected body to contain isApproved, but none provided.');
  } else {
    try {
      const paypalResponse = await paypalCaptureOrder(id);
      response.status(200).json({
        orderId: paypalResponse.id,
        paypalStatus: paypalResponse.status,
      });
    } catch (err) {
      response.status(500).send(`Internal server error. ${err}`);
    }
  }
}

type PatchRequestBody = {
  id: string;
  isApproved: boolean;
};