#!/usr/bin/env node
/**
 * CS HTTP front door. Internally prefers NATS account-balance, then HTTP.
 */
import fs from 'node:fs';
import http from 'node:http';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { SUBJECTS, billingRequest } from './nats-billing.js';

const PUBLIC = path.join(path.dirname(fileURLToPath(import.meta.url)), '..', 'public');

const PORT = Number(process.env.PORT || 3011);
const BOOKS = (process.env.ACCOUNT_BALANCE_URL || 'http://127.0.0.1:3010').replace(/\/$/, '');
const EDGE = (process.env.ZAPPIER_ADMIN_URL || 'http://127.0.0.1:3000').replace(/\/$/, '');
const KEY = process.env.ZAPPIER_ADMIN_KEY || 'admin-dev-key';

async function statement(customerId) {
  const nats = await billingRequest(SUBJECTS.STATEMENT_GET, { customerId });
  if (nats) return { status: 200, body: { ...nats, source: 'nats' } };
  const r = await fetch(`${BOOKS}/statement/${customerId}`);
  if (r.ok) return { status: r.status, body: { ...(await r.json()), source: 'account-balance' } };
  const e = await fetch(`${EDGE}/admin/api/statement/${customerId}`, { headers: { 'x-admin-key': KEY } });
  return { status: e.status, body: { ...(await e.json().catch(() => ({}))), source: 'edge' } };
}

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url || '/', `http://127.0.0.1:${PORT}`);
  const json = (code, obj) => {
    res.writeHead(code, { 'content-type': 'application/json' });
    res.end(JSON.stringify(obj));
  };
  try {
    if (req.method === 'GET' && (url.pathname === '/' || url.pathname === '/index.html')) {
      res.writeHead(200, { 'content-type': 'text/html; charset=utf-8' });
      res.end(fs.readFileSync(path.join(PUBLIC, 'index.html')));
      return;
    }
    if (req.method === 'GET' && url.pathname === '/health') {
      return json(200, { ok: true, role: 'zappier-customer-service', nats: Boolean(process.env.NATS_URL) });
    }
    const review = url.pathname.match(/^\/review\/([^/]+)$/);
    if (req.method === 'GET' && review) {
      const out = await statement(review[1]);
      return json(out.status, out.body);
    }
    if (req.method === 'POST' && url.pathname === '/credits') {
      const chunks = [];
      for await (const c of req) chunks.push(c);
      const payload = JSON.parse(Buffer.concat(chunks).toString('utf8') || '{}');
      const nats = await billingRequest(SUBJECTS.BALANCE_ADJUST, { ...payload, kind: 'credit' });
      if (nats) return json(200, { ...nats, source: 'nats' });
      const r = await fetch(`${BOOKS}/adjust`, {
        method: 'POST',
        headers: { 'content-type': 'application/json' },
        body: JSON.stringify(payload),
      });
      const body = await r.json().catch(() => ({}));
      await fetch(`${EDGE}/admin/api/credits`, {
        method: 'POST',
        headers: { 'content-type': 'application/json', 'x-admin-key': KEY },
        body: JSON.stringify(payload),
      }).catch(() => {});
      return json(r.status, body);
    }
    if (req.method === 'GET' && url.pathname === '/credits') {
      const id = url.searchParams.get('customerId');
      if (!id) return json(400, { error: 'customerId required' });
      const out = await statement(id);
      return json(out.status, { credits: out.body.credits || [] });
    }
    json(404, { error: 'not found' });
  } catch (err) {
    json(502, { error: err.message });
  }
});

server.listen(PORT, '0.0.0.0', () => {
  process.stdout.write(`zappier-customer-service http://0.0.0.0:${PORT}/\n`);
});