// @applet-input-schema {"type":"object","properties":{"month":{"type":"string","title":"Month (YYYY-MM)","default":"","description":"Only include orders placed in this month. Leave empty for all months."},"limit":{"type":"integer","title":"Max rows","default":50,"minimum":1,"maximum":500}}}
// @applet-output-schema month:string;orders:integer;positions:integer;net:number
// @applet-description "Order revenue by month — orders grouped per calendar month."
//
// Order revenue by month — orders grouped per calendar month.
//
// Demonstrates: paging, then aggregating into a Map keyed by `YYYY-MM` and rendering a small
// report. `GET /order` list rows already carry their line items, so no detail call is needed.
// Endpoints: GET /order (paged).

module.exports = async function (applet_input) {
  const only = String(applet_input.month || '').trim();
  const maxRows = Math.max(1, Number(applet_input.limit) || 50);

  // 1. Page through orders.
  const orders = [];
  let offset = 0;
  for (;;) {
    const res = await fetch(`/order?offset=${offset}&limit=100`);
    if (!res.ok) throw new Error(`GET /order failed: ${res.status}`);
    const data = await res.json();
    const page = data.orders || [];
    orders.push(...page);
    offset += page.length;
    if (page.length === 0 || offset >= (data.total ?? orders.length)) break;
  }

  // 2. Aggregate per calendar month.
  const buckets = new Map();
  for (const order of orders) {
    const month = String(order.date || '').slice(0, 7);
    if (!month) continue;
    if (only && month !== only) continue;
    const bucket = buckets.get(month) || { month, orders: 0, positions: 0, net: 0 };
    bucket.orders += 1;
    for (const line of order.lines || []) {
      bucket.positions += 1;
      bucket.net += (line.amount || 0) * (line.net || 0);
    }
    buckets.set(month, bucket);
  }

  const rows = [...buckets.values()]
    .map((b) => ({ ...b, net: Math.round(b.net * 100) / 100 }))
    .sort((a, b) => a.month.localeCompare(b.month))
    .slice(-maxRows);

  const totalNet = rows.reduce((sum, r) => sum + r.net, 0);
  console.log(`${rows.length} month(s), ${rows.reduce((n, r) => n + r.orders, 0)} order(s), net ${totalNet.toFixed(2)}.`);
  return rows;
};