点餐系统选型验收中的重复下单与请求冲突检查

const assert = require('node:assert/strict');
const orders = new Map();
function placeOrder(store, key, amount, channel) {
  if (!Number.isSafeInteger(amount) || amount <= 0) throw Error('amount');
  if (!['dine_in', 'takeaway'].includes(channel)) throw Error('channel');
  if (!store || !key) throw Error('identity');
  const identity = JSON.stringify([store, key]);
  const existing = orders.get(identity);
  if (existing) {
    if (existing.amount !== amount || existing.channel !== channel) {
      throw Error('idempotency_conflict');
    }
    return existing;
  }
  const order = {id: orders.size + 1, store, amount, channel, state: 'created'};
  orders.set(identity, order);
  return order;
}
const first = placeOrder('A', 'req1', 2300, 'dine_in');
assert.equal(placeOrder('A', 'req1', 2300, 'dine_in'), first);
assert.equal(orders.size, 1);
assert.throws(() => placeOrder('A', 'req1', 2400, 'dine_in'), /conflict/);
assert.throws(() => placeOrder('A', 'req1', 2300, 'takeaway'), /conflict/);
assert.equal(placeOrder('B', 'req1', 2300, 'dine_in').id, 2);
assert.throws(() => placeOrder('A', 'req2', -1, 'dine_in'), /amount/);
assert.throws(() => placeOrder('A', 'req2', 1.5, 'dine_in'), /amount/);
assert.throws(() => placeOrder('A', 'req2', 100, 'unknown'), /channel/);
assert.throws(() => placeOrder('', 'req2', 100, 'dine_in'), /identity/);
assert.equal(orders.size, 2);
console.log(JSON.stringify({assertions: 10, orders: [...orders.values()]}));