import { MeterEventClient, reportUsage, METER_EVENT_NAME } from '../src/billing/stripe';
import { UsageEntry } from '../src/usage';

const entry = (cents: number): UsageEntry => ({
  customerId: 'cust_1',
  endpointId: 'storage',
  cents,
  metadataBytes: 0,
  attachmentBytes: 0,
  timestamp: new Date(),
});

const fakeClient = () => {
  const calls: { eventName: string; customerId: string; value: string }[] = [];
  const client: MeterEventClient = {
    createMeterEvent: async (params) => {
      calls.push(params);
    },
  };
  return { client, calls };
};

describe('reportUsage', () => {
  it('reports usage minus the monthly credit as one meter event', async () => {
    const { client, calls } = fakeClient();
    const reported = await reportUsage(client, 'cus_123', [entry(112), entry(4)], 100);
    expect(reported).toBe(16); // 116 - 100 credit
    expect(calls).toEqual([
      { eventName: METER_EVENT_NAME, customerId: 'cus_123', value: '16' },
    ]);
  });

  it('reports nothing when the credit covers all usage', async () => {
    const { client, calls } = fakeClient();
    const reported = await reportUsage(client, 'cus_123', [entry(4)], 100);
    expect(reported).toBe(0);
    expect(calls).toHaveLength(0);
  });
});