import { buildInvoice, Invoice } from '../src/invoicing';
import { Customer } from '../src/auth';
import { TierConfig } from '../src/pricing';
import { UsageEntry } from '../src/usage';

const pro: TierConfig = { id: 'pro', name: 'Pro', multiplier: 0.5, monthlyCreditCents: 1000 };

const customer: Customer = {
  id: 'cust_2',
  name: 'Grace',
  tierId: 'pro',
  apiKey: 'key-grace',
  stripeCustomerId: 'cus_123',
};

const entry = (endpointId: string, cents: number): UsageEntry => ({
  customerId: customer.id,
  endpointId,
  cents,
  metadataBytes: 0,
  attachmentBytes: 0,
  timestamp: new Date('2026-07-10T12:00:00Z'),
});

describe('buildInvoice', () => {
  it('groups usage entries into lines per endpoint, sorted', () => {
    const inv = buildInvoice({
      customer,
      period: '2026-07',
      sequence: 1,
      tier: pro,
      entries: [entry('transform', 3), entry('storage', 6), entry('transform', 3)],
    });
    expect(inv.lines).toEqual([
      { endpointId: 'storage', calls: 1, cents: 6 },
      { endpointId: 'transform', calls: 2, cents: 6 },
    ]);
    expect(inv.totalCents).toBe(12);
  });

  it('applies a partial monthly credit', () => {
    const inv = buildInvoice({
      customer,
      period: '2026-07',
      sequence: 1,
      tier: pro,
      entries: [entry('storage', 1500)],
    });
    expect(inv.totalCents).toBe(1500);
    expect(inv.creditCents).toBe(1000);
    expect(inv.billableCents).toBe(500);
  });

  it('floors billable at zero when credit exceeds usage', () => {
    const inv = buildInvoice({
      customer,
      period: '2026-07',
      sequence: 1,
      tier: pro,
      entries: [entry('storage', 400)],
    });
    expect(inv.creditCents).toBe(400);
    expect(inv.billableCents).toBe(0);
  });

  it('formats the id as INV-<period>-<padded sequence> and starts as draft', () => {
    const inv = buildInvoice({ customer, period: '2026-07', sequence: 7, tier: pro, entries: [] });
    expect(inv.id).toBe('INV-2026-07-0007');
    expect(inv.status).toBe('draft');
    expect(inv.billingType).toBe('stripe');
  });

  it('carries purchase-order billing fields', () => {
    const poCustomer: Customer = { ...customer, billingType: 'purchase_order' };
    const inv = buildInvoice({
      customer: poCustomer,
      period: '2026-07',
      sequence: 2,
      tier: pro,
      entries: [entry('storage', 2000)],
      poNumber: 'PO-9982',
    });
    expect(inv.billingType).toBe('purchase_order');
    expect(inv.poNumber).toBe('PO-9982');
  });
});