edr-platform/apps/edr-freight-api/src/modules/train-scheduling/booking-batch.smart-need.spec.ts

import { Booking } from '../bookings/entities/booking.entity';
import { BookingBatchService } from './booking-batch.service';
import { WagonStockLedger } from './wagon-stock-ledger.util';

/**
 * smartBulkNeed math in isolation: the private helpers it touches
 * (allowedDimsWithTypes) read only their arguments, so a bare prototype
 * instance is enough — no Nest wiring.
 *///
describe('BookingBatchService.smartBulkNeed', () => {
  const service = Object.create(BookingBatchService.prototype) as BookingBatchService;
  const call = (
    booking: Booking,
    stock: WagonStockLedger,
    rank: Map<string, number>,
  ) =>
    (
      service as unknown as {
        smartBulkNeed: (
          b: Booking,
          d: unknown,
          s: WagonStockLedger,
          l: { fromEdge: number; toEdge: number },
          r: Map<string, number>,
          ids: readonly string[],
        ) => { need: { wagons: number }; perType: Array<{ wagonTypeId: string; wagons: number }> } | null;
      }
    ).smartBulkNeed(booking, wagonDims, stock, { fromEdge: 0, toEdge: 1 }, rank, allowedIds);

  const nw5 = { id: 'wt-nw5', capacityTons: 70 };
  const pw2 = { id: 'wt-pw2', capacityTons: 70 };
  // Shaped like a BATCH POOL entity: cargoType WITHOUT the wagonTypes
  // relation (the pool query never joins it) — allowed types must come from
  // the ids parameter, or every pool bulk booking reads as unseatable.
  const perishable = {
    id: 'cargo-perishable',
    tonsPerWagonMap: { [nw5.id]: 30, [pw2.id]: 20 },
  };
  const allowedIds = [nw5.id, pw2.id];
  const wagonDims = {
    container: { lengthMeters: 14, tareWeightTons: 24, capacityTons: 70 },
    bulk: { lengthMeters: 14, tareWeightTons: 24, capacityTons: 70 },
    byWagonTypeId: new Map([
      [nw5.id, { lengthMeters: 14, tareWeightTons: 24, capacityTons: 70 }],
      [pw2.id, { lengthMeters: 14, tareWeightTons: 24, capacityTons: 70 }],
    ]),
  };
  const booking = (tons: number): Booking =>
    ({
      id: 'b1',
      reference: 'b1',
      freightType: 'BULK',
      cargoTotalWeightVgm: tons,
      cargoTypeId: perishable.id,
      cargoType: perishable,
      bookingContainers: [],
    }) as unknown as Booking;
  // Containers compete for NW5 → NW5 rank 2, PW2 rank 1.
  const contested = new Map([
    [nw5.id, 2],
    [pw2.id, 1],
  ]);

  it('seats 695T as 10 PW2 (20T) + 17 NW5 (30T) = 27 wagons, PW2 first', () => {
    const stock = new WagonStockLedger(
      new Map([
        [nw5.id, 18],
        [pw2.id, 10],
      ]),
      1,
    );
    const smart = call(booking(695), stock, contested);
    expect(smart).not.toBeNull();
    expect(smart!.need.wagons).toBe(27);
    expect(smart!.perType).toEqual([
      { wagonTypeId: pw2.id, wagons: 10 },
      { wagonTypeId: nw5.id, wagons: 17 },
    ]);
  });

  it('returns null when the free stock cannot seat the whole booking', () => {
    const stock = new WagonStockLedger(
      new Map([
        [nw5.id, 5],
        [pw2.id, 10],
      ]),
      1,
    );
    // 10×20 + 5×30 = 350T < 695T.
    expect(call(booking(695), stock, contested)).toBeNull();
  });

  it('S-2026-00020 shape: 42x40ft eat the NW5, 200T bulk still seats on the 10 coupled PW2', () => {
    // The staging complaint: a built train of 42 NW5 + 10 PW2, containers
    // hold every NW5, and a bulk booking sits in "Ready for batch" while the
    // PW2 ride empty. The chain: committed containers drain NW5 from the
    // ledger (their types cannot touch PW2), then the smart gate must seat
    // 200T of Perishable on the 10 PW2 at the 20T cap.
    const stock = new WagonStockLedger(
      new Map([
        [nw5.id, 42],
        [pw2.id, 10],
      ]),
      2, // DCT -> Dire -> GMP: two edges
    );
    // Committed container booking rides Dire->GMP (edge 1) on 42 NW5 —
    // container-capable types only, exactly how stockLedgerFor debits it.
    stock.consume([nw5.id], 42, { fromEdge: 1, toEdge: 2 });
    expect(stock.availableFor([nw5.id], { fromEdge: 0, toEdge: 2 })).toBe(0);
    expect(stock.availableFor([pw2.id], { fromEdge: 0, toEdge: 2 })).toBe(10);

    const smart = (
      service as unknown as {
        smartBulkNeed: (
          b: Booking,
          d: unknown,
          s: WagonStockLedger,
          l: { fromEdge: number; toEdge: number },
          r: Map<string, number>,
          ids: readonly string[],
        ) => { need: { wagons: number }; perType: Array<{ wagonTypeId: string; wagons: number }> } | null;
      }
    ).smartBulkNeed(booking(200), wagonDims, stock, { fromEdge: 0, toEdge: 2 }, contested, allowedIds);
    expect(smart).not.toBeNull();
    expect(smart!.perType).toEqual([{ wagonTypeId: pw2.id, wagons: 10 }]);
  });

  it('uncontested types fall back to biggest per-cargo take (fewest wagons)', () => {
    const stock = new WagonStockLedger(
      new Map([
        [nw5.id, 10],
        [pw2.id, 10],
      ]),
      1,
    );
    const even = new Map([
      [nw5.id, 1],
      [pw2.id, 1],
    ]);
    const smart = call(booking(60), stock, even);
    expect(smart!.perType).toEqual([{ wagonTypeId: nw5.id, wagons: 2 }]);
  });
});