import fs from 'node:fs/promises';
import os from 'node:os';
import path from 'node:path';
import { eq } from 'drizzle-orm';
import { afterAll, beforeAll, describe, expect, it, vi } from 'vitest';
import { openGameDb, type GameDb } from '@/lib/db/client';
import * as schema from '@/lib/db/schema';
import { loadAirportsGeoJson } from '@/lib/airports';
import { haversineKm } from '@/lib/geo';
import { requiredFuelFor } from '@/lib/sim/movement';
import { FUEL_PRICE_PER_L, PLANE_TYPES, SELL_FRACTION } from './catalog';
import { HUB_ICAO } from './seed';
import {
  abandonPackage,
  buyPlane,
  cancelQueuedLeg,
  flyPlane,
  GameActionError,
  loadPackage,
  queueLeg,
  refuelPlane,
  sellPlane,
} from './actions';

// Action tests run against throwaway DB files (openGameDb) with fake timers so
// the seeded sim clock is a known constant. Actions are called directly (no tick —
// engine.runAction() wraps them in production; its lock/tick behavior is covered
// by the route tests and e2e).

let dir: string;
const T0 = 1_750_000_000_000; // seed moment / fake "now" at DB open

beforeAll(async () => {
  vi.useFakeTimers();
  vi.setSystemTime(T0);
  dir = await fs.mkdtemp(path.join(os.tmpdir(), 'flight-actions-'));
});

afterAll(async () => {
  vi.useRealTimers();
  await fs.rm(dir, { recursive: true, force: true });
});

async function freshDb(name: string): Promise<GameDb> {
  vi.setSystemTime(T0); // each throwaway DB is seeded at the same fake "now"
  return openGameDb(path.join(dir, name));
}

function expectActionError(promise: Promise<unknown>, status: number, messagePart?: RegExp) {
  return promise.then(
    () => {
      throw new Error(`expected GameActionError(${status}) but the action succeeded`);
    },
    (err) => {
      expect(err).toBeInstanceOf(GameActionError);
      expect((err as GameActionError).status).toBe(status);
      if (messagePart) expect((err as GameActionError).message).toMatch(messagePart);
    },
  );
}

// Insert a known OPEN package EDDF → LEMD for load tests.
async function insertOpenPackage(inst: GameDb, id = 'p-open', over: Partial<schema.PackageRow> = {}): Promise<void> {
  await inst.db.insert(schema.packages).values({
    id,
    originIcao: HUB_ICAO,
    destIcao: 'LEMD',
    reward: 1_000,
    cargoType: 'Mail',
    cargoCount: 4,
    deadlineSimTime: T0 + 24 * 3_600_000,
    status: 'open',
    planeId: null,
    createdSimTime: T0,
    ...over,
  });
}

describe('loadPackage', () => {
  it('binds an open package to a grounded plane at its origin', async () => {
    const inst = await freshDb('load-ok.db');
    await insertOpenPackage(inst);

    await loadPackage(inst, 'p-open', 'plane-starter'); // seeded starter is grounded at EDDF

    const row = (await inst.db.select().from(schema.packages).where(eq(schema.packages.id, 'p-open')))[0];
    expect(row.status).toBe('loaded');
    expect(row.planeId).toBe('plane-starter');
  });

  it.each(['loaded', 'delivered', 'expired', 'abandoned'] as const)(
    'rejects a %s package with 409 (must be open)',
    async (status) => {
      const inst = await freshDb(`load-${status}.db`);
      await insertOpenPackage(inst, 'p-x', { status });

      await expectActionError(loadPackage(inst, 'p-x', 'plane-starter'), 409, new RegExp(status));
    },
  );

  it('rejects an unknown package id with 404', async () => {
    const inst = await freshDb('load-punknown.db');
    await expectActionError(loadPackage(inst, 'nope', 'plane-starter'), 404);
  });

  it('rejects an unknown plane id with 404', async () => {
    const inst = await freshDb('load-ghost.db');
    await insertOpenPackage(inst);
    await expectActionError(loadPackage(inst, 'p-open', 'ghost'), 404);
  });

  it('rejects a flying plane with 409', async () => {
    const inst = await freshDb('load-flying.db');
    await insertOpenPackage(inst);
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, destIcao: 'LEMD' })
      .where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(loadPackage(inst, 'p-open', 'plane-starter'), 409);
  });

  it('rejects a plane that is not at the origin with 409', async () => {
    const inst = await freshDb('load-notatorigin.db');
    await insertOpenPackage(inst); // originates at EDDF
    await inst.db.update(schema.planes).set({ locationIcao: 'LEMD' }).where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(loadPackage(inst, 'p-open', 'plane-starter'), 409, /at LEMD/);
  });

  it('rejects loading when the plane has no free slot (capacity from catalog)', async () => {
    const inst = await freshDb('load-full.db');
    await insertOpenPackage(inst, 'p-new');
    // Fill all atr72 slots with loaded cargo…
    for (let i = 0; i < PLANE_TYPES.atr72.capacity; i++) {
      await insertOpenPackage(inst, `p-fill-${i}`, { status: 'loaded', planeId: 'plane-starter' });
    }

    await expectActionError(loadPackage(inst, 'p-new', 'plane-starter'), 409, /no free slots/i);
  });

  it('counts expired packages as occupying their slot too', async () => {
    const inst = await freshDb('load-expiredslot.db');
    await insertOpenPackage(inst, 'p-new');
    // capacity − 1 loaded + 1 expired = full.
    for (let i = 0; i < PLANE_TYPES.atr72.capacity - 1; i++) {
      await insertOpenPackage(inst, `p-fill-${i}`, { status: 'loaded', planeId: 'plane-starter' });
    }
    await insertOpenPackage(inst, 'p-expired-slot', { status: 'expired', planeId: 'plane-starter' });

    await expectActionError(loadPackage(inst, 'p-new', 'plane-starter'), 409, /no free slots/i);
  });
});

describe('flyPlane', () => {
  it('sets flying + departure at current clock + dest_icao + origin coords', async () => {
    const inst = await freshDb('fly-ok.db');

    await flyPlane(inst, 'plane-starter', 'LEMD');

    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.status).toBe('flying');
    expect(plane.destIcao).toBe('LEMD');
    expect(plane.departureSimTime).toBe(T0); // seeded clock, no tick in direct calls
    const fc = await loadAirportsGeoJson();
    const origin = fc.features.find((f) => f.properties.icao === HUB_ICAO)!.properties;
    expect(plane.lat).toBe(origin.lat);
    expect(plane.lon).toBe(origin.lon);
    // Fuel is frozen at the departure value while flying (live fuel is analytic).
    expect(plane.fuel).toBe(PLANE_TYPES.atr72.maxFuel);
  });

  it('clears paused on dispatch (ISS-041) — speed is left untouched', async () => {
    const inst = await freshDb('fly-unpause.db');
    // The last landing pauses the sim at whatever scale was in use.
    await inst.db.update(schema.simState).set({ paused: true, timeScale: 250 });

    await flyPlane(inst, 'plane-starter', 'LEMD');

    const sim = (await inst.db.select().from(schema.simState))[0];
    expect(sim.paused).toBe(false); // dispatch auto-resumes…
    expect(sim.timeScale).toBe(250); // …with the stored speed preserved
  });

  it('rejects a flying plane with 409', async () => {
    const inst = await freshDb('fly-flying.db');
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, destIcao: 'LEMD' })
      .where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(flyPlane(inst, 'plane-starter', 'EDDM'), 409);
  });

  it('rejects an unknown plane id with 404', async () => {
    const inst = await freshDb('fly-ghost.db');
    await expectActionError(flyPlane(inst, 'ghost', 'LEMD'), 404);
  });

  it('rejects an ICAO not in the airport dataset with 400', async () => {
    const inst = await freshDb('fly-unknownicao.db');
    await expectActionError(flyPlane(inst, 'plane-starter', 'ZZZZ'), 400, /unknown airport/);
  });

  it('rejects a leg the plane cannot fuel with 409 (burn > fuel)', async () => {
    const inst = await freshDb('fly-nofuel.db'); // EDDF → LEMD ≈ 1950 km × 1.75 L/km ≈ 3400 L
    await inst.db.update(schema.planes).set({ fuel: 1 }).where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(flyPlane(inst, 'plane-starter', 'LEMD'), 409, /insufficient fuel/i);
  });
});

describe('queueLeg (v0.25.0, ISS-043)', () => {
  it('appends legs to the queue in order and persists them as JSON', async () => {
    const inst = await freshDb('qleg-ok.db');

    await queueLeg(inst, 'plane-starter', 'LEMD');
    let plane = (await inst.db.select().from(schema.planes))[0];
    expect(JSON.parse(plane.queue)).toEqual(['LEMD']);

    await queueLeg(inst, 'plane-starter', 'EHAM'); // pre-building a route
    plane = (await inst.db.select().from(schema.planes))[0];
    expect(JSON.parse(plane.queue)).toEqual(['LEMD', 'EHAM']); // order preserved
  });

  it('works on a flying plane too — the active leg is untouched, nothing auto-starts', async () => {
    const inst = await freshDb('qleg-flying.db');
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, destIcao: 'LEMD' })
      .where(eq(schema.planes.id, 'plane-starter'));

    await queueLeg(inst, 'plane-starter', 'EHAM');

    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.status).toBe('flying'); // still on its active leg…
    expect(plane.destIcao).toBe('LEMD'); // …unchanged — queueing never starts a flight
    expect(JSON.parse(plane.queue)).toEqual(['EHAM']);
  });

  it('rejects an unknown plane id with 404', async () => {
    const inst = await freshDb('qleg-ghost.db');
    await expectActionError(queueLeg(inst, 'ghost', 'LEMD'), 404);
  });

  it('rejects an ICAO not in the airport dataset with 400', async () => {
    const inst = await freshDb('qleg-unknownicao.db');
    await expectActionError(queueLeg(inst, 'plane-starter', 'ZZZZ'), 400, /unknown airport/);
  });
});

describe('cancelQueuedLeg (v0.25.0, ISS-043)', () => {
  it('removes the leg at the given index and keeps the rest in order', async () => {
    const inst = await freshDb('qcancel-ok.db');
    await queueLeg(inst, 'plane-starter', 'LEMD');
    await queueLeg(inst, 'plane-starter', 'EHAM');
    await queueLeg(inst, 'plane-starter', 'EDDV');

    await cancelQueuedLeg(inst, 'plane-starter', 1); // drop EHAM (the middle leg)

    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(JSON.parse(plane.queue)).toEqual(['LEMD', 'EDDV']);
  });

  it('rejects an out-of-range index with 400', async () => {
    const inst = await freshDb('qcancel-oob.db');
    await queueLeg(inst, 'plane-starter', 'LEMD'); // one leg → only index 0 is valid
    await expectActionError(cancelQueuedLeg(inst, 'plane-starter', 1), 400);
    await expectActionError(cancelQueuedLeg(inst, 'plane-starter', -1), 400);
  });

  it('rejects cancelling from an empty queue with 400', async () => {
    const inst = await freshDb('qcancel-empty.db'); // seeded starter has no queued legs
    await expectActionError(cancelQueuedLeg(inst, 'plane-starter', 0), 400);
  });

  it('rejects an unknown plane id with 404', async () => {
    const inst = await freshDb('qcancel-ghost.db');
    await expectActionError(cancelQueuedLeg(inst, 'ghost', 0), 404);
  });
});

describe('abandonPackage', () => {
  // A loaded package created at T0 with a 10h window; the seeded sim clock is T0.
  const REWARD = 1_000;
  const WINDOW_MS = 10 * 3_600_000;

  async function setupLoaded(name: string, status: 'loaded' | 'expired' = 'loaded') {
    const inst = await freshDb(name);
    // Always insert OPEN and load it through the real action…
    await insertOpenPackage(inst, 'p-ab', { reward: REWARD, createdSimTime: T0, deadlineSimTime: T0 + WINDOW_MS });
    await loadPackage(inst, 'p-ab', 'plane-starter');
    // …then flip to expired in place (what the tick would do once the deadline passes).
    if (status === 'expired') {
      await inst.db.update(schema.packages).set({ status: 'expired' }).where(eq(schema.packages.id, 'p-ab'));
    }
    return inst;
  }

  it('charges exactly 15% of the payout right after creation (clock at createdSimTime)', async () => {
    const inst = await setupLoaded('ab-start.db');
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { penalty } = await abandonPackage(inst, 'p-ab');

    expect(penalty).toBe(Math.round(REWARD * 0.15 * 100) / 100);
    const row = (await inst.db.select().from(schema.packages).where(eq(schema.packages.id, 'p-ab')))[0];
    expect(row.status).toBe('abandoned');
    expect(row.planeId).toBeNull(); // slot freed
    const account = (await inst.db.select().from(schema.account))[0];
    expect(account.cash).toBeCloseTo(cashBefore - penalty, 6);
  });

  it('scales to exactly 37.5% at the midpoint of the window', async () => {
    const inst = await setupLoaded('ab-mid.db');
    await inst.db.update(schema.simState).set({ clockMs: T0 + WINDOW_MS / 2 }); // runAction ticks first in prod

    const { penalty } = await abandonPackage(inst, 'p-ab');

    expect(penalty).toBe(Math.round(REWARD * (0.15 + 0.45 * 0.5) * 100) / 100);
  });

  it('caps at exactly 60% at and past the deadline', async () => {
    for (const [name, clock] of [
      ['ab-deadline.db', T0 + WINDOW_MS],
      ['ab-pastdeadline.db', T0 + WINDOW_MS * 2], // clamped — a not-yet-ticked loaded package past its deadline
    ] as const) {
      const inst = await setupLoaded(name);
      await inst.db.update(schema.simState).set({ clockMs: clock });

      const { penalty } = await abandonPackage(inst, 'p-ab');
      expect(penalty).toBe(Math.round(REWARD * 0.6 * 100) / 100);
    }
  });

  it('is free for an already-expired package', async () => {
    const inst = await setupLoaded('ab-expired.db', 'expired');
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { penalty } = await abandonPackage(inst, 'p-ab');

    expect(penalty).toBe(0);
    expect((await inst.db.select().from(schema.account))[0].cash).toBe(cashBefore);
    const row = (await inst.db.select().from(schema.packages).where(eq(schema.packages.id, 'p-ab')))[0];
    expect(row.status).toBe('abandoned');
  });

  it('floors cash at €0 — no debt', async () => {
    const inst = await setupLoaded('ab-floor.db');
    await inst.db.update(schema.account).set({ cash: 10 }); // penalty is 150 > 10

    const { penalty } = await abandonPackage(inst, 'p-ab');

    expect(penalty).toBe(150);
    expect((await inst.db.select().from(schema.account))[0].cash).toBe(0);
  });

  it('rejects abandoning while the plane is in flight with 409', async () => {
    const inst = await setupLoaded('ab-flying.db');
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, destIcao: 'LEMD' })
      .where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(abandonPackage(inst, 'p-ab'), 409, /in flight/i);
  });

  it.each(['open', 'delivered', 'abandoned'] as const)('rejects a %s package with 409', async (status) => {
    const inst = await freshDb(`ab-${status}.db`);
    await insertOpenPackage(inst, 'p-x', { status });

    await expectActionError(abandonPackage(inst, 'p-x'), 409, new RegExp(status));
  });

  it('rejects an unknown id with 404', async () => {
    const inst = await freshDb('ab-unknown.db');
    await expectActionError(abandonPackage(inst, 'nope'), 404);
  });
});

describe('buyPlane', () => {
  it('deducts the full price and delivers a full-tank plane at the home base', async () => {
    const inst = await freshDb('buy-ok.db');
    await inst.db.update(schema.account).set({ cash: 500_000 });

    const before = (await inst.db.select().from(schema.planes)).length;
    const { planeId } = await buyPlane(inst, 'atr72');

    const account = (await inst.db.select().from(schema.account))[0];
    expect(account.cash).toBe(500_000 - PLANE_TYPES.atr72.price);

    const planes = await inst.db.select().from(schema.planes);
    expect(planes.length).toBe(before + 1);
    const bought = planes.find((p) => p.id === planeId)!;
    expect(bought.model).toBe('atr72');
    expect(bought.status).toBe('available');
    expect(bought.fuel).toBe(PLANE_TYPES.atr72.maxFuel); // full tank on delivery
    expect(bought.maxFuel).toBe(PLANE_TYPES.atr72.maxFuel);
    expect(bought.locationIcao).toBe(HUB_ICAO);
    const fc = await loadAirportsGeoJson();
    const hub = fc.features.find((f) => f.properties.icao === HUB_ICAO)!.properties;
    expect(bought.lat).toBe(hub.lat);
    expect(bought.lon).toBe(hub.lon);
  });

  it('rejects an unknown catalog model with 400', async () => {
    const inst = await freshDb('buy-unknown.db');
    await expectActionError(buyPlane(inst, 'boeing747'), 400, /unknown plane model/);
  });

  it('rejects the purchase when cash is below the price with 409', async () => {
    const inst = await freshDb('buy-poor.db'); // seeded cash is 20k < 200k
    await expectActionError(buyPlane(inst, 'atr72'), 409, /insufficient funds/i);
  });
});

describe('sellPlane', () => {
  it('pays out SELL_FRACTION of the catalog price and deletes the row', async () => {
    const inst = await freshDb('sell-ok.db');
    // A second plane so the starter is not "the last remaining one".
    await inst.db.insert(schema.planes).values({
      id: 'plane-extra', model: 'atr72', status: 'available', fuel: 100, maxFuel: PLANE_TYPES.atr72.maxFuel,
      locationIcao: HUB_ICAO, destIcao: null, lat: 50, lon: 8, departureSimTime: null,
    });
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { payout } = await sellPlane(inst, 'plane-extra');

    expect(payout).toBe(Math.round(PLANE_TYPES.atr72.price * SELL_FRACTION * 100) / 100);
    const account = (await inst.db.select().from(schema.account))[0];
    expect(account.cash).toBeCloseTo(cashBefore + payout, 6);
    const ids = (await inst.db.select().from(schema.planes)).map((p) => p.id);
    expect(ids).not.toContain('plane-extra'); // row deleted
    expect(ids).toContain('plane-starter');
  });

  it('rejects selling a flying plane with 409', async () => {
    const inst = await freshDb('sell-flying.db');
    await inst.db.insert(schema.planes).values({
      id: 'plane-extra', model: 'atr72', status: 'flying', fuel: 100, maxFuel: PLANE_TYPES.atr72.maxFuel,
      locationIcao: HUB_ICAO, destIcao: 'LEMD', lat: 50, lon: 8, departureSimTime: T0,
    });

    await expectActionError(sellPlane(inst, 'plane-extra'), 409, /flying/);
  });

  it('rejects selling the last remaining plane with 409', async () => {
    const inst = await freshDb('sell-last.db'); // only the starter exists
    await expectActionError(sellPlane(inst, 'plane-starter'), 409, /last remaining/);
  });

  it('rejects an unknown id with 404', async () => {
    const inst = await freshDb('sell-unknown.db');
    await expectActionError(sellPlane(inst, 'ghost'), 404);
  });
});

describe('refuelPlane', () => {
  it('fills to maxFuel and deducts (maxFuel − fuel) × FUEL_PRICE_PER_L from cash', async () => {
    const inst = await freshDb('refuel-ok.db');
    await inst.db.update(schema.planes).set({ fuel: 1_000 }).where(eq(schema.planes.id, 'plane-starter'));
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { cost } = await refuelPlane(inst, 'plane-starter');

    expect(cost).toBe(Math.round((PLANE_TYPES.atr72.maxFuel - 1_000) * FUEL_PRICE_PER_L * 100) / 100);
    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.fuel).toBe(PLANE_TYPES.atr72.maxFuel);
    const account = (await inst.db.select().from(schema.account))[0];
    expect(account.cash).toBeCloseTo(cashBefore - cost, 6);
  });

  it('is a free no-op when the tank is already full', async () => {
    const inst = await freshDb('refuel-full.db'); // seeded starter is full
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { cost } = await refuelPlane(inst, 'plane-starter');

    expect(cost).toBe(0);
    expect((await inst.db.select().from(schema.account))[0].cash).toBe(cashBefore);
  });

  it('rejects a flying plane with 409', async () => {
    const inst = await freshDb('refuel-flying.db');
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, destIcao: 'LEMD' })
      .where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(refuelPlane(inst, 'plane-starter'), 409, /flying/);
  });

  it('rejects the fill-up when cash is below the cost with 409', async () => {
    const inst = await freshDb('refuel-poor.db');
    await inst.db.update(schema.planes).set({ fuel: 1_000 }).where(eq(schema.planes.id, 'plane-starter'));
    await inst.db.update(schema.account).set({ cash: 10 }); // cost is ~4960

    await expectActionError(refuelPlane(inst, 'plane-starter'), 409, /insufficient funds/i);
  });

  it('rejects an unknown id with 404', async () => {
    const inst = await freshDb('refuel-unknown.db');
    await expectActionError(refuelPlane(inst, 'ghost'), 404);
  });

  // --- forFlight mode (v0.16.0) ---

  it('forFlight adds exactly the liters needed for the package leg and deducts L × price', async () => {
    const inst = await freshDb('refuel-forflight-ok.db');
    await insertOpenPackage(inst, 'p-ff', { destIcao: 'LEMD' }); // EDDF → LEMD
    await loadPackage(inst, 'p-ff', 'plane-starter');

    const fc = await loadAirportsGeoJson();
    const from = fc.features.find((f) => f.properties.icao === HUB_ICAO)!.properties;
    const to = fc.features.find((f) => f.properties.icao === 'LEMD')!.properties;
    const km = haversineKm(from.lat, from.lon, to.lat, to.lon);
    const type = PLANE_TYPES.atr72;
    const required = requiredFuelFor(type.burnPerKm, type.emptyWeightKg, type.maxFuel, km);

    // Partial tank below the requirement so L > 0.
    const startFuel = Math.round(required / 2);
    await inst.db.update(schema.planes).set({ fuel: startFuel }).where(eq(schema.planes.id, 'plane-starter'));
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { cost } = await refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-ff' });

    expect(cost).toBe(Math.round((required - startFuel) * FUEL_PRICE_PER_L * 100) / 100);
    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.fuel).toBeCloseTo(required, 6); // topped up to exactly the leg requirement
    const account = (await inst.db.select().from(schema.account))[0];
    expect(account.cash).toBeCloseTo(cashBefore - cost, 6);
  });

  it('forFlight leaves an exactly-feasible tank — flyPlane to the package dest succeeds right after', async () => {
    const inst = await freshDb('refuel-ff-flyafter.db');
    await insertOpenPackage(inst, 'p-fa', { destIcao: 'LEMD' }); // EDDF → LEMD
    await loadPackage(inst, 'p-fa', 'plane-starter');

    const fc = await loadAirportsGeoJson();
    const from = fc.features.find((f) => f.properties.icao === HUB_ICAO)!.properties;
    const to = fc.features.find((f) => f.properties.icao === 'LEMD')!.properties;
    const km = haversineKm(from.lat, from.lon, to.lat, to.lon);
    const type = PLANE_TYPES.atr72;
    const required = requiredFuelFor(type.burnPerKm, type.emptyWeightKg, type.maxFuel, km);

    // Empty-ish tank: well below the leg requirement.
    await inst.db.update(schema.planes).set({ fuel: Math.round(required / 4) }).where(eq(schema.planes.id, 'plane-starter'));

    await refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-fa' });

    // The leg must now be flyable — no epsilon-short 409 (regression guard for the float-exact target).
    await flyPlane(inst, 'plane-starter', 'LEMD');
    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.status).toBe('flying');
    expect(plane.destIcao).toBe('LEMD');
  });

  it('forFlight is a free no-op when the tank already covers the leg', async () => {
    const inst = await freshDb('refuel-forflight-enough.db'); // seeded starter is full at EDDF
    await insertOpenPackage(inst, 'p-ff2', { destIcao: 'LEMD' });
    await loadPackage(inst, 'p-ff2', 'plane-starter');
    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;

    const { cost } = await refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-ff2' });

    expect(cost).toBe(0);
    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.fuel).toBe(PLANE_TYPES.atr72.maxFuel); // untouched
    expect((await inst.db.select().from(schema.account))[0].cash).toBe(cashBefore);
  });

  it('forFlight rejects a package that is not loaded on this plane with 409', async () => {
    const inst = await freshDb('refuel-ff-open.db'); // open — never loaded
    await insertOpenPackage(inst, 'p-x');
    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-x' }), 409);

    const inst2 = await freshDb('refuel-ff-other.db'); // loaded on ANOTHER plane
    await insertOpenPackage(inst2, 'p-y', { status: 'loaded', planeId: 'plane-someone-else' });
    await expectActionError(refuelPlane(inst2, 'plane-starter', { mode: 'forFlight', packageId: 'p-y' }), 409);
  });

  it('forFlight rejects an expired package with 409', async () => {
    const inst = await freshDb('refuel-ff-expired.db');
    await insertOpenPackage(inst, 'p-z', { status: 'expired', planeId: 'plane-starter' });
    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-z' }), 409);
  });

  it('forFlight rejects an unknown package id with 404', async () => {
    const inst = await freshDb('refuel-ff-unknown.db');
    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'nope' }), 404);
  });

  it('forFlight rejects a missing packageId with 400', async () => {
    const inst = await freshDb('refuel-ff-nopkg.db');
    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight' }), 400);
  });

  it('forFlight rejects a leg that does not fit even a full tank with 409', async () => {
    const inst = await freshDb('refuel-ff-nofit.db');
    // UNNT (Narsarsuaq, Greenland) ↔ LPPD are ~7670 km apart — far beyond the ATR's range.
    await insertOpenPackage(inst, 'p-far', { destIcao: 'LPPD' });
    await loadPackage(inst, 'p-far', 'plane-starter');
    await inst.db.update(schema.planes).set({ locationIcao: 'UNNT' }).where(eq(schema.planes.id, 'plane-starter'));

    await expectActionError(
      refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-far' }),
      409,
      /does not fit/i,
    );
  });
});