import { describe, expect, it } from 'vitest';
import type { StateSnapshot } from './game/state';
import { planesGeoJson, queuedRoutesGeoJson, routesGeoJson, hoverRouteGeoJson, hoverTraceGeoJson, greatCircleArc, ROUTE_ARC_SEGMENTS, type AirportCoord } from './mapData';
import { haversineKm } from './geo';

const AIRPORTS = new Map<string, AirportCoord>([
  ['EDDF', { lat: 50.03, lon: 8.56 }],
  ['EDDV', { lat: 52.46, lon: 9.68 }],
  ['EHAM', { lat: 52.31, lon: 4.76 }],
  ['LEMD', { lat: 40.47, lon: -3.56 }], // Madrid — ~1400 km from EDDF for the long-route test
  // ISS-120 (v0.53.0): real dataset pairs whose great circle crosses the antimeridian (±180).
  ['NZAA', { lat: -37.01199, lon: 174.786331 }], // Auckland — east of +170
  ['NFTF', { lat: -21.241438, lon: -175.149164 }], // Fua'amotu (Tonga) — west of −175; NZAA→NFTF crosses ±180 eastward
  ['NZCH', { lat: -43.489029, lon: 172.532065 }], // Christchurch — for the queue-chain joint test
]);

// ISS-120: longitude difference on the circle — two lons are "equal" when they differ by a multiple of 360.
const modDiff = (a: number, b: number): number => {
  const d = Math.abs(a - b) % 360;
  return Math.min(d, 360 - d);
};

// ISS-120: every consecutive pair of samples must be < 180° apart in longitude — the property that
// keeps MapLibre from drawing a chord across the map.
function expectContinuousLons(coords: [number, number][]): void {
  for (let i = 1; i < coords.length; i++) {
    expect(Math.abs(coords[i]![0] - coords[i - 1]![0]), `jump between samples ${i - 1} and ${i}`).toBeLessThan(180);
  }
}

function snapshot(overrides: Partial<StateSnapshot> = {}): StateSnapshot {
  return {
    account: { cash: 0, reputation: 0 },
    simState: { clockMs: 0 },
    planes: [],
    packages: [],
    catalog: [
      { model: 'atr72', label: 'ATR 72-600', price: 200_000, maxFuel: 6300, burnPerKm: 1.75, emptyWeightKg: 9_300, speedKmh: 510, maxPayloadKg: 4_800 },
    ],
    fuelPricePerL: 0.8,
    sellFraction: 0.5,
    ...overrides,
  };
}

describe('planesGeoJson', () => {
  it('returns an empty collection for a null snapshot', () => {
    expect(planesGeoJson(null)).toEqual({ type: 'FeatureCollection', features: [] });
  });

  it('emits one Point per plane at its polled lat/lon with popup properties', () => {
    const fc = planesGeoJson(
      snapshot({
        planes: [
          { id: 'plane-starter', model: 'atr72', status: 'available', fuel: 6300, maxFuel: 6300, locationIcao: 'EDDF', locationName: 'Frankfurt Main Airport', destIcao: null, destName: null, departureSimTime: null, lat: 50.03, lon: 8.56, health: 100, repairUntilSimTime: null, queue: [] },
          { id: 'plane-2', model: 'atr72', status: 'flying', fuel: 4000, maxFuel: 6300, locationIcao: 'EDDF', locationName: 'Frankfurt Main Airport', destIcao: 'EDDV', destName: 'Hannover Airport', departureSimTime: 1000, lat: 51.2, lon: 9.1, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
    );

    expect(fc.features).toHaveLength(2);
    const grounded = fc.features[0];
    expect(grounded.geometry.coordinates).toEqual([8.56, 50.03]); // [lon, lat]
    expect(grounded.properties.flying).toBe(false);
    expect(grounded.properties.modelLabel).toBe('ATR 72-600'); // catalog label, not raw model id
    expect(grounded.properties.fuelText).toBe('6300 / 6300 L');
    expect(grounded.properties.routeText).toBe('');

    const flying = fc.features[1];
    expect(flying.geometry.coordinates).toEqual([9.1, 51.2]); // live polled position
    expect(flying.properties.flying).toBe(true);
    expect(flying.properties.status).toBe('flying');
    expect(flying.properties.fuelText).toBe('4000 / 6300 L');
    expect(flying.properties.routeText).toBe('Frankfurt Main Airport → Hannover Airport'); // from the plane's own dest fields (v0.12.0)
  });

  it('falls back to the raw model id when the catalog has no entry', () => {
    const fc = planesGeoJson(
      snapshot({
        catalog: [],
        planes: [
          { id: 'p1', model: 'mystery', status: 'available', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'x', destIcao: null, destName: null, departureSimTime: null, lat: 0, lon: 0, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
    );
    expect(fc.features[0].properties.modelLabel).toBe('mystery');
  });

  it('leaves routeText empty for a flying plane without a destination name', () => {
    const fc = planesGeoJson(
      snapshot({
        planes: [
          { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'x', destIcao: null, destName: null, departureSimTime: 0, lat: 0, lon: 0, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
    );
    expect(fc.features[0].properties.routeText).toBe('');
  });
});

describe('routesGeoJson (v0.12.0 — one line per flying plane\'s current leg)', () => {
  it('returns an empty collection for a null snapshot', () => {
    expect(routesGeoJson(null, AIRPORTS)).toEqual({ type: 'FeatureCollection', features: [] });
  });

  it('draws nothing for grounded planes, whatever their packages', () => {
    const fc = routesGeoJson(
      snapshot({
        planes: [
          { id: 'p1', model: 'atr72', status: 'available', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: null, destName: null, departureSimTime: null, lat: 50.03, lon: 8.56, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(0);
  });

  it('flying plane → one line origin→dest_icao with the plane id', () => {
    const fc = routesGeoJson(
      snapshot({
        planes: [
          { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'EHAM', destName: 'A', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(1);
    expect(fc.features[0].properties).toEqual({ planeId: 'p1' });
    const coords = fc.features[0].geometry.coordinates;
    expect(coords.length).toBe(ROUTE_ARC_SEGMENTS + 1); // sampled great-circle arc, not a 2-point chord (v0.12.2)
    expect(coords[0]).toEqual([8.56, 50.03]); // EDDF [lon, lat] — exact endpoint
    expect(coords[coords.length - 1]).toEqual([4.76, 52.31]); // EHAM — exact endpoint
  });

  it('skips a flying plane whose endpoint is missing from the airport dataset', () => {
    const fc = routesGeoJson(
      snapshot({
        planes: [
          { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'ZZZZ', locationName: '?', destIcao: 'EDDV', destName: 'H', departureSimTime: 0, lat: 0, lon: 0, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(0);
  });

  it('one line per flying plane — multiple planes draw multiple legs', () => {
    const fc = routesGeoJson(
      snapshot({
        planes: [
          { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'EDDV', destName: 'H', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: [] },
          { id: 'p2', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDV', locationName: 'H', destIcao: 'EHAM', destName: 'A', departureSimTime: 0, lat: 52.4, lon: 9.6, health: 100, repairUntilSimTime: null, queue: [] },
        ],
      }),
      AIRPORTS,
    );
    expect(fc.features.map((f) => f.properties.planeId).sort()).toEqual(['p1', 'p2']);
  });
});

describe('queuedRoutesGeoJson (ISS-043 v0.26.0 — dotted queue line: dest → queued legs only; ISS-077 v0.41.0 — grounded queues too)', () => {
  it('grounded plane with a non-empty queue → one feature chaining locationIcao → queued legs (ISS-077)', () => {
    const fc = queuedRoutesGeoJson(
      [
        // Pre-built route while grounded: the line starts at the plane's current airport, not at any dest.
        { id: 'p1', model: 'atr72', status: 'available', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: null, destName: null, departureSimTime: null, lat: 50.03, lon: 8.56, health: 100, repairUntilSimTime: null, queue: ['EHAM'] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(1);
    expect(fc.features[0].properties).toEqual({ planeId: 'p1' });
    const coords = fc.features[0].geometry.coordinates;
    expect(coords.length).toBe(ROUTE_ARC_SEGMENTS + 1); // one arc, exact endpoints
    expect(coords[0]).toEqual([8.56, 50.03]); // starts at the plane's airport (EDDF)
    expect(coords[coords.length - 1]).toEqual([4.76, 52.31]); // ends at the queued airport (EHAM)
  });

  it('skips a grounded plane whose locationIcao is missing from the airport index', () => {
    const fc = queuedRoutesGeoJson(
      [
        { id: 'p1', model: 'atr72', status: 'available', fuel: 1, maxFuel: 2, locationIcao: 'ZZZZ', locationName: '?', destIcao: null, destName: null, departureSimTime: null, lat: 0, lon: 0, health: 100, repairUntilSimTime: null, queue: ['EHAM'] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(0);
  });

  it('draws nothing for a repairing plane, even with a non-empty queue', () => {
    const fc = queuedRoutesGeoJson(
      [
        { id: 'p1', model: 'atr72', status: 'repairing', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: null, destName: null, departureSimTime: null, lat: 50.03, lon: 8.56, health: 0, repairUntilSimTime: 1000, queue: ['EHAM'] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(0);
  });

  it('draws nothing for a flying plane with an empty queue', () => {
    const fc = queuedRoutesGeoJson(
      [
        { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'EHAM', destName: 'A', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: [] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(0);
  });

  it('flying plane with a 2-leg queue → one feature chaining dest → q0 → q1 with exact endpoints', () => {
    const fc = queuedRoutesGeoJson(
      [
        // Active leg EDDF→EHAM stays in routesGeoJson; the queue line is ONLY EHAM → EDDV → LEMD.
        { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'EHAM', destName: 'A', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: ['EDDV', 'LEMD'] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(1);
    expect(fc.features[0].properties).toEqual({ planeId: 'p1' });
    const coords = fc.features[0].geometry.coordinates;
    // Two concatenated arcs with the shared joint point dropped once: n_legs × SEGMENTS + 1 points.
    expect(coords.length).toBe(2 * ROUTE_ARC_SEGMENTS + 1);
    expect(coords[0]).toEqual([4.76, 52.31]); // starts at DEST (EHAM), not at the plane's origin
    expect(coords[coords.length - 1]).toEqual([-3.56, 40.47]); // ends at the last queued airport (LEMD)
    expect(coords[ROUTE_ARC_SEGMENTS]).toEqual([9.68, 52.46]); // joint point = first queued airport (EDDV), exact
  });

  it('skips a plane whose dest or a queued ICAO is missing from the airport index', () => {
    const fc = queuedRoutesGeoJson(
      [
        { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'ZZZZ', destName: '?', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: ['EHAM'] },
        { id: 'p2', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'EHAM', destName: 'A', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: ['ZZZZ'] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(0);
  });

  it('one feature per qualifying plane — flying and grounded queues draw; empty-queue planes do not', () => {
    const fc = queuedRoutesGeoJson(
      [
        { id: 'p1', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EDDF', locationName: 'F', destIcao: 'EHAM', destName: 'A', departureSimTime: 0, lat: 51, lon: 9, health: 100, repairUntilSimTime: null, queue: ['LEMD'] },
        { id: 'p2', model: 'atr72', status: 'flying', fuel: 1, maxFuel: 2, locationIcao: 'EHAM', locationName: 'A', destIcao: 'EDDV', destName: 'H', departureSimTime: 0, lat: 52.3, lon: 4.7, health: 100, repairUntilSimTime: null, queue: [] },
        { id: 'p3', model: 'atr72', status: 'available', fuel: 1, maxFuel: 2, locationIcao: 'EDDV', locationName: 'H', destIcao: null, destName: null, departureSimTime: null, lat: 52.46, lon: 9.68, health: 100, repairUntilSimTime: null, queue: ['LEMD'] },
      ],
      AIRPORTS,
    );
    expect(fc.features.map((f) => f.properties.planeId)).toEqual(['p1', 'p3']); // p2 has an empty queue
    const p3 = fc.features[1].geometry.coordinates;
    expect(p3[0]).toEqual([9.68, 52.46]); // grounded chain starts at the plane's airport (EDDV)
    expect(p3[p3.length - 1]).toEqual([-3.56, 40.47]); // …and ends at the queued airport (LEMD)
  });
});

describe('hoverRouteGeoJson (ISS-022/025/027 v0.22.0 — hover route trace)', () => {
  it('returns an empty collection for the no-hover "" sentinel', () => {
    expect(hoverRouteGeoJson('', '', AIRPORTS)).toEqual({ type: 'FeatureCollection', features: [] });
  });

  it('draws one great-circle line between two known airports with exact endpoints', () => {
    const fc = hoverRouteGeoJson('EDDF', 'EHAM', AIRPORTS);
    expect(fc.features).toHaveLength(1);
    expect(fc.features[0].properties).toEqual({ planeId: '' }); // pure overlay — no owning plane
    const coords = fc.features[0].geometry.coordinates;
    expect(coords.length).toBe(ROUTE_ARC_SEGMENTS + 1); // sampled arc, not a 2-point chord
    expect(coords[0]).toEqual([8.56, 50.03]); // EDDF [lon, lat] — exact endpoint
    expect(coords[coords.length - 1]).toEqual([4.76, 52.31]); // EHAM — exact endpoint
  });

  it('draws the same trace reversed (endpoints swapped, arc mirrored)', () => {
    const ab = hoverRouteGeoJson('EDDF', 'EHAM', AIRPORTS).features[0].geometry.coordinates;
    const ba = hoverRouteGeoJson('EHAM', 'EDDF', AIRPORTS).features[0].geometry.coordinates;
    expect(ba.length).toBe(ab.length);
    // The slerp is symmetric up to floating-point rounding (1 − t ≠ (N−t)/N bit-exactly), so
    // compare with a tolerance: each reversed point sits on the forward arc within ~1e-9 degrees.
    for (let i = 0; i < ab.length; i++) {
      expect(Math.abs(ba[i][0] - ab[ab.length - 1 - i][0])).toBeLessThan(1e-9);
      expect(Math.abs(ba[i][1] - ab[ab.length - 1 - i][1])).toBeLessThan(1e-9);
    }
  });

  it('returns an empty collection when the from airport is missing from the dataset', () => {
    expect(hoverRouteGeoJson('ZZZZ', 'EDDV', AIRPORTS)).toEqual({ type: 'FeatureCollection', features: [] });
  });

  it('returns an empty collection when the to airport is missing from the dataset', () => {
    expect(hoverRouteGeoJson('EDDF', 'ZZZZ', AIRPORTS)).toEqual({ type: 'FeatureCollection', features: [] });
  });
});

describe('hoverTraceGeoJson (ISS-040 v0.23.2 — on-board package trace from the carrier\'s live position)', () => {
  it('draws one great-circle line from the given start coord to the dest airport with exact endpoints', () => {
    const from = { lat: 51.2, lon: 9.1 }; // a mid-flight position — not an airport
    const fc = hoverTraceGeoJson(from, 'EHAM', AIRPORTS);
    expect(fc.features).toHaveLength(1);
    expect(fc.features[0].properties).toEqual({ planeId: '' }); // pure overlay — no owning plane
    const coords = fc.features[0].geometry.coordinates;
    expect(coords.length).toBe(ROUTE_ARC_SEGMENTS + 1); // sampled arc, not a 2-point chord
    expect(coords[0]).toEqual([9.1, 51.2]); // live start — exact endpoint
    expect(coords[coords.length - 1]).toEqual([4.76, 52.31]); // EHAM — exact endpoint
  });

  it('returns an empty collection when the dest airport is missing from the dataset', () => {
    expect(hoverTraceGeoJson({ lat: 0, lon: 0 }, 'ZZZZ', AIRPORTS)).toEqual({ type: 'FeatureCollection', features: [] });
  });

  // ISS-077 (v0.41.0): a flying carrier's trace starts at its landing airport — when that IS the
  // package's destination there is nothing to draw (the solid active-leg layer covers it).
  it('returns an empty collection when the start point equals the dest airport', () => {
    expect(hoverTraceGeoJson(AIRPORTS.get('EHAM')!, 'EHAM', AIRPORTS)).toEqual({ type: 'FeatureCollection', features: [] });
  });
});

describe('greatCircleArc (v0.12.2 — curved route traces)', () => {
  it('samples >2 points with the endpoints exactly at the airport coords', () => {
    const arc = greatCircleArc(AIRPORTS.get('EDDF')!, AIRPORTS.get('EHAM')!);
    expect(arc.length).toBe(ROUTE_ARC_SEGMENTS + 1); // 25 coordinates: 23 intermediate points
    expect(arc[0]).toEqual([8.56, 50.03]); // EDDF [lon, lat]
    expect(arc[arc.length - 1]).toEqual([4.76, 52.31]); // EHAM
  });

  it('midpoint of a long route deviates from the straight chord (it is actually curved)', () => {
    const from = AIRPORTS.get('EDDF')!;
    const to = AIRPORTS.get('LEMD')!; // ~1400 km — sagitta ≈ 40 km off the chord
    const arc = greatCircleArc(from, to);
    const mid = arc[Math.floor(arc.length / 2)]; // t = 0.5 exactly (index SEGMENTS/2)
    const chordMid: [number, number] = [(from.lon + to.lon) / 2, (from.lat + to.lat) / 2];
    expect(haversineKm(mid[1], mid[0], chordMid[1], chordMid[0])).toBeGreaterThan(5); // km off the straight line
  });

  it('short routes still fine: exact endpoints and a nearly-straight arc', () => {
    const from = AIRPORTS.get('EDDF')!;
    const to = AIRPORTS.get('EDDV')!; // ~280 km — sagitta ≈ 1.5 km, visually near-straight
    const arc = greatCircleArc(from, to);
    expect(arc.length).toBe(ROUTE_ARC_SEGMENTS + 1);
    expect(arc[0]).toEqual([from.lon, from.lat]);
    expect(arc[arc.length - 1]).toEqual([to.lon, to.lat]);
    const mid = arc[Math.floor(arc.length / 2)];
    const chordMid: [number, number] = [(from.lon + to.lon) / 2, (from.lat + to.lat) / 2];
    expect(haversineKm(mid[1], mid[0], chordMid[1], chordMid[0])).toBeLessThan(5); // stays close to the chord
  });
});

describe('greatCircleArc — antimeridian crossing (ISS-120 v0.53.0)', () => {
  const from = AIRPORTS.get('NZAA')!; // Auckland, lon +174.8
  const to = AIRPORTS.get('NFTF')!; // Fua'amotu, lon −175.1 — the short arc crosses ±180 EASTWARD

  it('eastward crossing: continuous lons (|Δlon| < 180), endpoints exact mod 360, length ≈ haversine', () => {
    const arc = greatCircleArc(from, to);
    expect(arc.length).toBe(ROUTE_ARC_SEGMENTS + 1);
    expectContinuousLons(arc); // no wrapped ±180 jump anywhere — the chord bug is gone
    expect(arc[0]).toEqual([from.lon, from.lat]); // first sample = raw origin, exact
    const last = arc[arc.length - 1]!;
    expect(modDiff(last[0], to.lon)).toBeLessThan(1e-9); // last ≡ dest (mod 360) — here unwrapped to +184.8
    expect(Math.abs(last[1] - to.lat)).toBeLessThan(1e-9);
    expect(arc.some((c) => c[0] > 180)).toBe(true); // the crossing samples sit on the east world copy

    const dist = haversineKm(from.lat, from.lon, to.lat, to.lon);
    let sum = 0;
    for (let i = 1; i < arc.length; i++) sum += haversineKm(arc[i - 1]![1], arc[i - 1]![0], arc[i]![1], arc[i]![0]);
    expect(Math.abs(sum - dist) / dist).toBeLessThan(0.01); // sampled chord length ≈ true great-circle distance
  });

  it('westward crossing (reversed pair): continuous lons below −180, endpoints exact mod 360', () => {
    const arc = greatCircleArc(to, from);
    expectContinuousLons(arc);
    expect(arc[0]).toEqual([to.lon, to.lat]); // raw origin, exact
    const last = arc[arc.length - 1]!;
    expect(modDiff(last[0], from.lon)).toBeLessThan(1e-9); // ≡ +174.8 (mod 360) — here unwrapped to −185.2
    expect(Math.abs(last[1] - from.lat)).toBeLessThan(1e-9);
    expect(arc.some((c) => c[0] < -180)).toBe(true); // the crossing samples sit on the west world copy
  });

  it('non-crossing routes are untouched: lons stay in [−180, 180]', () => {
    const arc = greatCircleArc(AIRPORTS.get('EDDF')!, AIRPORTS.get('LEMD')!);
    expectContinuousLons(arc);
    for (const c of arc) expect(c[0]).toBeGreaterThanOrEqual(-180);
    for (const c of arc) expect(c[0]).toBeLessThanOrEqual(180);
  });

  it('queuedRoutesGeoJson: a chain crossing the antimeridian stays continuous across the joint', () => {
    // Grounded at NZAA with queue [NFTF, NZCH]: leg 1 crosses ±180 eastward (ends unwrapped at +184.8),
    // leg 2 restarts at the RAW −175.1 — without the global re-unwrap the joint would jump ~360°.
    const fc = queuedRoutesGeoJson(
      [
        { id: 'p1', model: 'atr72', status: 'available', fuel: 1, maxFuel: 2, locationIcao: 'NZAA', locationName: 'A', destIcao: null, destName: null, departureSimTime: null, lat: -37.01, lon: 174.79, health: 100, repairUntilSimTime: null, queue: ['NFTF', 'NZCH'] },
      ],
      AIRPORTS,
    );
    expect(fc.features).toHaveLength(1);
    const coords = fc.features[0]!.geometry.coordinates;
    expect(coords.length).toBe(2 * ROUTE_ARC_SEGMENTS + 1); // two arcs, joint dropped once
    expectContinuousLons(coords); // the whole chain — including across the NFTF joint
    expect(coords[0]).toEqual([from.lon, from.lat]); // starts at the plane's airport, raw
    const last = coords[coords.length - 1]!;
    const nzch = AIRPORTS.get('NZCH')!;
    expect(modDiff(last[0], nzch.lon)).toBeLessThan(1e-9); // ends ≡ NZCH (mod 360)
    expect(Math.abs(last[1] - nzch.lat)).toBeLessThan(1e-9);
  });
});