import { describe, expect, it } from 'vitest';
import type { PackageState, PlaneState, StateSnapshot } from './game/state';
import { diffSnapshots } from './deriveEvents';

// ISS-008 (v0.17.0): snapshot-diffing event derivation — pure core of the toast/notification
// feature, unit-tested in node like advanceSimClock/fetchState.

const CATALOG = [
  { model: 'atr72', label: 'ATR 72-600', price: 200_000, maxFuel: 6300, burnPerKm: 1.75, emptyWeightKg: 9300, speedKmh: 510, maxPayloadKg: 4800 },
];

const basePlane = (id: string): PlaneState => ({
  id,
  model: 'atr72',
  status: 'available',
  fuel: 6300,
  maxFuel: 6300,
  locationIcao: 'EDDF',
  locationName: 'Frankfurt',
  destIcao: null,
  destName: null,
  departureSimTime: null,
  lat: 50.03,
  lon: 8.56,
  health: 100, // v0.39.0 (ISS-069) — full-health fixture default
  repairUntilSimTime: null,
  queue: [],
});

const basePackage = (id: string): PackageState => ({
  id,
  originIcao: 'EDDF',
  originName: 'Frankfurt',
  destIcao: 'LEMD',
  destName: 'Madrid–Barajas',
  reward: 1234.5,
  cargoType: 'mail',
  cargoCount: 2,
    weightKg: 600,
    special: null, // v0.37.0 (ISS-073) — no special status by default in fixtures
    distanceKm: 1839, // v0.48.0 (ISS-095) — EDDF→LEMD great-circle distance
    deadlineSimTime: 0,
  status: 'open',
  planeId: null,
  createdSimTime: 0,
});

const snapshot = (over: Partial<StateSnapshot> = {}): StateSnapshot => ({
  account: { cash: 20_000, reputation: 10 },
  simState: { clockMs: 0 },
  planes: [basePlane('plane-starter')],
  packages: [],
  catalog: CATALOG,
  fuelPricePerL: 0.8,
  sellFraction: 0.5,
  ...over,
});

describe('diffSnapshots', () => {
  it('returns [] for identical snapshots (only clock/cash drift)', () => {
    const prev = snapshot();
    const next = snapshot({ account: { cash: 21_000, reputation: 11 }, simState: { clockMs: 60_000 } });
    expect(diffSnapshots(prev, next)).toEqual([]);
  });

  it('returns [] for the first snapshot (no baseline — no "new package" spam on page load)', () => {
    const next = snapshot({ packages: [basePackage('pkg-1'), basePackage('pkg-2')] });
    expect(diffSnapshots(null, next)).toEqual([]);
  });

  it('emits a landing event when a plane goes flying → available (new locationName is the arrival)', () => {
    const prev = snapshot({
      planes: [
        {
          ...basePlane('plane-starter'),
          status: 'flying',
          destIcao: 'LEMD',
          destName: 'Madrid–Barajas',
          departureSimTime: 0,
        },
      ],
    });
    const next = snapshot({
      planes: [
        { ...basePlane('plane-starter'), locationIcao: 'LEMD', locationName: 'Madrid–Barajas' },
      ],
    });
    expect(diffSnapshots(prev, next)).toEqual([
      { kind: 'info', message: 'ATR 72-600 landed at Madrid–Barajas' },
    ]);
  });

  it('emits a delivery event with the reward when a loaded package is delivered on arrival', () => {
    const prev = snapshot({ packages: [{ ...basePackage('pkg-1'), status: 'loaded', planeId: 'plane-starter' }] });
    const next = snapshot({ packages: [{ ...basePackage('pkg-1'), status: 'delivered', planeId: 'plane-starter' }] });
    expect(diffSnapshots(prev, next)).toEqual([
      { kind: 'info', message: 'Package delivered: +€1,234.50' },
    ]);
  });

  it('emits an expiry event for open → expired and loaded → expired', () => {
    const fromOpen = diffSnapshots(
      snapshot({ packages: [basePackage('pkg-1')] }),
      snapshot({ packages: [{ ...basePackage('pkg-1'), status: 'expired' }] }),
    );
    expect(fromOpen).toEqual([{ kind: 'info', message: 'Package expired: Frankfurt → Madrid–Barajas' }]);

    const fromLoaded = diffSnapshots(
      snapshot({ packages: [{ ...basePackage('pkg-2'), status: 'loaded', planeId: 'plane-starter' }] }),
      snapshot({ packages: [{ ...basePackage('pkg-2'), status: 'expired', planeId: 'plane-starter' }] }),
    );
    expect(fromLoaded).toEqual([{ kind: 'info', message: 'Package expired: Frankfurt → Madrid–Barajas' }]);
  });

  it('emits a new-package event for ids only in the next snapshot', () => {
    const prev = snapshot({ packages: [basePackage('pkg-1')] });
    const next = snapshot({ packages: [basePackage('pkg-1'), basePackage('pkg-2')] });
    expect(diffSnapshots(prev, next)).toEqual([
      { kind: 'info', message: 'New package available: Frankfurt → Madrid–Barajas' },
    ]);
  });

  it('emits bought/sold events when the plane id set changes (with the model name)', () => {
    const bought = diffSnapshots(
      snapshot(),
      snapshot({ planes: [basePlane('plane-starter'), basePlane('plane-2')] }),
    );
    expect(bought).toEqual([{ kind: 'info', message: 'Bought ATR 72-600' }]);

    const sold = diffSnapshots(
      snapshot({ planes: [basePlane('plane-starter'), basePlane('plane-2')] }),
      snapshot(),
    );
    expect(sold).toEqual([{ kind: 'info', message: 'Sold ATR 72-600' }]);
  });

  it('reports every transition in one diff (planes first, then packages)', () => {
    const prev = snapshot({
      planes: [
        { ...basePlane('plane-starter'), status: 'flying', destIcao: 'LEMD', destName: 'Madrid–Barajas' },
        basePlane('plane-2'),
      ],
      packages: [{ ...basePackage('pkg-1'), status: 'loaded', planeId: 'plane-starter' }],
    });
    const next = snapshot({
      planes: [
        { ...basePlane('plane-starter'), locationIcao: 'LEMD', locationName: 'Madrid–Barajas' },
        basePlane('plane-3'),
      ],
      packages: [{ ...basePackage('pkg-1'), status: 'delivered', planeId: 'plane-starter' }],
    });
    expect(diffSnapshots(prev, next)).toEqual([
      { kind: 'info', message: 'ATR 72-600 landed at Madrid–Barajas' },
      { kind: 'info', message: 'Bought ATR 72-600' },
      { kind: 'info', message: 'Sold ATR 72-600' },
      { kind: 'info', message: 'Package delivered: +€1,234.50' },
    ]);
  });

  it('ignores transitions that are not events (open → loaded, available → flying)', () => {
    const prev = snapshot({ packages: [basePackage('pkg-1')] });
    const next = snapshot({
      planes: [{ ...basePlane('plane-starter'), status: 'flying', destIcao: 'LEMD', destName: 'Madrid–Barajas' }],
      packages: [{ ...basePackage('pkg-1'), status: 'loaded', planeId: 'plane-starter' }],
    });
    expect(diffSnapshots(prev, next)).toEqual([]);
  });
});