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 } from '@/lib/db/client';
import * as schema from '@/lib/db/schema';
import { loadAirportsGeoJson } from '@/lib/airports';
import { haversineKm } from '@/lib/geo';
import { PLANE_TYPES } from '@/lib/game/catalog';
import { MARKET_TARGET_OPEN_CONTRACTS, mulberry32 } from '@/lib/game/seed';
import { arrivalTimeFor } from './movement';
import {
  expireContracts,
  finalizeArrivals,
  MAX_TICK_ELAPSED_MS,
  reputationGainFor,
  spawnCoverageContracts,
  spawnOpenContracts,
  tickOnce,
} from './engine';

// Engine tests run against throwaway DB files (openGameDb) with fake timers so
// Date.now() — the only wall-clock input to a tick — is fully controlled. The
// public tickNow()/applyTimeControls() wrappers (singleton + lock) are covered
// by app/api/sim/route.test.ts and the e2e suite.

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-sim-'));
});

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

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

describe('tickOnce — clock advance', () => {
  it('advances the clock by elapsed real ms × timeScale', async () => {
    const inst = await freshDb('scale.db');
    vi.setSystemTime(T0 + 1_000); // one real second later
    await inst.db.update(schema.simState).set({ timeScale: 5 });

    const sim = await tickOnce(inst);

    expect(sim.clockMs).toBe(T0 + 5_000); // 1 s × 5
    expect(sim.lastRealTickMs).toBe(T0 + 1_000);
  });

  it('freezes the clock while paused but keeps tracking real time', async () => {
    const inst = await freshDb('pause.db');
    await inst.db.update(schema.simState).set({ paused: true, timeScale: 60 });

    vi.setSystemTime(T0 + 3_600_000); // an hour of real pause
    let sim = await tickOnce(inst);
    expect(sim.clockMs).toBe(T0); // frozen — no advance at all
    expect(sim.lastRealTickMs).toBe(T0 + 3_600_000);

    // Unpause: resumes from where it stopped, with NO catch-up for the pause.
    await inst.db.update(schema.simState).set({ paused: false });
    vi.setSystemTime(T0 + 3_600_500);
    sim = await tickOnce(inst);
    expect(sim.clockMs).toBe(T0 + 500 * 60); // only the 500 ms since unpausing × 60
  });

  it('clamps long absences: a 1-hour gap advances at most MAX_TICK_ELAPSED_MS × scale', async () => {
    const inst = await freshDb('clamp.db');
    vi.setSystemTime(T0 + 3_600_000); // server sat idle for an hour

    const sim = await tickOnce(inst); // timeScale is the seeded 1

    expect(sim.clockMs).toBe(T0 + MAX_TICK_ELAPSED_MS); // exactly one clamped tick, not a fast-forward
    vi.setSystemTime(T0); // reset for later tests in this file
  });

  it('does not advance when two ticks land in the same millisecond', async () => {
    const inst = await freshDb('same-ms.db');
    vi.setSystemTime(T0 + 1_000);
    const a = await tickOnce(inst);
    const b = await tickOnce(inst); // no real time passed since `a`
    expect(b.clockMs).toBe(a.clockMs);
  });
});

describe('expireContracts', () => {
  it('flips only open contracts past their deadline; accepted ones never expire', async () => {
    const inst = await freshDb('expiry.db');
    const clock = T0 + 100_000;

    await inst.db.insert(schema.contracts).values([
      { id: 'c-open-past', originIcao: 'EDDF', destIcao: 'LEMD', reward: 1, cargoType: 'Mail', cargoCount: 1, deadlineSimTime: clock - 1, status: 'open', planeId: null, createdSimTime: T0 },
      { id: 'c-open-future', originIcao: 'EDDF', destIcao: 'LEMD', reward: 1, cargoType: 'Mail', cargoCount: 1, deadlineSimTime: clock + 1, status: 'open', planeId: null, createdSimTime: T0 },
      { id: 'c-accepted-past', originIcao: 'EDDF', destIcao: 'LEMD', reward: 1, cargoType: 'Mail', cargoCount: 1, deadlineSimTime: clock - 1, status: 'accepted', planeId: null, createdSimTime: T0 },
    ]);

    const n = await expireContracts(inst, clock);
    expect(n).toBe(1);

    const byId = new Map((await inst.db.select().from(schema.contracts)).map((c) => [c.id, c.status]));
    expect(byId.get('c-open-past')).toBe('expired');
    expect(byId.get('c-open-future')).toBe('open'); // deadline not reached yet
    expect(byId.get('c-accepted-past')).toBe('accepted'); // accepted contracts complete, never expire
  });

  it('a deadline exactly at the clock counts as expired', async () => {
    const inst = await freshDb('expiry-edge.db');
    await inst.db.insert(schema.contracts).values({
      id: 'c-edge', originIcao: 'EDDF', destIcao: 'LEMD', reward: 1, cargoType: 'Mail', cargoCount: 1,
      deadlineSimTime: T0 + 50_000, status: 'open', planeId: null, createdSimTime: T0,
    });
    expect(await expireContracts(inst, T0 + 50_000)).toBe(1); // <= is inclusive
  });
});

describe('finalizeArrivals', () => {
  const FROM = 'EDDF';
  const TO = 'LEMD';

  async function setupFlight(name: string) {
    const inst = await freshDb(name);
    const fc = await loadAirportsGeoJson();
    const from = fc.features.find((f) => f.properties.icao === FROM)!.properties;
    const to = fc.features.find((f) => f.properties.icao === TO)!.properties;
    const km = haversineKm(from.lat, from.lon, to.lat, to.lon);
    const type = PLANE_TYPES.atr72;

    // A dispatched flight: contract accepted + bound to the plane, plane flying
    // with its fuel frozen at departure (the v0.8.0 dispatch step writes these).
    await inst.db.insert(schema.contracts).values({
      id: 'c-flight', originIcao: FROM, destIcao: TO, reward: 5_000, cargoType: 'Passengers',
      cargoCount: 60, deadlineSimTime: T0 + 24 * 3_600_000, status: 'accepted', planeId: 'plane-starter', createdSimTime: T0,
    });
    await inst.db.update(schema.planes)
      .set({ status: 'flying', contractId: 'c-flight', departureSimTime: T0, fuel: type.maxFuel })
      .where(eq(schema.planes.id, 'plane-starter'));

    return { inst, from, to, km, type };
  }

  it('does nothing before the arrival time', async () => {
    const { inst, km, type } = await setupFlight('finalize-early.db');
    const accountBefore = (await inst.db.select().from(schema.account))[0]!;

    const clock = T0 + travelMs(km, type.speedKmh) - 1; // one ms before arrival
    expect(await finalizeArrivals(inst, clock)).toBe(0);

    const plane = (await inst.db.select().from(schema.planes))[0];
    const account = (await inst.db.select().from(schema.account))[0]!;
    expect(plane.status).toBe('flying');
    expect(account.cash).toBe(accountBefore.cash); // no award before landing
  });

  it('awards cash + reputation exactly once and grounds the plane at the destination', async () => {
    const { inst, to, km, type } = await setupFlight('finalize-late.db');
    const accountBefore = (await inst.db.select().from(schema.account))[0]!;

    const clock = T0 + travelMs(km, type.speedKmh); // exactly at arrival
    expect(await finalizeArrivals(inst, clock)).toBe(1);

    const plane = (await inst.db.select().from(schema.planes))[0];
    expect(plane.status).toBe('available');
    expect(plane.locationIcao).toBe(TO);
    expect(plane.lat).toBe(to.lat);
    expect(plane.lon).toBe(to.lon);
    expect(plane.fuel).toBeCloseTo(Math.max(0, type.maxFuel - type.burnPerKm * km), 6); // remaining fuel
    expect(plane.departureSimTime).toBeNull();

    const contract = (await inst.db.select().from(schema.contracts)).find((c) => c.id === 'c-flight')!;
    expect(contract.status).toBe('completed');

    const account = (await inst.db.select().from(schema.account))[0]!;
    expect(account.cash).toBeCloseTo(accountBefore.cash + 5_000, 9); // exact reward
    expect(account.reputation).toBeCloseTo(
      Math.round((accountBefore.reputation + reputationGainFor(km)) * 100) / 100,
      9,
    );

    // A later tick must not award again — the plane is no longer 'flying'.
    expect(await finalizeArrivals(inst, clock + 3_600_000)).toBe(0);
    const accountAfter = (await inst.db.select().from(schema.account))[0]!;
    expect(accountAfter.cash).toBe(account.cash);
    expect(accountAfter.reputation).toBe(account.reputation);
  });

  it('leaves planes without route info alone', async () => {
    const inst = await freshDb('finalize-noroute.db');
    // Flying plane whose contract row is missing — defensive skip, no crash.
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, contractId: 'c-missing' });
    expect(await finalizeArrivals(inst, T0 + 3_600_000)).toBe(0);
  });
});

describe('spawnOpenContracts', () => {
  it('tops the market up to MARKET_TARGET_OPEN_CONTRACTS using the shared seed builder', async () => {
    const inst = await freshDb('spawn.db');
    const clock = T0 + 123_456;

    // Leave exactly 3 open contracts (the rest of the seeded set is "done").
    const all = await inst.db.select().from(schema.contracts);
    for (const c of all.slice(3)) {
      await inst.db.update(schema.contracts).set({ status: 'completed' }).where(eq(schema.contracts.id, c.id));
    }

    const needed = await spawnOpenContracts(inst, clock, mulberry32(7));
    expect(needed).toBe(MARKET_TARGET_OPEN_CONTRACTS - 3);

    const openRows = (await inst.db.select().from(schema.contracts)).filter((c) => c.status === 'open');
    expect(openRows.length).toBe(MARKET_TARGET_OPEN_CONTRACTS);

    const fc = await loadAirportsGeoJson();
    const icaoSet = new Set(fc.features.map((f) => f.properties.icao));
    for (const c of openRows.slice(3)) { // the spawned ones
      expect(c.createdSimTime).toBe(clock); // created at game time, not real time
      expect(icaoSet.has(c.originIcao)).toBe(true);
      expect(icaoSet.has(c.destIcao)).toBe(true);
      expect(c.originIcao).not.toBe(c.destIcao);
      expect(c.planeId).toBeNull();
      // Same deadline window as the seed: now + 6–72h game time.
      expect(c.deadlineSimTime).toBeGreaterThan(clock + 6 * 3_600_000 - 1);
      expect(c.deadlineSimTime).toBeLessThanOrEqual(clock + 72 * 3_600_000);
    }

    // Already at target → nothing more to spawn.
    expect(await spawnOpenContracts(inst, clock, mulberry32(7))).toBe(0);
  });

  it('is deterministic for an injected RNG (spawn matches the seed builder)', async () => {
    const a = await freshDb('spawn-a.db');
    const b = await freshDb('spawn-b.db');
    const clock = T0 + 999;

    // Wipe all contracts in both so both spawn from zero with the same RNG.
    for (const inst of [a, b]) {
      const rows = await inst.db.select().from(schema.contracts);
      for (const r of rows) {
        await inst.db.delete(schema.contracts).where(eq(schema.contracts.id, r.id));
      }
    }

    expect(await spawnOpenContracts(a, clock, mulberry32(42))).toBe(MARKET_TARGET_OPEN_CONTRACTS);
    expect(await spawnOpenContracts(b, clock, mulberry32(42))).toBe(MARKET_TARGET_OPEN_CONTRACTS);

    const strip = (rows: schema.ContractRow[]) =>
      rows.filter((c) => c.status === 'open').map(({ id: _id, ...rest }) => JSON.stringify(rest)).sort();
    expect(strip(await a.db.select().from(schema.contracts))).toEqual(
      strip(await b.db.select().from(schema.contracts)),
    );
  });
});

describe('spawnCoverageContracts (v0.8.0 spawn coverage rule)', () => {
  // The seeded starter plane is grounded at EDDF with no seeded contract from
  // there, so a fresh DB always has exactly one uncovered airport: EDDF.

  it('spawns an open contract originating at the airport of each uncovered grounded plane', async () => {
    const inst = await freshDb('coverage.db');
    const clock = T0 + 5_000;

    // Wipe all seeded contracts so coverage is the only source of new ones.
    for (const c of await inst.db.select().from(schema.contracts)) {
      await inst.db.delete(schema.contracts).where(eq(schema.contracts.id, c.id));
    }

    const n = await spawnCoverageContracts(inst, clock, mulberry32(7));
    expect(n).toBe(1); // only EDDF is uncovered (single grounded plane)

    const openRows = (await inst.db.select().from(schema.contracts)).filter((c) => c.status === 'open');
    expect(openRows.length).toBe(1);
    expect(openRows[0].originIcao).toBe('EDDF'); // origin forced to the plane's airport
    expect(openRows[0].createdSimTime).toBe(clock);
  });

  it('does nothing when every grounded airport already has an open contract', async () => {
    const inst = await freshDb('coverage-covered.db');
    for (const c of await inst.db.select().from(schema.contracts)) {
      await inst.db.delete(schema.contracts).where(eq(schema.contracts.id, c.id));
    }
    // One open contract from EDDF covers the starter plane's airport.
    await inst.db.insert(schema.contracts).values({
      id: 'c-cover', originIcao: 'EDDF', destIcao: 'LEMD', reward: 1, cargoType: 'Mail', cargoCount: 1,
      deadlineSimTime: T0 + 3_600_000, status: 'open', planeId: null, createdSimTime: T0,
    });

    expect(await spawnCoverageContracts(inst, T0 + 5_000, mulberry32(7))).toBe(0);
    expect((await inst.db.select().from(schema.contracts)).length).toBe(1); // nothing added
  });

  it('spawns one contract per uncovered airport when planes sit at several airports', async () => {
    const inst = await freshDb('coverage-multi.db');
    for (const c of await inst.db.select().from(schema.contracts)) {
      await inst.db.delete(schema.contracts).where(eq(schema.contracts.id, c.id));
    }
    // A second grounded plane at LEMD; two planes sharing EDDF must not double-spawn.
    await inst.db.insert(schema.planes).values([
      { id: 'p-2', model: 'atr72', status: 'available', fuel: 100, maxFuel: 6300, locationIcao: 'LEMD', contractId: null, lat: 40.4, lon: -3.6, departureSimTime: null },
      { id: 'p-3', model: 'atr72', status: 'available', fuel: 100, maxFuel: 6300, locationIcao: 'EDDF', contractId: null, lat: 50.03, lon: 8.57, departureSimTime: null },
    ]);

    const n = await spawnCoverageContracts(inst, T0 + 5_000, mulberry32(7));
    expect(n).toBe(2); // EDDF (×2 planes → one contract) and LEMD

    const origins = (await inst.db.select().from(schema.contracts))
      .filter((c) => c.status === 'open')
      .map((c) => c.originIcao)
      .sort();
    expect(origins).toEqual(['EDDF', 'LEMD']);
  });

  it('ignores flying planes — they cannot take new work until they land', async () => {
    const inst = await freshDb('coverage-flying.db');
    for (const c of await inst.db.select().from(schema.contracts)) {
      await inst.db.delete(schema.contracts).where(eq(schema.contracts.id, c.id));
    }
    await inst.db.update(schema.planes)
      .set({ status: 'flying', departureSimTime: T0, contractId: 'c-gone' })
      .where(eq(schema.planes.id, 'plane-starter'));

    expect(await spawnCoverageContracts(inst, T0 + 5_000, mulberry32(7))).toBe(0); // no grounded planes
  });

  it('runs inside tickOnce: a fresh DB gains an EDDF-origin contract after one advancing tick', async () => {
    const inst = await freshDb('coverage-tick.db');
    vi.setSystemTime(T0 + 1_000); // one real second → advanceMs > 0 at scale 1

    await tickOnce(inst);

    const fromEdff = (await inst.db.select().from(schema.contracts)).filter(
      (c) => c.status === 'open' && c.originIcao === 'EDDF',
    );
    expect(fromEdff.length).toBeGreaterThanOrEqual(1); // coverage held through the full tick pipeline
  });
});

// Local helper mirroring lib/sim/movement.ts (kept private there on purpose — the
// engine composes arrivalTimeFor; tests just need the duration for fixtures).
function travelMs(km: number, speedKmh: number): number {
  return (km / speedKmh) * 3_600_000;
}