import { Packr } from 'msgpackr';
import { afterEach, describe, expect, it } from 'vitest';
import WebSocket from 'ws';
import { loadCharacterStats, loadMap } from '../src/server/assets';
import { Game } from '../src/server/game';
import { GameServer, type GameServerOptions } from '../src/server/net';
import { HASH_CHECK_INTERVAL_S, PROTOCOL_VERSION, START_COUNTDOWN_S, TICK_RATE } from '../src/shared/constants';
import { Button } from '../src/shared/input';
import type { ClientMessage, ServerMessage } from '../src/shared/protocol';
import type { TerrainBitmap } from '../src/shared/terrain/bitmap';
import { applyTerrainEvent } from '../src/shared/terrain/events';
import { ASSETS, realMaterials } from './helpers';

const packr = new Packr({ useRecords: false });
const materials = realMaterials();
const freshTerrain = (): TerrainBitmap => loadMap(ASSETS, 'gateau-etages', materials).terrain;
const flush = (ms = 30): Promise<void> => new Promise((r) => setTimeout(r, ms));

/** A headless client that keeps its own bitmap in sync, like the renderer does. */
class TestClient {
  readonly messages: ServerMessage[] = [];
  readonly socket: WebSocket;
  terrain = freshTerrain();
  lastSeq = 0;
  playerId = -1;
  hashChecks: { seq: number; server: number; mine: number }[] = [];

  constructor(port: number) {
    this.socket = new WebSocket(`ws://127.0.0.1:${port}`);
    this.socket.on('message', (data: Buffer) => this.onMessage(packr.unpack(data) as ServerMessage));
  }

  async hello(name: string, characterId = 'generic', version = PROTOCOL_VERSION): Promise<void> {
    await new Promise((r) => this.socket.once('open', r));
    this.send({ t: 'hello', version, name, characterId });
  }

  send(msg: ClientMessage): void {
    this.socket.send(packr.pack(msg));
  }

  last<T extends ServerMessage['t']>(t: T): Extract<ServerMessage, { t: T }> | undefined {
    return [...this.messages].reverse().find((m) => m.t === t) as Extract<ServerMessage, { t: T }> | undefined;
  }

  private onMessage(msg: ServerMessage): void {
    this.messages.push(msg);
    if (msg.t === 'welcome') {
      this.playerId = msg.playerId;
      for (const { seq, ev } of msg.events) this.apply(seq, ev);
    } else if (msg.t === 'start') {
      this.terrain = freshTerrain();
      this.lastSeq = 0;
    } else if (msg.t === 'terrain') {
      this.apply(msg.seq, msg.ev);
    } else if (msg.t === 'hash') {
      expect(this.lastSeq).toBe(msg.seq);
      this.hashChecks.push({ seq: msg.seq, server: msg.hash, mine: this.terrain.hash() });
    }
  }

  private apply(seq: number, ev: Parameters<typeof applyTerrainEvent>[1]): void {
    expect(seq).toBe(this.lastSeq + 1);
    this.lastSeq = seq;
    applyTerrainEvent(this.terrain, ev, materials);
  }
}

describe('LAN server (M3)', () => {
  let server: GameServer | null = null;
  const clients: TestClient[] = [];

  afterEach(() => {
    for (const c of clients) c.socket.close();
    clients.length = 0;
    server?.close();
    server = null;
  });

  async function startServer(pacing: Partial<GameServerOptions> = {}): Promise<GameServer> {
    await new Promise<void>((resolve) => {
      server = new GameServer({
        ...pacing,
        createGame: (seed, rules, stats) => {
          const { definition, terrain } = loadMap(ASSETS, 'gateau-etages', materials);
          return new Game({ map: definition, terrain, materials, seed, rules, stats, loadCharacter: (id) => loadCharacterStats(ASSETS, id) });
        },
        seed: 42,
        port: 0,
        host: '127.0.0.1',
        onListening: resolve,
      });
    });
    return server!;
  }

  function tick(n: number): void {
    for (let i = 0; i < n; i++) server!.tickOnce();
  }

  it('rejects a client with another protocol version', async () => {
    const s = await startServer();
    const c = new TestClient(s.port);
    clients.push(c);
    await c.hello('Vieux', 'generic', PROTOCOL_VERSION - 1);
    await flush();
    expect(c.last('reject')).toMatchObject({ reason: 'version', serverVersion: PROTOCOL_VERSION });
  });

  it('lobby → everyone ready → countdown → match on a fresh map, clients stay bit-identical', async () => {
    const s = await startServer();
    const a = new TestClient(s.port);
    const b = new TestClient(s.port);
    clients.push(a, b);
    await a.hello('Alice');
    await b.hello('Bob', 'castor');
    await flush();
    expect(a.last('lobby')).toMatchObject({ phase: 'lobby', countdown: null });
    expect(a.last('lobby')!.players.map((p) => p.name)).toEqual(['Alice', 'Bob']);

    // Warm-up destruction, then only one player ready: no countdown.
    tick(120);
    a.send({ t: 'ready', ready: true });
    await flush();
    tick(1);
    await flush();
    expect(b.last('lobby')).toMatchObject({ countdown: null });

    b.send({ t: 'ready', ready: true });
    await flush();
    expect(a.last('lobby')!.countdown).toBe(START_COUNTDOWN_S);
    tick(START_COUNTDOWN_S * TICK_RATE);
    await flush();
    expect(a.last('start')).toBeDefined();
    expect(b.last('start')!.players.map((p) => p.id).sort()).toEqual([a.playerId, b.playerId].sort());
    expect(a.last('lobby')).toMatchObject({ phase: 'playing' });

    // Both dig for a while; snapshots, terrain events and hash checks flow to both clients.
    for (let i = 0; i < HASH_CHECK_INTERVAL_S * TICK_RATE * 2; i++) {
      if (i % 10 === 0) {
        const snap = a.last('snapshot');
        for (const [c, dy] of [
          [a, 40],
          [b, 60],
        ] as const) {
          const me = snap?.players.find((p) => p.id === c.playerId);
          if (me) c.send({ t: 'input', buttons: c === a ? Button.Attack : Button.Special, aimX: Math.round(me.x), aimY: Math.round(me.y + dy) });
        }
        await flush(5);
      }
      tick(1);
    }
    await flush(100);
    expect(a.lastSeq).toBeGreaterThan(5);
    for (const c of [a, b]) {
      expect(c.hashChecks.length).toBeGreaterThanOrEqual(2);
      for (const h of c.hashChecks) expect(h.mine).toBe(h.server);
    }
    expect(a.terrain.hash()).toBe(b.terrain.hash());
  });

  it('a player leaving is announced and an empty server goes back to the lobby', async () => {
    const s = await startServer();
    const a = new TestClient(s.port);
    const b = new TestClient(s.port);
    clients.push(a, b);
    await a.hello('Alice');
    await b.hello('Bob');
    await flush();
    b.socket.close();
    await flush();
    expect(a.last('playerLeft')).toMatchObject({ id: b.playerId });
    expect(a.last('lobby')!.players).toHaveLength(1);
    a.socket.close();
    await flush();
    expect(s.currentPhase).toBe('lobby');
    expect(s.playerCount).toBe(0);
  });

  it('a whole match: rounds with results in between, final results with trophies, then back to the lobby', async () => {
    const s = await startServer({ rounds: 2, roundDuration: 1, roundEndPause: 0.25, matchEndPause: 0.25 });
    const a = new TestClient(s.port);
    clients.push(a);
    await a.hello('Alice', 'castor');
    await flush();
    a.send({ t: 'ready', ready: true });
    await flush();
    tick(START_COUNTDOWN_S * TICK_RATE);
    await flush();
    expect(a.last('start')).toMatchObject({ round: 1, rounds: 2 });

    // Alice eats the cake during round 1 so she earns a trophy.
    for (let i = 0; i < TICK_RATE + 2; i++) {
      const me = a.last('snapshot')?.players.find((p) => p.id === a.playerId);
      if (me && i % 10 === 0) {
        a.send({ t: 'input', buttons: Button.Special, aimX: Math.round(me.x), aimY: Math.round(me.y + 100) });
        await flush(5);
      }
      tick(1);
    }
    await flush();
    expect(a.last('roundEnd')).toMatchObject({ round: 1, rounds: 2 });
    expect(a.last('lobby')).toMatchObject({ phase: 'roundEnd' });

    tick(Math.round(0.25 * TICK_RATE));
    await flush();
    expect(a.last('start')).toMatchObject({ round: 2 });
    tick(TICK_RATE + 2);
    await flush();
    const end = a.last('matchEnd')!;
    expect(end).toBeDefined();
    expect(end.results.map((r) => r.id)).toEqual([a.playerId]);
    expect(end.trophies).toContainEqual(expect.objectContaining({ id: 'glutton', playerId: a.playerId }));

    tick(Math.round(0.25 * TICK_RATE));
    await flush();
    expect(a.last('start')).toMatchObject({ round: 0 });
    expect(a.last('lobby')).toMatchObject({ phase: 'lobby' });
    expect(a.last('lobby')!.players[0].ready).toBe(false);
  });
});