import crypto from 'node:crypto';
import { getGame } from './gameRegistry.js';

export class LobbyManager {
  constructor() {
    this.rooms = new Map();
  }

  list(gameSlug) {
    return [...this.rooms.values()]
      .filter((r) => !gameSlug || r.gameSlug === gameSlug)
      .map((r) => this.summary(r));
  }

  summary(room) {
    return {
      id: room.id,
      gameSlug: room.gameSlug,
      name: room.name,
      hostId: room.hostId,
      players: room.players.map((p) => ({ id: p.userId, username: p.username, seat: p.seat })),
      maxPlayers: room.maxPlayers,
      status: room.status,
    };
  }

  create({ gameSlug, hostUser, name }) {
    const game = getGame(gameSlug);
    if (!game) throw new Error(`Unknown game: ${gameSlug}`);
    if (!game.supportsMultiplayer) throw new Error(`${game.name} is not multiplayer.`);
    const id = crypto.randomBytes(6).toString('hex');
    const room = {
      id,
      gameSlug,
      name: name ?? `${hostUser.username}'s table`,
      hostId: hostUser.id,
      players: [{ userId: hostUser.id, username: hostUser.username, seat: 0 }],
      maxPlayers: game.maxPlayers,
      status: 'waiting',
    };
    this.rooms.set(id, room);
    return room;
  }

  join(roomId, user) {
    const room = this.rooms.get(roomId);
    if (!room) throw new Error('Room not found.');
    if (room.players.some((p) => p.userId === user.id)) return room;
    if (room.players.length >= room.maxPlayers) throw new Error('Room is full.');
    const usedSeats = new Set(room.players.map((p) => p.seat));
    let seat = 0;
    while (usedSeats.has(seat)) seat += 1;
    room.players.push({ userId: user.id, username: user.username, seat });
    return room;
  }

  leave(roomId, userId) {
    const room = this.rooms.get(roomId);
    if (!room) return null;
    room.players = room.players.filter((p) => p.userId !== userId);
    if (!room.players.length) {
      this.rooms.delete(roomId);
      return null;
    }
    if (room.hostId === userId) room.hostId = room.players[0].userId;
    return room;
  }

  get(roomId) {
    return this.rooms.get(roomId) ?? null;
  }
}

export const lobby = new LobbyManager();