A prototype multiplayer game for 3 pm?

class QuestionService {

  /**
   * Get redis key of question by id
   * @param id
   */
  public static getQuestionKey(id: string) {
    return `questions:${id}`;
  }

  /**
   * Get redis key of questions list
   */
  public static getQuestionsListKey() {
    return 'questions';
  }

  /**
   * Return question object
   * @param id
   */
  async getQuestion(id: string) {
    return JSON.parse(
      await this.redisService.getClient().get(QuestionService.getQuestionKey(id))
    );
  }

  /**
   * Add new question to the store
   * @param question
   */
  async addQuestion(message: string): Promise<string> {
    const data =  {
      id: randomStringGenerator(),
      createdAt: Date.now(),
      message,
    };
    await this.redisService.getClient()
      .set(QuestionService.getQuestionKey(data.id), JSON.stringify(data));
    await this.redisService.getClient()
      .sadd(QuestionService.getQuestionsListKey(), data.id);
    return data.id;
  }

  /**
   * Return ID of the random question
   */
  async getRandomQuestionId(): Promise<string> {
    return this.redisService.getClient()
      .srandmember(QuestionService.getQuestionsListKey());
  }

  /**
   * Return random question
   */
  async getRandomQuestion() {
    const id = await this.getRandomQuestionId(gameId);
    return this.getQuestion(id);
  }

}

private turnScores: number[] = [8, 5, 3, 2, 1, 1];

/**
 * Get key of list of the answers
 * @param questionId
 */
public static getAnswersKey(questionId: string): string {
  return `answers:${questionId}`;
}

async addAnswer(questionId: string, answer: string): Promise<string> {
  return this.redisService.getClient()
    .zincrby(QuestionService.getAnswersKey(questionId), 1, answer);
}

/**
 * Get all answers for the given question
 * @param questionId
 */
async getQuestionAnswers(questionId: string): Promise<string[]> {
  return this.redisService.getClient()
    .zrevrange(QuestionService.getAnswersKey(questionId), 0, -1);
}

/**
 * Top 6 answers
 * @param questionId
 */
async getTopAnswers(gameId: string, questionId: string): Promise<string[]> {
  const copiedAnswers = await this.redisService.getClient()
    .get(`answers:game:${gameId}:q:${questionId}`);
  if (!copiedAnswers) {
    const ans = await this.redisService.getClient()
      .zrevrange(QuestionService.getAnswersKey(questionId), 0, 5);
    await this.redisService.getClient()
      .set(`answers:game:${gameId}:q:${questionId}`, JSON.stringify(ans));
    return ans;
  }
  return JSON.parse(copiedAnswers);
}

/**
 * Find if answer already exists and return it if found
 * null if answer doesnt exist
 * @param questionId
 * @param answer
 */
async existingAnswer(questionId: string, answer: string): Promise<string | null> {
  const answers = await this.getQuestionAnswers(questionId);
  const matches = stringSimilarity.findBestMatch(answer, answers);
  return matches.bestMatch.rating >= 0.75
    ? 
    matches.bestMatch.target
    :
    null;
}

/**
 * Existing answer scores
 * @param questionId
 * @param answer
 */
async getExistingAnswerScore(
  gameId: string, questionId: string, answer: string
): Promise<number> {
    const topAnswers = await this.getTopAnswers(gameId, questionId);
    const matches = stringSimilarity.findBestMatch(answer, topAnswers);
    return matches.bestMatch.rating >= 0.75
      ?
      this.turnScores[matches.bestMatchIndex]
      :
      0;
}

/**
 * Submit the new answer. Updates answer counter, save if doesn't exist, return answer score
 * @param questionId
 * @param answer
 */
async submitAnswer(gameId: string, questionId: string, answer: string): Promise<number> {
  answer = answer.toLowerCase();
  const existingAnswer = await this.existingAnswer(questionId, answer);
  if (!existingAnswer) {
    await this.addAnswer(questionId, answer);
    return 0;
  } else {
    await this.addAnswer(questionId, existingAnswer);
    return this.getExistingAnswerScore(gameId, questionId, existingAnswer);
  }
}

class GameService {

  //       
  public static CHANNEL_G_CREATED = 'game-created';
  public static CHANNEL_G_STARTED = 'game-started';
  public static CHANNEL_G_ENDED = 'game-ended';
  public static CHANNEL_G_NEXT_ROUND = 'game-next-round';
  public static CHANNEL_G_NEXT_TURN = 'game-next-turn';
  public static CHANNEL_G_ANSWER_SUBMIT = 'game-next-turn';

  private defaultRounds: number; //  
  private defaultTurns: number; //     

  private timers: any = {}; // . -, any - 

    //  ,       
    //      
  constructor(
    private readonly redisService: RedisService,
    private readonly playerService: PlayerService,
    private readonly questionService: QuestionService,
    @Inject('EventPublisher') private readonly eventPublisher,
  ) {
    this.defaultRounds = config.game.defaultRounds;
    this.defaultTurns = config.game.defaultTurns;
  }

  /**
   * Get redis key of game
   * @param id string identifier of game
   */
  public static getGameKey(id: string) {
    return `game:${id}`;
  }

  /**
   * Get game object by id
   * @param gameId
   */
  async getGame(gameId: string): Promise<Game> {
    const game = await this.redisService.getClient()
      .get(GameService.getGameKey(gameId));
    if (!game) {
      throw new Error(`Game ${gameId} not found`);
    }
    return JSON.parse(game);
  }

  /**
   * Save the game state to database
   * @param game
   */
  async saveGame(game: Game) {
    return this.redisService.getClient().set(
      GameService.getGameKey(game.id),
      JSON.stringify(game)
    );
  }

  /**
   * Save round
   * @param gameId
   * @param round
   */
  async saveRound(gameId: string, round: GameRound) {
    return this.redisService.getClient().set(
      GameService.getRoundKey(gameId, round.index),
      JSON.stringify(round)
    );
  }

  /**
   * Initialize default game structure, generate id
   * and save new game to the storage
   *
   * @param player1
   * @param player2
   */
  async initGame(player1: string, player2: string): Promise<Game> {
    const game: Game = {
      id: randomStringGenerator(),
      player1,
      player2,
      joined: [],
      status: GameStatus.WaitingForPlayers,
      createdAt: Date.now(),
    };
    await this.saveGame(game);
    this.eventPublisher.emit(
      GameService.CHANNEL_G_CREATED, JSON.stringify(game)
    );
    return game;
  }

  /**
   * When the game is created and is in the  "Waiting for players" state
   * users can approve participation
   * @param playerId
   * @param gameId
   */
  async joinGame(playerId: string, gameId: string) {
    const game: Game = await this.getGame(gameId);
    if (!game) throw new Error('Game not found err')
    if (isUndefined(game.joined.find(element => element === playerId))) {
      game.joined.push(playerId);
      game.updatedAt = Date.now();
      await this.saveGame(game);
    }
    if (game.joined.length === 2) return this.startGame(game);
  }

  /**
   * Start the game
   * @param game
   */
  async startGame(game: Game) {
    game.round = 0;
    game.updatedAt = Date.now();
    game.status = GameStatus.Active;
    this.eventPublisher.emit(
      GameService.CHANNEL_G_STARTED, JSON.stringify(game)
    );
    await this.questionService.pickQuestionsForGame(game.id);
    await this.nextRound(game);
  }

  /**
   * Start the next round
   * @param game
   */
  async nextRound(game: Game) {
    clearTimeout(this.timers[game.id]);
    if (game.round >= this.defaultRounds) {
      return this.endGame(game);
    }
    game.round++;
    const round: GameRound = {
      index: game.round,
      question: await this.questionService.getRandomQuestionId(game.id),
      currentPlayer: game.player1,
      turn: 1,
      answers: [],
    };
    await this.saveGame(game);
    await this.saveRound(game.id, round);

    //        
    //     20    
    //        0 
    this.timers[game.id] = setTimeout(async () => {
      await this.submitAnswer(round.currentPlayer, game.id, '');
    }, 20000);
    await this.eventPublisher.emit(
      GameService.CHANNEL_G_NEXT_ROUND,
      JSON.stringify({game, round})
    );
  }

  /**
   * Switch round to next turn
   * @param game
   * @param round
   */
  async nextTurn(game: Game, round: GameRound) {
    clearTimeout(this.timers[game.id]);
    if (round.turn >= this.defaultTurns) {
      return this.nextRound(game);
    }
    round.turn++;
    round.currentPlayer = this.anotherPlayer(round.currentPlayer, game);
    round.updatedAt = Date.now();
    await this.eventPublisher.emit(
      GameService.CHANNEL_G_NEXT_TURN,
      JSON.stringify({game, round})
    );
    this.timers[game.id] = setTimeout(async () => {
      await this.submitAnswer(round.currentPlayer, game.id, '');
    }, 20000);
    return this.saveRound(game.id, round);
  }

  async answerExistInRound(round: GameRound, answer: string) {
    const existingKey = round.answers.find(
      rAnswer => stringSimilarity.compareTwoStrings(answer, rAnswer.value) >= 0.85
    );
    return !isUndefined(existingKey);
  }

  async submitAnswer(playerId: string, gameId: string, answer: string) {
    const game = await this.getGame(gameId);
    const round = await this.getCurrentRound(gameId);
    if (playerId !== round.currentPlayer) {
      throw new Error('Its not your turn');
    }
    if (answer.length === 0) {
      round.updatedAt = Date.now();
      this.eventPublisher.emit(
        GameService.CHANNEL_G_ANSWER_SUBMIT,
        JSON.stringify({game, answer, score: 0, playerId})
      );
      return this.nextTurn(game, round);
    }
    if (await this.answerExistInRound(round, answer)) {
      throw new Error('       ');
    }
    round.answers.push({ value: answer, playerId, turn: round.turn });
    const score = await this.questionService.submitAnswer(
      gameId, round.question, answer
    );
    if (score > 0) {
      await this.addGameScore(gameId, playerId, score);
    }
    round.updatedAt = Date.now();
    this.eventPublisher.emit(
      GameService.CHANNEL_G_ANSWER_SUBMIT,
      JSON.stringify({game, answer, score, playerId})
    );
    return this.nextTurn(game, round);
  }

  /**
   * Adds game score in specified game for specified player
   * @param gameId
   * @param playerId
   * @param score
   */
  async addGameScore(gameId: string, playerId: string, score: number) {
    await this.redisService.getClient()
      .zincrby(`game:${gameId}:player:scores`, score, playerId);
  }

  async endGame(game: Game) {
    clearTimeout(this.timers[game.id]);
    game.updatedAt = Date.now();
    game.status = GameStatus.Finished;
    game.updatedAt = Date.now();
    //  
    const places = await this.redisService.getClient()
      .zrevrange(`game:${game.id}:player:scores`, 0, -1);
    game.winner = places[0];
    //   
    const winnerRating: number = await this.playerService.getPlayerRating(game.winner);
    const looserRating: number = await this.playerService.getPlayerRating(places[1]);
    //   
    const newRatings = rating.calculate(winnerRating, looserRating);
    await this.playerService.winGame(game.winner, newRatings.playerRating); 
    await this.playerService.looseGame(places[1], newRatings.opponentRating);
    await this.redisService.getClient().expire(GameService.getGameKey(game.id), 600)
    this.eventPublisher.emit(GameService.CHANNEL_G_ENDED, JSON.stringify(game));
    return game;
  }
}