1-hangman.service.ts

import { Injectable } from "@nestjs/common";
import { DictionaryService } from "dictionary.service";
import { State, HangmanGame } from "hangman";
import { Observable } from "rxjs";
import { first } from "rxjs/operators";

const games = new Map<string, HangmanGame>()
var currentGameId = 1


@Injectable()
export class HangmanService {
    constructor(private readonly dictService: DictionaryService) {}

    createNewGame(): Observable<State> {
        const secretWord = this.dictService.randomWord()
        const gameId = `${currentGameId++}`
        const game = new HangmanGame(secretWord, gameId)
        games.set(gameId, game)
        return this.currentState(gameId)
    }

    currentState(gameId: string): Observable<State>{
        if (games.has(gameId)) {
            return games.get(gameId).currentState().pipe(first())
        }   
        return null     
    }

    guess(gameId: string, letter: string): Observable<State>{
        if (games.has(gameId)) {
            const game = games.get(gameId)
            return game.guess(letter).pipe(first())            
        }
        return null
    }

    subscribe(gameId: string, cb: (State)=>void) {
        if (games.has(gameId)) {
            games.get(gameId).currentState().subscribe(cb)
        } else {
            cb({
                status: '-'
            })
        }        
    }
    
}

2-dictionary.service.ts

import { Injectable } from "@nestjs/common";

@Injectable()
export class DictionaryService {
    words = [
        'adventurous',
        'courageous',
        'extramundane',
        'generous',
        'intransigent',
        'sympathetic',
        'vagarious',
        'witty'
    ]

    randomWord(): string {
        const idx = Math.floor((Math.random() * this.words.length));
        return this.words[idx]
    }
}