guessing-game.ts

import * as Alexa from '../src/index'

interface GuessingState {
  Name: 'Guessing'
  Target: number
  Guesses: number
}

type State = { Name: 'NotStarted' } | GuessingState | { Name: 'Finished' }

const State = {
  startGuessing: (): GuessingState => ({
    Name: 'Guessing',
    Target: Math.round(Math.random() * 99 + 1),
    Guesses: 0,
  }),
  nextGuess: (state: GuessingState): GuessingState => ({
    Name: 'Guessing',
    Target: state.Target,
    Guesses: state.Guesses + 1,
  }),
}

const startNewGame = (): Alexa.Response<State> => ({
  Say: {
    Text: "Try and guess the number I'm thinking of. It's between 1 and 100.",
  },
  NewState: State.startGuessing(),
})

const checkGuess = (
  state: GuessingState,
  slots: Alexa.Slots,
): Alexa.Response<State> => {
  let guess = slots.get('Guess')
  if (typeof guess === 'string') {
    guess = parseInt(guess, 10)
  }
  if (guess < state.Target) {
    return {
      Say: { Text: `Is it ${guess}? Nope, too low! Guess again.` },
      NewState: State.nextGuess(state),
    }
  } else if (guess > state.Target) {
    return {
      Say: { Text: `Is it ${guess}? Nope, too high! Guess again.` },
      NewState: State.nextGuess(state),
    }
  } else if (guess === state.Target) {
    return {
      Say: {
        Text: `Is it ${guess}? Yes! Congratulations, you guessed it in ${state.Guesses +
          1} tries. Would you like to play again?`,
      },
      NewState: { Name: 'Finished' },
    }
  } else {
    return { Say: { Text: "Sorry, I couldn't tell what number you said." } }
  }
}

const help = (): Alexa.Response<State> => ({
  Say: { Text: 'Guess a number between 1 and 100, or say "Stop".' },
})

const stop = (): Alexa.Response<State> => ({
  Say: { Text: '' },
  EndSession: true,
})

/** IntentSchema.json
 * {
 *   "intents": [
 *     {
 *       "intent": "GuessNumber",
 *       "slots": [{ "name": "Guess", "type": "AMAZON.NUMBER" }]
 *     },
 *     { "intent": "AMAZON.YesIntent" },
 *     { "intent": "AMAZON.NoIntent" },
 *     { "intent": "AMAZON.HelpIntent" },
 *     { "intent": "AMAZON.StopIntent" }
 *   ]
 * }
 *
 * Utterances.txt
 * GuessNumber I guess {Guess}
 * GuessNumber is it {Guess}
 * GuessNumber what about {Guess}
 * GuessNumber my guess is {Guess}
 * GuessNumber if the number is {Guess}
 * GuessNumber {Guess}
 */
const routes: Alexa.Routes<State> = {
  InitialState: { Name: 'NotStarted' },
  Launch: startNewGame,
  Standard: {
    Yes: state => {
      if (state.Name === 'Finished') {
        return startNewGame()
      } else {
        return help()
      }
    },
    No: state => {
      if (state.Name === 'Finished') {
        return stop()
      } else {
        return help()
      }
    },
    Help: help,
    Stop: stop,
  },
  Custom: [
    [
      'GuessNumber',
      (state, slots) => {
        if (state.Name === 'Guessing') {
          return checkGuess(state, slots)
        } else {
          return checkGuess(State.startGuessing(), slots)
        }
      },
    ],
  ],
}

const unhandled = () =>
  Alexa.response(
    {
      Say: { Text: "Sorry, I didn't get that, try saying a number." },
    },
    null,
  )

export const handler = Alexa.Lambda.pipe([
  // To host in AWS lambda
  Alexa.Pipe.tracer(),
  Alexa.Pipe.router(routes),
  unhandled,
])