requestPlaylist.js

/**
 * requestPlaylist: Callback for the say_request_playlist intent
 * @param {Object} assistant Assistant instance.
 */
const requestPlaylist = function(assistant) {
  
 	// formatted data from current intent
	let artists = assistant.data.artist || [];
	let genres = assistant.data.genre || [];
	let moods = assistant.data.mood || [];
  
  	// raw data from current intent
	let genres_original = assistant.data['genre.original'] || [];
	let moods_original = assistant.data['mood.original'] || [];

	if (artists.constructor !== Array) artists = [artists];
	if (genres.constructor !== Array) genres = [genres];
	if (moods.constructor !== Array) moods = [moods];
	if (genres_original.constructor !== Array) genres_original = [genres_original];
	if (moods_original.constructor !== Array) moods_original = [moods_original];
  
  	// assistant.data has consistent data object (probably better using cookies)
  	// Also in this case, probably better using context
	const savingPlaylist = assistant.data.saving_playlist || false;
	const hasStarted = assistant.data.hasStarted || false;
	assistant.data.currentStep = 'playlist';
  
  	// If it's an intent of adjusting the playlist during the review
  	// we redirect to the correct action
	if (hasStarted) {
 
		if (moods.length > 0) {
			add_mood(assistant);
			return;
		}
    
		if (genres.length > 0) {
			add_genre(assistant);
			return;
		}
    
		if (artists.length > 0) {
			add_artist(assistant);
			return;
		}
	}
  
  	// If you were trying to save but executes this action instead,
  	// we redirect
	if (savingPlaylist) {
		assistant.data.name = assistant.getRawInput();
		name_playlist(assistant);
		return;
	}

	// nothing given
	if (!Object.keys(assistant.data).length) {
		assistant.ask(ANSWERS.RESULT_FAILED);
		return;
	}
  
  	// Build Spotify object based on current data
	const spotify = new Spotify(assistant.data);

	// nothing given
	if (!genres.length && !artists.length && !moods.length) {
		assistant.ask(ANSWERS.RESULT_FAILED);
		return;
	}
  
  	// Construct answer
  	let hasGivenSomething = false;

	// Mood
	let moodStr = '';
	if (moods.length > 0) {
		const moodStrList = _addType(spotify, moods, moodsOriginal, 'MOOD');
		moodStr = ANSWERS.REQUEST_MOOD_START(moodStrList);
		hasGivenSomething = true;
	}

	// Genre
	let genreStr = '';
	if (genres.length > 0) {
		// add a comma on the previous string if has started already
		if (hasGivenSomething && moodStr) moodStr += ', ';

		const genreStrList = _addType(spotify, genres, genresOriginal, 'GENRE');
		genreStr = hasGivenSomething ? ANSWERS.REQUEST_GENRE_CONTINUE(genreStrList) : ANSWERS.REQUEST_GENRE_START(genreStrList);
		hasGivenSomething = true;
	}

	// Artist
	let artistStr = '';
	if (artists.length > 0) {
		// add a comma on the previous string if has started already
		if (hasGivenSomething && genreStr.length) genreStr += ', ';

		const artistStrList = _addType(spotify, artists, artists, 'ARTIST');
		artistStr = hasGivenSomething ? ANSWERS.REQUEST_ARTIST_CONTINUE(artistStrList) : ANSWERS.REQUEST_ARTIST_START(artistStrList);
		hasGivenSomething = true;
	}
  
	const answer = ANSWERS.REQUEST(moodStr, genreStr, artistStr);
  
  	// Call the spotify API
	spotify.call().then(function(result) {
    
    	// Set the current content
		assistant.setContext(CONTEXT.PLAYLIST);
		assistant.data.hasStarted = true;
  
    	// Save the data in the assistant.data
		_saveDataFromSpotify(assistant, spotify);
    
    	// reset intent data
		_resetDataParams(assistant);
    
    	// Finally, output the answer
		assistant.ask(answer);

	}).catch(function (reason) {
		error(assistant);
  });

}

app.post('/', function (req, res) {
  	// [...]
  	actionMap.set(INTENT.REQUEST_PLAYLIST, requestPlaylist);

  	assistant.handleRequest(actionMap);
});

/* UTILS */

/**
 * _saveDataFromSpotify: Save Spotify params as stringified JSON
 * so we can reconstruct a similar instance through different intents,
 * without loosing any data.
 * @param {Object} assistant Assistant instance.
 * @param {Object} spotify Spotify instance.
 */
const _saveDataFromSpotify = function(assistant, spotify) {
	assistant.data.params = JSON.stringify(spotify.params);
	assistant.data.currentPlaylist = JSON.stringify(spotify.currentPlaylist);
	assistant.data.currentIdxSong = spotify.currentIdxSong;
}

/**
 * _resetDataParams: Reset the assistant intent data
 * @param {Object} assistant Assistant instance.
 */
const _resetDataParams = function(assistant) {
	// reset current data
	assistant.data.artist = [];
	assistant.data.genre = [];
	assistant.data.mood = [];
	assistant.data['genre_original'] = [];
	assistant.data['mood_original'] = [];
}

/**
 * _addType: Format answer and add genres, artists or moods to the current spotify instance params.
 * @param {Object} spotify Spotify instance.
 * @param {Array} arr Array of genres, artists or moods.
 * @param {Array} arrOriginal Array of raw genres, artists or moods.
 * @param {String} type Type of data (MOOD, GENRE or ARTIST).
 * @param {Boolean} add Optional, adds to the Spotify instance or not.
 * @return String
 */
const _addType = function addType(spotify, arr, arrOriginal, type, add = true) {
	let str = '';
	if (arr.length > 0) {
		for (let i = 0; i < arr.length; i++) {
			str += arrOriginal[i];

			if (add) {
				switch (type) {
					case 'MOOD': spotify.addMood(arr[i]); break;
					case 'GENRE': spotify.addGenre(arr[i]); break;
					case 'ARTIST': spotify.addArtist(arr[i]); break;
					default: break;
				}
			}

			if (arr.length > 1 && i < arr.length - 1) {
				str += (i === arr.length - 2) ? ' and ' : ', ';
			}
		}
	}

	return str;
};