Factor out game enum/states/logic?

[samreid]

From https://github.com/phetsims/area-model-common/issues/99

// Copyright 2017-2018, University of Colorado Boulder

/**
 * Enumeration for all states that the game can be in.
 *
 * @author Jonathan Olson <jonathan.olson@colorado.edu>
 * REVIEW: These states and corresponding logic are duplicated across many games.  Do we have the potential to factor something out?
 * REVIEW*: Probably not easily, as showing a "correct" solution, giving two attempts, and having a "level complete"
 * REVIEW*: state are not-at-all universal for game sims.
 */
define( function( require ) {
  'use strict';

  // modules
  var areaModelCommon = require( 'AREA_MODEL_COMMON/areaModelCommon' );

  var GameState = {
    // "check" button, editable
    FIRST_ATTEMPT: 'FIRST_ATTEMPT',
    SECOND_ATTEMPT: 'SECOND_ATTEMPT',

    // "next" button, happy face with +1 or +2 depending on score. NOT editable
    CORRECT_ANSWER: 'CORRECT_ANSWER',

    // "try again" button, sad face (editable?) - triggers next state on edit?
    WRONG_FIRST_ANSWER: 'WRONG_FIRST_ANSWER',

    // "show solution" button, sad face (editable?) - no trigger on edit?
    WRONG_SECOND_ANSWER: 'WRONG_SECOND_ANSWER',

    // "next" button, NOT editable, replaced with a solution
    SHOW_SOLUTION: 'SHOW_SOLUTION',

    LEVEL_COMPLETE: 'LEVEL_COMPLETE'
  };

  areaModelCommon.register( 'GameState', GameState );

  // @public {Array.<GameState>} - All values the enumeration can take.
  GameState.VALUES = [
    GameState.FIRST_ATTEMPT,
    GameState.SECOND_ATTEMPT,
    GameState.CORRECT_ANSWER,
    GameState.WRONG_FIRST_ANSWER,
    GameState.WRONG_SECOND_ANSWER,
    GameState.SHOW_SOLUTION,
    GameState.LEVEL_COMPLETE
  ];

  // verify that enum is immutable, without the runtime penalty in production code
  if ( assert ) { Object.freeze( GameState ); }

  return GameState;
} );

I've seen several games that use these states, should this or corresponding logic be factored out? I'll run this past @jbphet first, since he has familiarity with vegas and some games.

[jbphet]

I had this same thought a while back and tried it in Area Builder, please see the file QuizGameModel.js. It was an attempt to do - I think - exactly what you're describing here, i.e. extract the logic for the basic flow of the game into a reusable object or set of objects. In the end, I found what I'd implemented a little awkward because there was some sim-specific logic that needed to be hooked up somehow, and I did that, and it worked, but I didn't feel like it worked well enough that I wanted to move it into the vegas repo. Please take a look and, if you think it would be worth the effort, we could potentially use this as a starting point and go from there. It does seem like it would be a cost savings if there was a grab-and-go object for this that wasn't too hard to use.

[jonathanolson]

@samreid is there something I should do here? It's the last blocking common non-a11y issue for area-model.

[samreid]

At some point we should move code like this and supporting logic into vegas. That will help us develop new games, factor out code from other games and will simplify PhET-iO development and API. It's really up to Ariel when we do that.

[ariel-phet]

@samreid I agree we should do this at some point. @jbphet next sim after EFAC is quite likely to be a new math sim....and math sims often seem to have games. I am going to mark this as deferred and perhaps we can consider this improvement with our next sim with a game.

[ariel-phet]

Marked as deferred but assigned to @jbphet to be revisited when we look at next math sim.