XZBT-NGN/test-fixtures/reference-exhibits/haunted-house/contract-adapter.js

/*
 * Haunted House — XZBT Exhibit Contract 5.2 adapter.
 *
 * This adapter is the one that has to be honest about capabilities. The
 * exhibit's audio engine cannot start until the browser has seen a user
 * gesture, so `audio` is declared `available` at boot and moves to
 * `loading` then `ready` when it really does. The adapter mirrors the
 * exhibit's real state into the capability registry; it never invents a
 * transition (Authoring Guide §M).
 *
 * The audio-dependent actions are gated on that capability, so invoking
 * `action.moan` before the engine is ready returns CAPABILITY_UNAVAILABLE
 * rather than silently doing nothing.
 */
(function () {
  'use strict';

  var Core = window.XZBTContractCore;

  var IDENTITY = {
    product: 'Haunted House',
    version: '1.0.0',
    build: 'reference-exhibit'
  };

  var DESCRIPTORS = [
    {
      id: 'room.current',
      kind: 'selection',
      label: 'Room',
      description: 'Room the visitor is standing in.',
      options: [
        { value: 'foyer', label: 'Foyer' },
        { value: 'library', label: 'Library' },
        { value: 'cellar', label: 'Cellar' },
        { value: 'attic', label: 'Attic' },
        { value: 'nursery', label: 'Nursery' }
      ],
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'room.spirit',
      kind: 'selection',
      label: 'Spirit',
      description: 'Which presence is currently resident.',
      options: [
        { value: 'restless', label: 'Restless' },
        { value: 'vengeful', label: 'Vengeful' },
        { value: 'mourning', label: 'Mourning' },
        { value: 'mischievous', label: 'Mischievous' }
      ],
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'room.haunt-level',
      kind: 'range',
      label: 'Haunt level',
      description: 'Intensity of the haunting, 0 (dormant) to 1 (manifest).',
      min: 0, max: 1, step: 0.01,
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'room.fog-density',
      kind: 'range',
      label: 'Fog density',
      description: 'Density of the ground fog.',
      min: 0, max: 1, step: 0.01,
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'room.candlelight',
      kind: 'range',
      label: 'Candlelight',
      description: 'Strength of the candle pool of light.',
      min: 0, max: 1, step: 0.01,
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'room.audio-enabled',
      kind: 'state',
      valueType: 'boolean',
      label: 'Audio enabled',
      description: 'Whether the house is permitted to make sound.',
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'room.paused',
      kind: 'state',
      valueType: 'boolean',
      label: 'Held',
      description: 'Whether the haunt simulation is frozen.',
      readable: true, writable: true, restorable: true,
      category: 'room', requires: []
    },
    {
      id: 'action.moan',
      kind: 'impulse',
      label: 'Moan',
      description: 'Emit a long descending moan.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: ['audio']
    },
    {
      id: 'action.slam-door',
      kind: 'impulse',
      label: 'Slam door',
      description: 'Slam a door somewhere in the house.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: ['audio']
    },
    {
      id: 'action.manifest',
      kind: 'impulse',
      label: 'Manifest',
      description: 'Bring the apparition to full manifestation.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: []
    },
    {
      id: 'action.calm',
      kind: 'impulse',
      label: 'Calm',
      description: 'Settle the house back to dormancy.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: []
    },
    {
      id: 'telemetry.audio-state',
      kind: 'state',
      valueType: 'string',
      label: 'Audio engine state',
      description: 'Live state of the Web Audio engine.',
      readable: true, writable: false, restorable: false,
      category: 'telemetry', requires: []
    },
    {
      id: 'telemetry.room-damp',
      kind: 'state',
      valueType: 'number',
      label: 'Room damping',
      description: 'How strongly the current room suppresses the haunt.',
      readable: true, writable: false, restorable: false,
      category: 'telemetry', requires: []
    }
  ];

  function createHauntedHouseContract(exhibit, ui) {
    var catalog = new Core.Catalog(DESCRIPTORS);

    var capabilities = new Core.CapabilityRegistry();
    capabilities.declare('render', 'ready');
    /* Honest initial state: the engine exists but the browser will not let
     * it start until a gesture arrives. */
    capabilities.declare('audio', 'available');

    var setters = {
      'room.current': function (v) { return exhibit.setRoom(v); },
      'room.spirit': function (v) { return exhibit.setSpirit(v); },
      'room.haunt-level': function (v) { return exhibit.setHauntLevel(v); },
      'room.fog-density': function (v) { return exhibit.setFogDensity(v); },
      'room.candlelight': function (v) { return exhibit.setCandlelight(v); },
      'room.audio-enabled': function (v) { return exhibit.setAudioEnabled(v); },
      'room.paused': function (v) { return exhibit.setPaused(v); }
    };

    var readers = {};
    var ids = catalog.ids();
    for (var i = 0; i < ids.length; i++) {
      (function (id) {
        readers[id] = function () { return exhibit.read(id); };
      })(ids[i]);
    }

    var actions = {
      'action.moan': function () { return exhibit.moan(); },
      'action.slam-door': function () { return exhibit.slamDoor(); },
      'action.manifest': function () { return exhibit.manifest(); },
      'action.calm': function () { return exhibit.calm(); }
    };

    var core = new Core.ContractCore({
      identity: IDENTITY,
      catalog: catalog,
      capabilities: capabilities,
      setters: setters,
      readers: readers,
      actions: actions
    });

    /* Mirror the exhibit's real audio lifecycle into the contract. This is
     * a genuine state change driven by the browser, not a scripted one. */
    exhibit.audio.onStateChange = function (state) {
      core.setCapabilityState('audio', state);
      ui.sync();
    };

    ui.dispatchOverride = function (targetId, value) {
      core.applyMutation(targetId, value, 'ui');
      ui.sync();
    };
    ui.invokeOverride = function (targetId) {
      core.invokeAction(targetId, {}, 'ui');
      ui.sync();
    };

    exhibit.onChange = function () { ui.sync(); };

    return core;
  }

  window.HauntedHouseContract = { create: createHauntedHouseContract, IDENTITY: IDENTITY };
})();