/*
 * Museum Gallery — domain model.
 *
 * Deliberately tiny (Step 6.2 brief: "prove the architecture, not to be
 * visually elaborate"). No DOM, no contract awareness, no transport — a
 * plain state object with absolute, idempotent setters, exactly the same
 * shape as Aquarium's and Haunted House's exhibit models.
 */
(function () {
  'use strict';

  var ARTIFACTS = ['the-orrery', 'star-map', 'meteorite'];
  var ARTIFACT_LABELS = {
    'the-orrery': 'The Orrery',
    'star-map': 'Star Map',
    meteorite: 'Meteorite Fragment'
  };

  function Gallery() {
    this.artifact = ARTIFACTS[0];
    this.lightingLevel = 0.6;
    this.rotationSpeed = 0.4;
    this.labelsEnabled = true;
    this.spotlightFlashCount = 0;
  }

  Gallery.prototype.setArtifact = function (value) {
    if (ARTIFACTS.indexOf(value) === -1 || this.artifact === value) return { changed: false };
    this.artifact = value;
    return { changed: true };
  };

  Gallery.prototype.setLightingLevel = function (value) {
    if (this.lightingLevel === value) return { changed: false };
    this.lightingLevel = value;
    return { changed: true };
  };

  Gallery.prototype.setRotationSpeed = function (value) {
    if (this.rotationSpeed === value) return { changed: false };
    this.rotationSpeed = value;
    return { changed: true };
  };

  Gallery.prototype.setLabelsEnabled = function (value) {
    if (this.labelsEnabled === value) return { changed: false };
    this.labelsEnabled = value;
    return { changed: true };
  };

  Gallery.prototype.read = function (id) {
    switch (id) {
      case 'artifact.selected': return this.artifact;
      case 'lighting.level': return this.lightingLevel;
      case 'rotation.speed': return this.rotationSpeed;
      case 'labels.enabled': return this.labelsEnabled;
      default: return null;
    }
  };

  Gallery.prototype.flashSpotlight = function () {
    this.spotlightFlashCount += 1;
    return { ok: true };
  };

  window.MuseumGalleryExhibit = {
    Gallery: Gallery,
    ARTIFACTS: ARTIFACTS,
    ARTIFACT_LABELS: ARTIFACT_LABELS
  };
})();