/*
 * Aquarium — XZBT Exhibit Contract 5.3 adapter.
 *
 * This file is the only place in the exhibit that knows the contract exists.
 * It does three things and nothing else:
 *
 *   1. declares the public target catalog against the exhibit's real model
 *   2. binds each target to a real exhibit service (setter / reader / action)
 *   3. routes the native UI through the canonical mutation path
 *
 * It holds no state of its own. Every value it reports is read live from the
 * exhibit, so there is no shadow copy that can drift (Authoring Guide §W).
 */
(function () {
  'use strict';

  var Core = window.XZBTContractCore;

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

  /* ------------------------------------------------------------------ *
   * Public target catalog.
   *
   * IDs are canonical and domain-shaped. They are not DOM ids, CSS
   * selectors, or widget names (Authoring Guide §W).
   * ------------------------------------------------------------------ */

  var DESCRIPTORS = [
    {
      id: 'tank.species',
      kind: 'selection',
      label: 'Species',
      description: 'The species currently stocked in the tank.',
      options: [
        { value: 'clownfish', label: 'Clownfish' },
        { value: 'blue-tang', label: 'Blue Tang' },
        { value: 'neon-tetra', label: 'Neon Tetra' },
        { value: 'angelfish', label: 'Angelfish' },
        { value: 'guppy', label: 'Guppy' }
      ],
      readable: true, writable: true, restorable: true,
      category: 'tank', requires: []
    },
    {
      id: 'tank.population',
      kind: 'range',
      label: 'Population',
      description: 'Number of fish in the tank.',
      min: 1, max: 40, step: 1, unit: 'fish',
      readable: true, writable: true, restorable: true,
      category: 'tank', requires: []
    },
    {
      id: 'tank.lighting',
      kind: 'selection',
      label: 'Lighting',
      description: 'Lighting programme for the tank.',
      options: [
        { value: 'daylight', label: 'Daylight' },
        { value: 'twilight', label: 'Twilight' },
        { value: 'moonlight', label: 'Moonlight' },
        { value: 'blackwater', label: 'Blackwater' }
      ],
      readable: true, writable: true, restorable: true,
      category: 'tank', requires: []
    },
    {
      id: 'tank.current',
      kind: 'range',
      label: 'Water current',
      description: 'Strength of the circulation pump, 0 (still) to 1 (strong).',
      min: 0, max: 1, step: 0.01,
      readable: true, writable: true, restorable: true,
      category: 'tank', requires: []
    },
    {
      id: 'tank.temperature',
      kind: 'range',
      label: 'Temperature',
      description: 'Heater setting, 0 (18 C) to 1 (28 C).',
      min: 0, max: 1, step: 0.01,
      readable: true, writable: true, restorable: true,
      category: 'tank', requires: []
    },
    {
      id: 'tank.paused',
      kind: 'state',
      valueType: 'boolean',
      label: 'Paused',
      description: 'Whether the simulation is frozen.',
      readable: true, writable: true, restorable: true,
      category: 'tank', requires: []
    },
    {
      id: 'action.feed',
      kind: 'impulse',
      label: 'Feed',
      description: 'Scatter food across the surface.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: []
    },
    {
      id: 'action.startle',
      kind: 'impulse',
      label: 'Startle',
      description: 'Send a pressure wave through the tank.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: []
    },
    {
      id: 'action.clean-glass',
      kind: 'impulse',
      label: 'Clean glass',
      description: 'Run the glass-cleaning cycle.',
      readable: false, writable: false, restorable: false,
      category: 'action', requires: []
    },
    {
      id: 'telemetry.fish-count',
      kind: 'state',
      valueType: 'number',
      label: 'Fish count',
      description: 'Live number of fish currently rendered.',
      readable: true, writable: false, restorable: false,
      category: 'telemetry', requires: []
    },
    {
      id: 'telemetry.food-level',
      kind: 'state',
      valueType: 'number',
      label: 'Food level',
      description: 'Remaining food in the water column, 0 to 1.',
      readable: true, writable: false, restorable: false,
      category: 'telemetry', requires: []
    },
    {
      id: 'telemetry.water-temp',
      kind: 'state',
      valueType: 'number',
      unit: 'C',
      label: 'Water temperature',
      description: 'Actual water temperature in degrees Celsius.',
      readable: true, writable: false, restorable: false,
      category: 'telemetry', requires: []
    }
  ];

  /* ------------------------------------------------------------------ *
   * Wiring
   * ------------------------------------------------------------------ */

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

    /* The exhibit has no capability that can fail: it is pure canvas and
     * needs no device, no network, and no permission. Reporting `ready`
     * once is honest; inventing loading/error transitions would not be
     * (Authoring Guide §M). */
    var capabilities = new Core.CapabilityRegistry();
    capabilities.declare('render', 'ready');

    var setters = {
      'tank.species': function (v) { return exhibit.setSpecies(v); },
      'tank.population': function (v) { return exhibit.setPopulation(v); },
      'tank.lighting': function (v) { return exhibit.setLighting(v); },
      'tank.current': function (v) { return exhibit.setCurrent(v); },
      'tank.temperature': function (v) { return exhibit.setTemperature(v); },
      'tank.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.feed': function () { return exhibit.feed(); },
      'action.startle': function () { return exhibit.startle(); },
      'action.clean-glass': function () { return exhibit.cleanGlass(); }
    };

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

    /* Route the native UI through the canonical path. From here on, a
     * slider drag and a host `set` are the same transaction, and both are
     * reported with the same source semantics (Authoring Guide §H). */
    ui.dispatchOverride = function (targetId, value) {
      core.applyMutation(targetId, value, 'ui');
      ui.sync();
    };
    ui.invokeOverride = function (targetId) {
      core.invokeAction(targetId, {}, 'ui');
      ui.sync();
    };

    /* Keep the controls honest when the exhibit changes for any reason. */
    exhibit.onChange = function () { ui.sync(); };

    return core;
  }

  window.AquariumContract = { create: createAquariumContract, IDENTITY: IDENTITY };
})();