/**
 * A/B Test Variant Logic
 */
(function () {
  'use strict';

  var App = window.BenchmarkApp;
  var STORAGE_KEY = 'benchmark_ab_variant';

  /**
   * Determine A/B variant.
   * Priority: URL override → localStorage → random 50/50.
   * @returns {string} 'A' or 'B'
   */
  App.getVariant = function () {
    // 1. URL override (extracted by params.js before URL cleanup)
    if (App._variantOverride) {
      try { localStorage.setItem(STORAGE_KEY, App._variantOverride); } catch (e) {}
      return App._variantOverride;
    }

    // 2. Persisted variant
    try {
      var stored = localStorage.getItem(STORAGE_KEY);
      if (stored === 'A' || stored === 'B') return stored;
    } catch (e) {}

    // 3. Random assignment
    var variant = Math.random() < 0.5 ? 'A' : 'B';
    try { localStorage.setItem(STORAGE_KEY, variant); } catch (e) {}
    return variant;
  };
})();