import { typeOf } from '@ember/utils';

/**
 * Convert state values into an Ember template consumable POJO
 *
 *     @tracked state;
 *
 *     get stateComparators() {
 *       return stateComparators(this.state.value);
 *     }
 *
 * Will result in a POJO where each key is a state (nested) and the values are
 * either nested or the value true. This allows easy use in templates as dot
 * notation in templates is a truthy comparison and both an object and true are
 * truthy while undefined is falsey.
 *
 *     {{#if this.stateComparators.foo.bar}}
 *       …
 *     {{else if this.stateComparators.foo}}
 *       …
 *     {{else if this.stateComparators.baz}}
 *       …
 *     {{else}}
 *       …
 *     {{/if}}
 *
 * @function
 * @param {StateValue} states the result of an XState machine's state.value
 * @return {StateConmarator} a nested POJO of current states
 */
export function stateComparators(stateValue) {
  let foundKeys = [];
  function recurse(states) {
    if (typeOf(states) === 'string') {
      foundKeys.push(states);
      return { [states]: true };
    }
    let comparator = {};
    for (let [key, value] of Object.entries(states)) {
      foundKeys.push(key);
      comparator[key] = recurse(value);
    }
    return comparator;
  }
  let top = recurse(stateValue);
  for (let key of foundKeys) {
    top[key] = top[key] ?? true;
  }
  return top;
}