'use strict';

function evolve(evolveObject) {
  return function curriedEvolve(objectToEvolve, handlers = evolveObject) {
    const result = {};
    for (let key of Object.keys(objectToEvolve)) {
      if (!Array.isArray(objectToEvolve[key]) && typeof objectToEvolve[key] === 'object') {
        result[key] = curriedEvolve(objectToEvolve[key], handlers[key]);
      } else {
        result[key] = handlers[key] ? handlers[key](objectToEvolve[key]) : objectToEvolve[key];
      }
    }
    return result;
  }
}

const evolver = evolve({
  hello: value => `Hello, ${value}!`,
  toggle: value => !value,
  count: value => value + 1,
  unexistingProp: () => 'I won\'t be called',
  nested: {
    doubleArray: value => [...value, ...value],
  },
});

const result = evolver({
  hello: 'Frontend Raccoon', // -> Hello, Frontend Raccoon!
  toggle: false, // -> true
  count: 0, // -> 1
  nested: {
    doubleArray: [1, 2, 3], // -> [1, 2, 3, 1, 2, 3]
    dontTouchThis: true, // -> не изменяется, так как не обозначено в evolve
  }
});

const expectedResult = {
  hello: 'Hello, Frontend Raccoon!',
  toggle: true,
  count: 1,
  nested: {
    doubleArray: [1, 2, 3, 1, 2, 3],
    dontTouchThis: true,
  }
};

console.log(_.isEqual(result, expectedResult));