function solution() {

  let supplies = { protein: 0, carbohydrate: 0, fat: 0, flavour: 0 }

  let foodRecipes = {
    apple: { protein: 0, carbohydrate: 1, fat: 0, flavour: 2 },
    lemonade: { protein: 0, carbohydrate: 10, fat: 0, flavour: 20 },
    burger: { protein: 0, carbohydrate: 5, fat: 7, flavour: 3 },
    eggs: { protein: 5, carbohydrate: 0, fat: 1, flavour: 1 },
    turkey: { protein: 10, carbohydrate: 10, fat: 10, flavour: 10 },
    cookRecipe(recipe, quantity) {

      let deductedQuantity = {};

      for (const value in this[recipe]) {
        if (this[recipe][value] * quantity > supplies[value]) {
          return `Error: not enough ${value} in stock`;
        }
        deductedQuantity[value] = supplies[value] - this[recipe][value] * quantity;
      }

      Object.assign(supplies, deductedQuantity);
      return 'Success';

    }
  }

  return controller = (str) => {

    if (str.includes('restock')) {
      let [, nutrient, quantity] = str.split(' ');
      supplies[nutrient] += Number(quantity);
      return 'Success';
    }

    if (str.includes('prepare')) {
      let [,  recipe, quantity] = str.split(' ');
      return foodRecipes.cookRecipe(recipe, Number(quantity));
    }

    return `protein=${supplies.protein} carbohydrate=${supplies.carbohydrate} fat=${supplies.fat} flavour=${supplies.flavour}`;

  }

}