valera/calories/calories.go

package calories

import (
	"strconv"
	"strings"
)

var (
	productsMap = map[string]struct {
		caloriesIn100G int
		awgWeightG     int
	}{
		"чай":    {caloriesIn100G: 65, awgWeightG: 200},
		"яблоко": {caloriesIn100G: 52, awgWeightG: 242},
		"хлеб":   {caloriesIn100G: 245, awgWeightG: 35},
	}
)

func CalcCalories(text string) (int, error) {
	product, ok := productsMap[strings.ToLower(text)]
	if ok {
		return product.caloriesIn100G * product.awgWeightG / 100, nil
	}
	arr := strings.Split(text, " ")
	if len(arr) == 2 {
		product, ok := productsMap[strings.ToLower(arr[0])]
		if ok {
			count, err := strconv.Atoi(arr[1])
			if err != nil {
				return 0, nil
			}
			return product.caloriesIn100G * count / 100, nil
		}
		count1, err := strconv.Atoi(arr[0])
		if err != nil {
			return 0, nil
		}
		count2, err := strconv.Atoi(arr[1])
		if err != nil {
			return 0, nil
		}
		return count1 * count2 / 100, nil
	}
	count, err := strconv.Atoi(text)
	if err != nil {
		return 0, nil
	}
	return count, nil
}