// Package wordy parses the question and answers it.
package wordy
import (
	"strconv"
	"strings"
)
// Answer gives the answer for input question.
func Answer(input string) (int, bool) {
	input = strings.Replace(input, "by", "", -1)
	input = strings.TrimRight(input, "?")
	// drop "What is"
	fields := strings.Fields(input)[2:]
	if len(fields) == 0 {
		return 0, false
	}
	var res int64
	for i, f := range fields {
		if i == 0 {
			var err error
			res, err = strconv.ParseInt(f, 10, 64)
			if err != nil {
				return 0, false
			}
		} else if i%2 != 0 {
			// there is no next item in slice to parse
			if i+1 >= len(fields) {
				return 0, false
			}
			tmp, err := strconv.ParseInt(fields[i+1], 10, 64)
			if err != nil {
				return 0, false
			}
			switch f {
			case "plus":
				res += tmp
			case "minus":
				res -= tmp
			case "multiplied":
				res *= tmp
			case "divided":
				res /= tmp
			default:
				return 0, false
			}
		}
	}
	return int(res), true
}