package romantoint

import "strings"

type conversion struct {
	roman   string
	decimal int
}

var conversions = []conversion{
	{"M", 1000},
	{"CM", 900},
	{"D", 500},
	{"CD", 400},
	{"C", 100},
	{"XC", 90},
	{"L", 50},
	{"XL", 40},
	{"X", 10},
	{"IX", 9},
	{"V", 5},
	{"IV", 4},
	{"I", 1},
}

func romanToInt(s string) int {
	for _, c := range conversions {
		if strings.HasPrefix(s, c.roman) {
			return c.decimal + romanToInt(s[len(c.roman):])
		}
	}

	return 0
}

func RomanToInt(s string) int {
	return romanToInt(s)
}