package tmp

import (
	"math/rand"
	"testing"
)

func randRoman() string {
	letters := "MDCCLXXVII"
	bm := 1 + rand.Intn((1<<(len(letters)))-1)
	var res []byte
	for i := range letters {
		if bm&(1<<i) > 0 {
			res = append(res, letters[i])
		}
	}
	return string(res)
}

var res int

func a(x int) int {
	return x
}

func BenchmarkRoman(b *testing.B) {
	const n = 1e5
	nums := make([]string, n)
	for i := range nums {
		nums[i] = randRoman()
	}
	b.Run("map", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			res = romanToIntMap(nums[i%n])
			a(res)
		}
	})
	b.Run("array", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			res = romanToIntArr(nums[i%n])
			a(res)
		}
	})
	b.Run("func", func(b *testing.B) {
		for i := 0; i < b.N; i++ {
			res = romanToIntFunc(nums[i%n])
			a(res)
		}
	})
}

func romanToIntMap(s string) int {
	var romanMap = map[byte]int{'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
	var result = romanMap[s[len(s)-1]]

	for i := len(s) - 2; i >= 0; i-- {
		if romanMap[s[i]] < romanMap[s[i+1]] {
			result -= romanMap[s[i]]
		} else {
			result += romanMap[s[i]]
		}
	}
	return result
}

func romanToIntArr(s string) int {
	var romanMap = [...]int{'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
	var result = romanMap[s[len(s)-1]]

	for i := len(s) - 2; i >= 0; i-- {
		if romanMap[s[i]] < romanMap[s[i+1]] {
			result -= romanMap[s[i]]
		} else {
			result += romanMap[s[i]]
		}
	}
	return result
}

func romanToIntFunc(s string) int {
	var result = getVal(s[len(s)-1])

	for i := len(s) - 2; i >= 0; i-- {
		if getVal(s[i]) < getVal(s[i+1]) {
			result -= getVal(s[i])
		} else {
			result += getVal(s[i])
		}
	}
	return result
}

func getVal(s byte) int {
	switch s {
	case 'I':
		return 1
	case 'V':
		return 5
	case 'X':
		return 10
	case 'L':
		return 50
	case 'C':
		return 100
	case 'D':
		return 500
	case 'M':
		return 1000
	default:
		return 0
	}
}