package main

import (
	"fmt"
	"math"
	"os"
	"strings"
)

func contains(arr [3]string, str string) bool {
	for _, a := range arr {
		if a == str {
			return true
		}
	}
	return false
}

func main() {

	var charsets map[string]string
	var usedCharsets[] string
	var possibleSymbols int = 0

	if len(os.Args) == 1 {
			fmt.Println("Usage:\n\tpassphrase-entropy passphrase\n\nNo passphrase given.")
			os.Exit(0)
	}

	passphrase := strings.Join(os.Args[1:]," ")
	passphraseLength := len(passphrase)

	fmt.Println("\nEvaluated string:", passphrase)

	charsets = make(map[string]string)
	charsets["Numbers"] = "0123456789"
	charsets["Lowercase"] = "abcdefghijklmnopqrstuvwxyz"
	charsets["Uppercase"] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	charsets["Common Special Characters"] = " !\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~‚"
	charsets["Extended ASCII"] = "€‚ƒ„…†‡ˆ‰Š‹ŒŽ‘’“”•–—˜™š›œžŸ¡¢£¤¥¦§¨©ª«¬®¯°±²³´µ¶·¸¹º»¼½¾¿ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖ×ØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõö÷øùúûüýþÿ"

	for key, value := range charsets {
		if strings.ContainsAny(passphrase, value) {
			possibleSymbols += len(value)
			usedCharsets = append(usedCharsets, key)
		}
	}

	entropy := math.Log2(math.Pow(float64(possibleSymbols), float64(passphraseLength)))

	fmt.Println("\nNumber of characters:", passphraseLength)
	fmt.Println("\nUsed character sets:", strings.Join(usedCharsets, ", "))
	fmt.Println("\nPassphrase entropy:", entropy)
}