passwordgen.go

package main

import (
	"crypto/rand"
	"flag"
	"fmt"
	"log"
	"strings"
)

const (
	lowerChars  = "abcdefghijklmnopqrstuvwxyz"
	upperChars  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
	numberChars = "0123456789"
	symbolChars = "!@#$%^&*()-_=+[]{}|;:,.<>?/`~"
)

func randomInt(max int) (int, error) {
	if max <= 0 {
		return 0, fmt.Errorf("Invalid maximum value")
	}
	b := make([]byte, 1)
	if _, err := rand.Read(b); err != nil {
		return 0, fmt.Errorf("Error generating random number: %v", err)
	}
	randomNumber := int(b[0]) % max
	return randomNumber, nil
}

func generatePassword(length int, useUpper, useNumbers, useSymbols bool) (string, error) {
	if length < 1 {
		return "", fmt.Errorf("password length must be greater than 0")
	}

	var charSet strings.Builder
	charSet.WriteString(lowerChars)
	if useUpper {
		charSet.WriteString(upperChars)
	}
	if useNumbers {
		charSet.WriteString(numberChars)
	}
	if useSymbols {
		charSet.WriteString(symbolChars)
	}

	if charSet.Len() == 0 {
		return "", fmt.Errorf("no character sets selected")
	}

	password := make([]byte, length)
	for i := range password {
		randomIndex, err := randomInt(charSet.Len())
		if err != nil {
			return "", fmt.Errorf("error generating random password: %v", err)
		}
		password[i] = charSet.String()[randomIndex]
	}

	return string(password), nil
}

func main() {
	length := flag.Int("length", 12, "Length of the password (default: 12)")
	useUpper := flag.Bool("upper", true, "Include uppercase letters (default: true)")
	useNumbers := flag.Bool("numbers", true, "Include numbers (default: true)")
	useSymbols := flag.Bool("symbols", true, "Include special characters (default: true)")

	flag.Parse()

	password, err := generatePassword(*length, *useUpper, *useNumbers, *useSymbols)
	if err != nil {
		log.Fatalf("Error generating password: %v", err)
	}

	fmt.Println("Generated password:", password)
}