package randomizer

import (
	"crypto/rand"
	"math/big"
)

var (
	ValidChars      = []rune("$~!@#%^&*_-+=`|(){}[]:;'<>,.?0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	validSaltChars  = []rune("./0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
	ActivationChars = []rune("23456789ABCDEFGHJKLMNPQRSTUVWXYZ")
)

// Generate a cryptographically secure random salt
func GenerateRandomSalt(length int) (string, error) {
	salt := make([]rune, length)
	for i := 0; i < length; i++ {
		letterIndex, err := rand.Int(rand.Reader, big.NewInt(int64(len(validSaltChars))))
		if err != nil {
			return "", err
		}
		salt[i] = validSaltChars[letterIndex.Int64()]
	}
	return string(salt), nil
}

func GenerateRandomBytes(n int) ([]byte, error) {
	b := make([]byte, n)
	if _, err := rand.Read(b); err != nil {
		return nil, err
	}
	return b, nil
}

// Create random plain text password
func GenerateRandomPlainPwd(pwdLength int) (string, error) {
	return generateRandomPhrase(ValidChars, pwdLength)
}

// Generate password of random length between bounds
func RandomPassLength(minLength, maxLength int) (int, error) {
	pwdLen, err := rand.Int(rand.Reader, big.NewInt(int64(maxLength-minLength)))
	if err != nil {
		return -1, err
	}
	return int(pwdLen.Int64()) + maxLength, nil
}

// Create random plain text password
func GenerateRandomActivationCode(length int) (string, error) {
	return generateRandomPhrase(ActivationChars, length)
}

func generateRandomPhrase(letters []rune, phraseLength int) (string, error) {
	length := int64(len(letters))
	chars := make([]rune, phraseLength)
	for i := range chars {
		letterIndex, err := rand.Int(rand.Reader, big.NewInt(length))
		if err != nil {
			return "", err
		}
		chars[i] = letters[letterIndex.Int64()]
	}
	return string(chars), nil
}