rand.go

package dry

import (
	cryptoRand "crypto/rand"
	"fmt"
	mathRand "math/rand"
	"time"
)

// RandSeedWithTime calls rand.Seed() with the current time.
func RandSeedWithTime() {
	mathRand.Seed(time.Now().UTC().UnixNano())
}

func getRandomHexString(length int, formatStr string) string {
	var buffer []byte
	if length%2 == 0 {
		buffer = make([]byte, length/2)
	} else {
		buffer = make([]byte, (length+1)/2)
	}
	_, err := cryptoRand.Read(buffer)
	if err != nil {
		return ""
	}
	hexString := fmt.Sprintf(formatStr, buffer)
	return hexString[:length]
}

// RandomHexString returns a random lower case hex string with length.
func RandomHexString(length int) string {
	return getRandomHexString(length, "%x")
}

// RandomHEXString returns a random upper case hex string with length.
func RandomHEXString(length int) string {
	return getRandomHexString(length, "%X")
}

// deprecated except for strings. you can copy this oneline implementation
func RandomChooseString(items ...string) string {
	return items[mathRand.Intn(len(items))]
}

func RandomBytes(size int) []byte {
	b := make([]byte, size)
	_, _ = mathRand.Read(b)
	return b
}

// deprecated except for strings. you can copy this oneline implementation
func RandomChoose(items ...any) any {
	return items[mathRand.Intn(len(items))]
}