BCB PIX End To End Identification Generation in Golang.

bcb-pix-e2e.go

package helpers

import (
	"fmt"
	"math/rand"
	"time"
	"unsafe"
)

const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789"
const (
    letterIdxBits = 6
    letterIdxMask = 1<<letterIdxBits - 1
    letterIdxMax  = 63 / letterIdxBits
)

var src = rand.NewSource(time.Now().UnixNano())

// Receive a transaction type and ISPB and returns a 32 characters string.
// TransactionType should contain a single character.
// ISPB should be 8 characters.
func GenerateE2E(transactionType string, ispb string) (string) {
    location := time.FixedZone("GMT-3", -3*60*60)
    date := time.Now().In(location).Format("200601021504")
    randString := randString(11)
    return fmt.Sprintf("%s%s%s%s", transactionType, ispb, date, randString)
}

func randString(n int) string {
    b := make([]byte, n)
    for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
        if remain == 0 {
            cache, remain = src.Int63(), letterIdxMax
        }
        if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
            b[i] = letterBytes[idx]
            i--
        }
        cache >>= letterIdxBits
        remain--
    }

    return *(*string)(unsafe.Pointer(&b))
}