package fake
import (
"strings"
"strconv"
)
type creditCard struct {
vendor string
length int
prefixes []int
}
var creditCards = map[string]creditCard{
"visa": {"VISA", 16, []int{4539, 4556, 4916, 4532, 4929, 40240071, 4485, 4716, 4}},
"mastercard": {"MasterCard", 16, []int{51, 52, 53, 54, 55}},
"amex": {"American Express", 15, []int{34, 37}},
"discover": {"Discover", 16, []int{6011}},
}
// CreditCardType returns one of the following credit values:
// VISA, MasterCard, American Express and Discover
func CreditCardType() string {
n := len(creditCards)
var vendors []string
for _, cc := range creditCards {
vendors = append(vendors, cc.vendor)
}
return vendors[r.Intn(n)]
}
// CreditCardNum generated credit card number according to the card number rules
func CreditCardNum(vendor string) string {
if vendor != "" {
vendor = strings.ToLower(vendor)
} else {
var vendors []string
for v := range creditCards {
vendors = append(vendors, v)
}
vendor = vendors[r.Intn(len(vendors))]
}
card := creditCards[vendor]
prefix := strconv.Itoa(card.prefixes[r.Intn(len(card.prefixes))])
num := []rune(prefix)
for i := 0; i < card.length-len(prefix); i++ {
num = append(num, genCCDigit(num))
}
return string(num)
}
func genCCDigit(num []rune) rune {
sum := 0
for i := len(num) - 1; i >= 0; i-- {
n := int(num[i])
if i%2 != 0 {
sum += n
} else {
if n*2 > 9 {
sum += n*2 - 9
} else {
sum += n * 2
}
}
}
return rune(((sum/10+1)*10 - sum) % 10)
}
