This commit is contained in:
Greg 2025-01-31 19:28:11 +02:00
commit 06198ced9a
6 changed files with 125 additions and 0 deletions

0
Dockerfile Normal file
View file

0
README.md Normal file
View file

0
cmd/api.go Normal file
View file

3
go.mod Normal file
View file

@ -0,0 +1,3 @@
module git.tertyshy.dev/cards
go 1.23.2

62
lib/validate.go Normal file
View file

@ -0,0 +1,62 @@
package validate
import (
"slices"
"strconv"
"strings"
)
type Card struct {
Pan string
Month string
Year string
}
type ValidationResult struct {
Code int
Error error
}
func Luhn(pan string) bool {
if pan == "" {
return false
}
lastIndex := len(pan) - 1
asDigits := []int{}
for _, char := range strings.Split(pan, "") {
digit, err := strconv.Atoi(char)
if err != nil {
return false
}
asDigits = append(asDigits, digit)
}
sum := 0
// do we really need reversed array?
for i, digit := range slices.Backward(asDigits[:lastIndex]) {
if i%2 == len(pan)%2 {
if digit > 4 {
sum += 2*digit - 9
} else {
sum += 2 * digit
}
} else {
sum += digit
}
}
return asDigits[lastIndex] == (10-(sum%10))%10
}
func Validate(card Card) (bool, ValidationResult) {
return true, ValidationResult{}
}

60
lib/validate_test.go Normal file
View file

@ -0,0 +1,60 @@
package validate
import "testing"
func TestLuhn(t *testing.T) {
tests := []struct {
name string
pan string
want bool
}{
{
"Mastercard",
"5555555555554444",
true,
},
{
"Visa",
"4111111111111111",
true,
},
{
"example from wiki",
"17893729974",
true,
},
{
"another example",
"79927398713",
true,
},
{
"worong check digit",
"17893729975",
false,
},
{
"off by one error",
"27893729974",
false,
},
{
"empty",
"",
false,
},
{
"not a digit",
"27893a29974",
false,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got := Luhn(tt.pan)
if got != tt.want {
t.Errorf("Luhn(%s) = %v, want %v", tt.name, got, tt.want)
}
})
}
}