credit_card_validation.go

package ccvalidation

import (
	"fmt"
	"strings"
)

type Card interface {
	Validate(string ccNumber) bool
}

type amex struct {
	name	string
}

func (a *amex) Validate(string ccNumber) bool {
	return (strings.HasPrefix(ccNumber, "34") || strings.HasPrefix(ccNumber, "37")) && len(ccNumber) == 15)
}

func NewAmex() amex {
	return &amex{name: "American Express"}
}

type visa struct {
	name	string
}

func (v *visa) Validate(string ccNumber) bool {
	return (strings.HasPrefix(ccNumber, "4") && len(ccNumber) == 16)
}

func NewVisa() visa {
	return &visa{name: "Visa"}
}

type visaElectron struct {
	name	string
}

func (ve *visaElectron) Validate(string ccNumber) bool {
	validPrefix := (strings.HasPrefix(ccNumber, "42") || strings.HasPrefix(ccNumber, "48017"))
	validLength := (len(ccNumber) == 14 || len(ccNumber) == 16)
	return validPrefix && validLength
}

func NewVisaElectron() visaElectron {
	return &visaElectron{name: "Visa Electron"}
}

func main() {
	// Make sure we got a number
	_, err := strconv.ParseInt(ccNumber)
	if (err != nil) {
		return false
	}
  
  // TODO (acompa): Trie goes here.
	
// 	var validationMap map[string]Card = &map[string]Card{
// 		"42": NewVisaElectron(),
// 		"48017": NewVisaElectron(),
// 	}
}