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Updated to Swift 4.1 #2

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307 changes: 147 additions & 160 deletions CardParser.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -10,199 +10,186 @@ import Foundation
//MARK: - CardType

enum CardType {
case amex
case diners
case discover
case jcb
case masterCard
case visa

static let allValues: [CardType] = [.visa, .masterCard, .amex, .diners, .discover, .jcb]

private var validationRequirements: ValidationRequirement {
let prefix: [PrefixContainable], length: [Int]

switch self {
/* // IIN prefixes and length requriements retreived from https://en.wikipedia.org/wiki/Bank_card_number on June 28, 2016 */

case .amex: prefix = ["34", "37"]
length = [15]

case .diners: prefix = ["300"..."305", "309", "36", "38"..."39"]
length = [14]

case .discover: prefix = ["6011", "65", "644"..."649", "622126"..."622925"]
length = [16]

case .jcb: prefix = ["3528"..."3589"]
length = [16]

case .masterCard: prefix = ["51"..."55", "2221"..."2720"]
length = [16]

case .visa: prefix = ["4"]
length = [13, 16, 19]

}

return ValidationRequirement(prefixes: prefix, lengths: length)
case amex
case diners
case discover
case jcb
case masterCard
case visa

static let allValues: [CardType] = [.visa, .masterCard, .amex, .diners, .discover, .jcb]

private var validationRequirements: ValidationRequirement {
let prefix: [PrefixContainable], length: [Int]

switch self {
/* // IIN prefixes and length requriements retreived from https://en.wikipedia.org/wiki/Bank_card_number on June 28, 2016 */

case .amex: prefix = ["34", "37"]
length = [15]

case .diners: prefix = ["300"..."305", "309", "36", "38"..."39"]
length = [14]

case .discover: prefix = ["6011", "65", "644"..."649", "622126"..."622925"]
length = [16]

case .jcb: prefix = ["3528"..."3589"]
length = [16]

case .masterCard: prefix = ["51"..."55", "2221"..."2720"]
length = [16]

case .visa: prefix = ["4"]
length = [13, 16, 19]

}

var segmentGroupings: [Int] {
switch self {
case .amex: return [4, 6, 5]
case .diners: return [4, 6, 4]
default: return [4, 4, 4, 4]
}

return ValidationRequirement(prefixes: prefix, lengths: length)
}

var segmentGroupings: [Int] {
switch self {
case .amex: return [4, 6, 5]
case .diners: return [4, 6, 4]
default: return [4, 4, 4, 4]
}

var maxLength: Int {
return validationRequirements.lengths.max() ?? 16
}

var cvvLength: Int {
switch self {
case .amex: return 4
default: return 3
}
}

var maxLength: Int {
return validationRequirements.lengths.max() ?? 16
}

var cvvLength: Int {
switch self {
case .amex: return 4
default: return 3
}
}

func isValid(_ accountNumber: String) -> Bool {
return validationRequirements.isValid(accountNumber) && CardType.luhnCheck(accountNumber)
}

func isPrefixValid(_ accountNumber: String) -> Bool {
return validationRequirements.isPrefixValid(accountNumber)
}

}

fileprivate extension CardType {

struct ValidationRequirement {
let prefixes: [PrefixContainable]
let lengths: [Int]

func isValid(_ accountNumber: String) -> Bool {
return validationRequirements.isValid(accountNumber) && CardType.luhnCheck(accountNumber)
return isLengthValid(accountNumber) && isPrefixValid(accountNumber)
}

func isPrefixValid(_ accountNumber: String) -> Bool {
return validationRequirements.isPrefixValid(accountNumber)
guard prefixes.count > 0 else { return true }
return prefixes.contains { $0.hasCommonPrefix(with: accountNumber) }
}

}

fileprivate extension CardType {

struct ValidationRequirement {
let prefixes: [PrefixContainable]
let lengths: [Int]

func isValid(_ accountNumber: String) -> Bool {
return isLengthValid(accountNumber) && isPrefixValid(accountNumber)
}

func isPrefixValid(_ accountNumber: String) -> Bool {
guard prefixes.count > 0 else { return true }
return prefixes.contains { $0.hasCommonPrefix(with: accountNumber) }
}

func isLengthValid(_ accountNumber: String) -> Bool {
guard lengths.count > 0 else { return true }
return lengths.contains { accountNumber.length == $0 }
}

func isLengthValid(_ accountNumber: String) -> Bool {
guard lengths.count > 0 else { return true }
return lengths.contains { accountNumber.count == $0 }
}

// from: https://gist.github.com/cwagdev/635ce973e8e86da0403a
static func luhnCheck(_ cardNumber: String) -> Bool {
var sum = 0
let reversedCharacters = cardNumber.characters.reversed().map { String($0) }
for (idx, element) in reversedCharacters.enumerated() {
guard let digit = Int(element) else { return false }
switch ((idx % 2 == 1), digit) {
case (true, 9): sum += 9
case (true, 0...8): sum += (digit * 2) % 9
default: sum += digit
}
}
return sum % 10 == 0
}

// from: https://gist.github.com/cwagdev/635ce973e8e86da0403a
static func luhnCheck(_ cardNumber: String) -> Bool {
var sum = 0
let reversedCharacters = cardNumber.reversed().map { String($0) }
for (idx, element) in reversedCharacters.enumerated() {
guard let digit = Int(element) else { return false }
switch ((idx % 2 == 1), digit) {
case (true, 9): sum += 9
case (true, 0...8): sum += (digit * 2) % 9
default: sum += digit
}
}

return sum % 10 == 0
}

}

//MARK: - CardState

enum CardState {
case identified(CardType)
case indeterminate([CardType])
case invalid
case identified(CardType)
case indeterminate([CardType])
case invalid
}

extension CardState: Equatable {}
func ==(lhs: CardState, rhs: CardState) -> Bool {
switch (lhs, rhs) {
case (.invalid, .invalid): return true
case (let .indeterminate(cards1), let .indeterminate(cards2)): return cards1 == cards2
case (let .identified(card1), let .identified(card2)): return card1 == card2
default: return false
}
switch (lhs, rhs) {
case (.invalid, .invalid): return true
case (let .indeterminate(cards1), let .indeterminate(cards2)): return cards1 == cards2
case (let .identified(card1), let .identified(card2)): return card1 == card2
default: return false
}
}

extension CardState {

init(fromNumber number: String) {
if let card = CardType.allValues.first(where: { $0.isValid(number) }) {
self = .identified(card)
}
else {
self = .invalid
}

init(fromNumber number: String) {
if let card = CardType.allValues.first(where: { $0.isValid(number) }) {
self = .identified(card)
}

init(fromPrefix prefix: String) {
let possibleTypes = CardType.allValues.filter { $0.isPrefixValid(prefix) }
if possibleTypes.count >= 2 {
self = .indeterminate(possibleTypes)
}
else if possibleTypes.count == 1, let card = possibleTypes.first {
self = .identified(card)
}
else {
self = .invalid
}
else {
self = .invalid
}

}

init(fromPrefix prefix: String) {
let possibleTypes = CardType.allValues.filter { $0.isPrefixValid(prefix) }
if possibleTypes.count >= 2 {
self = .indeterminate(possibleTypes)
}
else if possibleTypes.count == 1, let card = possibleTypes.first {
self = .identified(card)
}
else {
self = .invalid
}
}

}

//MARK: - PrefixContainable

fileprivate protocol PrefixContainable {

func hasCommonPrefix(with text: String) -> Bool

func hasCommonPrefix(with text: String) -> Bool
}

extension ClosedRange: PrefixContainable {

func hasCommonPrefix(with text: String) -> Bool {
//cannot include Where clause in protocol conformance, so have to ensure Bound == String :(
guard let lower = lowerBound as? String, let upper = upperBound as? String else { return false }

let trimmedRange: ClosedRange<String> = {
let length = text.length
let trimmedStart = lower.prefix(length)
let trimmedEnd = upper.prefix(length)
return trimmedStart...trimmedEnd
}()

let trimmedText = text.prefix(trimmedRange.lowerBound.characters.count)
return trimmedRange ~= trimmedText
}

func hasCommonPrefix(with text: String) -> Bool {
//cannot include Where clause in protocol conformance, so have to ensure Bound == String :(
guard let lower = lowerBound as? String, let upper = upperBound as? String else { return false }
let trimmedRange: ClosedRange<Substring> = {
let length = text.count
let trimmedStart = lower.prefix(length)
let trimmedEnd = upper.prefix(length)
return trimmedStart...trimmedEnd
}()
let trimmedText = text.prefix(trimmedRange.lowerBound.count)
return trimmedRange ~= trimmedText
}
}

extension String: PrefixContainable {

func hasCommonPrefix(with text: String) -> Bool {
return hasPrefix(text) || text.hasPrefix(self)
}

func hasCommonPrefix(with text: String) -> Bool {
return hasPrefix(text) || text.hasPrefix(self)
}
}

fileprivate extension String {

func prefix(_ maxLength: Int) -> String {
return String(characters.prefix(maxLength))
}

var length: Int {
return characters.count
}

}