// MARK: - Properties

private(set) public var text: String = "" {

didSet {

if let handler = changeTextHandler {

handler(text)

}

updateText()

}

}

public var isEmpty: Bool {

return text.isEmpty

}

public var isFilled: Bool {

return text.count == digit

}

public var hasText: Bool {

return !(text.isEmpty)

}

override public var intrinsicContentSize: CGSize {

return stackView.bounds.size

}

private let digit: Int

private let itemSpacing: CGFloat

private var changeTextHandler: ((String) -> Void)? = nil

private let stackView: UIStackView = .init()

private var items: [ContainerItemView<T>] = []

private let itemFactory: () -> UIView

private var appearance: ItemAppearance?

private let autoResizes: Bool

// MARK: - UITextInputTraits

public var autocapitalizationType = UITextAutocapitalizationType.none

public var autocorrectionType = UITextAutocorrectionType.no

public var spellCheckingType = UITextSpellCheckingType.no

public var keyboardType = UIKeyboardType.numberPad

public var keyboardAppearance = UIKeyboardAppearance.default

public var returnKeyType = UIReturnKeyType.done

public var enablesReturnKeyAutomatically = true

// MARK: - Initializers

public init(

digit: Int,

itemSpacing: CGFloat,

itemFactory: @escaping (() -> T),

autoresizes: Bool = false) {

self.digit = digit

self.itemSpacing = itemSpacing

self.itemFactory = itemFactory

self.autoResizes = autoresizes

super.init(frame: .zero)

self.items = (0..<digit).map { _ in

let item = ContainerItemView(itemView: itemFactory())

item.setHandler {

self.showCursor()

self.becomeFirstResponder()

}

return item

}

self.stackView.frame = self.bounds

addSubview(stackView)

items.forEach { stackView.addArrangedSubview($0) }

stackView.spacing = itemSpacing

stackView.axis = .horizontal

stackView.distribution = .fillEqually

}

required init?(coder aDecoder: NSCoder) {

fatalError("init(coder:) has not been implemented")

}

// MARK: - Functions

override public func layoutSubviews() {

super.layoutSubviews()

guard let appearance = appearance else {

stackView.frame = bounds

return

}

stackView.bounds = CGRect(

x: 0,

y: 0,

width: (appearance.itemSize.width * CGFloat(digit)) + (itemSpacing * CGFloat(digit - 1)),

height: appearance.itemSize.height

)

stackView.center = CGPoint(x: bounds.width / 2, y: bounds.height / 2)

}

public func set(text: String) {

if Validator.isPinCode(text: text, digit: digit) {

self.text = text

}

}

public func set(changeTextHandler: @escaping (String) -> ()) {

self.changeTextHandler = changeTextHandler

}

public func set(appearance: ItemAppearance) {

self.appearance = appearance

if autoResizes {

self.appearance = ItemAppearance(itemSize: CGSize(width: (self.bounds.width - (self.itemSpacing * CGFloat(self.digit))) / CGFloat(self.digit), height: appearance.itemSize.height), font: appearance.font, textColor: appearance.textColor, backgroundColor: appearance.backgroundColor, cursorColor: appearance.cursorColor, cornerRadius: appearance.cornerRadius, borderColor: appearance.borderColor)

}

items.forEach { $0.itemView.set(appearance: appearance) }

}

private func updateText() {

items.enumerated().forEach { (index, item) in

if (0..<text.count).contains(index) {

let _index = text.index(text.startIndex, offsetBy: index)

item.itemView.text = text[_index]

} else {

item.itemView.text = nil

}

}

showCursor()

}

private func showCursor() {

let cursorPosition = text.count

items.enumerated().forEach { (arg) in

let (index, item) = arg

item.itemView.isHiddenCursor = (index == cursorPosition) ? false : true

}

}

private func hiddenCursor() {

items.forEach { $0.itemView.isHiddenCursor = true }

}

// MARK: - UIKeyInput

public func insertText(_ textToInsert: String) {

if isEnabled && text.count + textToInsert.count <= digit && Validator.isOnlyNumeric(text: textToInsert) {

text.append(textToInsert)

sendActions(for: .editingChanged)

}

}

public func deleteBackward() {

if isEnabled && !text.isEmpty {

text.removeLast()

sendActions(for: .editingChanged)

}

}

// MARK: - UIResponder

@discardableResult

override public func becomeFirstResponder() -> Bool {

showCursor()

return super.becomeFirstResponder()

}

override public var canBecomeFirstResponder: Bool {

return true

}

@discardableResult

override public func resignFirstResponder() -> Bool {

hiddenCursor()

return super.resignFirstResponder()

}

// MARK: - private class

private class ContainerItemView<T: UIView & ItemType>: UIView {

var itemView: T

private let surfaceView: UIView = .init()

private var didTapHandler: (() -> ())?

init(itemView: T) {

self.itemView = itemView

super.init(frame: .zero)

addSubview(itemView)

addSubview(surfaceView)

let tapGesture = UITapGestureRecognizer(target: self, action: #selector(didTap))

surfaceView.addGestureRecognizer(tapGesture)

}

required init?(coder aDecoder: NSCoder) {

fatalError("init(coder:) has not been implemented")

}

override func layoutSubviews() {

super.layoutSubviews()

itemView.frame = bounds

surfaceView.frame = bounds

}

func setHandler(handler: @escaping () -> ()) {

didTapHandler = handler

}

@objc private func didTap() {

if let handler = didTapHandler {

handler()

}

}

}