vds_ios/VDS/Components/DatePicker/DatePicker.swift

import Foundation
import UIKit
import VDSTokens
import Combine

/// A dropdown select is an expandable menu of predefined options that allows a customer to make a single selection.
@objc(VDSDatePicker)
open class DatePicker: EntryFieldBase, DatePickerPopoverViewControllerDelegate, UIPopoverPresentationControllerDelegate {
    //--------------------------------------------------
    // MARK: - Initializers
    //--------------------------------------------------
    required public init() {
        super.init(frame: .zero)
    }
    
    public override init(frame: CGRect) {
        super.init(frame: .zero)
    }
    
    public required init?(coder: NSCoder) {
        super.init(coder: coder)
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// A callback when the selected option changes. Passes parameters (option).
    open var onDateSelected: ((Date, DatePicker) -> Void)?
        
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    internal var minWidthDefault = 186.0
        
    internal var bottomStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .vertical
            $0.distribution = .fill
            $0.alignment = .top
            $0.spacing = VDSLayout.space2X
        }
    }()

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    open var calendarIcon = Icon().with {
        $0.name = .calendar
        $0.size = .medium
    }
    
    open var selectedDate: Date? { didSet { setNeedsUpdate() } }
    
    open override var value: String? {
        get { selectedDateLabel.text }
        set { }
    }
    
    open var selectedDateLabel = Label().with {
        $0.setContentCompressionResistancePriority(.required, for: .vertical)
        $0.textAlignment = .left
        $0.textStyle = .bodyLarge
        $0.lineBreakMode = .byCharWrapping
    }
    
    public enum DateFormat: String, CaseIterable, CustomStringConvertible {
        case shortNumeric
        case longAlphabetic
        case mediumNumeric
        case consiseNumeric
        
        public var format: String {
            switch self {
            case .shortNumeric: "MM/dd/yy"
            case .longAlphabetic: "MMMM d, yyyy"
            case .mediumNumeric: "MM/dd/yyyy"
            case .consiseNumeric: "M/d/yyyy"
            }
        }
        
        public var description: String {
            return format
        }
    }
    
    open var dateFormat: DateFormat = .shortNumeric { didSet{ setNeedsUpdate() } }

    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    internal override var containerSize: CGSize { CGSize(width: minWidthDefault, height: 44) }

    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    
    /// Called once when a view is initialized and is used to Setup additional UI or other constants and configurations.
    open override func setup() {
        super.setup()

        accessibilityLabel = "Dropdown Select"
                
        // setting color config
        selectedDateLabel.textColorConfiguration = primaryColorConfiguration.eraseToAnyColorable()
              
        // tap gesture
        fieldStackView
            .publisher(for: UITapGestureRecognizer())
            .sink { [weak self] _ in
                guard let self else { return }
                if self.isEnabled && !self.isReadOnly {
                    self.togglePicker()
                }
            }
            .store(in: &subscribers)
    }
    
    open override func getFieldContainer() -> UIView {
        // stackview for controls in EntryFieldBase.controlContainerView
        let controlStackView = UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .horizontal
            $0.spacing = VDSLayout.space3X
        }
        controlStackView.addArrangedSubview(calendarIcon)
        controlStackView.addArrangedSubview(selectedDateLabel)
        return controlStackView
    }
        
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        
        if let selectedDate {
            formatDate(selectedDate)
        }
        
        selectedDateLabel.surface = surface
        selectedDateLabel.isEnabled = isEnabled
        calendarIcon.color = iconColorConfiguration.getColor(self)
    }
        
    /// Resets to default settings.
    open override func reset() {
        super.reset()
        selectedDateLabel.textStyle = .bodyLarge
    }
    
    internal func formatDate(_ date: Date) {
        let formatter = DateFormatter()
        formatter.dateFormat = dateFormat.format
        selectedDateLabel.text = formatter.string(from: date)
    }
    
    internal func togglePicker() {
        let calendarVC = DatePickerPopoverViewController(calendar: Calendar(identifier: .gregorian), delegate: self)
        calendarVC.modalPresentationStyle = .popover
        calendarVC.selectedDate = selectedDate ?? Date()
        if let popoverController = calendarVC.popoverPresentationController {
            popoverController.delegate = self
            popoverController.sourceView = containerView
            popoverController.sourceRect = containerView.bounds
            popoverController.permittedArrowDirections = .any
        }
        if let viewController = UIApplication.topViewController() {
            viewController.present(calendarVC, animated: true, completion: nil)
        }
    }
    
    internal func didSelectDate(_ controller: DatePickerPopoverViewController, date: Date) {
        selectedDate = date
        controller.dismiss(animated: true)
        sendActions(for: .valueChanged)
    }
    
    public func adaptivePresentationStyle(for controller: UIPresentationController) -> UIModalPresentationStyle {
        return .none
    }
}

protocol DatePickerPopoverViewControllerDelegate: NSObject {
    func didSelectDate(_ controller: DatePickerPopoverViewController, date: Date)
}

class DatePickerPopoverViewController: UIViewController {

    private let picker = UIDatePicker()
    weak var delegate: DatePickerPopoverViewControllerDelegate?

    init(calendar: Calendar, delegate: DatePickerPopoverViewControllerDelegate?) {
        self.delegate = delegate
        super.init(nibName: nil, bundle: nil)
        picker.datePickerMode = .date
        picker.preferredDatePickerStyle = .inline
        picker.addTarget(self, action: #selector(dateChanged(_:)), for: .valueChanged)
    }
    
    var selectedDate: Date = Date() {
        didSet {
            picker.date = selectedDate
        }
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func loadView() {
        view = picker
        view.backgroundColor = .white
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        preferredContentSize = CGSize(width: 300, height: 400) // Adjust as needed
    }

    @objc private func dateChanged(_ sender: UIDatePicker) {
        delegate?.didSelectDate(self, date: sender.date)
    }
}