vds_ios/VDS/Components/Buttons/ButtonGroup/ButtonGroup.swift

//
//  ButtonGroup.swift
//  VDS
//
//  Created by Matt Bruce on 11/3/22.
//

import Foundation
import UIKit
import VDSColorTokens
import VDSFormControlsTokens
import Combine

/// A button group contains combinations of related CTAs including ``Button``, ``TextLink``, and ``TextLinkCaret``. This group component controls a combination's orientation, spacing, size and allowable size pairings.
@objc(VDSButtonGroup)
open class ButtonGroup: View, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate, ButtongGroupPositionLayoutDelegate {
  
    //--------------------------------------------------
    // MARK: - Enums
    //--------------------------------------------------
    public enum Alignment: String, CaseIterable {
        case left, center, right
    }

    public enum ChildWidth {
        case percentage(CGFloat)
        case value(CGFloat)
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    //An object containing number of Button components per row for iPhones
    open var rowQuantityPhone: Int = 0 { didSet { setNeedsUpdate() } }

    //An object containing number of Button components per row for iPads
    open var rowQuantityTablet: Int = 0 { didSet { setNeedsUpdate() } }

    // An object containing number of Button components per row
    open var rowQuantity: Int { UIDevice.isIPad ? rowQuantityTablet : rowQuantityPhone }

    //If provided, aligns TextLink/TextLinkCaret alignment when rowQuantity is set one.
    open var alignment: Alignment = .center { didSet { setNeedsUpdate() }}
    
    /// Array of Buttonable Views that are shown in the group.
    open var buttons: [Buttonable] = [] { didSet { setNeedsUpdate() }}

    /// If provided, width of Button components will be rendered based on this value. If omitted, default button widths are rendered.
    private var _childWidth: ChildWidth?
    open var childWidth: ChildWidth? {
        get { _childWidth }
        set {
            if let newValue {
                switch newValue {
                case .percentage(let percentage):
                    if percentage <= 100.0, rowQuantity > 0 {
                        _childWidth = newValue
                    }
                case .value(let value):
                    if value > 0 {
                        _childWidth = newValue
                    }
                }
            } else {
                _childWidth = nil
            }
            setNeedsUpdate()
        }
    }
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    fileprivate lazy var positionLayout = ButtonGroupPositionLayout().with {
        $0.position = .center
        $0.delegate = self
    }

    fileprivate lazy var collectionView: SelfSizingCollectionView = {

        return SelfSizingCollectionView(frame: .zero, collectionViewLayout: positionLayout).with {
            $0.backgroundColor = .clear
            $0.showsHorizontalScrollIndicator = false
            $0.showsVerticalScrollIndicator = false
            $0.isScrollEnabled = false
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.dataSource = self
            $0.delegate = self
            $0.register(ButtonGroupCollectionViewCell.self, forCellWithReuseIdentifier: "collectionViewCell")
        }
    }()

    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    /// Whether this object is enabled or not
    override open var isEnabled: Bool {
        didSet {
            buttons.forEach { $0.isEnabled = isEnabled }
        }
    }
    
    /// Current Surface and this is used to pass down to child objects that implement Surfacable
    override open var surface: Surface {
        didSet {
            buttons.forEach { button in
                var b = button
                b.surface = surface
            }
        }
    }

    //--------------------------------------------------
    // 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 Methods
    //--------------------------------------------------
    /// 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()
        addSubview(collectionView)
        collectionView.pinToSuperView()
    }
    
    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        positionLayout.position = alignment
        positionLayout.rowQuantity = rowQuantity
        
        var percentage: CGFloat?
        var width: CGFloat?
        if let childWidth {
            switch childWidth {
            case .value(let value): width = value
            case .percentage(let value): percentage = value
            }
        }
        buttons.forEach { ($0 as? Button)?.width = width }
        positionLayout.buttonPercentage = percentage
        
        collectionView.reloadData()
    }
    
    open override func layoutSubviews() {
        super.layoutSubviews()
        // Accounts for any collection size changes
        DispatchQueue.main.async { [weak self] in
            guard let self else { return }
            self.collectionView.collectionViewLayout.invalidateLayout()
        }
    }
        
    //--------------------------------------------------
    // MARK: - UICollectionViewDataSource
    //--------------------------------------------------
    public func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return buttons.count
    }

    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let button = buttons[indexPath.row]
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "collectionViewCell", for: indexPath) as? ButtonGroupCollectionViewCell else { return UICollectionViewCell() }
        cell.subviews.forEach { $0.removeFromSuperview() }
        cell.addSubview(button)
        button.pinToSuperView()
        if hasDebugBorder {
            cell.addDebugBorder()
        } else {
            cell.removeDebugBorder()
        }
        return cell
    }
    
    public func collectionView(_ collectionView: UICollectionView, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
        buttons[indexPath.row].intrinsicContentSize
    }
    
    public func collectionView(_ collectionView: UICollectionView, isButtonTypeForItemAtIndexPath indexPath: IndexPath) -> Bool {
        if let _ = buttons[indexPath.row] as? Button {
            return true
        } else {
            return false
        }
    }
    
    public func collectionView(_ collectionView: UICollectionView, buttonableAtIndexPath indexPath: IndexPath) -> Buttonable {
        buttons[indexPath.row]
    }
}