vds_ios/VDS/Components/Footnote/FootnoteGroup.swift

//
//  FootnoteGroup.swift
//  VDS
//
//  Created by Kanamarlapudi, Vasavi on 29/08/24.
//

import Foundation
import UIKit
import VDSCoreTokens

/// This must always be paired with one or more ``Footnote`` in  a FootnoteGroup.
@objcMembers
@objc(VDSFootnoteGroup)
open class FootnoteGroup: View {
    
    //--------------------------------------------------
    // 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: - enums
    //--------------------------------------------------
    /// Enum used to describe the width of a fixed value or percentage of parent's width.
    public enum Width {
        case percentage(CGFloat)
        case value(CGFloat)
    }
    
    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    /// Array of ``Footnote`` for the Footnote items.
    open var footnoteItems: [Footnote] = [] { didSet { setNeedsUpdate() } }
    
    /// Any percentage or pixel value and cannot exceed container size.
    /// If there is a width that is larger than container size, the footnote will resize to container's width.
    open var width: Width? {
        get { _width }
        set {
            if let newValue {
                switch newValue {
                case .percentage(let percentage):
                    if percentage <= 100.0 {
                        _width = newValue
                    }
                case .value(let value):
                    if value > 0 {
                        _width = newValue
                    }
                }
            } else {
                _width = nil
            }
            setNeedsUpdate()
        }
    }
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private var _width: Width? = nil
    
    private lazy var stackView = UIStackView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.axis = .vertical
        $0.alignment = .top
        $0.distribution = .fill
        $0.spacing = VDSLayout.space3X
        $0.backgroundColor = .clear
    }
    
    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    internal var maxWidth: CGFloat { frame.size.width }
    internal var minWidth: CGFloat { containerSize.width }
    internal var containerSize: CGSize { CGSize(width: 55, height: 44) }
    
    //--------------------------------------------------
    // MARK: - Constraints
    //--------------------------------------------------
    internal var widthConstraint: NSLayoutConstraint?
    internal var trailingEqualsConstraint: NSLayoutConstraint?
    internal var trailingLessThanEqualsConstraint: NSLayoutConstraint?
    
    //--------------------------------------------------
    // 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()
        
        // add footnote item stackview.
        addSubview(stackView)
        stackView.pinTop().pinBottom().pinLeading()
        trailingEqualsConstraint = stackView.pinTrailing(anchor: trailingAnchor)
        
        // width constraints
        trailingLessThanEqualsConstraint = stackView.pinTrailingLessThanOrEqualTo(anchor: trailingAnchor)?.deactivate()
        widthConstraint = stackView.widthAnchor.constraint(equalToConstant: 0).deactivate()
    }
    
    open override func setDefaults() {
        super.setDefaults()
        width = nil
        footnoteItems = []
    }
    
    /// Resets to default settings.
    open override func reset() {
        super.reset()
    }
    
    /// Used to make changes to the View based off a change events or from local properties.
    open override func updateView() {
        super.updateView()
        updateContainerWidth()
        
        // symbol containers are as wide as the widest symbol container in the group.
        var symbolMaxWidth = 0.0
        if footnoteItems.count > 0 {
            for index in 0...footnoteItems.count - 1 {
                let footnote: Footnote = footnoteItems[index]
                let separatorWidth = Label().with { $0.text = footnote.symbolType; $0.sizeToFit() }.intrinsicContentSize.width
                symbolMaxWidth = separatorWidth > symbolMaxWidth ? separatorWidth : symbolMaxWidth
            }
        }
        
        stackView.subviews.forEach{$0.removeFromSuperview()}
        // add symbol label, text label to stack.
        if footnoteItems.count > 0 {
            for index in 0...footnoteItems.count - 1 {
                let footnote: Footnote = footnoteItems[index]
                footnote.symbolWiderWidth = symbolMaxWidth
                footnote.surface = surface
                stackView.addArrangedSubview(footnote)
            }
        }
    }
    
    /// Update container width after updating content.
    internal func updateContainerWidth() {
        var newWidth = 0.0
        switch width {
        case .percentage(let percentage):
            newWidth = max(maxWidth * ((percentage) / 100), minWidth)
            
        case .value(let value):
            newWidth = value > maxWidth ? maxWidth : value
            
        case nil:
            newWidth = maxWidth
        }
        
        widthConstraint?.deactivate()
        trailingLessThanEqualsConstraint?.deactivate()
        trailingEqualsConstraint?.deactivate()
        
        if newWidth > minWidth && newWidth < maxWidth {
            widthConstraint?.constant = newWidth
            widthConstraint?.activate()
            trailingLessThanEqualsConstraint?.activate()
        } else {
            trailingEqualsConstraint?.activate()
        }
    }
}