//
//  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: [FootnoteItem] = [] { didSet { updateFootnoteItems() } }
    
    /// 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
            }
            updateContainerWidth()
        }
    }
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private var _width: Width? = nil
    
    private lazy var stackView = UIStackView().with {
        $0.translatesAutoresizingMaskIntoConstraints = false
        $0.axis = .vertical
        $0.distribution = .fill
        $0.spacing = VDSLayout.space3X
        $0.backgroundColor = .clear
    }
    
    //--------------------------------------------------
    // MARK: - Configuration Properties
    //--------------------------------------------------
    internal var maxWidth: CGFloat { horizontalPinnedWidth() ?? (superview?.frame.size.width ?? frame.size.width) }
    internal var minWidth: CGFloat { containerSize.width }
    internal var containerSize: CGSize { CGSize(width: 55, height: 44) }
    
    //--------------------------------------------------
    // MARK: - Constraints
    //--------------------------------------------------
    internal var widthConstraint: 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.pinToSuperView()
        widthConstraint = widthAnchor.constraint(equalToConstant: 0).deactivate()
    }
    
    open override func setDefaults() {
        super.setDefaults()
        width = nil
        footnoteItems = []
    }
       
    internal func updateFootnoteItems() {
        // symbol containers are as wide as the widest symbol container in the group.
        var symbolMaxWidth = 0.0
        
        footnoteItems.forEach { footnote in
            let separatorWidth = Label().with {
                $0.text = footnote.symbolType
                $0.textStyle = footnote.symbolLabel.textStyle
                $0.sizeToFit()
            }.intrinsicContentSize.width
            symbolMaxWidth = max(separatorWidth, symbolMaxWidth)
        }
        
        stackView.removeArrangedSubviews()
        
        // add symbol label, text label to stack.
        footnoteItems.forEach { footnote in
            footnote.symbolWidth = 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: break
            
        }
        
        widthConstraint?.deactivate()
        
        if newWidth > minWidth && newWidth < maxWidth {
            widthConstraint?.constant = newWidth
            widthConstraint?.activate()
        }
    }
}