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

import Foundation
import UIKit
import VDSColorTokens
import VDSFormControlsTokens
import Combine

@objc(VDSButtonGroup)
open class ButtonGroup: View, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate, ButtongGroupPositionLayoutDelegate {
  
    //--------------------------------------------------
    // MARK: - Enums
    //--------------------------------------------------
    public enum ButtonPosition: String, CaseIterable {
        case left, center, right
    }

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    //An object containing number of Button components per row, in each viewport
    open var rowQuantityPhone: Int = 0 { didSet { didChange() } }

    open var rowQuantityTablet: Int = 0 { didSet { didChange() } }

    public var rowQuantity: Int { UIDevice.isIPad ? rowQuantityTablet : rowQuantityPhone }

    //If provided, aligns TextLink/TextLinkCaret alignment when rowQuantity is set one.
    open var buttonPosition: ButtonPosition = .center { didSet { didChange() }}

    open var buttons: [Buttonable] = [] { didSet { didChange() }}

    //If provided, width of Button components will be rendered based on this value. If omitted, default button widths are rendered.
    open var buttonWidth: CGFloat? {
        didSet {
            if let buttonWidth, let buttonPercentage, buttonWidth > 0, buttonPercentage > 0{
                self.buttonPercentage = nil
            }
            buttons.forEach { button in
                if let button = button as? Button {
                    button.width = buttonWidth
                }
            }
            didChange()
        }
    }
    
    var _buttonPercentage: CGFloat?
    open var buttonPercentage: CGFloat? {
        get { _buttonPercentage }
        set {
            if let newValue, newValue <= 100.0, rowQuantity > 0 {
                _buttonPercentage = newValue
            } else {
                _buttonPercentage = nil
            }
            if let buttonWidth, let buttonPercentage, buttonWidth > 0, buttonPercentage > 0 {
                self.buttonWidth = nil
            }
            positionLayout.buttonPercentage = buttonPercentage
            didChange()
        }
    }

    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private let lineSpacing: CGFloat = 12.0
    private let itemSpacing: CGFloat = 16.0
    private let estimatedCellHeight: CGFloat = 40.0
    private let estimatedCellWidth: CGFloat = 150.0

    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
    //--------------------------------------------------
    override public var disabled: Bool {
        didSet {
            buttons.forEach { button in
                button.disabled = disabled
            }
        }
    }

    override public var surface: Surface {
        didSet {
            buttons.forEach { button in
                button.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 Functions
    //--------------------------------------------------
    open override func setup() {
        super.setup()
        isAccessibilityElement = true
        accessibilityTraits = .button
        addSubview(collectionView)
        collectionView.pinToSuperView()
    }

    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    open override func updateView() {
        super.updateView()
        positionLayout.position = buttonPosition
        positionLayout.rowQuantity = rowQuantity
        collectionView.reloadData()
    }
    
    open override func layoutSubviews() {
        super.layoutSubviews()
        // Accounts for any collection size changes
        DispatchQueue.main.async {
            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)
        cell.buttonable = button
        button.pinLeading()
        button.pinTrailing()
        button.centerYAnchor.constraint(equalTo: cell.centerYAnchor).isActive = true
        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]
    }

    
}