vds_ios/VDS/Components/RadioSwatch/RadioSwatchGroup.swift

//
//  RadioSwatchGroup.swift
//  VDS
//
//  Created by Matt Bruce on 8/25/22.
//

import Foundation
import UIKit

public class RadioSwatchGroup: Control<DefaultRadioSwatchGroupModel>, Changable {
    public typealias ModelHandlerType = RadioSwatch

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    @Proxy(\.model.selectedModel)
    public var selectedModel: ModelHandlerType.ModelType?
    
    public var onChange: Blocks.ActionBlock?
    
    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    private var mainStackView: UIStackView = {
        return UIStackView().with {
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.axis = .vertical
            $0.spacing = 24
        }
    }()

    private var label = Label()

    private let cellSize: CGFloat = 48.0
    private let lineSpacing: CGFloat = 12.0
    private let itemSpacing: CGFloat = 16.0

    public var collectionViewHeight: NSLayoutConstraint?
    public var collectionViewWidth: NSLayoutConstraint?

    private lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout().with {
            $0.minimumLineSpacing = lineSpacing
            $0.minimumInteritemSpacing = itemSpacing
            $0.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
        }
        return UICollectionView(frame: .zero, collectionViewLayout: layout).with {
            $0.backgroundColor = .clear
            $0.translatesAutoresizingMaskIntoConstraints = false
            $0.register(CollectionViewCell<ModelHandlerType>.self, forCellWithReuseIdentifier: "collectionViewCell")
        }
    }()
    
    //--------------------------------------------------
    // MARK: - Overrides
    //--------------------------------------------------
    override public var disabled: Bool {
        didSet {
            updateSelectors()
        }
    }
    
    override public var surface: Surface {
        didSet {
            updateSelectors()
        }
    }
        
    open override func setup() {
        super.setup()
        isAccessibilityElement = true
        accessibilityTraits = .button
        addSubview(mainStackView)
        mainStackView.addArrangedSubview(label)
        mainStackView.addArrangedSubview(collectionView)

        NSLayoutConstraint.activate([
            mainStackView.topAnchor.constraint(equalTo: topAnchor),
            mainStackView.leadingAnchor.constraint(equalTo: leadingAnchor),
            mainStackView.trailingAnchor.constraint(equalTo: trailingAnchor),
            mainStackView.bottomAnchor.constraint(equalTo: bottomAnchor)
        ])
        
        collectionViewHeight = collectionView.heightAnchor.constraint(greaterThanOrEqualToConstant: cellSize)
        collectionViewHeight?.isActive = true
        collectionViewWidth = collectionView.widthAnchor.constraint(greaterThanOrEqualToConstant: cellSize * 5)
        collectionViewWidth?.isActive = true
    }
    
    open override func shouldUpdateView(viewModel: ModelType) -> Bool {
        return viewModel != model
    }

    public override func initialSetup() {
        super.initialSetup()
        collectionView.delegate = self
        collectionView.dataSource = self
    }
    
    open override func updateView(viewModel: ModelType) {
        collectionView.reloadData()
        setNeedsLayout()
    }
    
    //--------------------------------------------------
    // MARK: - Lifecycle
    //--------------------------------------------------
    open override func layoutSubviews() {
        super.layoutSubviews()
        // Accounts for any collection size changes
        setHeight()
        DispatchQueue.main.async { [weak self] in
            self?.collectionView.collectionViewLayout.invalidateLayout()
        }
    }

    open func setHeight() {
        let bounds = collectionView.bounds
        if bounds.width <= 0 {
            return
        }
        if model.selectors.count > 0  {
            // Calculate the height
            let swatchesInRow = floor(CGFloat(bounds.width/(cellSize + itemSpacing)))
            let numberOfRows = ceil(CGFloat(model.selectors.count)/swatchesInRow)
            let height = (numberOfRows * cellSize) + (itemSpacing * (numberOfRows-1))
            
            if let oldHeight = collectionViewHeight?.constant,
                height != oldHeight {
            }
            collectionViewHeight?.constant = CGFloat(height)
        } else {
            collectionViewHeight?.constant = 0
        }
    }

    //Refactor into new CollectionView Selector protocol
    public func updateSelectors(){
        let selectors = model.selectors.compactMap { existing in
            return existing.copyWith {
                $0.disabled = disabled
                $0.surface = surface
            }
        }
        model.selectors = selectors
    }
    
    public func replace(viewModel: ModelHandlerType.ModelType){
        if let  index = model.selectors.firstIndex(where: { element in
            return element.inputId == viewModel.inputId
        }) {
            model.selectors[index] = viewModel
        }
    }
}

extension RadioSwatchGroup: UICollectionViewDelegateFlowLayout {
    open func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: cellSize, height: cellSize)
    }
}

extension RadioSwatchGroup: UICollectionViewDelegate {
    open func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
        return !model.selectors[indexPath.row].disabled
    }
    
    open func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? CollectionViewCell<ModelHandlerType> else { return }
                
        //reset the old model
        if let selectedModel {
            let oldSelectedModel = selectedModel.copyWith {
                $0.selected = false
            }
            replace(viewModel: oldSelectedModel)
        }
        
        //set the new model
        let newSelectedModel = cell.model.copyWith {
            $0.selected = true
        }
        
        label.text = newSelectedModel.text
        replace(viewModel: newSelectedModel)
        selectedModel = newSelectedModel

    }
    
    open func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? CollectionViewCell<ModelHandlerType> else { return }
        cell.isSelected = false
    }
}

extension RadioSwatchGroup: UICollectionViewDataSource {
    public func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return model.selectors.count
    }
    
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "collectionViewCell", for: indexPath) as? CollectionViewCell<ModelHandlerType>
        let model = model.selectors[indexPath.row]
        cell?.modelHandler.isUserInteractionEnabled = false
        cell?.set(with: model)
        return cell ?? UICollectionViewCell()
    }
}