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

import Foundation
import UIKit
import Combine

public class RadioSwatchGroup: RadioSwatchGroupBase<RadioSwatch> {
    
    public override func didSelect(selector: RadioSwatch) {        
        if let index = selectorViews.firstIndex(where: {$0.isSelected == true }),
           let cell = collectionView.cellForItem(at: IndexPath(item: index, section: 0)) as? CollectionViewCell<RadioSwatch> {
                cell.modelHandler.toggle()
        }
        selector.toggle()
        label.text = selector.text
        valueChanged()
    }
    
}

public class RadioSwatchGroupBase<ModelHandlerType: RadioSwatchBase>: SelectorGroupSelectedHandlerBase<ModelHandlerType>, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate {

    //--------------------------------------------------
    // MARK: - Public Properties
    //--------------------------------------------------
    public override var selectorViews: [ModelHandlerType] {
        didSet {
            collectionView.reloadData()
        }
    }

    //--------------------------------------------------
    // MARK: - Private Properties
    //--------------------------------------------------
    public var label = Label()
    private let cellSize: CGFloat = 48.0
    private let labelSpacing: CGFloat = 24.0
    private let labelHeight: CGFloat = 16.0
    private let lineSpacing: CGFloat = 12.0
    private let itemSpacing: CGFloat = 16.0
    private var collectionViewHeight: NSLayoutConstraint?
    private var collectionViewWidth: NSLayoutConstraint?

    fileprivate lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout().with {
            $0.minimumLineSpacing = lineSpacing
            $0.minimumInteritemSpacing = itemSpacing
        }
        return UICollectionView(frame: .zero, collectionViewLayout: layout).with {
            $0.backgroundColor = .clear
            $0.showsHorizontalScrollIndicator = false
            $0.showsVerticalScrollIndicator = false
            $0.isScrollEnabled = false
            $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(label)
        addSubview(collectionView)
        NSLayoutConstraint.activate([
            label.topAnchor.constraint(equalTo: topAnchor),
            label.leadingAnchor.constraint(equalTo: leadingAnchor),
            label.trailingAnchor.constraint(equalTo: trailingAnchor),
            label.heightAnchor.constraint(equalToConstant: labelHeight),
            collectionView.topAnchor.constraint(equalTo: label.bottomAnchor, constant: labelSpacing),
            collectionView.leadingAnchor.constraint(equalTo: leadingAnchor),
            collectionView.trailingAnchor.constraint(equalTo: trailingAnchor),
            collectionView.bottomAnchor.constraint(equalTo: bottomAnchor),
        ])
        //TODO: Look at this width stuff, we should NOT need it!
        collectionViewWidth = collectionView.widthAnchor.constraint(equalToConstant: cellSize * 20)
        collectionViewWidth?.isActive = true

        collectionViewHeight = collectionView.heightAnchor.constraint(equalToConstant: cellSize)
        collectionViewHeight?.isActive = true
    }
    
    open override func layoutSubviews() {
        super.layoutSubviews()
        // Accounts for any collection size changes
        setHeight()
        DispatchQueue.main.async {
            self.collectionView.collectionViewLayout.invalidateLayout()
        }
    }

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

        collectionViewHeight?.constant = CGFloat(height)
    }

    public override func initialSetup() {
        super.initialSetup()
        collectionView.delegate = self
        collectionView.dataSource = self
    }
    
    open override func updateView() {
        label.textPosition = .left
        label.typograpicalStyle = .BodySmall
        label.text = selectedHandler?.text ?? " "
        label.surface = surface
        label.disabled = disabled
        collectionView.reloadData()
    }
    
    private func updateSelectors() {
        for selector in selectorViews {
            selector.surface = surface
            selector.disabled = disabled
        }
    }

    //--------------------------------------------------
    // MARK: - UICollectionViewDelegateFlowLayout
    //--------------------------------------------------
    open func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: cellSize, height: cellSize)
    }
    
    //--------------------------------------------------
    // MARK: - UICollectionViewDelegate
    //--------------------------------------------------
    open func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
        return !selectorViews[indexPath.row].disabled
    }
    
    open func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        guard let cell = collectionView.cellForItem(at: indexPath) as? CollectionViewCell<ModelHandlerType> else { return }
        didSelect(selector: cell.modelHandler)
    }
    
    //--------------------------------------------------
    // MARK: - UICollectionViewDataSource
    //--------------------------------------------------
    public func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    public func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return selectorViews.count
    }
    
    
    public func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "collectionViewCell", for: indexPath) as? CollectionViewCell<ModelHandlerType> else { return UICollectionViewCell() }
        
        let model = selectorViews[indexPath.row]
        cell.modelHandler = selectorViews[indexPath.row]
        cell.modelHandler.isUserInteractionEnabled = false
        return cell
        
    }
    
    open func didSelect(selector: ModelHandlerType) {
        fatalError("Must override didSelect")
    }
}