import UIKit

class TimersViewController: UIViewController {

    @IBOutlet weak var tableView: BaseTableView!

    var timerArr = [Int]()

    let cellId = "cellId"

    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .blue

        setupTableView()

        setupNavigationBar()
    }

    fileprivate func setupNavigationBar() {
        let add = UIBarButtonItem(title: "Add", style: .plain, target: self, action: #selector(onAddClicked))

        navigationItem.rightBarButtonItems = [add]
    }

    @objc
    fileprivate func onAddClicked() {
        self.timerArr.append(100)

        tableView.reloadAsync()
    }

    fileprivate func setupTableView() {
        tableView.backgroundColor = UIColor.red.withAlphaComponent(0.3)

        tableView.delegate = self
        tableView.dataSource = self

        tableView.register(CustomCell.self, forCellReuseIdentifier: cellId)
    }
}

extension TimersViewController: UITableViewDelegate,UITableViewDataSource {

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.timerArr.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! CustomCell

        cell.configure(with: self.timerArr[indexPath.row])

        cell.handler = {[weak self] (counter) in
            print(indexPath.row , counter)

            self?.timerArr[indexPath.row] = counter
        }

        return cell
    }
}


class CustomCell: UITableViewCell {
    //MARK: Outlets
    @IBOutlet weak var label: UILabel!

    //MARK: Internal Properties
    var handler: ((Int)->())?

    //MARK: Private Properties
    private var timer: Timer?
    private var counter = 100 {
        didSet {
            DispatchQueue.main.async {
                self.lblTitle.text = "\(self.counter)"

                self.handler?(self.counter)
            }
        }
    }

    fileprivate var lblTitle: UILabel = {
        let lbl = UILabel()
        lbl.font = UIFont.systemFont(ofSize: 50)

        return lbl
    }()

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        commonInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        commonInit()
    }

    fileprivate func commonInit() {
        self.setupView()
    }

    //MARK: Internal Methods
    func configure(with counter: Int) {

        self.lblTitle.text = "\(counter)"

        self.counter = counter

        self.setTimer()
    }

    //MARK: Private Methods
    private func setTimer() {
        self.timer?.invalidate()
        self.timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true, block: {[weak self] (timer) in
            if let counter = self?.counter, counter > 0 {
                self?.counter -= 1

            } else {
                timer.invalidate()
            }
        })
    }

    fileprivate func setupView() {
        //This sets the label equal to superview with padding
        lblTitle.safeArea(equalTo: self, padding: 10)
    }
}

class BaseTableView: UITableView {
    override init(frame: CGRect, style: UITableView.Style) {
        super.init(frame: frame, style: style)

        commonInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        commonInit()
    }

    fileprivate func commonInit() {
        tableFooterView = UIView()
    }
}


extension UITableView {
    func reloadAsync() {
        DispatchQueue.main.async {
            self.reloadData()
        }
    }
}