class TransactionCell: UITableViewCell {
}

class TransactionsHeaderView: UITableViewHeaderFooterView {
    static let reuseId = "CustomHeader"
}

class TransactionsViewController: UIViewController {

    let cellId = "cellID"
    let numSections: Int = 4

    lazy var tableView = UITableView()

    override func viewDidLoad() {
        super.viewDidLoad()

        commonInit()
    }

    private func commonInit() {

        //view.backgroundColor = .clear

        tableView.backgroundColor = .systemBackground
        tableView.rowHeight = 74
        tableView.sectionHeaderHeight = 50

        tableView.register(TransactionCell.self, forCellReuseIdentifier: cellId)
        tableView.register(TransactionsHeaderView.self, forHeaderFooterViewReuseIdentifier: TransactionsHeaderView.reuseId)

        tableView.delegate = self
        tableView.dataSource = self

        tableView.contentInsetAdjustmentBehavior = .never
        tableView.separatorInset = UIEdgeInsets(top: 0, left: 32, bottom: 0, right: 16)
        tableView.tableFooterView = UIView()

        view.addSubview(tableView)

        tableView.translatesAutoresizingMaskIntoConstraints = false

        let g = view.safeAreaLayoutGuide

        NSLayoutConstraint.activate([

            tableView.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
            tableView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            tableView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            tableView.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),

        ])

    }

}

extension TransactionsViewController: UITableViewDelegate, UITableViewDataSource, UIScrollViewDelegate {

    func numberOfSections(in tableView: UITableView) -> Int {
        return numSections // self.sections.count
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return 4 //sections[section].transactions.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        guard let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as? TransactionCell  else {
            fatalError("The dequeued cell is not an instance of HomeTableViewCell.")
        }
        return cell
    }

    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        print(#function, section)

        let header = tableView.dequeueReusableHeaderFooterView(withIdentifier: TransactionsHeaderView.reuseId) as! TransactionsHeaderView
        header.contentView.backgroundColor = .orange
        return header
    }

    func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        print(#function, section)
        return 50
    }

}