// resizing table view cells on data change

import UIKit

struct MyDataStruct {
	var title: String = ""
	var tapCount: Int = 0
}

class SimpleCell: UITableViewCell {
	
	var callback: ((Int, UITableViewCell)->())?
	
	let theLabel: UILabel = {
		let v = UILabel()
		v.numberOfLines = 0
		v.backgroundColor = .yellow
		return v
	}()
	
	let btn: UIButton = {
		let v = UIButton()
		v.backgroundColor = .systemRed
		return v
	}()
	
	private var title: String = ""
	private var tapCount: Int = 0
	
	override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
		super.init(style: style, reuseIdentifier: reuseIdentifier)
		commonInit()
	}
	required init?(coder: NSCoder) {
		super.init(coder: coder)
		commonInit()
	}
	func setData(_ d: MyDataStruct) -> Void {
		title = d.title
		tapCount = d.tapCount
		theLabel.text = title + " Taps: \(tapCount)"
	}
	func commonInit() -> Void {
		[theLabel, btn].forEach { v in
			v.translatesAutoresizingMaskIntoConstraints = false
			contentView.addSubview(v)
		}
		let g = contentView.layoutMarginsGuide
		
		NSLayoutConstraint.activate([
			
			theLabel.topAnchor.constraint(equalTo: g.topAnchor),
			theLabel.leadingAnchor.constraint(equalTo: g.leadingAnchor),
			theLabel.bottomAnchor.constraint(lessThanOrEqualTo: g.bottomAnchor),
			
			btn.topAnchor.constraint(equalTo: g.topAnchor),
			btn.trailingAnchor.constraint(equalTo: g.trailingAnchor),
			btn.bottomAnchor.constraint(lessThanOrEqualTo: g.bottomAnchor),
			btn.widthAnchor.constraint(equalToConstant: 100.0),
			
			btn.leadingAnchor.constraint(equalTo: theLabel.trailingAnchor, constant: 8.0),
		])
		
		btn.setTitle("Tap Me", for: [])
		btn.addTarget(self, action: #selector(gotTap(_:)), for: .touchUpInside)
	}
	
	@objc func gotTap(_ sender: Any) {
		tapCount += 1
		theLabel.text = title + " Taps: \(tapCount)"
		callback?(tapCount, self)
	}
	
}

class RowSizingTableViewController: UITableViewController {

	var myData: [MyDataStruct] = []
	
    override func viewDidLoad() {
        super.viewDidLoad()
		
		for i in 0..<20 {
			let t = MyDataStruct(title: "Row: \(i)", tapCount: 0)
			myData.append(t)
		}
		
		tableView.register(SimpleCell.self, forCellReuseIdentifier: "cell")
    }

    // MARK: - Table view data source

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

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

	override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
		print(#function, indexPath, myData[indexPath.row])
		return CGFloat(60 + (myData[indexPath.row].tapCount * 20))
	}

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

		cell.setData(myData[indexPath.row])

		cell.callback = { [weak self] n, c in
			guard let self = self,
				  let pth = self.tableView.indexPath(for: c)
			else { return }

			// update data
			self.myData[pth.row].tapCount = n
			
			// both
			//	beginUpdates() / endUpdates()
			// and
			//	performBatchUpdates()
			// seem to work fine...
			
			self.tableView.beginUpdates()
			self.tableView.endUpdates()
			
			//self.tableView.performBatchUpdates(nil, completion: nil)
			
		}
		
        return cell
    }

}