class StackVC: UIViewController {

	var noHeightSVs: [UIStackView] = []
	var withHeightSVs: [UIStackView] = []

	let bottomText: String = "Another label with different content"
	
	var topTexts: [String] = [
		"This is a long label with dynamic content",
		"Here is even more text being changed after the initial display to show how it automatically resizes",
	]
	
	override func viewDidLoad() {
		super.viewDidLoad()

		view.backgroundColor = .systemBackground

		let labelColors: [UIColor] = [.cyan, .green,]

		let topText: String = topTexts.removeFirst()
		topTexts.append(topText)
		
		var sv: UIStackView!
		for _ in 0..<5 {
			sv = UIStackView()
			sv.axis = .vertical
			sv.spacing = 10
			sv.widthAnchor.constraint(equalToConstant: 200.0).isActive = true
			sv.heightAnchor.constraint(equalToConstant: 300.0).isActive = true
			for (str, clr) in zip([topText, bottomText], labelColors) {
				let label = UILabel()
				label.numberOfLines = 0
				label.backgroundColor = clr
				label.text = str
				sv.addArrangedSubview(label)
			}
			withHeightSVs.append(sv)

			sv = UIStackView()
			sv.axis = .vertical
			sv.spacing = 10
			sv.widthAnchor.constraint(equalToConstant: 200.0).isActive = true
			// NO height anchor
			for (str, clr) in zip([topText, bottomText], labelColors) {
				let label = UILabel()
				label.numberOfLines = 0
				label.backgroundColor = clr
				label.text = str
				sv.addArrangedSubview(label)
			}
			noHeightSVs.append(sv)
		}
		
		let g = view.safeAreaLayoutGuide
		
		let instruction = UILabel()
		instruction.font = .italicSystemFont(ofSize: 20.0)
		instruction.text = "Tap anywhere to toggle top label text."
		instruction.translatesAutoresizingMaskIntoConstraints = false
		view.addSubview(instruction)
		NSLayoutConstraint.activate([
			instruction.topAnchor.constraint(equalTo: g.topAnchor, constant: 100.0),
			instruction.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 60.0),
		])

		let titleLabelW = UILabel()
		titleLabelW.text = "Stack Views WITH height constraints:"
		titleLabelW.textColor = .blue
		
		let titleLabelN = UILabel()
		titleLabelN.text = "Stack Views WITHOUT height constraints:"
		titleLabelN.textColor = .blue

		[titleLabelW, titleLabelN].forEach { v in
			v.translatesAutoresizingMaskIntoConstraints = false
			view.addSubview(v)
		}
		
		titleLabelW.topAnchor.constraint(equalTo: instruction.bottomAnchor, constant: 40.0).isActive = true
		titleLabelW.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 60.0).isActive = true

		var prevView: UIStackView!

		prevView = nil
		withHeightSVs.forEach { v in
			v.backgroundColor = .yellow
			v.translatesAutoresizingMaskIntoConstraints = false
			view.addSubview(v)
			v.topAnchor.constraint(equalTo: titleLabelW.bottomAnchor, constant: 40.0).isActive = true
			if prevView == nil {
				v.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 60.0).isActive = true
			} else {
				v.leadingAnchor.constraint(equalTo: prevView.trailingAnchor, constant: 20.0).isActive = true
			}
			prevView = v
		}

		titleLabelN.topAnchor.constraint(equalTo: withHeightSVs[0].bottomAnchor, constant: 60.0).isActive = true
		titleLabelN.leadingAnchor.constraint(equalTo: titleLabelW.leadingAnchor, constant: 0.0).isActive = true
		
		prevView = nil
		noHeightSVs.forEach { v in
			v.backgroundColor = .yellow
			v.translatesAutoresizingMaskIntoConstraints = false
			view.addSubview(v)
			v.topAnchor.constraint(equalTo: titleLabelN.bottomAnchor, constant: 40.0).isActive = true
			if prevView == nil {
				v.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 60.0).isActive = true
			} else {
				v.leadingAnchor.constraint(equalTo: prevView.trailingAnchor, constant: 20.0).isActive = true
			}
			prevView = v
		}

		let dists: [UIStackView.Distribution] = [
			.fill, .equalSpacing, .equalCentering, .fillEqually, .fillProportionally,
		]
		for (sv, d) in zip(withHeightSVs, dists) {
			sv.distribution = d
		}
		for (sv, d) in zip(noHeightSVs, dists) {
			sv.distribution = d
		}
		
		let infos: [String] = [
			".fill", ".equalSpacing", ".equalCentering", ".fillEqually", ".fillProportionally",
		]

		for (str, sv) in zip(infos, withHeightSVs) {
			let label = UILabel()
			label.font = .systemFont(ofSize: 16, weight: .bold)
			label.textColor = .red
			label.textAlignment = .center
			label.text = str
			label.translatesAutoresizingMaskIntoConstraints = false
			view.addSubview(label)
			NSLayoutConstraint.activate([
				label.leadingAnchor.constraint(equalTo: sv.leadingAnchor),
				label.trailingAnchor.constraint(equalTo: sv.trailingAnchor),
				label.bottomAnchor.constraint(equalTo: sv.topAnchor, constant: -8.0),
			])
		}
		for (str, sv) in zip(infos, noHeightSVs) {
			let label = UILabel()
			label.font = .systemFont(ofSize: 16, weight: .bold)
			label.textColor = .red
			label.textAlignment = .center
			label.text = str
			label.translatesAutoresizingMaskIntoConstraints = false
			view.addSubview(label)
			NSLayoutConstraint.activate([
				label.leadingAnchor.constraint(equalTo: sv.leadingAnchor),
				label.trailingAnchor.constraint(equalTo: sv.trailingAnchor),
				label.bottomAnchor.constraint(equalTo: sv.topAnchor, constant: -8.0),
			])
		}
		
	}
	
	override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
		
		let topText: String = topTexts.removeFirst()
		topTexts.append(topText)

		withHeightSVs.forEach { sv in
			if let v = sv.arrangedSubviews.first as? UILabel {
				v.text = topText
			}
		}
		noHeightSVs.forEach { sv in
			if let v = sv.arrangedSubviews.first as? UILabel {
				v.text = topText
			}
		}
	}
	
}