// a replacement for UILabel
class TextViewLabel: UITextView {
	
	public var numberOfLines: Int = 0 {
		didSet {
			textContainer.maximumNumberOfLines = numberOfLines
		}
	}
	public var lineBreakMode: NSLineBreakMode = .byTruncatingTail {
		didSet {
			textContainer.lineBreakMode = lineBreakMode
		}
	}
	
	override init(frame: CGRect, textContainer: NSTextContainer?) {
		super.init(frame: frame, textContainer: textContainer)
		commonInit()
	}
	
	required init?(coder aDecoder: NSCoder) {
		super.init(coder: aDecoder)
		commonInit()
	}
	
	private func commonInit() -> Void {
		isScrollEnabled = false
		isEditable = false
		isSelectable = false
		textContainerInset = UIEdgeInsets.zero
		textContainer.lineFragmentPadding = 0
	}
	
}

class ViewController: UIViewController {
	
	let labelStackView = UIStackView()
	let textViewStackView = UIStackView()
	
	override func viewDidLoad() {
		super.viewDidLoad()
		
		let scrollView = UIScrollView()
		
		let hStack = UIStackView()
		hStack.axis = .horizontal
		hStack.spacing = 8
		hStack.distribution = .fillEqually
		hStack.alignment = .top
		
		[labelStackView, textViewStackView].forEach { v in
			v.axis = .vertical
			v.spacing = 4
			hStack.addArrangedSubview(v)
		}
		
		hStack.translatesAutoresizingMaskIntoConstraints = false
		scrollView.addSubview(hStack)

		scrollView.translatesAutoresizingMaskIntoConstraints = false
		view.addSubview(scrollView)
		
		let g = view.safeAreaLayoutGuide
		let cg = scrollView.contentLayoutGuide
		let fg = scrollView.frameLayoutGuide

		NSLayoutConstraint.activate([
			
			scrollView.topAnchor.constraint(equalTo: g.topAnchor, constant: 20.0),
			scrollView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
			scrollView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
			scrollView.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),

			hStack.topAnchor.constraint(equalTo: cg.topAnchor, constant: 8.0),
			hStack.leadingAnchor.constraint(equalTo: cg.leadingAnchor, constant: 8.0),
			hStack.trailingAnchor.constraint(equalTo: cg.trailingAnchor, constant: -8.0),
			hStack.bottomAnchor.constraint(equalTo: cg.bottomAnchor, constant: -8.0),

			hStack.widthAnchor.constraint(equalTo: fg.widthAnchor, constant: -16.0),
			
		])
		
		let infoFont: UIFont = .italicSystemFont(ofSize: 10.0)
		let testFont: UIFont = .systemFont(ofSize: 12.0)
		
		var testStr: String = "This is some example text to test truncation consistency. At the end of this line, is a pair of newline chars:\n\nA HEADLINE\n\nThe headline was also followed by a pair of newline chars."

		for i in 3...10 {
			
			let infoLabel = UILabel()
			infoLabel.font = infoFont
			infoLabel.text = "UILabel - numLines: \(i)"
			labelStackView.addArrangedSubview(infoLabel)
			
			let v = UILabel()
			v.font = testFont
			v.numberOfLines = i
			v.text = testStr
			v.backgroundColor = .yellow
			v.lineBreakMode = .byTruncatingTail
			labelStackView.addArrangedSubview(v)
			
			labelStackView.setCustomSpacing(16.0, after: v)
			
		}
		
		for i in 3...10 {
			
			let infoLabel = UILabel()
			infoLabel.font = infoFont
			infoLabel.text = "TextViewLabel - numLines: \(i)"
			textViewStackView.addArrangedSubview(infoLabel)
			
			let v = TextViewLabel()
			v.font = testFont
			v.numberOfLines = i
			v.text = testStr
			v.backgroundColor = .cyan
			v.lineBreakMode = .byTruncatingTail
			textViewStackView.addArrangedSubview(v)
			
			textViewStackView.setCustomSpacing(16.0, after: v)
			
		}
		
		scrollView.backgroundColor = UIColor(white: 0.95, alpha: 1.0)
		
	}
	
}