TappableUILabelDemoViewController.swift

//
//  TappableUILabelDemoViewController.swift
//  Label Link Test
//
//  Created by Kyle Howells on 2024-03-20.
//

import UIKit


// MARK: - TappableUILabelDemoViewController

class TappableUILabelDemoViewController: UIViewController {
	
	// MARK: - Setup View
	
	override func loadView() {
		self.view = MainView()
	}
	
	var _view: MainView {
		return self.view as! MainView
	}
	
	override func viewDidLoad() {
		super.viewDidLoad()
		
		let tapGesture = UITapGestureRecognizer.init(target: self, action: #selector(self.tappedOnLabel(tapGesture: )))
		self._view.label.addGestureRecognizer(tapGesture)
	}
	
	
	// MARK: - Tap Label
	
	@objc func tappedOnLabel(tapGesture: UITapGestureRecognizer) {
		guard tapGesture.state == .recognized else { return }
		
		print("tapGesture.state: \(tapGesture.state)")
		
		let locationOfTouchInLabel: CGPoint = tapGesture.location(in: self._view.label)
		
		print("self.tapLabel( locationOfTouchInLabel: \(locationOfTouchInLabel) )")
		
		let label: UILabel = self._view.label
		
		let attributedText: NSAttributedString = label.attributedText!
		
		// Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
		let layoutManager: NSLayoutManager = NSLayoutManager()
		let textContainer: NSTextContainer = NSTextContainer(size: CGSize.zero)
		let textStorage: NSTextStorage = NSTextStorage(attributedString: attributedText)
		
		// Configure layoutManager and textStorage
		layoutManager.addTextContainer(textContainer)
		textStorage.addLayoutManager(layoutManager)
		
		// Configure textContainer
		textContainer.lineFragmentPadding = 0.0
		textContainer.lineBreakMode = label.lineBreakMode
		textContainer.maximumNumberOfLines = label.numberOfLines
		
		let labelSize: CGSize = label.bounds.size
		textContainer.size = labelSize
		
		let textBoundingBox: CGRect = layoutManager.usedRect(for: textContainer)
		
		// - NSTextStorage
		
		let textContainerOffset: CGPoint = CGPoint(
			x: (labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x,
			y: (labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y
		)
		
		let locationOfTouchInTextContainer: CGPoint = CGPoint(
			x: locationOfTouchInLabel.x - textContainerOffset.x,
			y: locationOfTouchInLabel.y - textContainerOffset.y
		)
		
		let indexOfCharacter: Int = layoutManager.characterIndex(
			for: locationOfTouchInTextContainer,
			in: textContainer,
			fractionOfDistanceBetweenInsertionPoints: nil
		)
		
		let attachment = attributedText.attribute(.attachment, at: indexOfCharacter, effectiveRange: nil)
		
		print("attachment: \(attachment) - \( type(of: attachment) )")
		
		if let textLink: String = attachment as? String,
		   let url: URL = URL(string: textLink)
		{
			UIApplication.shared.open(url)
		}
	}
	
}


// MARK: - View

class MainView: UIView {
	
	// MARK: - Views
	
	let label: UILabel = {
		let label = UILabel()
		label.isUserInteractionEnabled = true
		
		label.adjustsFontSizeToFitWidth = true
		label.numberOfLines = 0
		
		label.textColor = UIColor(white: 0, alpha: 1)
		label.tintColor = UIColor.red
		
		label.textAlignment = .center
		
		let fontSize: CGFloat = 20
		
		label.font = UIFont.systemFont(ofSize: fontSize, weight: .medium)
		
		// - Attributes
		
		let attributes: [NSAttributedString.Key : Any] = [
			.font : UIFont.systemFont(ofSize: fontSize, weight: .regular),
			.foregroundColor: UIColor(white: 0, alpha: 0.6)
		]
		
		let linkAttributes: [NSAttributedString.Key : Any] = [
			.font : UIFont.systemFont(ofSize: fontSize, weight: .medium),
			.foregroundColor: UIColor(white: 0, alpha: 1),
			.attachment: "https://google.com"
		]
		
		let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: "", attributes: attributes)
		
		attributedString.append(NSAttributedString(
			string: "Hello",
			attributes: attributes
		))
		
		attributedString.append(NSAttributedString(
			string: " World ",
			attributes: linkAttributes
		))
		
		attributedString.append(NSAttributedString(
			string: "Testing",
			attributes: attributes
		))
		
		label.attributedText = attributedString
		
		label.layer.borderWidth = 1
		label.layer.borderColor = UIColor(white: 0, alpha: 1).cgColor
		
		return label
	}()
	
	
	// MARK: - Setup
	
	override init(frame: CGRect) {
		super.init(frame: frame)
		self.commonInit()
	}
	
	required init?(coder: NSCoder) {
		super.init(coder: coder)
		self.commonInit()
	}
	
	func commonInit() {
		self.backgroundColor = UIColor(white: 1, alpha: 1)
		
		self.addSubview(self.label)
	}
	
	
	// MARK: - Layout
	
	override func layoutSubviews() {
		super.layoutSubviews()
		let size = self.bounds.size
		let safeArea = self.safeAreaInsets
		
		let contentBounds = self.bounds.inset(by: safeArea)
		
		self.label.frame = {
			//let labelSize = self.label.sizeThatFits(size)
			
			var frame = CGRect()
			frame.size.width = size.width
			frame.size.height = contentBounds.height * 0.5
			frame.origin.y = contentBounds.minY
			return frame
		}()
	}
	
}


// MARK: - Swift Preview

#if DEBUG

// Not meant to be touched. Updates itself because of the binding
import SwiftUI

struct TappableUILabelDemoViewController_Preview: PreviewProvider {
	static var previews: some View {
		return Wrapper(noOp: Binding.constant("no-op"))
			.edgesIgnoringSafeArea(.all)
			.previewDisplayName("TappableUILabelDemoViewController")
	}
}

// Could probably use a generic, for easier reuse
fileprivate struct Wrapper: UIViewControllerRepresentable {
	
	@Binding var noOp: String // no-op -> binding just to trigger updateUIView
	
	func makeUIViewController(context: Context) -> UIViewController {
		return TappableUILabelDemoViewController()
	}
	
	func updateUIViewController(_ uiViewController: UIViewController, context: Context) {
		uiViewController.view.setNeedsLayout()
		uiViewController.view.layoutIfNeeded()
	}
}

#endif