Emphasis Playground

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport

struct Constants {
    static let digraphes = ["ou", "ai", "oi", "on", "en", "an", "ch", "ei", "em", "am"]
}

extension String {
    var digraphs: [String] {
        guard let regex = try? NSRegularExpression(pattern: "\\((.+)\\)") else {
            return []
        }
                
        return regex.matches(in: self, range: .init(startIndex..., in: self)).reduce([]) { digraphs, match in
            if let range = Range(match.range, in: self) {
                return digraphs + Constants.digraphes.filter { self[range].contains($0) }
            } else {
                return digraphs
            }
        }
    }
}

extension Array where Element == String {
    var commonDigraphs: [String] {
        map { $0.digraphs }
            .reduce([], +)
            .reduce(into: [:]) { counts, digraph in counts[digraph, default: 0] += 1 }
            .sorted(by: { $0.value > $1.value })
            .map { $0.key }
    }
}

class MyViewController : UIViewController {
    private let emphasisColor: UIColor = .systemRed

    private let CHWords = ["(ch)u(ch)", "(ch)aton", "(cha)ton", "tor(chon)", "polo(chon)", "mou(choir)"]
    private let ANENWords = ["(chen)(ten)", "(chan)ton", "(ban)(den)", "(pan)(chan)", "(nen)(ran)", "(chen)(dan)", "p(em)b(an)", "(mem)bo", "pi(den)", "re(chan)", "lou(ren)", "(ban)(sen)", "(ram)bé", "(men)tir", "mar(chan?d)", "mé(chan?t)", "début(an?t)", "pim(en?t)"]
    private let AIEIWords = ["(ai)(sei)", "(chai)che", "(chai)gon", "(chei)(chei)", "(bei)choi", "(cai)(bei)"]
    
    private lazy var stackView: UIStackView = {
        let view = UIStackView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.axis = .horizontal
        view.alignment = .top
        view.spacing = UIStackView.spacingUseSystem
        return view
    }()
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        stackView.center = view.center
    }
        
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white
        
        for words in [CHWords, AIEIWords, ANENWords] {
            appendList(for: words)
        }
        
        view.addSubview(stackView)
        self.view = view
    }
    
    private func appendList(for words: [String]) {
        let stackView = UIStackView()
        stackView.translatesAutoresizingMaskIntoConstraints = false
        stackView.axis = .vertical
        stackView.alignment = .center
        stackView.spacing = UIStackView.spacingUseSystem
        
        let digraphs = words.commonDigraphs
        
        for word in words {
            if word.filter({ $0 == "?"}).count % 2 != 0 {
                appendLabel(for: word.appending("?"), withDigraphs: digraphs, in: stackView)
            } else {
                appendLabel(for: word, withDigraphs: digraphs, in: stackView)
            }
        }

        self.stackView.addArrangedSubview(stackView)
    }
    
    private func appendLabel(for word: String, withDigraphs digraphs: [String], in stackView: UIStackView) {
        var attributes = [NSAttributedString.Key : Any]()
        attributes[.font] = UIFont(name: "HelveticaNeue", size: 18)
        attributes[.foregroundColor] = UIColor.black
        attributes[.strikethroughColor] = UIColor.black

        let attributedString = NSMutableAttributedString(string: word, attributes: attributes)
        let range = NSRange(word.startIndex..., in: word)
        
        // Highlighting emphasis part
        
        if let regex = try? NSRegularExpression(pattern: "\\((.+)\\)") {
            for match in regex.matches(in: word, range: range) {
                var attrs = attributes
                attrs[.font] = UIFont(name: "HelveticaNeue-Bold", size: 18)
                attrs[.foregroundColor] = emphasisColor.withAlphaComponent(0.5)
                attributedString.addAttributes(attrs, range: match.range)
                
                if let matchRange = Range(match.range, in: word),
                   let digraph = digraphs.first(where: { word[matchRange].contains($0) }),
                   let digraphRange = word.range(of: digraph) {
                    attrs[.foregroundColor] = emphasisColor
                    attributedString.addAttributes(attrs, range: NSRange(digraphRange, in: word))
                }
            }
        }
        
        // Marking silent letters
        
        if let regex = try? NSRegularExpression(pattern: "\\?(.+)\\?") {
            for match in regex.matches(in: word, range: range) {
                var attrs = attributes
                attrs[.strikethroughStyle] = NSUnderlineStyle.single.rawValue
                attrs[.strikethroughColor] = attributedString.attribute(.foregroundColor, at: <#T##Int#>, effectiveRange: <#T##NSRangePointer?#>)
                attributedString.setAttributes(attributes, range: match.range)
            }
        }
        
        // Deleting separator characters
        
        if let regex = try? NSRegularExpression(pattern: "[(,),?]") {
            for match in regex.matches(in: word, range: range).reversed() {
                attributedString.deleteCharacters(in: match.range)
            }
        }
        
        let label = UILabel()
        label.backgroundColor = .secondarySystemBackground
        label.layer.cornerRadius = 8
        label.clipsToBounds = true
        label.attributedText = attributedString
        
        stackView.addArrangedSubview(label)
    }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()