language4english/LearnEnglish/LearnEnglish/Views/WordListViewController.swift

import UIKit

final class WordListViewController: UIViewController {
    private let category: WordCategory
    private let colorIndex: Int
    private var words: [Word]
    private var subcategories: [Subcategory]?
    private let tableView = UITableView(frame: .zero, style: .plain)
    private let ctaBackground = UIVisualEffectView(effect: UIBlurEffect(style: .systemMaterial))
    private let quizButton = UIButton(type: .system)
    private var speechObserver: NSObjectProtocol?

    private var displaySubcategories: [Subcategory]? {
        subcategories.flatMap { $0.isEmpty ? nil : $0 }
    }

    init(category: WordCategory, colorIndex: Int) {
        self.category = category
        self.colorIndex = colorIndex
        self.words = category.words
        self.subcategories = category.subcategories
        super.init(nibName: nil, bundle: nil)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) { fatalError() }

    deinit {
        if let speechObserver {
            NotificationCenter.default.removeObserver(speechObserver)
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        title = category.name
        navigationItem.largeTitleDisplayMode = .never
        navigationItem.rightBarButtonItem = UIBarButtonItem(
            image: UIImage(systemName: "arrow.triangle.2.circlepath"),
            style: .plain,
            target: self,
            action: #selector(shuffleWords)
        )
        view.backgroundColor = .systemBackground

        tableView.dataSource = self
        tableView.delegate = self
        tableView.register(WordCardCell.self, forCellReuseIdentifier: "cell")
        tableView.separatorStyle = .none
        tableView.backgroundColor = .systemBackground
        tableView.tableHeaderView = makeHeader()
        tableView.contentInset.bottom = 92
        tableView.verticalScrollIndicatorInsets.bottom = 92

        var buttonConfig = UIButton.Configuration.borderedProminent()
        buttonConfig.title = "开始测验"
        buttonConfig.image = UIImage(systemName: "pencil.and.list.clipboard")
        buttonConfig.imagePadding = 6
        buttonConfig.contentInsets = .init(top: 14, leading: 16, bottom: 14, trailing: 16)
        buttonConfig.background.cornerRadius = Theme.Metrics.controlRadius
        buttonConfig.titleTextAttributesTransformer = .init { incoming in
            var outgoing = incoming
            outgoing.font = .preferredFont(forTextStyle: .headline)
            return outgoing
        }
        quizButton.configuration = buttonConfig
        quizButton.addAction(UIAction { [weak self] _ in self?.startQuiz() }, for: .touchUpInside)

        view.addSubview(tableView)
        view.addSubview(ctaBackground)
        ctaBackground.contentView.addSubview(quizButton)
        tableView.translatesAutoresizingMaskIntoConstraints = false
        ctaBackground.translatesAutoresizingMaskIntoConstraints = false
        quizButton.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            tableView.topAnchor.constraint(equalTo: view.topAnchor),
            tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            tableView.bottomAnchor.constraint(equalTo: view.bottomAnchor),

            ctaBackground.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            ctaBackground.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            ctaBackground.bottomAnchor.constraint(equalTo: view.bottomAnchor),

            quizButton.topAnchor.constraint(equalTo: ctaBackground.contentView.topAnchor, constant: 12),
            quizButton.leadingAnchor.constraint(equalTo: ctaBackground.contentView.leadingAnchor, constant: 16),
            quizButton.trailingAnchor.constraint(equalTo: ctaBackground.contentView.trailingAnchor, constant: -16),
            quizButton.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -12)
        ])

        speechObserver = NotificationCenter.default.addObserver(
            forName: SpeechService.speakingDidChangeNotification, object: nil, queue: .main
        ) { [weak self] _ in
            self?.updateVisibleSpeakers()
        }
    }

    private func makeHeader() -> UIView {
        let color = Theme.Color.category(at: colorIndex)
        let header = UIView(frame: CGRect(x: 0, y: 0, width: 0, height: 56))

        let tile = UIView()
        tile.backgroundColor = color.withAlphaComponent(0.12)
        tile.layer.cornerRadius = 10
        let icon = UIImageView(image: UIImage(systemName: category.icon,
                                              withConfiguration: UIImage.SymbolConfiguration(pointSize: 16, weight: .medium)))
        icon.tintColor = color
        icon.contentMode = .scaleAspectFit
        tile.addSubview(icon)
        header.addSubview(tile)
        tile.translatesAutoresizingMaskIntoConstraints = false
        icon.translatesAutoresizingMaskIntoConstraints = false

        let label = UILabel()
        label.text = "共 \(category.words.count) 个单词"
        label.font = .preferredFont(forTextStyle: .subheadline)
        label.textColor = .secondaryLabel
        header.addSubview(label)
        label.translatesAutoresizingMaskIntoConstraints = false

        NSLayoutConstraint.activate([
            tile.leadingAnchor.constraint(equalTo: header.leadingAnchor, constant: 16),
            tile.centerYAnchor.constraint(equalTo: header.centerYAnchor),
            tile.widthAnchor.constraint(equalToConstant: 32),
            tile.heightAnchor.constraint(equalToConstant: 32),
            icon.centerXAnchor.constraint(equalTo: tile.centerXAnchor),
            icon.centerYAnchor.constraint(equalTo: tile.centerYAnchor),
            label.leadingAnchor.constraint(equalTo: tile.trailingAnchor, constant: 10),
            label.centerYAnchor.constraint(equalTo: header.centerYAnchor)
        ])
        return header
    }

    private func startQuiz() {
        Haptics.selection()
        let quizWords: [Word]
        if category.id == "numbers" {
            quizWords = NumberWords.randomWords(count: 50)
        } else {
            quizWords = words
        }
        let request = QuizSetupRequest(words: quizWords)
        navigationController?.pushViewController(QuizSetupViewController(request: request), animated: true)
    }

    @objc private func shuffleWords() {
        Haptics.selection()
        if var subs = subcategories {
            subs = subs.shuffled().map { sub in
                var s = sub
                s.words = sub.words.shuffled()
                return s
            }
            subcategories = subs
        } else {
            words.shuffle()
        }
        tableView.reloadData()
    }

    private func updateVisibleSpeakers() {
        for cell in tableView.visibleCells.compactMap({ $0 as? WordCardCell }) {
            cell.updateSpeakerState()
        }
    }
}

extension WordListViewController: UITableViewDataSource, UITableViewDelegate {
    func numberOfSections(in tableView: UITableView) -> Int {
        displaySubcategories?.count ?? 1
    }

    func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
        displaySubcategories?[section].name
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if let subs = displaySubcategories {
            return subs[section].words.count
        }
        return words.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! WordCardCell
        let word: Word
        if let subs = displaySubcategories {
            word = subs[indexPath.section].words[indexPath.row]
        } else {
            word = words[indexPath.row]
        }
        cell.configure(with: word)
        cell.onSpeak = { word in
            SpeechService.shared.speak(word.word)
        }
        cell.onLearn = { [weak self] word in
            guard let self else { return }
            let config = QuizConfig(mode: .spelling, words: [word], isStudyMode: true)
            navigationController?.pushViewController(QuizViewController(config: config), animated: true)
        }
        return cell
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        Haptics.selection()
        let word: Word
        if let subs = displaySubcategories {
            word = subs[indexPath.section].words[indexPath.row]
        } else {
            word = words[indexPath.row]
        }
        let detail = WordDetailViewController(word: word, categoryName: category.name)
        navigationController?.pushViewController(detail, animated: true)
    }
}