//
//  ScenicQueueSettingChangeLogViewController.swift
//  suixinkan
//

import SnapKit
import UIKit

/// 排队配置日志页，按 Android 时间轴样式展示变更历史。
final class ScenicQueueSettingChangeLogViewController: BaseViewController {
    private let viewModel = ScenicQueueSettingChangeLogViewModel()
    private let api: ScenicQueueAPIProtocol
    private let tableView = UITableView(frame: .zero, style: .plain)
    private let emptyLabel = UILabel()
    private let loadingIndicator = UIActivityIndicatorView(style: .medium)
    private let footerLabel = UILabel()
    private var dataSource: UITableViewDiffableDataSource<Int, ScenicQueueSettingChangeLogItem>!

    @MainActor
    init(api: ScenicQueueAPIProtocol? = nil) {
        self.api = api ?? NetworkServices.shared.scenicQueueAPI
        super.init(nibName: nil, bundle: nil)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }

    override func viewDidLoad() {
        super.viewDidLoad()
        Task { await viewModel.refresh(api: api) }
    }

    override func setupNavigationBar() { title = "配置日志" }

    override func setupUI() {
        view.backgroundColor = .white
        tableView.backgroundColor = .white
        tableView.separatorStyle = .none
        tableView.rowHeight = UITableView.automaticDimension
        tableView.estimatedRowHeight = 132
        tableView.delegate = self
        tableView.register(ScenicQueueLogTimelineCell.self, forCellReuseIdentifier: ScenicQueueLogTimelineCell.reuseIdentifier)
        tableView.refreshControl = UIRefreshControl()
        tableView.refreshControl?.addTarget(self, action: #selector(refreshPulled), for: .valueChanged)
        dataSource = UITableViewDiffableDataSource<Int, ScenicQueueSettingChangeLogItem>(tableView: tableView) { [weak self] tableView, indexPath, item in
            let cell = tableView.dequeueReusableCell(withIdentifier: ScenicQueueLogTimelineCell.reuseIdentifier, for: indexPath) as! ScenicQueueLogTimelineCell
            cell.configure(item: item, showDot: self?.shouldShowDot(at: indexPath.row) ?? false)
            return cell
        }
        emptyLabel.text = "暂无配置变更记录"
        emptyLabel.textColor = AppColor.textSecondary
        emptyLabel.font = ScenicQueueTokens.emptyStateFont
        emptyLabel.textAlignment = .center
        loadingIndicator.color = ScenicQueueTokens.bannerBlue
        footerLabel.textAlignment = .center
        footerLabel.textColor = AppColor.textSecondary
        footerLabel.font = .systemFont(ofSize: 14)
        view.addSubview(tableView)
        view.addSubview(emptyLabel)
        view.addSubview(loadingIndicator)
    }

    override func setupConstraints() {
        tableView.snp.makeConstraints { $0.edges.equalTo(view.safeAreaLayoutGuide) }
        emptyLabel.snp.makeConstraints { $0.center.equalToSuperview() }
        loadingIndicator.snp.makeConstraints { $0.center.equalToSuperview() }
    }

    override func bindActions() {
        viewModel.onStateChange = { [weak self] in Task { @MainActor in self?.applyState() } }
        viewModel.onShowMessage = { [weak self] message in Task { @MainActor in self?.showToast(message) } }
    }

    private func applyState() {
        tableView.refreshControl?.endRefreshing()
        viewModel.initialLoading && viewModel.items.isEmpty ? loadingIndicator.startAnimating() : loadingIndicator.stopAnimating()
        emptyLabel.isHidden = viewModel.initialLoading || viewModel.isRefreshing || !viewModel.items.isEmpty
        var snapshot = NSDiffableDataSourceSnapshot<Int, ScenicQueueSettingChangeLogItem>()
        snapshot.appendSections([0])
        snapshot.appendItems(viewModel.items)
        dataSource.apply(snapshot, animatingDifferences: true)
        if viewModel.items.isEmpty {
            tableView.tableFooterView = UIView()
        } else {
            footerLabel.text = viewModel.isLoadingMore ? "加载中…" : (viewModel.canLoadMore ? "" : "没有更多")
            footerLabel.frame = CGRect(x: 0, y: 0, width: view.bounds.width, height: 52)
            tableView.tableFooterView = footerLabel
        }
    }

    private func shouldShowDot(at index: Int) -> Bool {
        let estimatedRowHeight: CGFloat = 132
        let itemsPerThird = max(1, Int(((view.bounds.height / 3) / estimatedRowHeight).rounded()))
        let stride = max(3, min(12, itemsPerThird))
        return index % stride == 0
    }

    @objc private func refreshPulled() { Task { await viewModel.refresh(api: api) } }
}

extension ScenicQueueSettingChangeLogViewController: UITableViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        guard !viewModel.items.isEmpty,
              scrollView.contentOffset.y > scrollView.contentSize.height - scrollView.bounds.height - 180 else { return }
        Task { await viewModel.loadMore(api: api) }
    }
}

/// 配置日志的时间轴卡片单元格。
final class ScenicQueueLogTimelineCell: UITableViewCell {
    static let reuseIdentifier = "ScenicQueueLogTimelineCell"
    private let rail = UIView()
    private let dot = UIView()
    private let card = UIView()
    private let metaLabel = UILabel()
    private let summaryLabel = UILabel()

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        selectionStyle = .none
        backgroundColor = .white
        rail.backgroundColor = ScenicQueueTokens.timelineLine
        dot.backgroundColor = ScenicQueueTokens.timelineDot
        dot.layer.cornerRadius = 4
        card.backgroundColor = ScenicQueueTokens.logCardBackground
        card.layer.cornerRadius = 12
        metaLabel.font = .systemFont(ofSize: 12)
        metaLabel.textColor = AppColor.textSecondary
        metaLabel.numberOfLines = 3
        summaryLabel.font = .systemFont(ofSize: 15, weight: .semibold)
        summaryLabel.textColor = AppColor.textPrimary
        summaryLabel.numberOfLines = 0
        let stack = UIStackView(arrangedSubviews: [metaLabel, summaryLabel])
        stack.axis = .vertical
        stack.spacing = 8
        contentView.addSubview(rail)
        contentView.addSubview(dot)
        contentView.addSubview(card)
        card.addSubview(stack)
        rail.snp.makeConstraints { make in
            make.centerX.equalTo(contentView.snp.leading).offset(UIScreen.main.bounds.width * 0.10)
            make.top.bottom.equalToSuperview()
            make.width.equalTo(1.5)
        }
        dot.snp.makeConstraints { make in make.centerX.equalTo(rail); make.top.equalToSuperview().offset(18); make.size.equalTo(8) }
        card.snp.makeConstraints { make in
            make.leading.equalTo(rail.snp.trailing).offset(20)
            make.trailing.equalToSuperview().offset(-16)
            make.top.equalToSuperview().offset(6)
            make.bottom.equalToSuperview().offset(-6)
        }
        stack.snp.makeConstraints { $0.edges.equalToSuperview().inset(15) }
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") }

    /// 绑定日志内容与时间轴圆点显隐。
    func configure(item: ScenicQueueSettingChangeLogItem, showDot: Bool) {
        metaLabel.text = item.metadataLine
        summaryLabel.text = item.cardSummary
        dot.isHidden = !showDot
    }
}