//
//  TabNavigationController.swift
//  suixinkan
//

import UIKit

@MainActor
/// 单个 Tab 的 UIKit 导航栈，负责承载该 Tab 内部页面层级。
final class TabNavigationController: UINavigationController {

    let appTab: AppTab
    private let services: AppServices

    /// 初始化实例。
    init(tab: AppTab, services: AppServices) {
        self.appTab = tab
        self.services = services
        super.init(nibName: nil, bundle: nil)
        delegate = self
        navigationBar.prefersLargeTitles = false
        setViewControllers([tab.makeRootViewController(services: services)], animated: false)
    }

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

    /// Push 指定应用路由，并统一设置底部 TabBar 隐藏策略。
    func push(route: AppRoute, animated: Bool = true) {
        let viewController = AppRouteViewControllerFactory.makeViewController(for: route, services: services)
        viewController.hidesBottomBarWhenPushed = route.hidesTabBarWhenPushed
        pushViewController(viewController, animated: animated)
    }

    /// Push 页面时按目标页同步系统导航栏状态，覆盖各页面直接调用系统 push 的场景。
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        updateNavigationBarVisibility(for: viewController, animated: animated)
        super.pushViewController(viewController, animated: animated)
    }

    /// 设置导航栈时按最终栈顶同步系统导航栏状态。
    override func setViewControllers(_ viewControllers: [UIViewController], animated: Bool) {
        if let topViewController = viewControllers.last {
            updateNavigationBarVisibility(for: topViewController, animated: animated)
        }
        super.setViewControllers(viewControllers, animated: animated)
    }

    /// 弹出页面后按新的栈顶同步系统导航栏状态。
    override func popViewController(animated: Bool) -> UIViewController? {
        let poppedViewController = super.popViewController(animated: animated)
        if !animated, let topViewController {
            updateNavigationBarVisibility(for: topViewController, animated: false)
        }
        return poppedViewController
    }

    /// 回到根页面后按根页面同步系统导航栏状态。
    override func popToRootViewController(animated: Bool) -> [UIViewController]? {
        let poppedViewControllers = super.popToRootViewController(animated: animated)
        if !animated, let topViewController {
            updateNavigationBarVisibility(for: topViewController, animated: false)
        }
        return poppedViewControllers
    }

    /// 弹到指定页面后按该页面同步系统导航栏状态。
    override func popToViewController(_ viewController: UIViewController, animated: Bool) -> [UIViewController]? {
        let poppedViewControllers = super.popToViewController(viewController, animated: animated)
        if !animated, let topViewController {
            updateNavigationBarVisibility(for: topViewController, animated: false)
        }
        return poppedViewControllers
    }

    /// 根据页面类型判断系统导航栏是否应隐藏。
    private func shouldHideNavigationBar(for viewController: UIViewController) -> Bool {
        viewController is HomeViewController
    }

    /// 将系统导航栏显示状态同步到目标页面，避免首页隐藏状态泄漏到子页面。
    private func updateNavigationBarVisibility(for viewController: UIViewController, animated: Bool) {
        setNavigationBarHidden(shouldHideNavigationBar(for: viewController), animated: animated)
    }
}

extension TabNavigationController: UINavigationControllerDelegate {
    /// 导航转场即将展示页面时更新系统导航栏显隐状态。
    func navigationController(
        _ navigationController: UINavigationController,
        willShow viewController: UIViewController,
        animated: Bool
    ) {
        updateNavigationBarVisibility(for: viewController, animated: animated)
    }
}