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

import UIKit

@MainActor
/// 单个 Tab 的导航栈，与 `AppRouter` 路径同步并在 push 时隐藏底部 TabBar。
final class TabNavigationController: UINavigationController, UINavigationControllerDelegate {

    let appTab: AppTab
    private let services: AppServices
    private var isSyncingStack = false

    /// 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)
        registerNavigationBridge()
        services.appRouter.router(for: appTab).onChange = { [weak self] in
            self?.syncFromRouterPath()
        }
    }

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

    /// Push 指定应用路由，并同步写入 RouterPath。
    func pushRoute(_ route: AppRoute, animated: Bool = true) {
        let viewController = AppRouteViewControllerFactory.makeViewController(for: route, services: services)
        viewController.hidesBottomBarWhenPushed = route.hidesTabBarWhenPushed
        isSyncingStack = true
        services.appRouter.router(for: appTab).navigate(to: route)
        isSyncingStack = false
        pushViewController(viewController, animated: animated)
    }

    /// navigationController相关逻辑。
    func navigationController(
        _ navigationController: UINavigationController,
        didShow viewController: UIViewController,
        animated: Bool
    ) {
        syncRouterPathFromStack()
    }

    /// 注册NavigationBridge。
    private func registerNavigationBridge() {
        switch appTab {
        case .home:
            UIKitAppNavigation.homeNavigationController = self
        case .profile:
            UIKitAppNavigation.profileNavigationController = self
        default:
            break
        }
    }

    /// 同步FromRouterPath状态。
    private func syncFromRouterPath() {
        guard !isSyncingStack else { return }

        let routerPath = services.appRouter.router(for: appTab)
        let targetDepth = routerPath.path.count
        let currentDepth = max(viewControllers.count - 1, 0)

        if targetDepth > currentDepth {
            // Router 路径变深：按路径依次 push 缺失页面
            for index in currentDepth..<targetDepth {
                let route = routerPath.path[index]
                let viewController = AppRouteViewControllerFactory.makeViewController(for: route, services: services)
                viewController.hidesBottomBarWhenPushed = route.hidesTabBarWhenPushed
                pushViewController(viewController, animated: true)
            }
            return
        }

        if targetDepth < currentDepth {
            // Router 路径变浅：pop 至目标深度
            if targetDepth == 0 {
                popToRootViewController(animated: true)
            } else if targetDepth < viewControllers.count {
                popToViewController(viewControllers[targetDepth], animated: true)
            }
        }
    }

    /// 同步RouterPathFromStack状态。
    private func syncRouterPathFromStack() {
        guard !isSyncingStack else { return }

        let routerPath = services.appRouter.router(for: appTab)
        let depth = max(viewControllers.count - 1, 0)
        if depth < routerPath.path.count {
            isSyncingStack = true
            routerPath.path = Array(routerPath.path.prefix(depth))
            isSyncingStack = false
        }
    }
}