import SwiftUI

@main
struct RouterOSAssistantApp: App {
    @StateObject private var connectionService = ConnectionService()
    @StateObject private var manualNavigator = ManualNavigator()
    /// Manual language override — independent of the system locale, per the user's explicit
    /// request for an in-app toggle button. `.environment(\.locale, ...)` does NOT make
    /// `Text(LocalizedStringKey)` re-resolve against Localizable.xcstrings at runtime (confirmed
    /// live: toggling had no visible effect), so views read this same AppStorage key directly and
    /// translate via `L10n.t(_:_:)` instead.
    @AppStorage("appLanguage") private var appLanguage: String = "de"
    @AppStorage(AppPreferences.textSizeKey) private var textSizeRaw: String = AppTextSize.standard.rawValue
    @AppStorage(AppPreferences.uiDensityKey) private var uiDensityRaw: String = UIDensity.standard.rawValue

    init() {
        AppPreferences.registerDefaults()
    }

    var body: some Scene {
        WindowGroup {
            TabView {
                ConnectView(connectionService: connectionService)
                    .tabItem { Label(L10n.t("Verbinden", appLanguage), systemImage: "network") }
                SetupView(connectionService: connectionService)
                    .tabItem { Label(L10n.t("Einrichten", appLanguage), systemImage: "checklist") }
                OverviewView(connectionService: connectionService)
                    .tabItem { Label(L10n.t("Übersicht", appLanguage), systemImage: "point.3.connected.trianglepath.dotted") }
                DevicesView(connectionService: connectionService)
                    .tabItem { Label(L10n.t("LAN-Scanner", appLanguage), systemImage: "laptopcomputer.and.iphone") }
                ExpertView(connectionService: connectionService)
                    .tabItem { Label(L10n.t("Experte", appLanguage), systemImage: "wrench.and.screwdriver") }
                BackupListView(connectionService: connectionService)
                    .tabItem { Label(L10n.t("Sicherungen", appLanguage), systemImage: "clock.arrow.circlepath") }
            }
            .toolbar {
                ToolbarItem {
                    Button {
                        appLanguage = (appLanguage == "de") ? "en" : "de"
                    } label: {
                        // Flag of the language a tap switches TO — matches the "DE"/"EN" text
                        // labels this replaces, which showed the same "switch to" target.
                        Text(appLanguage == "de" ? "🇬🇧" : "🇩🇪")
                    }
                    .help(appLanguage == "de" ? "Switch to English" : "Auf Deutsch umschalten")
                }
            }
            .controlSize((UIDensity(rawValue: uiDensityRaw) ?? .standard).controlSize)
            .environment(\.appFontScale, (AppTextSize(rawValue: textSizeRaw) ?? .standard).scale)
            // Fallback for every `Text`/`TextField`/`Label` that has no explicit `.font(...)` of
            // its own (confirmed live: the Experte tab's whole sidebar list and every Parameter/
            // Wert `TextField` have none — `.appFont(...)` only touches call sites that already
            // had a `.font(...)` to replace, so unstyled text stayed fixed-size). `.environment
            // (\.font, ...)` only ever supplies a *default*: anywhere `.appFont(...)` already sets
            // an explicit font, that still wins.
            .environment(\.font, .system(size: 13 * ((AppTextSize(rawValue: textSizeRaw) ?? .standard).scale)))
            .environmentObject(manualNavigator)
        }
        .environment(\.locale, Locale(identifier: appLanguage))

        Settings {
            SettingsView()
                .environmentObject(manualNavigator)
        }

        Window(L10n.t("Handbuch", appLanguage), id: "manual") {
            ManualView()
                .environmentObject(manualNavigator)
        }
    }
}