import SwiftUI

/// The tab bar, a navigation stack per tab, the mini player and the Now Playing sheet.
struct RootView: View {
    @State private var ui = Ui(overlays: Overlays())
    private var g: AppGraph { .shared }

    var body: some View {
        let s = g.settings
        let p = Palette.of(s.theme, s.accent)
        TabView(selection: Binding(get: { ui.tab }, set: { ui.selectTab($0) })) {
            ForEach(Tab.allCases, id: \.self) { t in
                NavigationStack(path: ui.path(t)) {
                    root(t).miniPlayerRoom()
                        .navigationDestination(for: Route.self) { destination($0).miniPlayerRoom() }
                }
                // Floats over the screens; each screen leaves room for it so nothing ends up underneath.
                .overlay(alignment: .bottom) {
                    if g.playback.current != nil { MiniPlayer().transition(.move(edge: .bottom).combined(with: .opacity)) }
                }
                .animation(.spring(duration: 0.35), value: g.playback.current != nil)
                .tabItem { Label(t.rawValue, systemImage: t.icon) }
                .tag(t)
            }
        }
        .sheet(isPresented: Binding(get: { ui.nowPlayingOpen }, set: { ui.nowPlayingOpen = $0 })) {
            NowPlayingScreen()
                .overlayHost(ui.overlays, level: 1)
                .environment(ui)
                .environment(\.palette, p)
                .preferredColorScheme(s.theme == .White ? .light : .dark)
                .tint(p.accent)
        }
        .overlayHost(ui.overlays, level: 0)
        .onChange(of: g.playback.message) { _, m in
            if let m { ui.overlays.hud(m.text, "info.circle") }
        }
        .environment(ui)
        .environment(\.palette, p)
        .preferredColorScheme(s.theme == .White ? .light : .dark)
        .tint(p.accent)
    }

    @ViewBuilder private func root(_ t: Tab) -> some View {
        switch t {
        case .Library: LibraryHome()
        case .Playlists: PlaylistsScreen()
        case .Search: SearchScreen()
        case .Downloads: DownloadsScreen()
        case .Settings: SettingsScreen()
        }
    }

    @ViewBuilder private func destination(_ r: Route) -> some View {
        switch r {
        case .Artists: ArtistsScreen()
        case .Albums: AlbumsScreen()
        case .Songs: SongsScreen()
        case .Playlists: PlaylistsScreen()
        case .Eq: EqScreen()
        case .EqFilters(let id): EqFiltersScreen(profileId: id)
        case .EqFilterPage(let id, let f): EqFilterPage(profileId: id, filterId: f)
        case .PlexAccount: PlexAccountScreen()
        case .StemServer: StemServerScreen()
        case .Quality: QualityScreen()
        case .Storage: StorageScreen()
        case .Appearance: AppearanceScreen()
        case .ArtistPage(let a): ArtistScreen(artist: a)
        case .AlbumPage(let a): AlbumScreen(album: a)
        case .PlaylistPage(let pl): PlaylistScreen(playlist: pl)
        }
    }
}

private struct MiniPlayerRoom: ViewModifier {
    private var g: AppGraph { .shared }
    func body(content: Content) -> some View {
        content.safeAreaInset(edge: .bottom, spacing: 0) {
            if g.playback.current != nil { Color.clear.frame(height: 66) }
        }
    }
}

private extension View {
    func miniPlayerRoom() -> some View { modifier(MiniPlayerRoom()) }
}