import SwiftUI

// MARK: - View ▸ Appearance

/// View ▸ Appearance — Auto / Light / Dark (11-command-nexus.md ▸ View; 03-board-ui.md ▸ Toolbar).
///
/// **App-wide and always enabled**, unlike `ZoomCommands` beside it in the View menu: appearance is a
/// preference about how *every* window in the app draws, welcome included, so this row needs no
/// `@FocusedValue` scoping and no board window in front — `NewBoardCommand`'s posture (everywhere, no
/// focus required) rather than `ZoomCommands`' (board windows only).
///
/// A `Picker` rather than three independent toggles: SwiftUI renders one placed directly in a
/// menu-bar command group as a submenu — "Appearance" as its title, "Auto" / "Light" / "Dark" as its
/// rows, a checkmark on whichever is selected — which is the three-way exclusive choice a trio of
/// `Toggle`s cannot express (nothing stops more than one, or none, from reading as checked). `nil` is
/// the Auto tag; `AppearanceStore.setOverride` is the single write path the board-toolbar item shares
/// (`BoardZoomStore.step`'s rule — a toolbar item is a menu command with a different face, never a
/// second implementation of it).
struct AppearanceCommands: View {

    /// A plain `let` rather than an `@Environment` read, `ZoomCommands`' reason: menu commands live in
    /// the menu bar, outside every scene's environment; the row re-renders on a change because
    /// `AppModel` is `@Observable` (`NewBoardCommand`'s pattern).
    let appModel: AppModel

    var body: some View {
        Picker("Appearance", selection: Binding(
            get: { appModel.appearance.override },
            set: { appModel.appearance.setOverride($0) }
        )) {
            Text("Auto").tag(nil as AppAppearance?)
            Text("Light").tag(AppAppearance.light as AppAppearance?)
            Text("Dark").tag(AppAppearance.dark as AppAppearance?)
        }
    }
}
