libnovel/ios/LibNovel/LibNovel/Extensions/NavDestination.swift

import SwiftUI

// MARK: - Navigation destination enum used across all tabs

enum NavDestination: Hashable {
    case book(String)               // slug
    case chapter(String, Int)       // slug + chapter number
}

// MARK: - View extensions for shared navigation + error alert patterns

extension View {
    /// Registers the app-wide navigation destinations for NavDestination values.
    /// Apply once per NavigationStack instead of repeating the switch in every tab.
    func appNavigationDestination() -> some View {
        navigationDestination(for: NavDestination.self) { dest in
            switch dest {
            case .book(let slug): BookDetailView(slug: slug)
            case .chapter(let slug, let n): ChapterReaderView(slug: slug, chapterNumber: n)
            }
        }
    }

    /// Presents a standard "Error" alert driven by an optional String binding.
    /// Dismissing the alert sets the binding back to nil.
    func errorAlert(_ error: Binding<String?>) -> some View {
        alert("Error", isPresented: Binding(
            get: { error.wrappedValue != nil },
            set: { if !$0 { error.wrappedValue = nil } }
        )) {
            Button("OK") { error.wrappedValue = nil }
        } message: {
            Text(error.wrappedValue ?? "")
        }
    }
}