import SwiftUI

/// Central app state — drives navigation between Login → Business Select → Scan
@MainActor
final class AppState: ObservableObject {

    enum Screen {
        case login
        case businessList
        case scan(business: Business)
    }

    @Published var currentScreen: Screen = .login
    @Published var token: String?
    @Published var userId: String?

    /// When true, skip auto-navigation in BusinessListView (user explicitly went back)
    var skipAutoNav = false

    init() {
        // Restore saved session
        if let saved = SecureStorage.loadSession() {
            self.token = saved.token
            self.userId = saved.userId
            self.currentScreen = .businessList
        }
    }

    func didLogin(token: String, userId: String) {
        self.token = token
        self.userId = userId
        SecureStorage.saveSession(token: token, userId: userId)
        currentScreen = .businessList
    }

    func selectBusiness(_ business: Business) {
        AppPrefs.lastBusinessId = business.id
        currentScreen = .scan(business: business)
    }

    func backToBusinessList() {
        AppPrefs.lastBusinessId = nil
        skipAutoNav = true
        currentScreen = .businessList
    }

    func logout() {
        token = nil
        userId = nil
        SecureStorage.clearSession()
        currentScreen = .login
    }
}