import SwiftUI

// Enum to represent the three theme options
enum Theme: String, CaseIterable {
    case system = "System"
    case light = "Light"
    case oledDark = "Oled"
//    case dark = "Dark" // TODO
    
    var colorScheme: ColorScheme? {
        switch self {
        case .system:
            return nil
        case .light:
            return .light
        case .oledDark:
            return .dark
        }
    }
}

// Observable class to manage the theme state
class ThemeManager: ObservableObject {
    @AppStorage("selectedTheme") private var selectedThemeValue: String = Theme.system.rawValue
    
    @Published var theme: Theme
    
    init() {
        // Read directly from UserDefaults to avoid using self before initialization is complete.
        let storedThemeValue = UserDefaults.standard.string(forKey: "selectedTheme") ?? ""
        self.theme = Theme(rawValue: storedThemeValue) ?? .system
    }
    
    func setTheme(_ theme: Theme) {
        self.theme = theme
        selectedThemeValue = theme.rawValue
    }
    
    // This will be called from the button
    func toggleTheme(from currentSystemScheme: ColorScheme) {
        let newTheme: Theme
        
        switch theme {
        case .system:
            // If system is active, toggle to the opposite of the current system theme
            newTheme = currentSystemScheme == .dark ? .light : .oledDark
        case .light:
            newTheme = .oledDark
        case .oledDark:
            newTheme = .light
        }
        setTheme(newTheme)
    }
}