import Combine
import SwiftUI

class AppIconHelper: ObservableObject {

    static let shared = AppIconHelper()

    @Published var isDarkMode: Bool = false

    private init() {
    }

    func updateDarkModeStatus(for colorScheme: ColorScheme) {
        isDarkMode = colorScheme == .dark
    }

    func isInDarkMode(for colorScheme: ColorScheme) -> Bool {
        return colorScheme == .dark
    }

    var supportsModernIconFeatures: Bool {
        if #available(iOS 17.0, *) {
            return true
        }
        return false
    }

    func getRecommendedIconVariant(for colorScheme: ColorScheme) -> IconVariant {
        if colorScheme == .dark {
            return .dark
        }
        return .standard
    }

    var supportsAlternateIcons: Bool {
        if #available(iOS 10.3, *) {
            return true
        }
        return false
    }
}

enum IconVariant {
    case standard
    case dark
    case tinted

    var description: String {
        switch self {
        case .standard:
            return "Standard"
        case .dark:
            return "Dark Mode"
        case .tinted:
            return "Tinted"
        }
    }
}

enum AppIconError: Error, LocalizedError {
    case notSupported
    case invalidIconName
    case systemError(Error)

    var errorDescription: String? {
        switch self {
        case .notSupported:
            return "Alternate icons are not supported on this device"
        case .invalidIconName:
            return "The specified icon name is invalid"
        case .systemError(let error):
            return "System error: \(error.localizedDescription)"
        }
    }
}

struct IconAppearanceModifier: ViewModifier {
    @Environment(\.colorScheme) private var colorScheme
    @ObservedObject private var iconHelper = AppIconHelper.shared
    let onChange: (IconVariant) -> Void

    func body(content: Content) -> some View {
        content
            .onChange(of: colorScheme) {
                iconHelper.updateDarkModeStatus(for: colorScheme)
                onChange(iconHelper.getRecommendedIconVariant(for: colorScheme))
            }
            .onAppear {
                iconHelper.updateDarkModeStatus(for: colorScheme)
                onChange(iconHelper.getRecommendedIconVariant(for: colorScheme))
            }
    }
}

extension View {
    func onIconAppearanceChange(_ onChange: @escaping (IconVariant) -> Void) -> some View {
        modifier(IconAppearanceModifier(onChange: onChange))
    }
}

#if DEBUG
    extension AppIconHelper {
        static var preview: AppIconHelper {
            let helper = AppIconHelper()
            helper.isDarkMode = false
            return helper
        }

        static var darkModePreview: AppIconHelper {
            let helper = AppIconHelper()
            helper.isDarkMode = true
            return helper
        }
    }
#endif