import AppKit

@MainActor
final class AppDelegate: NSObject, NSApplicationDelegate {
    private var appearanceObservation: NSKeyValueObservation?

    func applicationDidFinishLaunching(_ notification: Notification) {
        appearanceObservation = NSApp.observe(
            \.effectiveAppearance,
            options: [.initial, .new]
        ) { [weak self] _, _ in
            Task { @MainActor in
                self?.applyIconForCurrentAppearance()
            }
        }
    }

    private func applyIconForCurrentAppearance() {
        let match = NSApp.effectiveAppearance.bestMatch(from: [.darkAqua, .aqua])
        let resourceName = match == .darkAqua ? "DataTestIcon-Dark" : "DataTestIcon"
        guard let url = Bundle.main.url(forResource: resourceName, withExtension: "icns"),
              let image = NSImage(contentsOf: url) else {
            return
        }
        NSApp.applicationIconImage = image
    }
}