import SwiftUI
import NetworkExtension
import ProxyCore

@Observable
@MainActor
final class AppState {
    var vpnStatus: NEVPNStatus = .disconnected
    var isCertificateInstalled: Bool = false
    var isCertificateTrusted: Bool = false

    private var vpnManager: NETunnelProviderManager?
    private var statusObservation: NSObjectProtocol?

    init() {
        Task {
            await loadVPNManager()
        }
    }

    func loadVPNManager() async {
        do {
            let managers = try await NETunnelProviderManager.loadAllFromPreferences()
            if let existing = managers.first {
                vpnManager = existing
            } else {
                let manager = NETunnelProviderManager()
                let proto = NETunnelProviderProtocol()
                proto.providerBundleIdentifier = ProxyConstants.extensionBundleIdentifier
                proto.serverAddress = ProxyConstants.proxyHost
                manager.protocolConfiguration = proto
                manager.localizedDescription = "Proxy"
                manager.isEnabled = true
                try await manager.saveToPreferences()
                try await manager.loadFromPreferences()
                vpnManager = manager
            }
            observeVPNStatus()
            vpnStatus = vpnManager?.connection.status ?? .disconnected
        } catch {
            print("[AppState] Failed to load VPN manager: \(error)")
        }
    }

    func toggleVPN() async {
        guard let manager = vpnManager else {
            await loadVPNManager()
            return
        }

        switch manager.connection.status {
        case .connected, .connecting:
            manager.connection.stopVPNTunnel()
        case .disconnected, .invalid:
            do {
                // Ensure saved and fresh before starting
                manager.isEnabled = true
                try await manager.saveToPreferences()
                try await manager.loadFromPreferences()
                try manager.connection.startVPNTunnel()
            } catch {
                print("[AppState] Failed to start VPN: \(error)")
            }
        default:
            break
        }
    }

    var isVPNConnected: Bool {
        vpnStatus == .connected
    }

    var vpnStatusText: String {
        switch vpnStatus {
        case .connected: "Connected"
        case .connecting: "Connecting..."
        case .disconnecting: "Disconnecting..."
        case .disconnected: "Disconnected"
        case .invalid: "Not Configured"
        case .reasserting: "Reconnecting..."
        @unknown default: "Unknown"
        }
    }

    private func observeVPNStatus() {
        guard let manager = vpnManager else { return }

        // Remove existing observer
        if let existing = statusObservation {
            NotificationCenter.default.removeObserver(existing)
        }

        statusObservation = NotificationCenter.default.addObserver(
            forName: .NEVPNStatusDidChange,
            object: manager.connection,
            queue: .main
        ) { [weak self] _ in
            Task { @MainActor in
                self?.vpnStatus = manager.connection.status
            }
        }
    }
}