cloud-dns-ios/dns/ViewModel.swift

//
//  ViewModel.swift
//  dns
//
//  Created by Benjamin Erhart on 14.04.26.
//

import Foundation
import Combine
import NetworkExtension
import OSLog

class ViewModel: NSObject, ObservableObject {

    // TODO: Store this in UserDefaults
    @Published
    var blocklist: BlocklistOption = .secure

    // TODO: Store this in UserDefaults
    @Published
    var isDnsEnabled = false {
        didSet {
            if !isProgrammaticChange {
                toggleDns()
            }
            else {
                // Reset, so next one is recognized as coming from the user again.
                isProgrammaticChange = false
            }
        }
    }

    private var isProgrammaticChange = false


    private let manager = NEDNSSettingsManager.shared()

    private let log = Logger(subsystem: String(describing: ViewModel.self), category: String(describing: ViewModel.self))


    func toggleDns() {
        Task {
            if isDnsEnabled {
                do {
                    try await manager.loadFromPreferences()
                }
                catch {
                    log.error("Error loading preferences: \(error)")

                    delayedToggle(false)

                    return
                }

                let settings = NEDNSOverHTTPSSettings(servers: [blocklist.ipv4, blocklist.ipv6])
                settings.serverURL = URL(string: "https://\(blocklist.server)")
                settings.matchDomains = [""]


                manager.dnsSettings = settings
                manager.localizedDescription = blocklist.description

                do {
                    try await manager.saveToPreferences()
                }
                catch {
                    log.error("Error storing preferences: \(error)")

                    delayedToggle(false)
                }
            }
            else {
                do {
                    try await manager.removeFromPreferences()
                }
                catch {
                    log.error("Error removing preferences: \(error)")

                    delayedToggle(true)
                }
            }
        }
    }

    private func delayedToggle(_ enabled: Bool) {
        Task {
            try? await Task.sleep(nanoseconds: 500_000_000)

            await MainActor.run {
                isProgrammaticChange = true
                isDnsEnabled = enabled
            }
        }
    }
}