import AppKit
import ApplicationServices
import AVFoundation
import Combine

/// Reads the three macOS permissions and keeps them current: on every app activation and while polling is on.
@MainActor
final class PermissionMonitor: ObservableObject {
    enum Kind: CaseIterable, Identifiable {
        case microphone, accessibility, inputMonitoring

        var id: Self { self }

        var title: String {
            switch self {
            case .microphone: Strings.microphone
            case .accessibility: Strings.accessibility
            case .inputMonitoring: Strings.inputMonitoring
            }
        }

        fileprivate var pane: String {
            switch self {
            case .microphone: "Privacy_Microphone"
            case .accessibility: "Privacy_Accessibility"
            case .inputMonitoring: "Privacy_ListenEvent"
            }
        }
    }

    @Published private(set) var microphone = false
    @Published private(set) var accessibility = false
    @Published private(set) var inputMonitoring = false

    private var timer: Timer?
    private var activation: AnyCancellable?

    init() {
        refresh()
        activation = NotificationCenter.default
            .publisher(for: NSApplication.didBecomeActiveNotification)
            .sink { [weak self] _ in MainActor.assumeIsolated { self?.refresh() } }
    }

    var allGranted: Bool { microphone && accessibility && inputMonitoring }

    func isGranted(_ kind: Kind) -> Bool {
        switch kind {
        case .microphone: microphone
        case .accessibility: accessibility
        case .inputMonitoring: inputMonitoring
        }
    }

    func refresh() {
        microphone = AVCaptureDevice.authorizationStatus(for: .audio) == .authorized
        accessibility = AXIsProcessTrusted()
        inputMonitoring = CGPreflightListenEventAccess()
    }

    /// Asks macOS for every permission that is still missing (each shows its own system prompt).
    func requestMissing() async {
        if !microphone { _ = await AVCaptureDevice.requestAccess(for: .audio) }
        if !inputMonitoring { _ = CGRequestListenEventAccess() }
        if !accessibility { _ = AXIsProcessTrustedWithOptions(["AXTrustedCheckOptionPrompt": true] as CFDictionary) }
        refresh()
    }

    func openSettings(for kind: Kind) {
        if let url = URL(string: "x-apple.systempreferences:com.apple.preference.security?\(kind.pane)") {
            NSWorkspace.shared.open(url)
        }
    }

    /// Polls while a view that shows the lamps is visible, so granting a permission shows up without a click.
    func startPolling(every interval: TimeInterval = 2) {
        guard timer == nil else { return }
        timer = Timer.scheduledTimer(withTimeInterval: interval, repeats: true) { [weak self] _ in
            MainActor.assumeIsolated { self?.refresh() }
        }
    }

    func stopPolling() {
        timer?.invalidate()
        timer = nil
    }
}