import AppKit
import ApplicationServices
import Combine

/// One live menu bar (status/tray) item discovered via the Accessibility API.
struct MenuBarItem: Identifiable, Equatable {
    let id: String
    let pid: pid_t
    let appName: String
    let title: String
    let appIcon: NSImage
    let element: AXUIElement

    static func == (lhs: MenuBarItem, rhs: MenuBarItem) -> Bool {
        lhs.id == rhs.id && lhs.title == rhs.title
    }
}

/// Enumerates every other app's menu bar items so they can be shown (and
/// pressed) from SimpleTopBar's hamburger panel. Requires Accessibility
/// permission; without it the list is empty.
@MainActor
final class MenuBarItemManager: ObservableObject {
    static let shared = MenuBarItemManager()

    @Published private(set) var items: [MenuBarItem] = []
    @Published private(set) var authorized = AXIsProcessTrusted()

    private var observers: [NSObjectProtocol] = []

    private init() {}

    func start() {
        authorized = AXIsProcessTrusted()
        refresh()
        let center = NSWorkspace.shared.notificationCenter
        let names: [Notification.Name] = [
            NSWorkspace.didLaunchApplicationNotification,
            NSWorkspace.didTerminateApplicationNotification,
            NSWorkspace.didActivateApplicationNotification,
            NSWorkspace.didHideApplicationNotification,
            NSWorkspace.didUnhideApplicationNotification,
        ]
        for name in names {
            observers.append(center.addObserver(forName: name, object: nil, queue: .main) { [weak self] _ in
                Task { @MainActor in self?.refresh() }
            })
        }
    }

    func refresh() {
        authorized = AXIsProcessTrusted()
        guard authorized else {
            items = []
            return
        }
        items = Self.enumerate()
    }

    nonisolated static func enumerate(includeOwn: Bool = false) -> [MenuBarItem] {
        let ownPID = ProcessInfo.processInfo.processIdentifier
        var found: [MenuBarItem] = []

        for app in NSWorkspace.shared.runningApplications {
            let pid = app.processIdentifier
            if !includeOwn && pid == ownPID { continue }
            let axApp = AXUIElementCreateApplication(pid)
            guard let bar = extrasMenuBar(of: axApp),
                  let children = children(of: bar) else { continue }

            var seenTitles = Set<String>()
            for (index, child) in children.enumerated() {
                // Control Center reports every module it owns, including the
                // ones not in the menu bar, which are parked off-screen around
                // y=982. Keep only items actually sitting in the bar.
                if let position = pointAttribute(child, kAXPositionAttribute), position.y > 60 {
                    continue
                }

                let title = stringAttribute(child, kAXDescriptionAttribute)
                    ?? stringAttribute(child, kAXTitleAttribute)
                    ?? app.localizedName
                    ?? "Item"
                // Several Control Center modules share the generic title
                // "Control Center"; show each distinct title once per app.
                if !seenTitles.insert(title).inserted { continue }

                found.append(MenuBarItem(
                    id: "\(pid)-\(index)",
                    pid: pid,
                    appName: app.localizedName ?? app.bundleIdentifier ?? "Unknown",
                    title: title,
                    appIcon: app.icon ?? NSImage(named: NSImage.applicationIconName) ?? NSImage(),
                    element: child
                ))
            }
        }

        return found.sorted { a, b in
            let byApp = a.appName.localizedCaseInsensitiveCompare(b.appName)
            if byApp == .orderedSame { return a.title.localizedCaseInsensitiveCompare(b.title) == .orderedAscending }
            return byApp == .orderedAscending
        }
    }

    /// Opens the real menu bar item by pressing its accessibility element, so
    /// its menu/popover appears at its true screen location.
    @discardableResult
    func press(_ item: MenuBarItem) -> Bool {
        if AXUIElementPerformAction(item.element, kAXPressAction as CFString) == .success {
            return true
        }
        return AXUIElementPerformAction(item.element, kAXShowMenuAction as CFString) == .success
    }

    // MARK: - AX helpers

    nonisolated static func extrasMenuBar(of app: AXUIElement) -> AXUIElement? {
        var value: CFTypeRef?
        guard AXUIElementCopyAttributeValue(app, kAXExtrasMenuBarAttribute as CFString, &value) == .success,
              let value,
              CFGetTypeID(value) == AXUIElementGetTypeID() else { return nil }
        return (value as! AXUIElement)
    }

    nonisolated static func children(of element: AXUIElement) -> [AXUIElement]? {
        var value: CFTypeRef?
        guard AXUIElementCopyAttributeValue(element, kAXChildrenAttribute as CFString, &value) == .success else {
            return nil
        }
        return value as? [AXUIElement]
    }

    nonisolated static func stringAttribute(_ element: AXUIElement, _ attribute: String) -> String? {
        var value: CFTypeRef?
        guard AXUIElementCopyAttributeValue(element, attribute as CFString, &value) == .success,
              let string = value as? String,
              !string.isEmpty else { return nil }
        return string
    }

    nonisolated static func pointAttribute(_ element: AXUIElement, _ attribute: String) -> CGPoint? {
        var value: CFTypeRef?
        guard AXUIElementCopyAttributeValue(element, attribute as CFString, &value) == .success,
              let value,
              CFGetTypeID(value) == AXValueGetTypeID() else { return nil }
        var point = CGPoint.zero
        guard AXValueGetValue(value as! AXValue, .cgPoint, &point) else { return nil }
        return point
    }
}

/// Best-effort menu bar item hiding. A zero-width spacer status item is created
/// at launch; expanding its length to a huge value pushes the other apps' icons
/// off the visible menu bar, so they can only be reached through SimpleTopBar's
/// panel. On by default; the choice is persisted. Always restored on quit, and
/// a crash cleans up automatically because status items die with the process.
@MainActor
final class MenuBarHider: ObservableObject {
    static let shared = MenuBarHider()

    /// Width that pushes the neighbouring items off the visible menu bar.
    static let hiddenLength: CGFloat = 10_000

    private static let defaultsKey = "hideMenuBarItems"

    @Published private(set) var isHiding = false
    @Published var enabled: Bool {
        didSet {
            guard enabled != oldValue else { return }
            UserDefaults.standard.set(enabled, forKey: Self.defaultsKey)
            apply(enabled)
        }
    }

    private var spacer: NSStatusItem?

    private init() {
        // Hide by default: the menu bar then shows only SimpleTopBar's hamburger
        // plus the Apple items macOS will not let us move.
        enabled = UserDefaults.standard.object(forKey: Self.defaultsKey) as? Bool ?? true
    }

    /// Create the spacer early (at launch) so it lands as far right as possible.
    func prepare() {
        guard spacer == nil else { return }
        let name = "SimpleTopBarHider"
        let key = "NSStatusItem Preferred Position \(name)"
        // The boundary between "hidden" and "kept" falls just left of Wi-Fi at
        // ~250, so the other apps hide while Apple's Wi-Fi/Clock/Battery/Control
        // Center/Spotlight stay visible. `debug.spacerPos` overrides the seed.
        if let override = UserDefaults.standard.object(forKey: "debug.spacerPos") as? Double {
            UserDefaults.standard.set(override, forKey: key)
        } else if UserDefaults.standard.object(forKey: key) == nil {
            UserDefaults.standard.set(250.0, forKey: key)
        }
        let item = NSStatusBar.system.statusItem(withLength: 0)
        item.autosaveName = name
        item.button?.isHidden = true
        spacer = item
        apply(enabled)
    }

    private func apply(_ hiding: Bool) {
        spacer?.length = hiding ? Self.hiddenLength : 0
        isHiding = hiding
    }

    /// Put the menu bar back the way we found it. Called on quit. Leaves the
    /// user's preference intact.
    func restore() {
        spacer?.length = 0
        isHiding = false
    }
}

enum AccessibilityPermission {
    static var isGranted: Bool { AXIsProcessTrusted() }

    static func request() {
        let options = [kAXTrustedCheckOptionPrompt.takeUnretainedValue() as String: true] as CFDictionary
        _ = AXIsProcessTrustedWithOptions(options)
    }
}