import AppKit
import SwiftUI

@MainActor
final class MenuBarController: NSObject {
    static let shared = MenuBarController()

    private var statusItem: NSStatusItem?
    private var popover: NSPopover?
    private var labelHostingView: NSHostingView<MenuBarLabelView>?

    private let settings = AppSettings.shared
    private let refreshService = UsageRefreshService.shared

    func install() {
        guard statusItem == nil else { return }

        let item = NSStatusBar.system.statusItem(withLength: NSStatusItem.variableLength)
        statusItem = item

        guard let button = item.button else { return }

        button.image = nil
        button.title = ""
        button.imagePosition = .noImage

        let labelView = MenuBarLabelView(refreshService: refreshService, settings: settings)
        let hostingView = NSHostingView(rootView: labelView)
        hostingView.translatesAutoresizingMaskIntoConstraints = false
        labelHostingView = hostingView

        button.addSubview(hostingView)
        NSLayoutConstraint.activate([
            hostingView.leadingAnchor.constraint(equalTo: button.leadingAnchor, constant: 2),
            hostingView.trailingAnchor.constraint(equalTo: button.trailingAnchor, constant: -2),
            hostingView.topAnchor.constraint(equalTo: button.topAnchor),
            hostingView.bottomAnchor.constraint(equalTo: button.bottomAnchor),
        ])
        hostingView.layoutSubtreeIfNeeded()

        button.target = self
        button.action = #selector(statusItemClicked(_:))
        button.sendAction(on: [.leftMouseUp, .rightMouseUp])

        let popover = NSPopover()
        popover.behavior = .transient
        popover.contentViewController = NSHostingController(
            rootView: PopoverView(refreshService: refreshService, settings: settings)
        )
        self.popover = popover
    }

    @objc private func statusItemClicked(_ sender: NSStatusBarButton) {
        guard let event = NSApp.currentEvent else { return }

        if event.type == .rightMouseUp {
            showContextMenu(on: sender)
            return
        }

        togglePopover(on: sender)
    }

    private func togglePopover(on button: NSStatusBarButton) {
        guard let popover else { return }

        if popover.isShown {
            popover.performClose(nil)
            return
        }

        popover.show(relativeTo: button.bounds, of: button, preferredEdge: .minY)
        popover.contentViewController?.view.window?.makeKey()
    }

    private func showContextMenu(on button: NSStatusBarButton) {
        let menu = NSMenu()
        menu.addItem(
            withTitle: "Settings…",
            action: #selector(openSettings),
            keyEquivalent: ","
        )
        menu.addItem(.separator())
        menu.addItem(
            withTitle: "Quit AI Menubar Usage",
            action: #selector(quitApp),
            keyEquivalent: "q"
        )
        menu.items.forEach { $0.target = self }
        statusItem?.menu = menu
        button.performClick(nil)
        statusItem?.menu = nil
    }

    @objc private func openSettings() {
        popover?.performClose(nil)
        NSApp.activate(ignoringOtherApps: true)
        NSApp.sendAction(Selector(("showSettingsWindow:")), to: nil, from: nil)
    }

    @objc private func quitApp() {
        NSApplication.shared.terminate(nil)
    }
}

final class AppDelegate: NSObject, NSApplicationDelegate {
    func applicationDidFinishLaunching(_ notification: Notification) {
        MenuBarController.shared.install()
    }

    func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
        false
    }
}