import SwiftUI
import AppKit

class WindowManager: NSObject {
    static let shared = WindowManager()
    
    private static let mainWindowIdentifier = NSUserInterfaceItemIdentifier("com.prakashjoshipax.voiceink.mainWindow")
    private static let mainWindowAutosaveName = NSWindow.FrameAutosaveName("VoiceInkMainWindowFrame")
    
    private weak var mainWindow: NSWindow?
    private var didApplyInitialPlacement = false
    
    private override init() {
        super.init()
    }
    
    func configureWindow(_ window: NSWindow) {
        let requiredStyleMask: NSWindow.StyleMask = [.titled, .closable, .miniaturizable, .resizable, .fullSizeContentView]
        window.styleMask.formUnion(requiredStyleMask)
        window.titlebarAppearsTransparent = true
        window.titleVisibility = .hidden
        window.backgroundColor = .windowBackgroundColor
        window.isReleasedWhenClosed = false
        window.title = "VoiceInk"
        window.collectionBehavior = [.fullScreenPrimary]
        window.level = .normal
        window.isOpaque = true
        window.isMovableByWindowBackground = false
        window.minSize = NSSize(width: 0, height: 0)
        window.setFrameAutosaveName(Self.mainWindowAutosaveName)
        applyInitialPlacementIfNeeded(to: window)
        registerMainWindowIfNeeded(window)
        window.orderFrontRegardless()
    }
    
    func configureOnboardingPanel(_ window: NSWindow) {
        let requiredStyleMask: NSWindow.StyleMask = [.titled, .fullSizeContentView, .resizable]
        window.styleMask.formUnion(requiredStyleMask)
        window.titlebarAppearsTransparent = true
        window.titleVisibility = .hidden
        window.isMovableByWindowBackground = true
        window.level = .normal
        window.backgroundColor = .clear
        window.isReleasedWhenClosed = false
        window.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]
        window.title = "VoiceInk Onboarding"
        window.isOpaque = false
        window.minSize = NSSize(width: 900, height: 780)
        window.makeKeyAndOrderFront(nil)
    }

    func registerMainWindow(_ window: NSWindow) {
        mainWindow = window
        window.identifier = Self.mainWindowIdentifier
        window.delegate = self
    }
    
    func showMainWindow() -> NSWindow? {
        guard let window = resolveMainWindow() else {
            return nil
        }
        
        window.makeKeyAndOrderFront(nil)
        NSApplication.shared.activate(ignoringOtherApps: true)
        return window
    }
    
    func hideMainWindow() {
        guard let window = resolveMainWindow() else {
            return
        }
        window.orderOut(nil)
    }
    
    func currentMainWindow() -> NSWindow? {
        resolveMainWindow()
    }
    
    private func registerMainWindowIfNeeded(_ window: NSWindow) {
        // Only register the primary content window, identified by the hidden title bar style
        if window.identifier == nil || window.identifier != Self.mainWindowIdentifier {
            registerMainWindow(window)
        }
    }
    
    private func applyInitialPlacementIfNeeded(to window: NSWindow) {
        guard !didApplyInitialPlacement else { return }
        // Attempt to restore previous frame if one exists; otherwise fall back to a centered placement
        if !window.setFrameUsingName(Self.mainWindowAutosaveName) {
            window.center()
        }
        didApplyInitialPlacement = true
    }
    
    private func resolveMainWindow() -> NSWindow? {
        if let window = mainWindow {
            return window
        }
        
        if let window = NSApplication.shared.windows.first(where: { $0.identifier == Self.mainWindowIdentifier }) {
            mainWindow = window
            window.delegate = self
            return window
        }
        
        return nil
    }
}

extension WindowManager: NSWindowDelegate {
    func windowWillClose(_ notification: Notification) {
        guard let window = notification.object as? NSWindow else { return }
        if window.identifier == Self.mainWindowIdentifier {
            window.orderOut(nil)
        }
    }
    
    func windowDidBecomeKey(_ notification: Notification) {
        guard let window = notification.object as? NSWindow,
              window.identifier == Self.mainWindowIdentifier else { return }
        NSApplication.shared.activate(ignoringOtherApps: true)
    }
}