//
// Copyright 2025 Element Creations Ltd.
// Copyright 2023-2025 New Vector Ltd.
//
// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
// Please see LICENSE files in the repository root for full details.
//

import Combine
import SwiftUI

class WindowManager: SecureWindowManagerProtocol {
    private let appDelegate: AppDelegate
    weak var mainScene: UIWindowScene?
    weak var mainSession: UISceneSession?
    weak var delegate: SecureWindowManagerDelegate?
    
    private(set) var mainWindow: UIWindow!
    private(set) var overlayWindow: UIWindow!
    private(set) var globalSearchWindow: UIWindow!
    private(set) var alternateWindow: UIWindow!
    
    private(set) var openWindowAction: OpenWindowAction!
    private(set) var dismissWindowAction: DismissWindowAction!
    
    var secondaryWindowsEnabled = true {
        didSet {
            if secondaryWindowsEnabled == false {
                closeAllSecondaryWindows()
            }
        }
    }
        
    var windows: [UIWindow] {
        [mainWindow, overlayWindow, globalSearchWindow, alternateWindow]
    }
    
    // periphery:ignore - auto cancels when reassigned
    /// The task used to switch windows, so that we don't get stuck in the wrong state with a quick switch.
    @CancellableTask private var switchTask: Task<Void, Error>?
    /// A duration that allows window switching to wait a couple of frames to avoid a transition through black.
    private let windowHideDelay = Duration.milliseconds(33)
    
    private var coordinators: [SecondaryWindowType: (coordinator: CoordinatorProtocol, flowCoordinator: FlowCoordinatorProtocol?)] = [:]
    
    init(appDelegate: AppDelegate) {
        self.appDelegate = appDelegate
    }
    
    func configure(withScene scene: UIWindowScene, session: UISceneSession) {
        // This gets called for all opened windows, we're only interested in the main window.
        guard let userInfo = session.userInfo, userInfo[SceneDelegate.sceneIDKey] as? String == SceneDelegate.mainSceneID else {
            scene.windows.forEach { $0.tintColor = .compound.textActionPrimary } // SecondaryWindow tinting.
            return
        }
        
        // Don't allow more than 1 main window to be presented.
        if mainScene != nil {
            // The window will be presented momentarily, so lets leave it blank.
            scene.keyWindow?.rootViewController = UIHostingController(rootView: Color.clear)
            UIApplication.shared.requestSceneSessionDestruction(session, options: nil)
            return
        }
        
        mainScene = scene
        mainSession = session
        
        // Restore the previous window size on macOS as this isn't automatic.
        if let previousSize = mainWindow?.frame.size {
            scene.resizeWindowOnMac(to: previousSize)
        }
        
        // `keyWindow` can be nil on iOS 26 until the scene becomes active, but the
        // SwiftUI WindowGroup's window is already attached to the scene by then.
        mainWindow = scene.keyWindow ?? scene.windows.first
        mainWindow.tintColor = .compound.textActionPrimary
        
        overlayWindow = PassthroughWindow(windowScene: scene)
        overlayWindow.tintColor = .compound.textActionPrimary
        overlayWindow.backgroundColor = .clear
        overlayWindow.isHidden = false
        
        globalSearchWindow = UIWindow(windowScene: scene)
        globalSearchWindow.tintColor = .compound.textActionPrimary
        globalSearchWindow.backgroundColor = .clear
        globalSearchWindow.isHidden = true
        
        alternateWindow = UIWindow(windowScene: scene)
        alternateWindow.tintColor = .compound.textActionPrimary
        
        delegate?.windowManagerDidConfigureWindows(self)
    }
    
    func configure(withOpenWindowAction openWindowAction: OpenWindowAction,
                   dismissWindowAction: DismissWindowAction) {
        self.openWindowAction = openWindowAction
        self.dismissWindowAction = dismissWindowAction
    }
    
    func handleSceneDisconnection(_ scene: UIWindowScene) {
        if scene == mainScene {
            mainScene = nil
            mainSession = nil
            // Leave the mainWindow so we can reapply it's size on macOS.
        }
    }
    
    func handleRoute(_ appRoute: AppRoute, windowType: SecondaryWindowType) {
        MXLog.info("Handling app route: \(appRoute) for window type: \(windowType)")
        
        guard let flowCoordinator = coordinators[windowType]?.flowCoordinator else {
            MXLog.error("Invalid flow coordinator")
            return
        }
        
        flowCoordinator.handleAppRoute(appRoute, animated: true)
    }
    
    func switchToMain() {
        mainWindow.isHidden = false
        overlayWindow.isHidden = false
        
        mainWindow.makeKey()
        
        switchTask = Task {
            // Delay hiding to make sure the main windows are visible.
            try await Task.sleep(for: windowHideDelay)
            
            alternateWindow.isHidden = true
        }
    }
    
    func switchToAlternate() {
        alternateWindow.isHidden = false
        
        // We don't know what route the app will use when returning back
        // to the main window, so end any editing operation now to avoid
        // e.g. the keyboard being displayed on top of a call sheet.
        mainWindow.endEditing(true)
        
        hideGlobalSearch()
        
        // alternateWindow.isHidden = false cannot got inside the Task otherwise the timing
        // is poor when you lock the phone - you briefly see the main window for a few
        // frames after you've unlocked the phone and then the placeholder animates in.
        switchTask = Task {
            // Delay hiding to make sure the alternate window is visible.
            try await Task.sleep(for: windowHideDelay)
            
            mainWindow.isHidden = true
            overlayWindow.isHidden = true
            globalSearchWindow.isHidden = true
        }
    }
    
    func showGlobalSearch() {
        MXLog.info("Received global search presentation request.")
        
        guard alternateWindow.isHidden else {
            MXLog.info("The alternate window is visible, ignoring.")
            return
        }
        
        if let mainSession {
            let request = UISceneSessionActivationRequest(session: mainSession)
            UIApplication.shared.activateSceneSession(for: request) { error in
                MXLog.error("Failed to focus window with error: \(error)")
            }
        }
        
        globalSearchWindow.isHidden = false
        globalSearchWindow.makeKeyAndVisible()
    }
    
    func hideGlobalSearch() {
        MXLog.info("Received global search dismissal request.")
        
        guard alternateWindow.isHidden else {
            MXLog.info("The alternate window is visible, ignoring.")
            return
        }
        
        globalSearchWindow.isHidden = true
        mainWindow.makeKey()
    }
    
    // MARK: - OrientationManager
    
    func setOrientation(_ orientation: UIInterfaceOrientationMask) {
        mainScene?.requestGeometryUpdate(.iOS(interfaceOrientations: orientation))
    }
    
    func lockOrientation(_ orientation: UIInterfaceOrientationMask) {
        appDelegate.orientationLock = orientation
    }
    
    // MARK: - Secondary window support
    
    func windowForType(_ type: SecondaryWindowType) -> AnyView {
        MXLog.info("Requesting window for type: \(type)")
        
        guard let coordinator = coordinators[type]?.coordinator else {
            MXLog.error("Invalid coordinator for window type: \(type)")
            return AnyView(InstantlyDismissingWindow())
        }
        
        // This behaves strangely and gets called late but cleans up enough
        // and is self contained enough to be just good .. enough
        return AnyView(coordinator.toPresentable().onDisappear { [weak self] in
            self?.coordinators[type] = nil
        })
    }
    
    func registerCoordinator(_ coordinator: CoordinatorProtocol, flowCoordinator: FlowCoordinatorProtocol?, forWindowType type: SecondaryWindowType) {
        if secondaryWindowsEnabled == false {
            MXLog.error("Cannot register coordinator, secondary windows are disabled.")
            return
        }
        
        coordinators[type] = (coordinator, flowCoordinator)
        openWindowAction(value: type)
    }
    
    func closeSecondaryWindow(forType type: SecondaryWindowType) {
        dismissWindowAction(value: type)
    }
    
    func closeAllSecondaryWindows() {
        for key in coordinators.keys {
            dismissWindowAction(value: key)
        }
        
        coordinators.removeAll()
    }
}

private class PassthroughWindow: UIWindow {
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        if #available(iOS 26, *) {
            // Passthrough UIWindow using SwiftUI in iOS 26
            // https://stackoverflow.com/a/79835964/730924
            guard let rootView = rootViewController?.view else {
                return nil
            }
            
            // Special handling for glass buttons
            // ".glass has a layer name of "@1" and and .glassProminent has a layer name of "@2""
            guard let name = rootView.layer.hitTest(point)?.name, !name.starts(with: "@") else {
                return rootView
            }
            
            return nil
        } else {
            guard let hitView = super.hitTest(point, with: event) else {
                return nil
            }
            
            guard let rootViewController else {
                return nil
            }
            
            guard hitView != self else {
                return nil
            }
            
            // If the returned view is the `UIHostingController`'s view, ignore.
            return rootViewController.view == hitView ? nil : hitView
        }
    }
}

/// Whenever restoring an app SwiftUI tries to restore its windows as well
/// which we're generally not prepared for so use this to just close them instead
private struct InstantlyDismissingWindow: View {
    @Environment(\.dismissWindow) var dismissWindow
    
    var body: some View {
        Rectangle()
            .task {
                dismissWindow()
            }
    }
}

private extension UIWindowScene {
    func resizeWindowOnMac(to size: CGSize) {
        // Hackity hack 🔨
        guard ProcessInfo.processInfo.isiOSAppOnMac, let sizeRestrictions else { return }
        
        self.sizeRestrictions?.minimumSize = size
        self.sizeRestrictions?.maximumSize = size
        
        Task {
            try await Task.sleep(for: .milliseconds(100))
            self.sizeRestrictions?.minimumSize = sizeRestrictions.minimumSize
            self.sizeRestrictions?.maximumSize = sizeRestrictions.maximumSize
        }
    }
}