//
//  SceneDelegate.swift
//  Mastodon
//
//  Created by MainasuK Cirno on 2021/1/22.
//

import os.log
import UIKit
import Combine
import CoreDataStack
import MastodonCore
import MastodonExtension
import MastodonUI
import MastodonSDK

#if PROFILE
import FPSIndicator
#endif

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var disposeBag = Set<AnyCancellable>()
    var observations = Set<NSKeyValueObservation>()
    
    var window: UIWindow?
    var coordinator: SceneCoordinator?

    #if PROFILE
    var fpsIndicator: FPSIndicator?
    #endif

    var savedShortCutItem: UIApplicationShortcutItem?

    let logger = Logger(subsystem: "SceneDelegate", category: "logic")

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let windowScene = scene as? UIWindowScene else { return }
        
        #if DEBUG
        let window = TouchesVisibleWindow(windowScene: windowScene)
        self.window = window
        #else
        let window = UIWindow(windowScene: windowScene)
        self.window = window
        #endif

        // set tint color
        window.tintColor = UIColor.label

        ThemeService.shared.currentTheme
            .receive(on: RunLoop.main)
            .dropFirst()
            .sink { [weak self] theme in
                guard let self = self else { return }
                guard let window = self.window else { return }
                window.subviews.forEach { view in
                    view.removeFromSuperview()
                    window.addSubview(view)
                }
            }
            .store(in: &disposeBag)
        
        let appContext = AppContext.shared
        let sceneCoordinator = SceneCoordinator(scene: scene, sceneDelegate: self, appContext: appContext)
        self.coordinator = sceneCoordinator
        
        sceneCoordinator.setup()
        window.makeKeyAndVisible()
        
        if let urlContext = connectionOptions.urlContexts.first {
            handleUrl(context: urlContext)
        }
        
        #if SNAPSHOT
        // speedup animation
        // window.layer.speed = 999
        
        // disable animation
        UIView.setAnimationsEnabled(false)
        #endif

        if let shortcutItem = connectionOptions.shortcutItem {
            // Save it off for later when we become active.
            savedShortCutItem = shortcutItem
        }
        
        UserDefaults.shared.observe(\.customUserInterfaceStyle, options: [.initial, .new]) { [weak self] defaults, _ in
            guard let self = self else { return }
            #if SNAPSHOT
            // toggle Dark Mode
            // https://stackoverflow.com/questions/32988241/how-to-access-launchenvironment-and-launcharguments-set-in-xcuiapplication-runn
            if ProcessInfo.processInfo.arguments.contains("UIUserInterfaceStyleForceDark") {
                self.window?.overrideUserInterfaceStyle = .dark
            }
            #else
            self.window?.overrideUserInterfaceStyle = defaults.customUserInterfaceStyle
            #endif
        }
        .store(in: &observations)

        #if PROFILE
        fpsIndicator = FPSIndicator(windowScene: windowScene)
        #endif
    }

    func sceneDidDisconnect(_ scene: UIScene) {
        // Called as the scene is being released by the system.
        // This occurs shortly after the scene enters the background, or when its session is discarded.
        // Release any resources associated with this scene that can be re-created the next time the scene connects.
        // The scene may re-connect later, as its session was not necessarily discarded (see `application:didDiscardSceneSessions` instead).
    }

    func sceneDidBecomeActive(_ scene: UIScene) {
        // Called when the scene has moved from an inactive state to an active state.
        // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.

        // update application badge
        AppContext.shared.notificationService.applicationIconBadgeNeedsUpdate.send()

        // trigger status filter update
        AppContext.shared.statusFilterService.filterUpdatePublisher.send()
        
        // trigger authenticated user account update
        AppContext.shared.authenticationService.updateActiveUserAccountPublisher.send()
        
        // update mutes and blocks and remove related data
        AppContext.shared.instanceService.updateMutesAndBlocks()

        if let shortcutItem = savedShortCutItem {
            Task {
                _ = await handler(shortcutItem: shortcutItem)
            }
            savedShortCutItem = nil
        }
    }

    func sceneWillResignActive(_ scene: UIScene) {
        // Called when the scene will move from an active state to an inactive state.
        // This may occur due to temporary interruptions (ex. an incoming phone call).
    }

    func sceneWillEnterForeground(_ scene: UIScene) {
        // Called as the scene transitions from the background to the foreground.
        // Use this method to undo the changes made on entering the background.
    }

    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
    }

}

extension SceneDelegate {
    
    func windowScene(_ windowScene: UIWindowScene, performActionFor shortcutItem: UIApplicationShortcutItem) async -> Bool {
        return await handler(shortcutItem: shortcutItem)
    }

    @MainActor
    private func handler(shortcutItem: UIApplicationShortcutItem) async -> Bool {
        logger.debug("\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): \(shortcutItem.type)")

        switch shortcutItem.type {
        case NotificationService.unreadShortcutItemIdentifier:
            guard let coordinator = self.coordinator else { return false }

            guard let accessToken = shortcutItem.userInfo?["accessToken"] as? String else {
                assertionFailure()
                return false
            }
            let request = MastodonAuthentication.sortedFetchRequest
            request.predicate = MastodonAuthentication.predicate(userAccessToken: accessToken)
            request.fetchLimit = 1

            guard let authentication = try? coordinator.appContext.managedObjectContext.fetch(request).first else {
                assertionFailure()
                return false
            }

            let _isActive = try? await coordinator.appContext.authenticationService.activeMastodonUser(
                domain: authentication.domain,
                userID: authentication.userID
            )
            
            guard _isActive == true else {
                return false
            }

            coordinator.switchToTabBar(tab: .notifications)

        case "org.joinmastodon.app.new-post":
            showComposeViewController()

        case "org.joinmastodon.app.search":
            coordinator?.switchToTabBar(tab: .search)
            logger.debug("\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): select search tab")

            if let searchViewController = coordinator?.tabBarController.topMost as? SearchViewController {
                searchViewController.searchBarTapPublisher.send("")
                logger.debug("\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): trigger search")
            }

        default:
            assertionFailure()
            break
        }

        return true
    }
    
    func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
        // Determine who sent the URL.
        if let urlContext = URLContexts.first {
            handleUrl(context: urlContext)
        }
    }
    
    private func showComposeViewController() {
        if coordinator?.tabBarController.topMost is ComposeViewController {
            logger.debug("\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): composing…")
        } else {
            if let authContext = coordinator?.authContext {
                let composeViewModel = ComposeViewModel(
                    context: AppContext.shared,
                    authContext: authContext,
                    destination: .topLevel
                )
                _ = coordinator?.present(scene: .compose(viewModel: composeViewModel), from: nil, transition: .modal(animated: true, completion: nil))
                logger.debug("\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): present compose scene")
            } else {
                logger.debug("\((#file as NSString).lastPathComponent, privacy: .public)[\(#line, privacy: .public)], \(#function, privacy: .public): not authenticated")
            }
        }
    }
    
    private func handleUrl(context: UIOpenURLContext) {
        let sendingAppID = context.options.sourceApplication
        let url = context.url

        if !UIApplication.shared.canOpenURL(url) { return }

        print("source application = \(sendingAppID ?? "Unknown")")
        print("url = \(url)")
        
        switch url.host {
        case "post":
            showComposeViewController()
        case "profile":
            let components = url.pathComponents
            if components.count == 2 && components[0] == "/" {
                let addr = components[1]
                if let authContext = coordinator?.authContext {
                    let profileViewModel = RemoteProfileViewModel(
                        context: AppContext.shared,
                        authContext: authContext,
                        acct: components[1]
                    )
                    self.coordinator?.present(
                        scene: .profile(viewModel: profileViewModel),
                        from: nil,
                        transition: .show
                    )
                }
            }
        case "status":
            let components = url.pathComponents
            if components.count == 2 && components[0] == "/" {
                let statusId = components[1]
                // View post from user
                if let authContext = coordinator?.authContext {
                    let threadViewModel = RemoteThreadViewModel(context: AppContext.shared,
                                                                authContext: authContext,
                                                                statusID: statusId)
                    coordinator?.present(scene: .thread(viewModel: threadViewModel), from: nil, transition: .show)
                }
            }
        default:
            return
        }
    }
}