//
//  MainSceneDelegate.swift
//  Tusker
//
//  Created by Shadowfacts on 1/6/20.
//  Copyright © 2020 Shadowfacts. All rights reserved.
//

import UIKit
import Pachyderm
import CrashReporter
import MessageUI

class MainSceneDelegate: UIResponder, UIWindowSceneDelegate {
    
    var window: UIWindow?

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
        guard let windowScene = scene as? UIWindowScene else { return }
        
        window = UIWindow(windowScene: windowScene)
        
        if let report = AppDelegate.pendingCrashReport {
            AppDelegate.pendingCrashReport = nil
            handlePendingCrashReport(report, session: session)
        } else {
            showAppOrOnboardingUI(session: session)
            if connectionOptions.urlContexts.count > 0 {
                self.scene(scene, openURLContexts: connectionOptions.urlContexts)
            }
        }

        window!.makeKeyAndVisible()
        
        NotificationCenter.default.addObserver(self, selector: #selector(themePrefChanged), name: .themePreferenceChanged, object: nil)
        themePrefChanged()
        
        if let shortcutItem = connectionOptions.shortcutItem {
            _ = AppShortcutItem.handle(shortcutItem)
        }
    }

    func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
        if URLContexts.count > 1 {
            fatalError("Cannot open more than 1 URL")
        }
        
        let url = URLContexts.first!.url
        
        if url.host == "x-callback-url" {
            _ = XCBManager.handle(url: url)
        } else if var components = URLComponents(url: url, resolvingAgainstBaseURL: false),
                  let rootViewController = window!.rootViewController as? TuskerRootViewController {
            components.scheme = "https"
            let query = components.string!
            rootViewController.performSearch(query: query)
        }
    }
    
    func scene(_ scene: UIScene, continue userActivity: NSUserActivity) {
        _ = userActivity.handleResume()
    }
    
    func windowScene(_ windowScene: UIWindowScene, performActionFor shortcutItem: UIApplicationShortcutItem, completionHandler: @escaping (Bool) -> Void) {
        completionHandler(AppShortcutItem.handle(shortcutItem))
    }
    
    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 neccessarily discarded (see `application:didDiscardSceneSessions` instead).
        
        Preferences.save()
        DraftsManager.save()
    }
    
    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.
    }
    
    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).
        
        Preferences.save()
        DraftsManager.save()
    }
    
    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.
        
        if let rootVC = window?.rootViewController as? BackgroundableViewController {
            rootVC.sceneDidEnterBackground()
        }
        
        try! scene.session.mastodonController?.persistentContainer.viewContext.save()
    }
    
    private func handlePendingCrashReport(_ report: PLCrashReport, session: UISceneSession) {
        #if !DEBUG
        guard MFMailComposeViewController.canSendMail() else {
            print("Cannot send email")
            showAppOrOnboardingUI(session: session)
            return
        }
        
        window!.rootViewController = CrashReporterViewController.create(report: report)
        #endif
    }
    
    func showAppOrOnboardingUI(session: UISceneSession? = nil) {
        let session = session ?? window!.windowScene!.session
        if LocalData.shared.onboardingComplete {
            let account = LocalData.shared.getMostRecentAccount()!
            if session.mastodonController == nil {
                session.mastodonController = MastodonController.getForAccount(account)
            }
            
            activateAccount(account, animated: false)
        } else {
            window!.rootViewController = createOnboardingUI()
        }
    }
    
    func activateAccount(_ account: LocalData.UserAccountInfo, animated: Bool) {
        let oldMostRecentAccount = LocalData.shared.mostRecentAccountID
        LocalData.shared.setMostRecentAccount(account)
        window!.windowScene!.session.mastodonController = MastodonController.getForAccount(account)
        
        let newRoot = createAppUI()
        if let container = window?.rootViewController as? AccountSwitchingContainerViewController {
            let direction: AccountSwitchingContainerViewController.AnimationDirection
            if animated,
               let oldIndex = LocalData.shared.accounts.firstIndex(where: { $0.id == oldMostRecentAccount }),
               let newIndex = LocalData.shared.accounts.firstIndex(of: account) {
                direction = newIndex > oldIndex ? .upwards : .downwards
            } else {
                direction = .none
            }
            container.setRoot(newRoot, animating: direction)
        } else {
            window!.rootViewController = AccountSwitchingContainerViewController(root: newRoot)
        }
    }
    
    func logoutCurrent() {
        LocalData.shared.removeAccount(LocalData.shared.getMostRecentAccount()!)
        if LocalData.shared.onboardingComplete {
            activateAccount(LocalData.shared.accounts.first!, animated: false)
        } else {
            window!.rootViewController = createOnboardingUI()
        }
    }

    func createAppUI() -> TuskerRootViewController {
        let mastodonController = window!.windowScene!.session.mastodonController!
        mastodonController.getOwnAccount()
        mastodonController.getOwnInstance()
        
        return MainSplitViewController(mastodonController: mastodonController)
    }
    
    func createOnboardingUI() -> UIViewController {
        let onboarding = OnboardingViewController()
        onboarding.onboardingDelegate = self
        return onboarding
    }
    
    @objc func themePrefChanged() {
        window?.overrideUserInterfaceStyle = Preferences.shared.theme
    }
    
}

extension MainSceneDelegate: OnboardingViewControllerDelegate {
    func didFinishOnboarding(account: LocalData.UserAccountInfo) {
        activateAccount(account, animated: false)
    }
}

extension MainSceneDelegate: MFMailComposeViewControllerDelegate {
    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
        controller.dismiss(animated: true) {
            self.showAppOrOnboardingUI()
        }
    }
}