//
//  AppDelegate.swift
//  NetNewsWire
//
//  Created by Maurice Parker on 4/8/19.
//  Copyright © 2019 Ranchero Software. All rights reserved.
//

import UIKit
import RSCore
import RSWeb
import Account
import UserNotifications
import BackgroundTasks
import os.log

var appDelegate: AppDelegate!

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, UISplitViewControllerDelegate, UnreadCountProvider {
	
	private var syncBackgroundUpdateTask = UIBackgroundTaskIdentifier.invalid
	
	var syncTimer: ArticleStatusSyncTimer?
	
	var shuttingDown = false {
		didSet {
			if shuttingDown {
				syncTimer?.shuttingDown = shuttingDown
				syncTimer?.invalidate()
			}
		}
	}
	
	var log = OSLog(subsystem: Bundle.main.bundleIdentifier!, category: "application")
	var window: UIWindow?
	
	var faviconDownloader: FaviconDownloader!
	var imageDownloader: ImageDownloader!
	var authorAvatarDownloader: AuthorAvatarDownloader!
	var feedIconDownloader: FeedIconDownloader!
	
	var unreadCount = 0 {
		didSet {
			if unreadCount != oldValue {
				postUnreadCountDidChangeNotification()
				UIApplication.shared.applicationIconBadgeNumber = unreadCount
			}
		}
	}
	
	override init() {
		
		super.init()
		appDelegate = self
		
		NotificationCenter.default.addObserver(self, selector: #selector(unreadCountDidChange(_:)), name: .UnreadCountDidChange, object: nil)
		NotificationCenter.default.addObserver(self, selector: #selector(accountRefreshDidFinish(_:)), name: .AccountRefreshDidFinish, object: nil)
		NotificationCenter.default.addObserver(self, selector: #selector(userDefaultsDidChange(_:)), name: UserDefaults.didChangeNotification, object: nil)
		
		// Reinitialize the shared state as early as possible
		_ = AccountManager.shared
		
	}
	
	func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
		
		registerBackgroundTasks()
		
		// Set up the split view
		let splitViewController = window!.rootViewController as! UISplitViewController
		let navigationController = splitViewController.viewControllers[splitViewController.viewControllers.count-1] as! UINavigationController
		navigationController.topViewController!.navigationItem.leftBarButtonItem = splitViewController.displayModeButtonItem
		splitViewController.delegate = self
		
		window!.tintColor = AppAssets.netNewsWireBlueColor
		
		AppDefaults.registerDefaults()
		let isFirstRun = AppDefaults.isFirstRun
		if isFirstRun {
			os_log("Is first run.", log: log, type: .info)
		}
		
		let localAccount = AccountManager.shared.defaultAccount
		DefaultFeedsImporter.importIfNeeded(isFirstRun, account: localAccount)
		
		let tempDir = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).first!
		let faviconsFolderURL = tempDir.appendingPathComponent("Favicons")
		try! FileManager.default.createDirectory(at: faviconsFolderURL, withIntermediateDirectories: true, attributes: nil)
		faviconDownloader = FaviconDownloader(folder: faviconsFolderURL.absoluteString)
		
		let imagesFolderURL = tempDir.appendingPathComponent("Images")
		try! FileManager.default.createDirectory(at: imagesFolderURL, withIntermediateDirectories: true, attributes: nil)
		imageDownloader = ImageDownloader(folder: imagesFolderURL.absoluteString)
		
		authorAvatarDownloader = AuthorAvatarDownloader(imageDownloader: imageDownloader)
		feedIconDownloader = FeedIconDownloader(imageDownloader: imageDownloader)
		
		DispatchQueue.main.async {
			self.unreadCount = AccountManager.shared.unreadCount
		}
		
		UNUserNotificationCenter.current().requestAuthorization(options:[.badge, .sound, .alert]) { (granted, error) in
			if granted {
				DispatchQueue.main.async {
					UIApplication.shared.registerForRemoteNotifications()
				}
			}
		}
		
		syncTimer = ArticleStatusSyncTimer()
		
		#if DEBUG
		syncTimer!.update()
		#endif
		
		return true
		
	}
	
	//	func application(_ application: UIApplication, shouldSaveApplicationState coder: NSCoder) -> Bool {
	//
	//		let versionNumber = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as! String
	//		coder.encode(versionNumber, forKey: "VersionNumber")
	//
	//		return true
	//
	//	}
	//
	//	func application(_ application: UIApplication, shouldRestoreApplicationState coder: NSCoder) -> Bool {
	//		if let storedVersionNumber = coder.decodeObject(forKey: "VersionNumber") as? String {
	//			let versionNumber = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as! String
	//			if versionNumber == storedVersionNumber {
	//				return true
	//			}
	//		}
	//		return false
	//	}
	
	func applicationWillResignActive(_ application: UIApplication) {
		// Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
		// Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
	}
	
	func applicationDidEnterBackground(_ application: UIApplication) {
		syncTimer?.invalidate()
		
		// Schedule background app refresh
		scheduleBackgroundFeedRefresh()
		
		// Sync article status
		let completeProcessing = { [unowned self] in
			UIApplication.shared.endBackgroundTask(self.syncBackgroundUpdateTask)
			self.syncBackgroundUpdateTask = UIBackgroundTaskIdentifier.invalid
		}
		
		DispatchQueue.global(qos: .background).async {
			self.syncBackgroundUpdateTask = UIApplication.shared.beginBackgroundTask {
				completeProcessing()
				os_log("Accounts sync processing terminated for running too long.", log: self.log, type: .info)
			}
			
			DispatchQueue.main.async {
				AccountManager.shared.syncArticleStatusAll() {
					completeProcessing()
				}
			}
		}
	}
	
	func applicationWillEnterForeground(_ application: UIApplication) {
		AccountManager.shared.syncArticleStatusAll()
		syncTimer?.update()
	}
	
	func applicationDidBecomeActive(_ application: UIApplication) {
		// If we haven't refreshed the database for 15 minutes, run a refresh automatically
		if let lastRefresh = AppDefaults.lastRefresh {
			if Date() > lastRefresh.addingTimeInterval(15 * 60) {
				AccountManager.shared.refreshAll(errorHandler: ErrorHandler.present)
			}
		} else {
			AccountManager.shared.refreshAll(errorHandler: ErrorHandler.present)
		}
		
	}
	
	func applicationWillTerminate(_ application: UIApplication) {
		shuttingDown = true
	}
	
	// MARK: - Split view
	
	func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController:UIViewController, onto primaryViewController:UIViewController) -> Bool {
		guard let secondaryAsNavController = secondaryViewController as? UINavigationController else { return false }
		guard let topAsDetailController = secondaryAsNavController.topViewController as? DetailViewController else { return false }
		if topAsDetailController.navState?.currentArticle == nil {
			// Return true to indicate that we have handled the collapse by doing nothing; the secondary controller will be discarded.
			return true
		}
		return false
	}
	
	// MARK: Notifications
	
	@objc func unreadCountDidChange(_ note: Notification) {
		if note.object is AccountManager {
			unreadCount = AccountManager.shared.unreadCount
		}
	}
	
	@objc func userDefaultsDidChange(_ note: Notification) {
		scheduleBackgroundFeedRefresh()
	}
	
	@objc func accountRefreshDidFinish(_ note: Notification) {
		AppDefaults.lastRefresh = Date()
	}
	
	// MARK: - API
	
	func logMessage(_ message: String, type: LogItem.ItemType) {
		print("logMessage: \(message) - \(type)")
		
	}
	
	func logDebugMessage(_ message: String) {
		logMessage(message, type: .debug)
	}
	
}


// MARK: - Background Tasks
private extension AppDelegate {
	
	/// Register all background tasks.
	func registerBackgroundTasks() {
		// Register background feed refresh.
		BGTaskScheduler.shared.register(forTaskWithIdentifier: "com.ranchero.NetNewsWire.FeedRefresh", using: nil) { (task) in
			self.performBackgroundFeedRefresh(with: task as! BGAppRefreshTask)
		}
	}
	
	/// Schedules a background app refresh based on `AppDefaults.refreshInterval`.
	func scheduleBackgroundFeedRefresh() {
		let request = BGAppRefreshTaskRequest(identifier: "com.ranchero.NetNewsWire.FeedRefresh")
		request.earliestBeginDate = Date(timeIntervalSinceNow: AppDefaults.refreshInterval.inSeconds())
		do {
			try BGTaskScheduler.shared.submit(request)
		} catch {
			os_log(.error, log: self.log, "Could not schedule app refresh: %@", error.localizedDescription)
		}
	}
	
	/// Performs background feed refresh.
	/// - Parameter task: `BGAppRefreshTask`
	/// - Warning: As of Xcode 11 beta 2, when triggered from the debugger this doesn't work.
	func performBackgroundFeedRefresh(with task: BGAppRefreshTask) {
		
		scheduleBackgroundFeedRefresh() // schedule next refresh
		
		var startingUnreadCount = 0
		
		DispatchQueue.global(qos: .background).async { [unowned self] in
			
			os_log("Woken to perform account refresh.", log: self.log, type: .info)
	
			os_log("Getting unread count.", log: self.log, type: .info)
			while(!AccountManager.shared.isUnreadCountsInitialized) {
				os_log("Waiting for unread counts to be initialized...", log: self.log, type: .info)
				sleep(1)
			}
			os_log(.info, log: self.log, "Got unread count: %i", self.unreadCount)
			startingUnreadCount = self.unreadCount
			
			DispatchQueue.main.async {
				AccountManager.shared.refreshAll(errorHandler: ErrorHandler.log)
			}
			os_log("Accounts requested to begin refresh.", log: self.log, type: .info)
			
			sleep(1)
			while (!AccountManager.shared.combinedRefreshProgress.isComplete) {
				os_log("Waiting for account refresh processing to complete...", log: self.log, type: .info)
				sleep(1)
			}
			
			if startingUnreadCount < self.unreadCount {
				os_log("Updating unread count badge, posting notification.", log: self.log, type: .info)
				self.sendReceivedArticlesUserNotification(newArticleCount: self.unreadCount - startingUnreadCount)
				task.setTaskCompleted(success: true)
			} else {
				os_log("Account refresh operation completed.", log: self.log, type: .info)
				task.setTaskCompleted(success: true)
			}
		}
		
		// set expiration handler
		task.expirationHandler = {
			os_log("Accounts refresh processing terminated for running too long.", log: self.log, type: .info)
			task.setTaskCompleted(success: false)
		}
	}
	
}

private extension AppDelegate {
	
	
	func sendReceivedArticlesUserNotification(newArticleCount: Int) {
		
		let content = UNMutableNotificationContent()
		content.title = NSLocalizedString("Article Download", comment: "New Articles")
		
		let body: String = {
			if newArticleCount == 1 {
				return NSLocalizedString("You have downloaded 1 new article.", comment: "Article Downloaded")
			} else {
				let formatString = NSLocalizedString("You have downloaded %d new articles.", comment: "Articles Downloaded")
				return NSString.localizedStringWithFormat(formatString as NSString, newArticleCount) as String
			}
		}()
		
		content.body = body
		content.sound = UNNotificationSound.default
		
		let request = UNNotificationRequest.init(identifier: "NewArticlesReceived", content: content, trigger: nil)
		UNUserNotificationCenter.current().add(request)
		
	}
	
}