//
//  LocalNotificationsManager.swift
//  PrivadoVPN
//
//  Created by Zhandos Bolatbekov on 28.01.2021.
//  Copyright © 2021 Privado LLC. All rights reserved.
//

import Foundation
import UIKit
import UserNotifications

final class LocalNotificationsManager: NSObject, UNUserNotificationCenterDelegate {
    
    private let notificationCenter: UNUserNotificationCenter
    private weak var application: UIApplication?
    private var applicationIconBadgeNumber = 0
    
    // MARK: - Static
    
    private static var instance: LocalNotificationsManager?
    
    static func shared(with notificationCenter: UNUserNotificationCenter = .current()) -> LocalNotificationsManager {
        
        if let manager = instance { return manager }
        
        let instance = LocalNotificationsManager(with: notificationCenter)
        self.instance = instance
        return instance
    }
    
    // MARK: - Init
    
    private init(with notificationCenter: UNUserNotificationCenter) {
        self.notificationCenter = notificationCenter
        super.init()
        self.notificationCenter.delegate = self
    }
    
    // MARK: - Interface
    
    func register(for application: UIApplication) {
        self.application = application
        self.notificationCenter.requestAuthorization(options: [.badge, .sound, .alert]) { granted, _ in
            print("Push notifications permission granted: \(granted)")
        }
    }
    
    func schedule(notification: LocalNotification) {
        switch notification.kind {
        case .interval:
            let request = self.createIntervalNotificationRequest(notification: notification)
            self.notificationCenter.add(request) { error in
                if let error = error {
                    print(error.localizedDescription)
                }
            }
        case .calendar, .location:
            break
        }
    }
    
    func resetAppBadgeCount() {
        self.applicationIconBadgeNumber = 0
        self.application?.applicationIconBadgeNumber = 0
    }
    
    // MARK: - UNUserNotificationCenterDelegate
    
    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                willPresent notification: UNNotification,
                                withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.badge, .sound, .alert])
    }
    
    // MARK: - Private
    
    private func createIntervalNotificationRequest(notification: LocalNotification) -> UNNotificationRequest {
        let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 1, repeats: false)
        let content = UNMutableNotificationContent()
        content.title = notification.title
        content.body = notification.body
        self.applicationIconBadgeNumber += 1
        content.badge = NSNumber(value: self.applicationIconBadgeNumber)
        let identifier = UUID().uuidString
        let request = UNNotificationRequest(identifier: identifier, content: content, trigger: trigger)
        return request
    }
}