import UserNotifications
import Foundation
import UIKit

/// Main notification service for iOS RSSuper
/// Handles push and local notifications using UserNotifications framework
class NotificationService {
    
    static let shared = NotificationService()
    
    private let unuserNotifications = UNUserNotificationCenter.current()
    private let notificationCenter = NotificationCenter.default
    private let defaultNotificationCategory = "Default"
    private let criticalNotificationCategory = "Critical"
    private let lowPriorityNotificationCategory = "Low Priority"
    
    private let defaultIcon: String = "rssuper-icon"
    private let criticalIcon: String = "rssuper-icon"
    private let lowPriorityIcon: String = "rssuper-icon"
    
    private let defaultTitle: String = "RSSuper"
    
    private var isInitialized = false
    
    private init() {}
    
    /// Initialize the notification service
    /// - Parameter context: Application context for initialization
    func initialize(_ context: Any) {
        guard !isInitialized else { return }
        
        unuserNotifications.delegate = self
        
        requestAuthorization(context: context)
        
        setDefaultNotificationSettings()
        
        setNotificationCategories()
        
        isInitialized = true
        print("NotificationService initialized")
    }
    
    /// Request notification authorization
    /// - Parameter context: Application context
    private func requestAuthorization(context: Any) throws {
        let options: UNAuthorizationOptions = [.alert, .sound, .badge]
        
        let authorized = try unuserNotifications.requestAuthorization(options: options)
        if authorized {
            print("Notification authorization authorized")
        } else {
            print("Notification authorization denied")
        }
    }
    
    /// Set default notification settings
    private func setDefaultNotificationSettings() {
        unuserNotifications.delegate = self
        print("Default notification settings configured")
    }
    
    /// Set notification categories
    private func setNotificationCategories() {
        print("Notification categories configured via UNNotificationCategory")
    }
    
    /// Show a local notification
    /// - Parameters:
    ///   - title: Notification title
    ///   - body: Notification body
    ///   - icon: Icon name (unused on iOS)
    ///   - urgency: Notification urgency
    ///   - contentDate: Scheduled content date
    ///   - userInfo: Additional user info
    func showNotification(
        title: String,
        body: String,
        icon: String,
        urgency: NotificationUrgency = .normal,
        contentDate: Date? = nil,
        userInfo: [AnyHashable: Any]? = nil
    ) {
        let notificationContent = UNMutableNotificationContent()
        
        notificationContent.title = title
        notificationContent.body = body
        notificationContent.sound = UNNotificationSound.default
        notificationContent.categoryIdentifier = urgency.rawValue
        
        if let contentDate = contentDate {
            notificationContent.deliveryDate = contentDate
        }
        
        if let userInfo = userInfo {
            notificationContent.userInfo = userInfo
        }
        
        let trigger = contentDate.map { UNCalendarNotificationTrigger(dateMatching: Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: $0), repeats: false) }
        
        let request = UNNotificationRequest(
            identifier: UUID().uuidString,
            content: notificationContent,
            trigger: trigger
        )
        
        unuserNotifications.add(request) { error in
            if let error = error {
                print("Failed to show notification: \(error)")
            } else {
                print("Notification shown: \(title)")
            }
        }
    }
    
    /// Show a critical notification
    /// - Parameters:
    ///   - title: Notification title
    ///   - body: Notification body
    ///   - icon: Icon name
    func showCriticalNotification(title: String, body: String, icon: String) {
        showNotification(
            title: title,
            body: body,
            icon: icon,
            urgency: .critical
        )
    }
    
    /// Show a low priority notification
    /// - Parameters:
    ///   - title: Notification title
    ///   - body: Notification body
    ///   - icon: Icon name
    func showLowPriorityNotification(title: String, body: String, icon: String) {
        showNotification(
            title: title,
            body: body,
            icon: icon,
            urgency: .low
        )
    }
    
    /// Show a normal priority notification
    /// - Parameters:
    ///   - title: Notification title
    ///   - body: Notification body
    ///   - icon: Icon name
    func showNormalNotification(title: String, body: String, icon: String) {
        showNotification(
            title: title,
            body: body,
            icon: icon,
            urgency: .normal
        )
    }
    
    /// Check if notification service is available
    var isAvailable: Bool {
        var authorized = false
        unuserNotifications.getNotificationSettings { settings in
            authorized = settings.authorizationStatus == .authorized
        }
        return authorized
    }
    
    /// Get current authorization status
    func authorizationStatus() -> UNAuthorizationStatus {
        var status: UNAuthorizationStatus = .denied
        unuserNotifications.getNotificationSettings { settings in
            status = settings.authorizationStatus
        }
        return status
    }
    
    /// Get the notification center
    func notificationCenter() -> UNUserNotificationCenter {
        return unuserNotifications
    }
}

extension NotificationService: UNUserNotificationCenterDelegate {
    
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.banner, .sound])
    }
    
    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
        completionHandler()
    }
}

/// Notification urgency enum
enum NotificationUrgency: Int {
    case critical = 5
    case normal = 1
    case low = 0
    
    var priority: UNNotificationPriority {
        switch self {
        case .critical: return .high
        case .normal: return .default
        case .low: return .low
        }
    }
}