import Foundation
import SwiftUI

@MainActor
class AppState: ObservableObject {
    @Published var selectedRoute: Route? = nil {
        didSet {
            if let routeId = selectedRoute?.id {
                Task {
                    await fetchSights(for: routeId)
                }
            } else {
                self.sights = []
                self.sightId = nil
            }
        }
    }
    
    @Published var allRoutes: [Route] = []
    @Published var sightId: Int? = nil
    @Published var sights: [SightModel] = [] // <- все достопримечательности маршрута
    
    // MARK: - Fetch Sights
    private func fetchSights(for routeId: Int) async {
        let urlString = "https://white-nights.krbl.ru/services/content/route/\(routeId)/sight"
        guard let url = URL(string: urlString) else { return }
        
        do {
            let (data, _) = try await URLSession.shared.data(from: url)
            let decodedSights = try JSONDecoder().decode([SightModel].self, from: data)
            
            DispatchQueue.main.async {
                self.sights = decodedSights
                self.sightId = decodedSights.first?.id
            }
            
            // 🔹 Предзагрузка миниатюр
            preloadThumbnails(for: decodedSights)
            
        } catch {
            print("Ошибка загрузки достопримечательностей: \(error)")
            DispatchQueue.main.async {
                self.sights = []
                self.sightId = nil
            }
        }
    }
    
    // MARK: - Preload thumbnails into URLCache
    private func preloadThumbnails(for sights: [SightModel]) {
        let session = URLSession.shared
        for sight in sights {
            guard let url = URL(string: "https://white-nights.krbl.ru/services/content/media/\(sight.thumbnail)/download") else { continue }
            let request = URLRequest(url: url)
            
            // Если уже в кэше, пропускаем
            if URLCache.shared.cachedResponse(for: request) != nil { continue }
            
            let task = session.dataTask(with: request) { data, response, _ in
                guard let data = data, let response = response else { return }
                let cachedResponse = CachedURLResponse(response: response, data: data)
                URLCache.shared.storeCachedResponse(cachedResponse, for: request)
            }
            task.resume()
        }
    }
    
    // Optional computed property
    var routeId: Int? {
        selectedRoute?.id
    }
}