import SwiftUI
import SwiftData

/// A view modifier that refreshes the view when CloudKit data changes
struct CloudKitSyncObserver: ViewModifier {
    @Environment(\.modelContext) private var modelContext
    @State private var refreshID = UUID()
    
    func body(content: Content) -> some View {
        content
            .id(refreshID) // Force view refresh when this changes
            .onReceive(NotificationCenter.default.publisher(for: .cloudKitDataDidChange)) { _ in
                refreshID = UUID()
                Task { @MainActor in
                    do {
                        let _ = try await fetchAll(of: Exercise.self, from: modelContext)
                        let _ = try await fetchAll(of: Split.self, from: modelContext)
                        let _ = try await fetchAll(of: Workout.self, from: modelContext)
                        let _ = try await fetchAll(of: WorkoutLog.self, from: modelContext)
                    } catch {
                        print("ERROR: failed to fetch \(error.localizedDescription)")
                    }
                }
            }
    }
    
    private func fetchAll<T: PersistentModel>(of type: T.Type,from modelContext: ModelContext) async throws -> [T]? {
        try modelContext.fetch(FetchDescriptor<T>())
    }
}

// Extension to make it easier to use the modifier
extension View {
    /// Adds observation for CloudKit sync changes and refreshes the view when changes occur
    func observeCloudKitChanges() -> some View {
        self.modifier(CloudKitSyncObserver())
    }
}