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 {
//                        for entity in modelContext.container.schema.entities {
//                            fetchAll<entity.Type>(of: entity.Type, from: modelContext)
//                        }
//                    } catch {
//                        print("ERROR: failed to fetch data on CloudKit change")
//                    }
//                    
//                    try? modelContext.fetch(FetchDescriptor<Exercise>())
//                    try? modelContext.fetch(FetchDescriptor<ExerciseType>())
//                    try? modelContext.fetch(FetchDescriptor<Muscle>())
//                    try? modelContext.fetch(FetchDescriptor<MuscleGroup>())
//                    try? modelContext.fetch(FetchDescriptor<Exercise>())
//                    try? modelContext.fetch(FetchDescriptor<Exercise>())
//                    try? modelContext.fetch(FetchDescriptor<Exercise>())
//                    try? modelContext.fetch(FetchDescriptor<Exercise>())
                    // TODO: add more entities?
                }
            }
    }
    
    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())
    }
}