TimelineProvider.swift

struct Provider: TimelineProvider {
    public typealias Entry = AccountEntry
    
    let viewModel = ViewModel()
    
    public func snapshot(with context: Context, completion: @escaping (AccountEntry) -> ()) {
        let entry = SimpleEntry(date: Date(), product: previewProduct, maskSensitiveData: false)
        completion(entry)
    }

    public func timeline(with context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
        let currentDate = Date()
        let refreshDate = Calendar.current.date(byAdding: .minute, value: 5, to: currentDate)!
        
        viewModel.fetchProducts() { products in
          guard let mainProduct = products.first(where: { $0.type == .main }) else { return }

          let entry = AccountEntry(date: currentDate, product: mainProduct)
          let timeline = Timeline(entries: [entry], policy: .after(refreshDate))
          completion(timeline)
        }
    }
}