import CoreData
import Models
import Services
import SwiftUI
import Utils

#if os(iOS)
  @MainActor final class WebReaderLoadingContainerViewModel: ObservableObject {
    @Published var item: LinkedItem?
    @Published var errorMessage: String?

    func loadItem(dataService: DataService, requestID: String) async {
      guard let objectID = try? await dataService.loadItemContentUsingRequestID(requestID: requestID) else { return }
      item = dataService.viewContext.object(with: objectID) as? LinkedItem
    }

    func trackReadEvent() {
      guard let item = item else { return }

      EventTracker.track(
        .linkRead(
          linkID: item.unwrappedID,
          slug: item.unwrappedSlug,
          originalArticleURL: item.unwrappedPageURLString
        )
      )
    }
  }

  public struct WebReaderLoadingContainer: View {
    let requestID: String

    @EnvironmentObject var dataService: DataService
    @StateObject var viewModel = WebReaderLoadingContainerViewModel()

    public var body: some View {
      if let item = viewModel.item, item.isReadyToRead {
        if let pdfItem = PDFItem.make(item: item), let urlStr = item.pageURLString, let remoteUrl = URL(string: urlStr) {
          PDFViewer(viewModel: PDFViewerViewModel(pdfItem: pdfItem))
            .navigationBarHidden(true)
            .navigationViewStyle(.stack)
            .accentColor(.appGrayTextContrast)
            .task { viewModel.trackReadEvent() }
        } else {
          WebReaderContainerView(item: item)
            .navigationBarHidden(true)
            .navigationViewStyle(.stack)
            .accentColor(.appGrayTextContrast)
            .task { viewModel.trackReadEvent() }
        }
      } else if let errorMessage = viewModel.errorMessage {
        Text(errorMessage)
      } else {
        ProgressView()
          .task { await viewModel.loadItem(dataService: dataService, requestID: requestID) }
      }
    }
  }
#endif