import SwiftUI

struct AsyncImageWithPreview<Placeholder: View>: View {
  @EnvironmentObject var settings: Settings
  var url: URL?
  @Binding var loadingState: PostLoadingState
  var finalLoadingState: PostLoadingState
  var postURL: URL?
  let placeholder: () -> Placeholder
  @State private var currentScale: CGFloat = 1.0
  @State private var finalScale: CGFloat = 1.0
  @State private var currentOffset: CGSize = .zero
  @State private var finalOffset: CGSize = .zero

  var keyWindow: UIWindow? {
    guard
      let window = UIApplication.shared.connectedScenes
        .compactMap({ $0 as? UIWindowScene })
        .flatMap(\.windows)
        .first(where: \.isKeyWindow)
    else {
      return nil
    }

    return window
  }

  var body: some View {
    AsyncImage(url: url) { image in
      ZoomableImageView(image: image)
        .onAppear {
          loadingState = finalLoadingState
        }
        .contextMenu {
          #if os(iOS)
            Button {
              guard let url else { return }

              URLSession.shared.dataTask(with: url) { data, _, _ in
                guard let data, let uiImage = UIImage(data: data) else { return }

                UIImageWriteToSavedPhotosAlbum(uiImage, nil, nil, nil)
              }
              .resume()
            } label: {
              Label("Save Image", systemImage: "square.and.arrow.down")
            }
          #endif

          #if os(iOS)
            if settings.enableShareShortcut {
              Button {
                keyWindow?.rootViewController?.present(
                  UIActivityViewController(
                    activityItems: [url ?? URL(string: "")!], applicationActivities: nil
                  ), animated: true
                )
              } label: {
                Label("Share Image", systemImage: "square.and.arrow.up")
              }
            }
          #endif

          if let url = postURL {
            Button {
              #if os(iOS)
                UIApplication.shared.open(url)
              #else
                NSWorkspace.shared.open(url)
              #endif
            } label: {
              Label("Open in Safari", systemImage: "safari")
            }
          }
        }
    } placeholder: {
      placeholder()
        .onAppear {
          loadingState = .loadingPreview
        }
    }
  }

  init(
    url: URL?,
    loadingStage: Binding<PostLoadingState>,
    finalLoadingState: PostLoadingState = .loadingFile,
    postURL: URL? = nil,
    @ViewBuilder placeholder: @escaping () -> Placeholder = {
      GeometryReader { geometry in
        ProgressView()
          .frame(width: geometry.size.width, height: geometry.size.height)
          .position(x: geometry.size.width / 2, y: geometry.size.height / 2)
          .padding()
      }
    }
  ) {
    self.url = url
    _loadingState = loadingStage
    self.finalLoadingState = finalLoadingState
    self.postURL = postURL
    self.placeholder = placeholder
  }
}