import NetworkImage
import SwiftUI

struct PostDetailsImageView<Placeholder: View>: View {
  @EnvironmentObject var settings: Settings
  @EnvironmentObject var manager: BooruManager
  var url: URL?
  @Binding var loadingState: BooruPostLoadingState
  var finalLoadingState: BooruPostLoadingState
  let placeholder: () -> Placeholder
  let post: BooruPost?
  @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

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

      return window
    }
  #endif

  var body: some View {
    let content = NetworkImage(
      url: url,
      transaction: Transaction(animation: .default)
    ) { image in
      InteractiveImageView(image: image)
        .onAppear {
          loadingState = finalLoadingState
        }
        .background(.background)
        .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(macOS)
            Button {
              saveImageToPicturesFolder()
            } label: {
              Label("Save Image", systemImage: "square.and.arrow.down")
            }
            .keyboardShortcut("s", modifiers: [.command])
          #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

          Button {
            openURL(postURL(for: post?.id ?? ""))
          } label: {
            Label("Open Post in Safari", systemImage: "safari")
          }

          if let source = post?.source {
            Button {
              openURL(URL(string: source)!)
            } label: {
              Label("Open Source in Safari", systemImage: "safari")
            }
          }
        }
    } placeholder: {
      placeholder()
        .onAppear {
          loadingState = .loadingPreview
        }
    }

    #if os(macOS)
      return content.overlay(
        Button(action: saveImageToPicturesFolder) {
          EmptyView()
        }
        .keyboardShortcut("s", modifiers: [.command])
        .frame(width: 0, height: 0)
        .opacity(0)
      )
    #else
      return content
    #endif
  }

  init(
    url: URL?,
    loadingStage: Binding<BooruPostLoadingState>,
    finalLoadingState: BooruPostLoadingState = .loadingFile,
    post: BooruPost? = 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.placeholder = placeholder
    self.post = post
  }

  private func postURL(for id: String) -> URL {
    switch manager.flavor {
    case .moebooru:
      return URL(string: "https://\(manager.domain)/post/show/\(id)")!

    case .gelbooru:
      return URL(string: "https://\(manager.domain)/index.php?page=post&s=view&id=\(id)")!
    }
  }

  #if os(macOS)
    private func saveImageToPicturesFolder() {
      guard let url = self.url else { return }

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

        let picturesURL = FileManager.default.homeDirectoryForCurrentUser
          .appendingPathComponent("Pictures/Sora/\(manager.provider.rawValue)")

        do {
          try FileManager.default.createDirectory(
            at: picturesURL,
            withIntermediateDirectories: true
          )
          try data.write(
            to:
              picturesURL
              .appendingPathComponent(
                "\(post.id)_\(settings.detailViewType.rawValue.lowercased()).\(url.pathExtension)"
              )
          )

          if settings.saveTagsToFile {
            try post.tags.joined(separator: "\n").write(
              to: picturesURL.appendingPathComponent(
                "\(post.id).txt"
              ),
              atomically: true,
              encoding: .utf8
            )
          }
        } catch {
          print("PostDetailsImageView.saveImageToPicturesFolder: \(error)")
        }
      }
      .resume()
    }
  #endif

  private func openURL(_ url: URL) {
    #if os(iOS)
      UIApplication.shared.open(url)
    #else
      NSWorkspace.shared.open(url)
    #endif
  }
}