import SwiftUI
import UniformTypeIdentifiers

struct SettingsSectionImportExportView: View {
  @EnvironmentObject private var settings: SettingsManager
  @State private var isFileExporterPresented = false
  @State private var isFileImporterPresented = false
  @State private var bookmarksExportDocument: JSONFileDocument?
  @State private var bookmarksExportFilename = "sora_bookmarks.json"
  @State private var exportError: Error?
  @State private var importError: Error?
  private let dateFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy-MM-dd_HH-mm-ss"
    return formatter
  }()

  var body: some View {
    Group {
      Button("Import Bookmarks") {
        isFileImporterPresented = true
      }

      Button("Export Bookmarks") {
        prepareBookmarksExport()
      }
    }
    #if os(macOS)
      .trailingFrame()
    #endif
    .fileExporter(
      isPresented: $isFileExporterPresented,
      document: bookmarksExportDocument,
      contentType: .json,
      defaultFilename: bookmarksExportFilename
    ) { result in
      bookmarksExportDocument = nil

      switch result {
      case .success:
        break

      case .failure(let error):
        if !isUserCancelled(error) {
          exportError = error
        }
      }
    }
    .fileImporter(
      isPresented: $isFileImporterPresented,
      allowedContentTypes: [.json],
      allowsMultipleSelection: false
    ) { result in
      handleImportResult(result)
    }
    .alert(
      "Export Failed",
      isPresented: Binding(
        get: { exportError != nil },
        set: { if !$0 { exportError = nil } }
      )
    ) {
      Button("OK", role: .cancel) { () }
    } message: {
      Text(exportError?.localizedDescription ?? "An unknown error occurred while exporting.")
    }
    .alert(
      "Import Failed",
      isPresented: Binding(
        get: { importError != nil },
        set: { if !$0 { importError = nil } }
      )
    ) {
      Button("OK", role: .cancel) { () }
    } message: {
      Text(importError?.localizedDescription ?? "An unknown error occurred while importing.")
    }
  }

  private func prepareBookmarksExport() {
    do {
      let data = try settings.exportBookmarks()
      let timestamp = dateFormatter.string(from: Date())

      bookmarksExportDocument = JSONFileDocument(data)
      bookmarksExportFilename = "sora_bookmarks_\(timestamp).json"
      isFileExporterPresented = true
    } catch {
      exportError = error
    }
  }

  private func handleImportResult(_ result: Result<[URL], Error>) {
    do {
      guard let selectedFile = try result.get().first else { return }
      guard selectedFile.startAccessingSecurityScopedResource() else {
        throw ImportError.accessDenied
      }

      defer { selectedFile.stopAccessingSecurityScopedResource() }

      let data = try Data(contentsOf: selectedFile)

      try settings.importBookmarks(from: data)
    } catch {
      importError = error
    }
  }

  private func isUserCancelled(_ error: Error) -> Bool {
    let error = error as NSError

    return error.domain == NSCocoaErrorDomain
      && error.code == CocoaError.userCancelled.rawValue
  }

  private enum ImportError: Error {
    case accessDenied
  }
}