func didClickAddBUILDFile()

in src/Tulsi/ProjectEditorPackageManagerViewController.swift [90:130]
37 lines of code
9 McCabe index (conditional complexity)

  func didClickAddBUILDFile(_ sender: AnyObject?) {
    guard let document = self.representedObject as? TulsiProjectDocument,
              let workspacePath = document.workspaceRootURL?.path else {
      return
    }

    let panel = FilteredOpenPanel.filteredOpenPanel() {
      (_: AnyObject, url: URL) -> Bool in
        var isDir: AnyObject?
        var isPackage: AnyObject?
        do {
          try (url as NSURL).getResourceValue(&isDir, forKey: URLResourceKey.isDirectoryKey)
          try (url as NSURL).getResourceValue(&isPackage, forKey: URLResourceKey.isPackageKey)
          if let isDir = isDir as? NSNumber, let isPackage = isPackage as? NSNumber, !isPackage.boolValue {
            if isDir.boolValue { return true }
            let filename = url.lastPathComponent
            if filename == "BUILD" || filename == "BUILD.bazel" {
              // Prevent anything outside of the selected workspace.
              return url.path.hasPrefix(workspacePath) && !document.containsBUILDFileURL(url)
            }
          }
        } catch _ {
          // Treat any exception as an invalid URL.
        }
        return false
    }

    panel.prompt = NSLocalizedString("ProjectEditor_AddBUILDFilePrompt",
                                     comment: "Label for the button used to confirm adding the selected BUILD file to the Tulsi project.")
    panel.canChooseDirectories = false
    panel.beginSheetModal(for: self.view.window!) { value in
      if value == NSApplication.ModalResponse.OK {
        guard let URL = panel.url else {
          return
        }
        if !document.addBUILDFileURL(URL) {
          NSSound.beep()
        }
      }
    }
  }