import AppKit

// This class will manufacture a delegate object for use with NSOutlineView,
// given the following:
//  - A setup function, that will take an NSTableViewCell or subclass of the
//      given type, and fill in its views.
//  - A cell identifier from the storyboard, associated to the outline view.
//  - A function that is called when a selection is made...
//      Since the selection handler doesn't actually provide the selected node,
//      you need to seal a reference to your outline view inside your Selection
//      Action closure.  Yuck.  Make sure to use a capture list to prevent memory cycles.
final class OutlineDelegate<CellType, ModelType> : NSObject, NSOutlineViewDelegate {

  typealias CellSetup = (CellType, ModelType) -> NSView?
  typealias SelectionAction = () -> Void
  typealias MoveAction = () -> Void

  private let cell_identifier: String
  private let configure_cell: CellSetup
  private let selectionAction: SelectionAction

  init(cell_identifier: String,
       configure_cell: @escaping CellSetup,
       selection_action: @escaping SelectionAction)
  {
    self.cell_identifier = cell_identifier
    self.configure_cell = configure_cell
    self.selectionAction = selection_action
  }

  func outlineView(_ outlineView: NSOutlineView, viewFor tableColumn: NSTableColumn?, item: Any) -> NSView? {
    let view = outlineView.makeView(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: cell_identifier), owner: self) as! CellType
    return configure_cell(view, item as! ModelType)
  }

  func outlineViewSelectionDidChange(_ notification: Notification) {
    selectionAction()
  }
}