import AppKit
import Quartz

/// Drives the native Quick Look panel for one URL at a time. Single-click a row
/// (or hit Space) to preview; the panel floats and closes itself like Finder.
final class QuickLook: NSObject, QLPreviewPanelDataSource, QLPreviewPanelDelegate {
    static let shared = QuickLook()
    private var url: URL?

    func preview(_ url: URL) {
        self.url = url
        guard let panel = QLPreviewPanel.shared() else { return }
        if panel.isVisible {
            panel.reloadData()
        } else {
            panel.dataSource = self
            panel.delegate = self
            panel.makeKeyAndOrderFront(nil)
        }
    }

    func numberOfPreviewItems(in panel: QLPreviewPanel) -> Int { url == nil ? 0 : 1 }
    func previewPanel(_ panel: QLPreviewPanel, previewItemAt index: Int) -> QLPreviewItem {
        (url as NSURL?) ?? NSURL()
    }
}