QuickLookCoordinator

@MainActor
final class QuickLookCoordinator: NSObject, QLPreviewPanelDataSource, QLPreviewPanelDelegate

static let shared = QuickLookCoordinator()

func preview(_ object: R2Object, credentials: R2Credentials)

// Example from QuickLookCoordinator.swift:27-45
func preview(_ object: R2Object, credentials: R2Credentials) {
    let panel = QLPreviewPanel.shared()!

    // Toggle: if already visible for same coordinator, close it
    if panel.isVisible && panel.dataSource === self {
        panel.close()
        return
    }

    // Generate a presigned URL and pass it directly to Quick Look — no download needed.
    // previewItemTitle supplies the filename so QL picks the right previewer plugin.
    guard let presignedURL = AWSV4Signer.presignedURL(for: object.key, credentials: credentials) else { return }
    previewItem = PreviewItem(url: presignedURL, title: object.name)

    panel.dataSource = self
    panel.delegate  = self
    panel.makeKeyAndOrderFront(nil)
    panel.reloadData()
}

private final class PreviewItem: NSObject, QLPreviewItem {
    let previewItemURL: URL?
    let previewItemTitle: String?

    init(url: URL, title: String) {
        self.previewItemURL = url
        self.previewItemTitle = title
    }
}

func numberOfPreviewItems(in panel: QLPreviewPanel!) -> Int {
    previewItem != nil ? 1 : 0
}

func previewPanel(_ panel: QLPreviewPanel!, previewItemAt index: Int) -> (any QLPreviewItem)! {
    previewItem
}

func previewPanel(_ panel: QLPreviewPanel!, handle event: NSEvent!) -> Bool {
    false
}

guard let presignedURL = AWSV4Signer.presignedURL(
    for: object.key,
    credentials: credentials
) else { return }

import SwiftUI

struct FileRowView: View {
    let object: R2Object
    let credentials: R2Credentials
    
    var body: some View {
        HStack {
            Image(systemName: "doc")
            Text(object.name)
        }
        .onTapGesture(count: 2) {
            // Double-click to preview
            QuickLookCoordinator.shared.preview(object, credentials: credentials)
        }
        .onKeyPress(.space) {
            // Spacebar to preview
            QuickLookCoordinator.shared.preview(object, credentials: credentials)
            return .handled
        }
    }
}

// If panel is already visible for this coordinator, close it
if panel.isVisible && panel.dataSource === self {
    panel.close()
    return
}

List(browserObjects) { object in
    FileRow(object: object)
        .onKeyPress(.space) {
            QuickLookCoordinator.shared.preview(object, credentials: credentials)
            return .handled
        }
}