import QuickLook
import SwiftUI
import UIKit

// 🤖 Quick Look preview for a downloaded attachment. NativeChatScreen.openFile
// decrypts the blob and writes its bytes to a temp URL (cleaned up on dismiss);
// this hands that URL to QLPreviewController, which renders PDFs, Office docs,
// text, images, … and carries a built-in action button — Save to Files,
// AirDrop, open-in — the iOS equivalent of the web file-chip's browser
// download. Wrapped in a UINavigationController so a Done button and Quick
// Look's own share button share one bar.
struct QuickLookPreview: UIViewControllerRepresentable {
    let url: URL
    let onDone: () -> Void

    func makeCoordinator() -> Coordinator { Coordinator(url: url, onDone: onDone) }

    func makeUIViewController(context: Context) -> UINavigationController {
        let preview = QLPreviewController()
        preview.dataSource = context.coordinator
        // QLPreviewController owns its right-hand share/action button; we add
        // the Done on the left (a sheet swipe-down also dismisses).
        preview.navigationItem.leftBarButtonItem = UIBarButtonItem(
            barButtonSystemItem: .done, target: context.coordinator,
            action: #selector(Coordinator.done))
        return UINavigationController(rootViewController: preview)
    }

    func updateUIViewController(_ controller: UINavigationController, context: Context) {}

    final class Coordinator: NSObject, QLPreviewControllerDataSource {
        private let item: Item
        private let onDone: () -> Void

        init(url: URL, onDone: @escaping () -> Void) {
            self.item = Item(url: url)
            self.onDone = onDone
        }

        func numberOfPreviewItems(in controller: QLPreviewController) -> Int { 1 }
        func previewController(_ controller: QLPreviewController,
                               previewItemAt index: Int) -> QLPreviewItem { item }

        @objc func done() { onDone() }
    }

    // Quick Look keys its preview + title off the URL's filename/extension —
    // which AttachmentDownload.safeFilename has already made sound.
    private final class Item: NSObject, QLPreviewItem {
        let previewItemURL: URL?
        init(url: URL) { previewItemURL = url }
    }
}