import SwiftUI
import VisionKit
import UIKit

#if canImport(VisionKit) && os(iOS)

/// VisionKit 文档扫描器的 SwiftUI 包装。
/// - 真机:全屏多页文档扫描,自动透视校正
/// - 模拟器:`VNDocumentCameraViewController.isSupported == false`,
///   父 View 不要 present 这个,改走 PhotosPicker 回退(见 PhotoPickerSheet)
struct DocumentScannerView: UIViewControllerRepresentable {
    let onFinish: ([UIImage]) -> Void
    let onCancel: () -> Void

    func makeUIViewController(context: Context) -> VNDocumentCameraViewController {
        let vc = VNDocumentCameraViewController()
        vc.delegate = context.coordinator
        return vc
    }

    func updateUIViewController(_ uiViewController: VNDocumentCameraViewController,
                                 context: Context) {}

    func makeCoordinator() -> Coordinator {
        Coordinator(onFinish: onFinish, onCancel: onCancel)
    }

    final class Coordinator: NSObject, VNDocumentCameraViewControllerDelegate {
        let onFinish: ([UIImage]) -> Void
        let onCancel: () -> Void

        init(onFinish: @escaping ([UIImage]) -> Void,
             onCancel: @escaping () -> Void) {
            self.onFinish = onFinish
            self.onCancel = onCancel
        }

        func documentCameraViewController(
            _ controller: VNDocumentCameraViewController,
            didFinishWith scan: VNDocumentCameraScan
        ) {
            var images: [UIImage] = []
            for i in 0..<scan.pageCount {
                images.append(scan.imageOfPage(at: i))
            }
            onFinish(images)
        }

        func documentCameraViewControllerDidCancel(
            _ controller: VNDocumentCameraViewController
        ) {
            onCancel()
        }

        func documentCameraViewController(
            _ controller: VNDocumentCameraViewController,
            didFailWithError error: Error
        ) {
            onCancel()
        }
    }

    static var isSupported: Bool {
        VNDocumentCameraViewController.isSupported
    }
}

#endif