Vorrania/ios/Sources/DateScanView.swift

import SwiftUI
import VisionKit

/// Liest das MHD per Texterkennung von der Verpackung ab.
///
/// Gefundene Daten werden als Vorschlag angezeigt; uebernommen wird erst,
/// was der Benutzer antippt.
struct DateScanView: View {
    var onPick: (Date, String) -> Void

    @Environment(\.dismiss) private var dismiss
    @State private var matches: [BestBeforeText.Match] = []

    /// Texterkennung braucht Geraete mit Neural Engine; auf aelteren fehlt sie.
    static var isSupported: Bool {
        DataScannerViewController.isSupported && DataScannerViewController.isAvailable
    }

    var body: some View {
        ZStack(alignment: .bottom) {
            if Self.isSupported {
                TextScannerRepresentable { text in
                    let neu = BestBeforeText.matches(in: text)
                    guard !neu.isEmpty else { return }
                    // Neueste Funde vorn, hoechstens eine Handvoll anzeigen.
                    for treffer in neu where !matches.contains(where: {
                        $0.date == treffer.date && $0.precision == treffer.precision
                    }) {
                        matches.insert(treffer, at: 0)
                    }
                    if matches.count > 5 { matches = Array(matches.prefix(5)) }
                }
                .ignoresSafeArea()
            } else {
                Color.black.ignoresSafeArea()
                Text("Dieses Gerät unterstützt keine Texterkennung.")
                    .foregroundStyle(.white)
            }

            VStack(spacing: 10) {
                if matches.isEmpty {
                    hinweis("Das Mindesthaltbarkeitsdatum in den Sucher halten.")
                } else {
                    ForEach(matches) { treffer in
                        Button {
                            onPick(treffer.date, treffer.precision)
                            dismiss()
                        } label: {
                            HStack {
                                Image(systemName: "calendar")
                                Text(treffer.label).font(.headline)
                                Spacer()
                                Text("Übernehmen").font(.subheadline)
                            }
                            .padding()
                            .frame(maxWidth: .infinity)
                            .background(.thinMaterial)
                            .clipShape(RoundedRectangle(cornerRadius: 12))
                        }
                        .buttonStyle(.plain)
                    }
                    hinweis("Bitte gegen den Aufdruck prüfen.")
                }
            }
            .padding()
        }
        .navigationTitle("MHD scannen")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .topBarLeading) { Button("Abbrechen") { dismiss() } }
        }
    }

    private func hinweis(_ text: String) -> some View {
        Text(text)
            .font(.caption)
            .padding(10)
            .frame(maxWidth: .infinity)
            .background(.ultraThinMaterial)
            .clipShape(RoundedRectangle(cornerRadius: 10))
    }
}

/// Duenne Huelle um den Text-Scanner von VisionKit.
private struct TextScannerRepresentable: UIViewControllerRepresentable {
    var onText: (String) -> Void

    func makeCoordinator() -> Coordinator { Coordinator(onText: onText) }

    func makeUIViewController(context: Context) -> DataScannerViewController {
        let controller = DataScannerViewController(
            recognizedDataTypes: [.text()],
            qualityLevel: .accurate,
            recognizesMultipleItems: true,
            isHighFrameRateTrackingEnabled: false,
            isHighlightingEnabled: true
        )
        controller.delegate = context.coordinator
        return controller
    }

    func updateUIViewController(_ controller: DataScannerViewController, context: Context) {
        guard !controller.isScanning else { return }
        try? controller.startScanning()
    }

    static func dismantleUIViewController(_ controller: DataScannerViewController, coordinator: Coordinator) {
        controller.stopScanning()
    }

    final class Coordinator: NSObject, DataScannerViewControllerDelegate {
        let onText: (String) -> Void
        init(onText: @escaping (String) -> Void) { self.onText = onText }

        func dataScanner(_ scanner: DataScannerViewController,
                         didAdd addedItems: [RecognizedItem],
                         allItems: [RecognizedItem]) {
            handle(allItems)
        }

        func dataScanner(_ scanner: DataScannerViewController,
                         didUpdate updatedItems: [RecognizedItem],
                         allItems: [RecognizedItem]) {
            handle(allItems)
        }

        private func handle(_ items: [RecognizedItem]) {
            let text = items.compactMap { item -> String? in
                if case .text(let erkannt) = item { return erkannt.transcript }
                return nil
            }.joined(separator: " ")
            guard !text.isEmpty else { return }
            onText(text)
        }
    }
}