import 'package:flutter/material.dart';
import 'package:mobile_scanner/mobile_scanner.dart';

class QRCodeScannerPage extends StatefulWidget {
  const QRCodeScannerPage({Key? key}) : super(key: key);

  @override
  State<QRCodeScannerPage> createState() => _QRCodeScannerPageState();
}

class _QRCodeScannerPageState extends State<QRCodeScannerPage> {
  bool lido = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Leia o QR Code')),
      body: Stack(
        children: [
          // 📷 Câmera
          MobileScanner(
            fit: BoxFit.cover,
            onDetect: (capture) {
              if (lido) return;

              final barcode = capture.barcodes.firstOrNull;
              final value = barcode?.rawValue;

              if (value == null) return;

              lido = true;
              debugPrint('[LOG] Leitura QRCode: $value');

              Navigator.pop(context, value);
            },
          ),

          // 🕶️ Overlay com janela central
          const Positioned.fill(
            child: ScannerOverlay(),
          ),
        ],
      ),
    );
  }
}

class ScannerOverlay extends StatelessWidget {
  const ScannerOverlay({super.key});

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(builder: (context, constraints) {
      final width = constraints.maxWidth;
      final height = constraints.maxHeight;
      final scanAreaSize = width * 0.6;
      final left = (width - scanAreaSize) / 2;
      final top = (height - scanAreaSize) / 2;

      return Stack(
        children: [
          // Camada escura
          Container(color: Colors.black.withOpacity(0.5)),

          // Janela central
          Positioned(
            left: left,
            top: top,
            width: scanAreaSize,
            height: scanAreaSize,
            child: Container(
              decoration: BoxDecoration(
                color: Colors.transparent,
                border: Border.all(color: Colors.white, width: 2),
                borderRadius: BorderRadius.circular(16),
              ),
            ),
          ),
        ],
      );
    });
  }
}