cb_prestige_qr/lib/features/scan/presentation/pages/scan_page.dart

import 'dart:async';

import 'package:cb_prestige_qr/core/presentation/widgets/start_loading_overlay.dart';
import 'package:cb_prestige_qr/features/scan/presentation/manager/scan_controller.dart';
import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';
import 'package:mobile_scanner/mobile_scanner.dart';

class ScanPage extends ConsumerStatefulWidget {
  const ScanPage({super.key});

  @override
  ConsumerState<ScanPage> createState() => _ScanPageState();
}

class _ScanPageState extends ConsumerState<ScanPage> {
  late final MobileScannerController _scannerController;

  @override
  void initState() {
    super.initState();
    _scannerController = MobileScannerController();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (!mounted) return;
      ref.read(scanControllerProvider.notifier).resumeScanning();
      unawaited(_scannerController.start());
    });
  }

  @override
  void dispose() {
    _scannerController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    ref.listen<bool>(scanControllerProvider.select((s) => s.isScanning), (
      previous,
      next,
    ) {
      if (previous == next) return;
      if (next) {
        unawaited(_scannerController.start());
      } else {
        unawaited(_scannerController.stop());
      }
    });

    final scanState = ref.watch(scanControllerProvider);

    void onDetect(BarcodeCapture capture) {
      if (!scanState.isScanning) return;
      final value = capture.barcodes.isEmpty
          ? null
          : capture.barcodes.first.rawValue;
      if (value == null || value.isEmpty) return;

      unawaited(
        ref.read(scanControllerProvider.notifier).onBarcodeDetected(value),
      );
    }

    return StartLoadingOverlay(
      child: Scaffold(
        appBar: AppBar(title: const Text('Scan QR')),
        body: Stack(
          children: [
            MobileScanner(controller: _scannerController, onDetect: onDetect),
            Align(
              alignment: Alignment.center,
              child: Container(
                width: 250,
                height: 250,
                decoration: BoxDecoration(
                  border: Border.all(color: Colors.white, width: 3),
                  borderRadius: BorderRadius.circular(12),
                ),
              ),
            ),
            if (scanState.isProcessing)
              const Positioned.fill(
                child: ColoredBox(
                  color: Color(0x66000000),
                  child: Center(child: CircularProgressIndicator()),
                ),
              ),
            if (!scanState.isProcessing &&
                (scanState.scannedValue != null ||
                    scanState.errorMessage != null))
              Positioned.fill(
                child: ColoredBox(
                  color: const Color(0x66000000),
                  child: SafeArea(
                    child: Center(
                      child: ConstrainedBox(
                        constraints: const BoxConstraints(maxWidth: 420),
                        child: Padding(
                          padding: const EdgeInsets.all(16),
                          child: Material(
                            borderRadius: BorderRadius.circular(16),
                            clipBehavior: Clip.antiAlias,
                            child: Padding(
                              padding: const EdgeInsets.all(16),
                              child: Column(
                                mainAxisSize: MainAxisSize.min,
                                crossAxisAlignment: CrossAxisAlignment.stretch,
                                children: [
                                  Text(
                                    scanState.errorMessage == null
                                        ? 'Scanned Result'
                                        : 'Scan Error',
                                    style: Theme.of(
                                      context,
                                    ).textTheme.titleLarge,
                                  ),
                                  const SizedBox(height: 12),
                                  SelectableText(
                                    scanState.errorMessage ??
                                        scanState.scannedValue ??
                                        '',
                                  ),
                                  const SizedBox(height: 16),
                                  Row(
                                    children: [
                                      Expanded(
                                        child: OutlinedButton(
                                          onPressed: () {
                                            ref
                                                .read(
                                                  scanControllerProvider
                                                      .notifier,
                                                )
                                                .resumeScanning();
                                          },
                                          child: const Text('Scan Again'),
                                        ),
                                      ),
                                      const SizedBox(width: 12),
                                      Expanded(
                                        child: FilledButton(
                                          onPressed: () {
                                            Navigator.pop(context);
                                          },
                                          child: const Text('Back'),
                                        ),
                                      ),
                                    ],
                                  ),
                                ],
                              ),
                            ),
                          ),
                        ),
                      ),
                    ),
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }
}