import 'dart:io';
    import 'dart:isolate';
    import 'dart:ui';
    import 'package:flutter/material.dart';
    import 'package:url_launcher/url_launcher.dart';
    import 'package:flutter_inappwebview/flutter_inappwebview.dart';
    import 'package:flutter_downloader/flutter_downloader.dart';
    import 'package:path_provider/path_provider.dart';
    Future main() async {
        WidgetsFlutterBinding.ensureInitialized();
        await FlutterDownloader.initialize(
            debug: true, // optional: set false to disable printing logs to console
        );
        runApp(new MyApp());
    }
    class MyApp extends StatelessWidget {
        @override
        Widget build(BuildContext context) {
            return MaterialApp(
                home: RpWebPage(
                    link: 'https://billpay.setu.co/1234',
                ), // Replace with the actual URL
            );
        }
    }
    class RpWebPage extends StatefulWidget {
        const RpWebPage({super.key, required this.link});
        final String link;
        @override
        State<RpWebPage> createState() => _RpWebPageState();
    }
    class _RpWebPageState extends State<RpWebPage> {
        late InAppWebViewController webView;
        bool isButtonClicked = false;
        @override
        void initState() {
            super.initState();
        }
        void _loadUrl() {
            setState(() {
                isButtonClicked = true;
            });
        }
        @override
        Widget build(BuildContext context) {
            return Scaffold(
                appBar: AppBar(
                    title: Text('Bill Payments'),
                ),
                body: Column(
                    children: [
                    if (!isButtonClicked)
                        ElevatedButton(
                            onPressed: _loadUrl,
                            child: Text('Load webview'),
                        ),
                    Expanded(
                        child: isButtonClicked
                            ? InAppWebView(
                                initialSettings: InAppWebViewSettings(
                                    allowFileAccess: true,
                                    allowFileAccessFromFileURLs: true
                                ),
                                initialUrlRequest: URLRequest(url: WebUri.uri(Uri.parse(widget.link))),
                                onWebViewCreated: (InAppWebViewController controller) {
                                    webView = controller;
                                },
                                onLoadStop: (controller, url) async {
                                    controller.addJavaScriptHandler(
                                        handlerName: 'initiatePayment',
                                        callback: (args) async {
                                            print('Received from WebView: $args');
                                            var paymentData = args[0];
                                            print('Payment data: $paymentData');
                                            // add your custom payment logic here
                                        },
                                    );
                                    controller.addJavaScriptHandler(
                                        handlerName: 'unload',
                                        callback: (args) async {
                                            // logic to close webview and return to app
                                        },
                                    );
                                },
                                // Handle downloading the receipt
                                onDownloadStartRequest: (controller, request) async {
                                    print("onDownloadStart $request");
                                    final dir = Platform.isAndroid
                                        ? (await getExternalStorageDirectory())?.path
                                        : (await getApplicationDocumentsDirectory()).uri.path;
                                    print("saving in $dir");
                                    final taskId = await FlutterDownloader.enqueue(
                                        url: request.url.toString(),
                                        savedDir: dir!,
                                        showNotification: true, // show download progress in status bar (for Android)
                                        openFileFromNotification: true, // click on notification to open downloaded file (for Android)
                                        saveInPublicStorage: true,
                                        allowCellular: true
                                    );
                                    // Open the downloaded file
                                    await FlutterDownloader.open(taskId: taskId!);
                                },
                            )
                            : Container(),
                        ),
                    ],
                ),
            );
        }
    }