import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';
import 'package:url_launcher/url_launcher.dart';
import 'package:webview_flutter/webview_flutter.dart';

/// Shared HTTPS WebView host. Mall-specific residency and attribution are
/// layered above this page so ordinary H5 links never receive mall state.
class AppWebPage extends StatefulWidget {
  const AppWebPage({
    super.key,
    required this.initialUri,
    this.hideTitle = false,
    this.allowedHosts = const <String>{},
  });

  final Uri initialUri;
  final bool hideTitle;
  final Set<String> allowedHosts;

  @override
  State<AppWebPage> createState() => _AppWebPageState();
}

class _AppWebPageState extends State<AppWebPage> {
  late final WebViewController _controller;
  var _progress = 0;
  String? _error;
  String _title = '';

  @override
  void initState() {
    super.initState();
    _controller = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..addJavaScriptChannel(
        'JinzhiBridge',
        onMessageReceived: (message) {
          if (message.message == 'close' && mounted) context.pop();
        },
      )
      ..setNavigationDelegate(
        NavigationDelegate(
          onProgress: (progress) => setState(() => _progress = progress),
          onPageFinished: (_) async {
            final title = await _controller.getTitle();
            if (mounted && title != null && title.trim().isNotEmpty) {
              setState(() => _title = title.trim());
            }
          },
          onWebResourceError: (error) {
            if (error.isForMainFrame == true && mounted) {
              setState(() => _error = error.description);
            }
          },
          onNavigationRequest: _onNavigationRequest,
        ),
      )
      ..loadRequest(widget.initialUri);
  }

  NavigationDecision _onNavigationRequest(NavigationRequest request) {
    final uri = Uri.tryParse(request.url);
    if (uri == null || !_isHttp(uri)) return NavigationDecision.prevent;
    if (_allowsInApp(uri)) return NavigationDecision.navigate;
    launchUrl(uri, mode: LaunchMode.externalApplication);
    return NavigationDecision.prevent;
  }

  bool _allowsInApp(Uri uri) {
    final host = uri.host.toLowerCase();
    if (host == widget.initialUri.host.toLowerCase()) return true;
    return widget.allowedHosts.any(
      (allowed) => host == allowed || host.endsWith('.$allowed'),
    );
  }

  bool _isHttp(Uri uri) =>
      uri.hasAuthority && (uri.scheme == 'https' || uri.scheme == 'http');

  Future<bool> _onPop() async {
    if (await _controller.canGoBack()) {
      await _controller.goBack();
      return false;
    }
    return true;
  }

  @override
  Widget build(BuildContext context) {
    final body = _error == null
        ? Stack(
            children: [
              WebViewWidget(controller: _controller),
              if (_progress < 100)
                LinearProgressIndicator(value: _progress / 100),
            ],
          )
        : Center(
            child: Padding(
              padding: const EdgeInsets.all(24),
              child: Text('页面加载失败\n$_error', textAlign: TextAlign.center),
            ),
          );
    return PopScope(
      canPop: false,
      onPopInvokedWithResult: (didPop, _) async {
        if (!didPop && await _onPop() && context.mounted) context.pop();
      },
      child: Scaffold(
        appBar: widget.hideTitle
            ? null
            : AppBar(title: Text(_title.isEmpty ? '加载中' : _title)),
        body: body,
      ),
    );
  }
}

Uri? parseSafeWebUri(String? raw) {
  final uri = Uri.tryParse(raw?.trim() ?? '');
  if (uri == null || !uri.hasAuthority) return null;
  return uri.scheme == 'https' || uri.scheme == 'http' ? uri : null;
}