import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:webview_flutter/webview_flutter.dart';
import '../services/api_service.dart';
import '../providers/app_provider.dart';
import '../models/problem.dart';

/// 题目预览 Widget — WebView 渲染服务端 HTML+MathML（Android）
class ProblemPreview extends ConsumerStatefulWidget {
  final Problem problem;
  final bool showAnswer;

  const ProblemPreview({super.key, required this.problem, this.showAnswer = true});

  @override
  ConsumerState<ProblemPreview> createState() => _ProblemPreviewState();
}

class _ProblemPreviewState extends ConsumerState<ProblemPreview> {
  WebViewController? _controller;

  @override
  void initState() {
    super.initState();
    _initController();
  }

  @override
  void didUpdateWidget(ProblemPreview oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (oldWidget.problem.id != widget.problem.id || oldWidget.showAnswer != widget.showAnswer) {
      _initController();
    }
  }

  void _initController() {
    _controller = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted);
    _loadContent();
  }

  Future<void> _loadContent() async {
    final api = ref.read(apiServiceProvider);
    final baseUrl = api.baseUrl ?? '';
    final token = api.token ?? '';
    final answerParam = widget.showAnswer ? 'true' : 'false';
    final viewUrl = '$baseUrl/api/problems/${widget.problem.id}/view'
        '?include_answer=$answerParam&token=$token';

    _controller?.loadRequest(Uri.parse(viewUrl));
  }

  @override
  Widget build(BuildContext context) {
    if (_controller == null) {
      return const Center(child: CircularProgressIndicator());
    }
    return WebViewWidget(controller: _controller!);
  }
}