import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:webview_flutter/webview_flutter.dart';

import '../../design/pencil_theme.dart';

/// 通用应用内 Web 页（任意 HTTPS/HTTP 链接），供用户协议、隐私政策及其他 H5 复用。
class AppWebViewScreen extends StatefulWidget {
  const AppWebViewScreen({
    super.key,
    required this.title,
    required this.initialUrl,
  });

  final String title;

  /// 完整 URL（含 `http`/`https`）。
  final String initialUrl;

  @override
  State<AppWebViewScreen> createState() => _AppWebViewScreenState();
}

class _AppWebViewScreenState extends State<AppWebViewScreen> {
  WebViewController? _controller;
  bool _loading = true;
  String? _loadError;

  @override
  void initState() {
    super.initState();
    final uri = _parseHttpUrl(widget.initialUrl);
    if (uri == null) {
      _loadError = 'Invalid link';
      _loading = false;
      return;
    }
    _controller = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..setNavigationDelegate(
        NavigationDelegate(
          onPageStarted: (_) {
            if (mounted) setState(() => _loading = true);
          },
          onPageFinished: (_) {
            if (mounted) setState(() => _loading = false);
          },
          onWebResourceError: (WebResourceError e) {
            if (mounted) {
              setState(() {
                _loading = false;
                _loadError = e.description.isNotEmpty
                    ? e.description
                    : 'Failed to load page';
              });
            }
          },
        ),
      )
      ..loadRequest(uri);
  }

  static Uri? _parseHttpUrl(String raw) {
    final u = Uri.tryParse(raw.trim());
    if (u == null || !u.hasScheme) return null;
    if (u.scheme != 'http' && u.scheme != 'https') return null;
    return u;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBar(
        backgroundColor: Colors.white,
        surfaceTintColor: Colors.transparent,
        elevation: 0,
        foregroundColor: PencilTheme.stone900,
        title: Text(
          widget.title,
          style: GoogleFonts.inter(
            fontSize: 17,
            fontWeight: FontWeight.w600,
            color: PencilTheme.stone900,
          ),
        ),
        leading: IconButton(
          icon: const Icon(Icons.arrow_back_ios_new_rounded, size: 20),
          onPressed: () => Navigator.of(context).pop(),
        ),
      ),
      body: _buildBody(),
    );
  }

  Widget _buildBody() {
    if (_loadError != null && _controller == null) {
      return Center(
        child: Padding(
          padding: const EdgeInsets.all(24),
          child: Text(
            _loadError!,
            textAlign: TextAlign.center,
            style: GoogleFonts.inter(
              fontSize: 15,
              color: PencilTheme.stone600,
            ),
          ),
        ),
      );
    }
    final c = _controller;
    if (c == null) {
      return const SizedBox.shrink();
    }
    return Stack(
      fit: StackFit.expand,
      children: [
        WebViewWidget(controller: c),
        if (_loading)
          const ColoredBox(
            color: Color(0x0F000000),
            child: Center(
              child: CircularProgressIndicator(
                color: PencilTheme.underlineGold,
              ),
            ),
          ),
        if (_loadError != null && _controller != null)
          Positioned(
            left: 0,
            right: 0,
            bottom: 0,
            child: Material(
              color: const Color(0xFFFFF7ED),
              child: SafeArea(
                top: false,
                child: Padding(
                  padding: const EdgeInsets.all(12),
                  child: Text(
                    _loadError!,
                    style: GoogleFonts.inter(
                      fontSize: 13,
                      color: const Color(0xFF9A3412),
                    ),
                  ),
                ),
              ),
            ),
          ),
      ],
    );
  }
}