// lib/utils/asset_server.dart
import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'package:flutter/services.dart' show rootBundle;
import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';

class AssetServer {
  AssetServer._internal();
  static final AssetServer _instance = AssetServer._internal();
  factory AssetServer() => _instance;

  HttpServer? _server;
  int? _port;
  bool get running => _server != null;

  Future<Uri> start() async {
    if (_server != null && _port != null) {
      return Uri.parse('http://127.0.0.1:$_port');
    }

    // Bind to ephemeral port
    _server = await HttpServer.bind(InternetAddress.loopbackIPv4, 0);
    _port = _server!.port;

    _server!.listen((HttpRequest request) async {
      try {
        final path = request.uri.path.isEmpty ? '/map.html' : request.uri.path;
        debugPrint('[AssetServer] -> Request: $path');

        // map to assets/map/<path>
        final assetPath = 'assets/map$path';

        // simple content-type detection
        final contentType = _contentTypeFromPath(path);

        if (assetPath.endsWith('.html') || assetPath.endsWith('.htm')) {
          // For HTML, we prefer to read as text
          final html = await rootBundle.loadString('assets/map/map.html');
          request.response.headers.contentType = ContentType('text', 'html', charset: 'utf-8');
          request.response.add(utf8.encode(html));
          await request.response.close();
          return;
        }

        // Other assets as bytes
        try {
          final bd = await rootBundle.load(assetPath);
          final bytes = bd.buffer.asUint8List();
          if (contentType != null) request.response.headers.contentType = contentType;
          request.response.add(bytes);
          await request.response.close();
        } catch (e) {
          debugPrint('[AssetServer] asset not found: $assetPath -> $e');
          request.response.statusCode = HttpStatus.notFound;
          request.response.write('Not Found');
          await request.response.close();
        }
      } catch (e) {
        debugPrint('[AssetServer] internal error: $e');
        try {
          request.response.statusCode = HttpStatus.internalServerError;
          request.response.write('Internal Server Error');
          await request.response.close();
        } catch (_) {}
      }
    });

    debugPrint('[AssetServer] started at http://127.0.0.1:$_port');
    return Uri.parse('http://127.0.0.1:$_port');
  }

  Future<void> stop() async {
    try {
      await _server?.close(force: true);
      _server = null;
      _port = null;
      debugPrint('[AssetServer] stopped');
    } catch (e) {
      debugPrint('[AssetServer] stop error: $e');
    }
  }

  ContentType? _contentTypeFromPath(String path) {
    final lower = path.toLowerCase();
    if (lower.endsWith('.js')) return ContentType('application', 'javascript', charset: 'utf-8');
    if (lower.endsWith('.css')) return ContentType('text', 'css', charset: 'utf-8');
    if (lower.endsWith('.html') || lower.endsWith('.htm')) return ContentType('text', 'html', charset: 'utf-8');
    if (lower.endsWith('.json')) return ContentType('application', 'json', charset: 'utf-8');
    if (lower.endsWith('.png')) return ContentType('image', 'png');
    if (lower.endsWith('.jpg') || lower.endsWith('.jpeg')) return ContentType('image', 'jpeg');
    if (lower.endsWith('.svg')) return ContentType('image', 'svg+xml');
    if (lower.endsWith('.gif')) return ContentType('image', 'gif');
    if (lower.endsWith('.webp')) return ContentType('image', 'webp');
    return ContentType('application', 'octet-stream');
  }
}