import 'dart:async';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';

class ScanLaunchService {
  ScanLaunchService._();

  static final ScanLaunchService instance = ScanLaunchService._();

  static const _methodChannel = MethodChannel('com.example.qrscanner/scan_launch');
  static const _eventChannel = EventChannel('com.example.qrscanner/scan_events');

  Stream<String>? _scanStream;

  bool get isAndroid => !kIsWeb && Platform.isAndroid;

  Stream<String> get scanStream {
    _scanStream ??= _eventChannel
        .receiveBroadcastStream()
        .where((event) => event is String && event.trim().isNotEmpty)
        .map((event) => (event as String).trim());
    return _scanStream!;
  }

  Future<bool> isSupported() async {
    if (!isAndroid) return false;
    try {
      final supported = await _methodChannel.invokeMethod<bool>('isSupported');
      return supported ?? false;
    } catch (_) {
      return false;
    }
  }

  Future<void> claimScanner() async {
    if (!isAndroid) return;
    try {
      await _methodChannel.invokeMethod<void>('claimScanner');
    } catch (_) {}
  }

  Future<void> releaseScanner() async {
    if (!isAndroid) return;
    try {
      await _methodChannel.invokeMethod<void>('releaseScanner');
    } catch (_) {}
  }

  Future<String?> consumePendingScan() async {
    if (!isAndroid) return null;
    try {
      final code = await _methodChannel.invokeMethod<String>('consumePendingScan');
      final trimmed = code?.trim();
      if (trimmed == null || trimmed.isEmpty) return null;
      return trimmed;
    } catch (_) {
      return null;
    }
  }
}