import 'dart:async';
import 'dart:io';
import 'package:call_log/call_log.dart';
import 'package:permission_handler/permission_handler.dart';

class OtpController {
  DateTime? _startTime;
  Timer? _pollTimer;
  String? _detectedOtp;
  bool _isPolling = false;

  // Callbacks
  Function(String status)? onStatusChanged;
  Function(String otp)? onOtpDetected;
  Function()? onTimeout;

  /// Start polling call log for missed calls
  Future<bool> startWaiting(String phone) async {
    if (Platform.isIOS) {
      // iOS: cannot read call log, skip to manual entry
      onStatusChanged?.call('manual_ios');
      return false;
    }

    // Request phone permissions (usually covers call log on many Android versions)
    var status = await Permission.phone.request();
    
    if (!status.isGranted) {
      onStatusChanged?.call('permission_denied');
      return false;
    }

    _startTime = DateTime.now();
    _isPolling = true;
    onStatusChanged?.call('waiting');

    // Poll every 1.5 seconds
    _pollTimer = Timer.periodic(const Duration(milliseconds: 1500), (_) {
      _checkCallLog(phone);
    });

    // Timeout after 120 seconds
    Future.delayed(const Duration(seconds: 120), () {
      if (_isPolling && _detectedOtp == null) {
        stopWaiting();
        onTimeout?.call();
      }
    });

    return true;
  }

  /// Check call log for missed calls since _startTime
  Future<void> _checkCallLog(String phone) async {
    try {
      final Iterable<CallLogEntry> entries = await CallLog.query(
        dateFrom: _startTime!.millisecondsSinceEpoch,
      );

      for (var entry in entries) {
        if (entry.callType == CallType.missed && entry.number != null) {
          final otp = extractOTP(entry.number!);
          if (otp.length == 4) {
            _detectedOtp = otp;
            stopWaiting();
            onStatusChanged?.call('call_detected');
            onOtpDetected?.call(otp);
            return;
          }
        }
      }
    } catch (e) {
      // Silently continue polling
    }
  }

  /// Extract OTP from caller number (last 4 digits)
  String extractOTP(String callerNumber) {
    final digitsOnly = callerNumber.replaceAll(RegExp(r'[^\d]'), '');
    if (digitsOnly.length >= 4) {
      return digitsOnly.substring(digitsOnly.length - 4);
    }
    return digitsOnly;
  }

  /// Stop polling
  void stopWaiting() {
    _isPolling = false;
    _pollTimer?.cancel();
    _pollTimer = null;
  }

  /// Dispose resources
  void dispose() {
    stopWaiting();
    onStatusChanged = null;
    onOtpDetected = null;
    onTimeout = null;
  }
}