import 'dart:convert';
import 'dart:math';
import 'package:http/http.dart' as http;
import 'package:flutter/foundation.dart';

/// Service for sending OTP via WhatsApp using Fonnte API
class FonnteService {
  // Fonnte Configuration
  static const String _apiUrl = 'https://api.fonnte.com/send';
  static const String _token = 'bXMkTXeLhVbmXmh6mYG5';
  static const String _countryCode = '62'; // Indonesia

  // Store OTP codes temporarily (in production, use backend)
  static final Map<String, _OTPData> _otpStore = {};

  // Store last generated OTP for dev mode display
  static String? lastGeneratedOTP;

  /// Generate a random 5-digit OTP
  static String generateOTP() {
    final random = Random();
    return (10000 + random.nextInt(90000)).toString();
  }

  /// Format phone number for Fonnte API
  /// Converts 08xx to 628xx format
  static String formatPhoneNumber(String phone) {
    phone = phone.replaceAll(RegExp(r'[^0-9]'), ''); // Remove non-digits
    if (phone.startsWith('0')) {
      phone = '62${phone.substring(1)}';
    } else if (!phone.startsWith('62')) {
      phone = '62$phone';
    }
    return phone;
  }

  /// Send OTP to WhatsApp number via Fonnte
  static Future<bool> sendOTP(String phoneNumber) async {
    try {
      final otp = generateOTP();
      final expiresAt = DateTime.now().add(const Duration(minutes: 5));
      final formattedPhone = formatPhoneNumber(phoneNumber);

      // Store OTP locally (for verification)
      _otpStore[formattedPhone] = _OTPData(otp: otp, expiresAt: expiresAt);
      // Also store with original number for flexible verification
      _otpStore[phoneNumber] = _OTPData(otp: otp, expiresAt: expiresAt);
      lastGeneratedOTP = otp;

      // Log for debugging purposes
      debugPrint('📤 Sending WhatsApp OTP to $formattedPhone via Fonnte...');

      // Send WhatsApp message via Fonnte API
      final message =
          '🔐 *Kode Verifikasi AMORI Assistant*\n\n'
          'Kode OTP Anda: *$otp*\n\n'
          'Kode ini berlaku selama 5 menit.\n'
          'Jangan bagikan kode ini kepada siapapun.';

      final response = await http.post(
        Uri.parse(_apiUrl),
        headers: {'Authorization': _token},
        body: {
          'target': formattedPhone,
          'message': message,
          'countryCode': _countryCode,
        },
      );

      debugPrint('📥 Fonnte Response: ${response.statusCode} ${response.body}');

      final responseData = jsonDecode(response.body);

      if (responseData['status'] == true) {
        debugPrint('✅ WhatsApp OTP sent successfully to $formattedPhone');
        return true;
      } else {
        debugPrint(
          '❌ Fonnte API error: ${responseData['reason'] ?? responseData['detail']}',
        );
        return false;
      }
    } catch (e) {
      debugPrint('❌ Error sending WhatsApp OTP: $e');
      return false;
    }
  }

  /// Verify OTP code
  static bool verifyOTP(String phoneNumber, String code) {
    final formattedPhone = formatPhoneNumber(phoneNumber);

    // Try both formatted and original number
    final otpData = _otpStore[formattedPhone] ?? _otpStore[phoneNumber];

    if (otpData == null) {
      debugPrint('❌ No OTP found for $phoneNumber');
      return false;
    }

    if (DateTime.now().isAfter(otpData.expiresAt)) {
      debugPrint('❌ OTP expired for $phoneNumber');
      _otpStore.remove(formattedPhone);
      _otpStore.remove(phoneNumber);
      return false;
    }

    if (otpData.otp != code) {
      debugPrint(
        '❌ Invalid OTP for $phoneNumber (expected: ${otpData.otp}, got: $code)',
      );
      return false;
    }

    debugPrint('✅ WhatsApp OTP verified for $phoneNumber');
    _otpStore.remove(formattedPhone);
    _otpStore.remove(phoneNumber);
    return true;
  }

  /// Check if OTP exists and is valid (not expired)
  static bool hasValidOTP(String phoneNumber) {
    final formattedPhone = formatPhoneNumber(phoneNumber);
    final otpData = _otpStore[formattedPhone] ?? _otpStore[phoneNumber];
    if (otpData == null) return false;
    return DateTime.now().isBefore(otpData.expiresAt);
  }

  /// Clear OTP for phone
  static void clearOTP(String phoneNumber) {
    final formattedPhone = formatPhoneNumber(phoneNumber);
    _otpStore.remove(formattedPhone);
    _otpStore.remove(phoneNumber);
  }

  /// Get last generated OTP (for dev mode display)
  static String? getLastOTP() => lastGeneratedOTP;
}

class _OTPData {
  final String otp;
  final DateTime expiresAt;

  _OTPData({required this.otp, required this.expiresAt});
}