kmobile/lib/features/auth/screens/sms_verification_helper.dart

import 'package:flutter/material.dart';
import 'package:kmobile/api/services/send_sms_service.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:uuid/uuid.dart';

class SmsVerificationHelper {
  final SmsService _smsService = SmsService();

  Future<void> _showPermanentlyDeniedDialog(BuildContext context) async {
    await showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text("Permission Required"),
        content: const Text("SMS and Phone permissions are required for device verification. Please enable them in your app settings to continue."),
        actions: [
          TextButton(
            child: const Text("Cancel"),
            onPressed: () => Navigator.of(context).pop(),
          ),
          TextButton(
            child: const Text("Open Settings"),
            onPressed: () {
              openAppSettings(); // Opens the phone's settings screen for this app
              Navigator.of(context).pop();
            },
          ),
        ],
      ),
    );
  }

  Future<void> _showRestrictedSmsDialog(BuildContext context) async {
    await showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text("SMS Permission Restricted"),
        content: const SingleChildScrollView(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text("It seems your device is restricting this app from sending SMS messages, which is required for verification. Please follow these steps to enable it:\n"),
              Text("1. Open your device Settings.", style: TextStyle(fontWeight: FontWeight.bold)),
              Text("2. Go to 'Apps' or 'Apps & notifications'."),
              Text("3. Find and tap on this app ('KMobile')."),
              Text("4. Tap on the three dots (⋮) in the top right corner."),
              Text("5. Select 'Allow restricted settings' and confirm. This is crucial to allow SMS permission."),
              Text("6. Now you have two options to allow SMS permission:"),
              Text("   a. Tap on 'Permissions', then find 'SMS' is set to 'Allow'."),
              Text("   b. Alternatively, you can return to the KMobile app, and the SMS permission pop-up should appear again, allowing you to grant it directly."),
              Text("\nSome devices have an additional setting for 'Premium SMS'. If the above doesn't work, look for a 'Premium SMS access' setting (you can search for it in your Settings app) and set it to 'Always Allow' for this app.\n"),
              Text("After you've enabled the permission, please come back to the app."),
            ],
          ),
        ),
        actions: [
          TextButton(
            child: const Text("I've Enabled It"),
            onPressed: () => Navigator.of(context).pop(),
          ),
        ],
      ),
    );
  }

  void _showSnackBar(BuildContext context, String message) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(message),
        duration: const Duration(seconds: 3),
      ),
    );
  }

  Future<String?> initiateSmsSequence({
    required BuildContext context,
  }) async {
    bool hasPermission = false;

    // --- PERMISSION LOOP ---
    while (!hasPermission) {
      // handleSmsPermission will check the status and request if not granted.
      final status = await _smsService.handleSmsPermission();

      switch (status) {
        case PermissionStatusResult.granted:
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(content: Text("Permissions Granted! Proceeding..."), duration: Duration(seconds: 2)),
          );
          hasPermission = true; // This will break the loop
          break;
        case PermissionStatusResult.denied:
          // The user denied the permission. We show a dialog to explain why we need it
          // and give them a chance to cancel or let the loop try again.
          final tryAgain = await showDialog<bool>(
            context: context,
            builder: (context) => AlertDialog(
              title: const Text("Permission Required"),
              content: const Text("This app requires SMS and Phone permissions to verify your device. Please grant the permissions to continue."),
              actions: [
                TextButton(
                  child: const Text("Cancel"),
                  onPressed: () => Navigator.of(context).pop(false),
                ),
                TextButton(
                  child: const Text("Try Again"),
                  onPressed: () => Navigator.of(context).pop(true),
                ),
              ],
            ),
          );
          if (tryAgain != true) {
            return null; // User chose to cancel.
          }
          // If they chose "Try Again", the loop will repeat.
          break;
        case PermissionStatusResult.permanentlyDenied:
          await _showPermanentlyDeniedDialog(context);
          // Give user time to come back from settings
          await Future.delayed(const Duration(seconds: 5));
          // The loop will repeat and re-check the status.
          break;
        case PermissionStatusResult.restricted:
          await _showRestrictedSmsDialog(context);
          // Give user time to come back from settings
          await Future.delayed(const Duration(seconds: 5));
          // The loop will repeat and re-check the status.
          break;
      }
    }

    // --- SMS SENDING LOOP ---
    // This part will only be reached if hasPermission is true.
    int retries = 3;
    while (retries > 0) {
      var uuid = const Uuid();
      String uniqueId = uuid.v4();
      String smsMessage = uniqueId;
      
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text("Attempting to send verification SMS... (${4 - retries})"), duration: const Duration(seconds: 2)),
      );

      bool isSmsSent = await _smsService.sendVerificationSms(
        context: context,
        destinationNumber: '9580079717', // Replace with your number
        message: smsMessage,
      );

      if (isSmsSent) {
         ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text("SMS sent successfully!"), duration: Duration(seconds: 2)),
        );
        return uniqueId;
      } else {
        retries--;
        if (retries > 0) {
           ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(content: Text("SMS failed to send. Retrying in 5 seconds..."), duration: Duration(seconds: 4)),
          );
          await Future.delayed(const Duration(seconds: 5));
        }
      }
    }
    
    // If all retries fail
    return null;
  }
}