Saba-dart/lib/screens/chat_screen.dart

import 'dart:async';
import 'dart:math';
import 'dart:ui';

import 'package:another_telephony/telephony.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_contacts/flutter_contacts.dart';
import 'package:permission_handler/permission_handler.dart';

import '../models/chat_model.dart';
import '../utils/app_theme.dart';
import '../utils/contact_helper.dart';
import '../utils/database_helper.dart';
import '../utils/message_processor.dart';
import '../utils/protocol_helper.dart';
import '../utils/secure_messaging_service.dart';
import '../widgets/message_bubble.dart';

class MeshBackgroundPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    // Optimization for Raspberry Pi 3: Use RadialGradient instead of MaskFilter blur
    // which is often hardware-accelerated and much cheaper than multi-pass blur.

    final Paint paint1 = Paint()
      ..shader = RadialGradient(
        colors: [
          const Color(0xFF7000FF).withValues(alpha: 0.12),
          const Color(0xFF7000FF).withValues(alpha: 0.0),
        ],
      ).createShader(Rect.fromCircle(
          center: Offset(size.width * 0.2, size.height * 0.15), radius: 300));

    canvas.drawCircle(
        Offset(size.width * 0.2, size.height * 0.15), 300, paint1);

    final Paint paint2 = Paint()
      ..shader = RadialGradient(
        colors: [
          const Color(0xFF00D2FF).withValues(alpha: 0.1),
          const Color(0xFF00D2FF).withValues(alpha: 0.0),
        ],
      ).createShader(Rect.fromCircle(
          center: Offset(size.width * 0.8, size.height * 0.8), radius: 400));

    canvas.drawCircle(Offset(size.width * 0.8, size.height * 0.8), 400, paint2);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}

class _MessageCandidate {
  final ChatModel message;
  final bool preferCandidate;

  const _MessageCandidate(
    this.message, {
    this.preferCandidate = false,
  });
}

class ChatScreen extends StatefulWidget {
  final String address;

  const ChatScreen({super.key, required this.address});

  @override
  State<ChatScreen> createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {
  final Telephony telephony = Telephony.instance;
  static const platform = MethodChannel('com.example.saba/sim_cards');
  static const nativeChannel = MethodChannel('com.example.saba/sms_native');
  static const asymmetricModeLabel = "رمزنگاری غیر متقارن (طولانی‌تر و امن‌تر)";

  final TextEditingController _msgController = TextEditingController();
  Color get primaryColor => Theme.of(context).primaryColor;
  Color get backgroundColor => const Color(0xFFF5F7FA);

  final ScrollController _scrollController = ScrollController();
  final ValueNotifier<List<ChatModel>> _messageNotifier = ValueNotifier([]);

  List<ChatModel> get messages => _messageNotifier.value;
  set messages(List<ChatModel> val) => _messageNotifier.value = val;

  List<Map<String, dynamic>> _simCards = [];
  Map<String, dynamic>? _selectedSim;
  bool _loadingSims = true;
  String displayName = "";
  String _selectedSecurityLevel = 'normal';
  Map<String, dynamic>? contactInfo;
  StreamSubscription? _messageSubscription;
  String? _dismissedBannerText;
  bool _isLoading = false;
  Timer? _debounceTimer;

  int _offset = 0;
  static const int _limit = 25;
  static const int _liveMessageGraceMs = 15000;
  bool _hasMore = true;

  int _compareMessages(ChatModel a, ChatModel b) {
    final dateComp = b.date.compareTo(a.date);
    if (dateComp != 0) return dateComp;

    final idComp = (b.id ?? -1).compareTo(a.id ?? -1);
    if (idComp != 0) return idComp;

    final packetComp = (_packetKey(b.packetId, b.packetMode) ?? '')
        .compareTo(_packetKey(a.packetId, a.packetMode) ?? '');
    if (packetComp != 0) return packetComp;

    final isMeComp = (b.isMe ? 1 : 0).compareTo(a.isMe ? 1 : 0);
    if (isMeComp != 0) return isMeComp;

    final bodyComp = (b.rawBody ?? b.body).compareTo(a.rawBody ?? a.body);
    if (bodyComp != 0) return bodyComp;

    return b.status.index.compareTo(a.status.index);
  }

  int _messageQuality(ChatModel message) {
    var score = 0;
    if (message.id != null) score += 40;
    if (_packetKey(message.packetId, message.packetMode) != null) score += 8;
    if ((message.rawBody?.isNotEmpty ?? false)) score += 3;
    if ((message.rawViewBody?.isNotEmpty ?? false)) score += 2;
    if ((message.encryptedPayload?.isNotEmpty ?? false)) score += 4;
    if (message.isSecure) score += 3;
    if (!message.isPendingMultipart) score += 6;
    if (message.status == MessageStatus.sent ||
        message.status == MessageStatus.received) {
      score += 2;
    }
    if (message.status == MessageStatus.sending) score -= 2;
    if (message.status == MessageStatus.failed) score -= 1;
    if (_isSecurePlaceholderBody(message.body)) score -= 1;
    return score;
  }

  void _publishMessages(List<ChatModel> items) {
    final sorted = List<ChatModel>.from(items)..sort(_compareMessages);
    _messageNotifier.value = sorted;
  }

  String? _packetKey(String? packetId, [String? packetMode]) {
    if (packetId == null || packetId.isEmpty) return null;
    final mode =
        (packetMode == null || packetMode.isEmpty) ? 'UNK' : packetMode;
    return '$mode::$packetId';
  }

  ChatModel _cloneMessage(ChatModel source) {
    return ChatModel(
      id: source.id,
      localId: source.localId,
      body: source.body,
      rawBody: source.rawBody,
      rawViewBody: source.rawViewBody,
      encryptedPayload: source.encryptedPayload,
      statusLabel: source.statusLabel,
      packetId: source.packetId,
      packetMode: source.packetMode,
      rawPacketId: source.rawPacketId,
      date: source.date,
      isMe: source.isMe,
      status: source.status,
      isSecure: source.isSecure,
      canRetryDecryption: source.canRetryDecryption,
      isPendingMultipart: source.isPendingMultipart,
      isRead: source.isRead,
    );
  }

  String _fallbackMessageKey(ChatModel message) {
    return 'fallback::${message.isMe ? 1 : 0}::${message.date}::${message.body.hashCode}';
  }

  String? _normalizedPayloadSignature(String? payload) {
    final normalized = (payload ?? '').replaceAll(RegExp(r'\s+'), '').trim();
    return normalized.isEmpty ? null : normalized;
  }

  String? _contentSignature(ChatModel message) {
    final rawSignature = (message.rawBody ?? '').trim();
    final bodySignature = message.body.trim();
    final contentSignature =
        rawSignature.isNotEmpty ? rawSignature : bodySignature;
    if (contentSignature.isEmpty ||
        _isSecurePlaceholderBody(contentSignature) ||
        _isProgressBody(contentSignature)) {
      return null;
    }
    return contentSignature;
  }

  int _timeBucket(int date, [int bucketMs = 5000]) {
    if (date <= 0) return 0;
    return date ~/ bucketMs;
  }

  List<String> _messageAliases(ChatModel message) {
    final aliases = <String>{};
    if (message.localId != null && message.localId!.isNotEmpty) {
      aliases.add('local::${message.localId}');
    }
    if (message.id != null) {
      aliases.add('db::${message.id}');
    }

    final packetKey = _packetKey(message.packetId, message.packetMode);
    if (packetKey != null) {
      aliases.add('packet::$packetKey');
    }

    final payload = _normalizedPayloadSignature(message.encryptedPayload);
    if (payload != null) {
      final mode = (message.packetMode ?? 'SEC').trim();
      aliases.add('payload::$mode::${message.isMe ? 1 : 0}::$payload');
      aliases.add('payload::$mode::$payload');
    }

    final rawBody = (message.rawBody ?? '').trim();
    if (rawBody.isNotEmpty) {
      aliases.add('raw::${message.isMe ? 1 : 0}::$rawBody');
      final parsed = ProtocolHelper.parseMessage(rawBody);
      final rawPayload =
          _normalizedPayloadSignature(parsed['payload'] as String?);
      final rawType = parsed['type'] as String? ?? 'plain';
      if (rawPayload != null) {
        final mode = (message.packetMode ??
                (rawType == 'asym' || rawType == 'afrag' ? 'AE' : 'SYM'))
            .trim();
        aliases.add('payload::$mode::${message.isMe ? 1 : 0}::$rawPayload');
        aliases.add('payload::$mode::$rawPayload');
      }
    }

    final content = _contentSignature(message);
    if (content != null) {
      aliases.add(
          'body::${message.isMe ? 1 : 0}::${_timeBucket(message.date)}::$content');
    }

    return aliases.toList(growable: false);
  }

  bool _hasAliasOverlap(Set<String> a, Set<String> b) {
    for (final key in a) {
      if (b.contains(key)) return true;
    }
    return false;
  }

  bool _isProgressBody(String body) {
    return body.contains('در حال دریافت قطعات') ||
        body.contains('در حال ارسال قطعات') ||
        body.contains('باقی قطعات پیام نرسیده‌اند');
  }

  String _pickPreferredBody(String primaryBody, String secondaryBody) {
    final primary = primaryBody.trim();
    final secondary = secondaryBody.trim();
    if (primary.isEmpty) return secondaryBody;
    if (secondary.isEmpty) return primaryBody;

    final primaryProgress = _isProgressBody(primaryBody);
    final secondaryProgress = _isProgressBody(secondaryBody);
    if (primaryProgress != secondaryProgress) {
      return primaryProgress ? secondaryBody : primaryBody;
    }

    final primaryPlaceholder = _isSecurePlaceholderBody(primaryBody);
    final secondaryPlaceholder = _isSecurePlaceholderBody(secondaryBody);
    if (primaryPlaceholder != secondaryPlaceholder) {
      return primaryPlaceholder ? secondaryBody : primaryBody;
    }

    return primary.length >= secondary.length ? primaryBody : secondaryBody;
  }

  String? _pickPreferredString(String? primary, String? secondary) {
    final a = (primary ?? '').trim();
    final b = (secondary ?? '').trim();
    if (a.isEmpty) return b.isEmpty ? null : secondary;
    if (b.isEmpty) return primary;
    return a.length >= b.length ? primary : secondary;
  }

  MessageStatus _pickPreferredStatus(ChatModel primary, ChatModel secondary) {
    final primaryFinal = primary.status == MessageStatus.sent ||
        primary.status == MessageStatus.received;
    final secondaryFinal = secondary.status == MessageStatus.sent ||
        secondary.status == MessageStatus.received;
    if (primaryFinal != secondaryFinal) {
      return primaryFinal ? primary.status : secondary.status;
    }
    if (primary.status == MessageStatus.failed &&
        secondary.status != MessageStatus.failed) {
      return secondary.status;
    }
    if (secondary.status == MessageStatus.failed &&
        primary.status != MessageStatus.failed) {
      return primary.status;
    }
    if (primary.status == MessageStatus.sending &&
        secondary.status != MessageStatus.sending) {
      return secondary.status;
    }
    return primary.status;
  }

  ChatModel _mergeModels(
    ChatModel existing,
    ChatModel candidate, {
    bool preferCandidate = false,
  }) {
    final candidateQuality = _messageQuality(candidate);
    final existingQuality = _messageQuality(existing);
    final useCandidateAsPrimary = preferCandidate ||
        candidateQuality > existingQuality ||
        (candidateQuality == existingQuality &&
            _compareMessages(candidate, existing) < 0);

    final primary = useCandidateAsPrimary ? candidate : existing;
    final secondary = useCandidateAsPrimary ? existing : candidate;

    final merged = ChatModel(
      id: primary.id ?? secondary.id,
      localId: primary.localId ?? secondary.localId,
      body: _pickPreferredBody(primary.body, secondary.body),
      rawBody: _pickPreferredString(primary.rawBody, secondary.rawBody),
      rawViewBody:
          _pickPreferredString(primary.rawViewBody, secondary.rawViewBody),
      encryptedPayload: _pickPreferredString(
          primary.encryptedPayload, secondary.encryptedPayload),
      statusLabel:
          _pickPreferredString(primary.statusLabel, secondary.statusLabel),
      packetId: _pickPreferredString(primary.packetId, secondary.packetId),
      packetMode:
          _pickPreferredString(primary.packetMode, secondary.packetMode),
      rawPacketId:
          _pickPreferredString(primary.rawPacketId, secondary.rawPacketId),
      date: primary.date == 0
          ? secondary.date
          : (secondary.date == 0
              ? primary.date
              : min(primary.date, secondary.date)),
      isMe: primary.isMe,
      status: _pickPreferredStatus(primary, secondary),
      isSecure: primary.isSecure ||
          secondary.isSecure ||
          (primary.packetMode ?? secondary.packetMode) != null ||
          (primary.encryptedPayload ?? secondary.encryptedPayload) != null,
      canRetryDecryption:
          primary.canRetryDecryption || secondary.canRetryDecryption,
      isPendingMultipart:
          primary.isPendingMultipart || secondary.isPendingMultipart,
      isRead: primary.isRead && secondary.isRead,
    );

    if (!_isProgressBody(merged.body)) {
      merged.isPendingMultipart = false;
      if (merged.statusLabel != null &&
          (merged.status == MessageStatus.sent ||
              merged.status == MessageStatus.received) &&
          !_isSecurePlaceholderBody(merged.body)) {
        merged.statusLabel = null;
      }
    }

    if (merged.isSecure ||
        merged.packetMode != null ||
        (merged.rawBody?.isNotEmpty ?? false)) {
      _enrichSecureModel(merged);
    } else {
      merged.rawViewBody ??= _buildRawViewBody(
        body: merged.body,
        rawBody: merged.rawBody,
        encryptedPayload: merged.encryptedPayload,
        packetMode: merged.packetMode,
        isSecure: merged.isSecure,
      );
    }

    return merged;
  }

  List<ChatModel> _reconcileCandidates(List<_MessageCandidate> candidates) {
    final mergedMessages = <ChatModel>[];
    final aliasSets = <Set<String>>[];

    for (final entry in candidates) {
      final prepared = _cloneMessage(entry.message);
      if (prepared.isSecure ||
          prepared.packetMode != null ||
          (prepared.rawBody?.isNotEmpty ?? false)) {
        _enrichSecureModel(prepared);
      } else {
        prepared.rawViewBody ??= _buildRawViewBody(
          body: prepared.body,
          rawBody: prepared.rawBody,
          encryptedPayload: prepared.encryptedPayload,
          packetMode: prepared.packetMode,
          isSecure: prepared.isSecure,
        );
      }

      final workingAliases = _messageAliases(prepared).toSet();
      final matches = <int>[];
      for (var i = 0; i < aliasSets.length; i++) {
        if (_hasAliasOverlap(aliasSets[i], workingAliases)) {
          matches.add(i);
        }
      }

      if (matches.isEmpty) {
        mergedMessages.add(prepared);
        aliasSets.add(
          workingAliases.isEmpty
              ? {_fallbackMessageKey(prepared)}
              : workingAliases,
        );
        continue;
      }

      var combined = prepared;
      for (final index in matches.reversed) {
        combined = _mergeModels(
          mergedMessages[index],
          combined,
          preferCandidate: entry.preferCandidate,
        );
        mergedMessages.removeAt(index);
        aliasSets.removeAt(index);
      }

      final combinedAliases = _messageAliases(combined).toSet()
        ..addAll(workingAliases);
      mergedMessages.add(combined);
      aliasSets.add(
        combinedAliases.isEmpty
            ? {_fallbackMessageKey(combined)}
            : combinedAliases,
      );
    }

    mergedMessages.sort(_compareMessages);
    return mergedMessages;
  }

  void _replaceMessagesWithCandidates(List<_MessageCandidate> candidates) {
    _publishMessages(_reconcileCandidates(candidates));
  }

  String? _findOutgoingDraftLocalId(ChatModel candidate) {
    if (!candidate.isMe) return null;

    ChatModel? best;
    var bestDelta = 1 << 30;
    for (final message in messages) {
      if (message.localId == null ||
          !message.isMe ||
          message.id != null ||
          (message.status != MessageStatus.sending &&
              message.status != MessageStatus.failed &&
              !message.isPendingMultipart)) {
        continue;
      }

      if (candidate.packetMode != null &&
          message.packetMode != null &&
          candidate.packetMode != message.packetMode) {
        continue;
      }

      final delta = (candidate.date - message.date).abs();
      if (delta > 30000 || delta >= bestDelta) continue;

      best = message;
      bestDelta = delta;
    }
    return best?.localId;
  }

  bool _shouldKeepTransientMessageDuringReload(ChatModel message) {
    if (message.id != null) return false;
    final ageMs = DateTime.now().millisecondsSinceEpoch - message.date;
    if (ageMs <= _liveMessageGraceMs) return true;
    if (message.status == MessageStatus.failed ||
        message.status == MessageStatus.sending ||
        message.isPendingMultipart) {
      return true;
    }
    return message.isMe;
  }

  bool _shouldPreferInMemoryMessage(ChatModel message) {
    return message.id == null &&
        ((DateTime.now().millisecondsSinceEpoch - message.date) <=
                _liveMessageGraceMs ||
            message.status == MessageStatus.failed ||
            message.status == MessageStatus.sending ||
            message.isPendingMultipart ||
            message.isMe);
  }

  String? _buildRawViewBody({
    required String body,
    String? rawBody,
    String? encryptedPayload,
    String? packetMode,
    bool isSecure = false,
  }) {
    // If it's a secure message, we want to show the underlying protocol string
    if (encryptedPayload != null && encryptedPayload.isNotEmpty) {
      switch (packetMode) {
        case 'AE':
          return '@S:AE|$encryptedPayload';
        case 'SYM':
        default:
          return '@S:SYM|$encryptedPayload';
      }
    }

    // Fallback to the original raw SMS body if available
    if (rawBody != null && rawBody.isNotEmpty && rawBody != body) {
      return rawBody;
    }

    return null;
  }

  void _debouncedLoadMessages() {
    _debounceTimer?.cancel();
    _debounceTimer = Timer(const Duration(milliseconds: 400), () {
      if (mounted) loadMessages();
    });
  }

  @override
  void initState() {
    super.initState();
    displayName = ContactHelper.getName(widget.address);
    SecureMessagingService.instance.currentChatPhone =
        ContactHelper.normalizePhone(widget.address);
    _scrollController.addListener(_onScroll);
    _fetchSimCards();
    _initMessageStreamListener();
    _syncAndLoad();
    DatabaseHelper.instance.markAsRead(widget.address);
  }

  void _onScroll() {
    if (!_scrollController.hasClients) return;
    final pos = _scrollController.position;
    if (pos.pixels >= pos.maxScrollExtent - 150 && !_isLoading && _hasMore) {
      loadMessages(isLoadMore: true);
    }
  }

  @override
  void dispose() {
    if (SecureMessagingService.instance.currentChatPhone ==
        ContactHelper.normalizePhone(widget.address)) {
      SecureMessagingService.instance.currentChatPhone = null;
    }
    _scrollController.dispose();
    _messageNotifier.dispose();
    _messageSubscription?.cancel();
    _msgController.dispose();
    _debounceTimer?.cancel();
    super.dispose();
  }

  void _initMessageStreamListener() {
    _messageSubscription =
        SecureMessagingService.instance.messageStream.listen((data) {
      final normalizedTarget = ContactHelper.normalizePhone(widget.address);
      final normalizedIncoming =
          ContactHelper.normalizePhone(data['phone'] as String);

      if (normalizedIncoming == normalizedTarget) {
        // Immediate UI feedback for security state
        final result = data['result'] as Map<String, dynamic>?;
        if (result != null) {
          final isSecure = result['isSecure'] == true;
          final body = data['body'] as String?;

          if (isSecure && body != null) {
            // Trigger a load immediately to reflect state changes
          }
        }

        final originalBody = data['originalBody'] as String? ?? '';
        final body = data['body'] as String? ?? '';
        final packetId = data['packetId'] as String?;
        final packetMode = data['packetMode'] as String?;
        final eventDate =
            data['date'] as int? ?? DateTime.now().millisecondsSinceEpoch;
        final isMultipartPending = data['isMultipartPending'] as bool? ?? false;
        final isMultipartComplete =
            data['isMultipartComplete'] as bool? ?? false;
        final receivedParts = data['receivedParts'] as int? ?? 0;
        final totalPartsFromEvent = data['totalParts'] as int? ?? 0;
        final isMeEvent = data['isMe'] as bool? ?? false;

        if (body == 'REFRESH') {
          _debouncedLoadMessages();
          return;
        }

        if (ProtocolHelper.parseMessage(originalBody)['type'] == 'plain' &&
            _looksLikeProtocolFragment(originalBody)) {
          _debouncedLoadMessages();
          return;
        }

        final bool isIntermediateFragment =
            body.contains('در حال دریافت قطعات') ||
                body.contains('در حال ارسال قطعات') ||
                body.contains('باقی قطعات پیام نرسیده‌اند');

        if (isIntermediateFragment) {
          if (!mounted) return;
          if (isMultipartPending && packetId != null) {
            final liveBody = body;
            final liveStatus = totalPartsFromEvent > 0 && receivedParts > 0
                ? '${isMeEvent ? 'ارسال' : 'دریافت'} زنده: $receivedParts از $totalPartsFromEvent قطعه'
                : '${isMeEvent ? 'ارسال' : 'دریافت'} قطعات در حال انجام است';
            final pendingMessage = ChatModel(
              localId: isMeEvent
                  ? _findOutgoingDraftLocalId(ChatModel(
                      body: liveBody,
                      date: eventDate,
                      isMe: true,
                      status: MessageStatus.sending,
                    ))
                  : null,
              body: liveBody,
              rawBody: originalBody,
              rawViewBody: _buildRawViewBody(
                body: liveBody,
                rawBody: originalBody,
                packetMode: packetMode,
                isSecure: true,
              ),
              packetId: packetId,
              packetMode: packetMode,
              statusLabel: liveStatus,
              date: eventDate,
              isMe: isMeEvent,
              status:
                  isMeEvent ? MessageStatus.sending : MessageStatus.received,
              isSecure: true,
              isPendingMultipart: true,
            );
            _replaceMessagesWithCandidates([
              ...messages.map((m) => _MessageCandidate(m)),
              _MessageCandidate(pendingMessage, preferCandidate: true),
            ]);
          }
          return;
        }

        if (!mounted) return;

        final payloadMarker = _extractPayloadFromProcessedBody(body);
        final cleanBody = payloadMarker != null
            ? body.substring(0, body.indexOf(' ::PAYLOAD::'))
            : body;
        final incomingMessage = ChatModel(
          body: cleanBody,
          rawBody: originalBody,
          rawViewBody: _buildRawViewBody(
            body: cleanBody,
            rawBody: originalBody,
            encryptedPayload: payloadMarker,
            packetMode: packetMode,
            isSecure: isMultipartComplete ||
                ProtocolHelper.parseMessage(originalBody)['type'] != 'plain',
          ),
          encryptedPayload: payloadMarker,
          packetId: packetId,
          packetMode: packetMode,
          date: eventDate,
          isMe: isMeEvent,
          status: isMeEvent ? MessageStatus.sent : MessageStatus.received,
          isSecure: isMultipartComplete ||
              ProtocolHelper.parseMessage(originalBody)['type'] != 'plain',
          canRetryDecryption: payloadMarker != null,
          isPendingMultipart: false,
          statusLabel: payloadMarker != null
              ? 'پیام کامل شد؛ برای بازگشایی کلید را وارد کنید'
              : null,
        );
        if (incomingMessage.isSecure || packetMode != null) {
          _enrichSecureModel(incomingMessage);
        }
        incomingMessage.localId ??= _findOutgoingDraftLocalId(incomingMessage);
        _replaceMessagesWithCandidates([
          ...messages.map((m) => _MessageCandidate(m)),
          _MessageCandidate(incomingMessage, preferCandidate: true),
        ]);
      }
    });
  }

  Future<void> _fetchSimCards() async {
    if (!await Permission.phone.request().isGranted) {
      if (mounted) setState(() => _loadingSims = false);
      return;
    }
    try {
      final List<dynamic> result = await platform.invokeMethod('getSimCards');
      final cleanList = result.map((e) {
        final rawMap = e as Map<Object?, Object?>;
        return rawMap.map((key, value) => MapEntry(key.toString(), value));
      }).toList();
      if (!mounted) return;
      setState(() {
        _simCards = cleanList;
        if (_simCards.isNotEmpty) _selectedSim = _simCards.first;
        _loadingSims = false;
      });
    } catch (_) {
      if (mounted) setState(() => _loadingSims = false);
    }
  }

  bool _isSecurePlaceholderBody(String body) {
    if (body.contains(' ::PAYLOAD::')) return true;

    return body.startsWith('پیام امن') ||
        body.startsWith('بازگشایی') ||
        body.startsWith('پیام رمزنگاری غیر متقارن');
  }

  bool _looksLikeProtocolFragment(String body) {
    final normalized = body.trimLeft().toUpperCase();
    return normalized.startsWith('@S:AF|') ||
        normalized.startsWith('@S:SFRA|') ||
        normalized.startsWith('@G:AF|') ||
        normalized.startsWith('@G:SFRA|');
  }

  void _enrichSecureModel(ChatModel msg) {
    final originalBody = msg.body;
    final payloadFromProcessed = _extractPayloadFromProcessedBody(originalBody);
    if (payloadFromProcessed != null) {
      msg.body =
          originalBody.substring(0, originalBody.indexOf(' ::PAYLOAD::'));
    }

    final protocolParsed =
        ProtocolHelper.parseMessage(msg.rawBody ?? originalBody);
    final protocolPayload = protocolParsed['payload'] as String?;
    final protocolPacketId = protocolParsed['packetId'] as String?;
    final protocolType = protocolParsed['type'] as String?;

    msg.encryptedPayload = payloadFromProcessed ??
        msg.encryptedPayload ??
        (protocolPayload?.trim().isNotEmpty == true
            ? protocolPayload!.trim()
            : null);

    if ((msg.packetId == null || msg.packetId!.isEmpty) &&
        protocolPacketId != null &&
        protocolPacketId.isNotEmpty) {
      msg.packetId = protocolPacketId;
    }

    if ((msg.packetMode == null || msg.packetMode!.isEmpty) &&
        protocolType != null) {
      if (protocolType == 'sym' || protocolType == 'sfra') {
        msg.packetMode = 'SYM';
      } else if (protocolType == 'asym' || protocolType == 'afrag') {
        msg.packetMode = 'AE';
      }
    }

    msg.rawViewBody = _buildRawViewBody(
      body: msg.body,
      rawBody: msg.rawBody,
      encryptedPayload: msg.encryptedPayload,
      packetMode: msg.packetMode,
      isSecure: true,
    );
    msg.canRetryDecryption = !msg.isMe && _isSecurePlaceholderBody(msg.body);
  }

  String? _extractPayloadFromProcessedBody(String body) {
    const separator = ' ::PAYLOAD::';
    final splitIndex = body.lastIndexOf(separator);
    if (splitIndex == -1) return null;
    final payload = body.substring(splitIndex + separator.length).trim();
    return payload.isEmpty ? null : payload;
  }

  String _securityLabel(String level) {
    switch (level) {
      case 'symmetric':
        return 'رمزنگاری متقارن';
      case 'asymmetric':
        return asymmetricModeLabel;
      default:
        return 'ارسال عادی';
    }
  }

  String _securityDescription(String level) {
    switch (level) {
      case 'symmetric':
        return 'سریع‌تر برای گفتگوهای مشترک با کلید ثابت';
      case 'asymmetric':
        return 'امن‌تر برای تبادل کلید و پیام‌های حساس';
      default:
        return 'پیامک معمولی بدون لایه امنیتی اضافه';
    }
  }

  IconData _securityIcon(String level) {
    switch (level) {
      case 'symmetric':
        return Icons.key_rounded;
      case 'asymmetric':
        return Icons.verified_user_rounded;
      default:
        return Icons.chat_bubble_outline_rounded;
    }
  }

  Color _securityAccent(String level) {
    switch (level) {
      case 'symmetric':
        return const Color(0xFF2E7D32);
      case 'asymmetric':
        return const Color(0xFF1565C0);
      default:
        return const Color(0xFF607D8B);
    }
  }

  ({String text, Color color}) _securityModeBadge(String level) {
    final secureState = contactInfo?['secure_state'] as String? ?? 'none';
    final verification =
        contactInfo?['verification_state'] as String? ?? 'unverified';
    final hasPeerKey =
        (contactInfo?['peer_public_key'] as String?)?.isNotEmpty == true;
    final hasSharedKey =
        (contactInfo?['ecc_shared_key'] as String?)?.isNotEmpty == true;
    final hasSymmetricKey =
        (contactInfo?['symmetric_key'] as String?)?.isNotEmpty == true;

    switch (level) {
      case 'symmetric':
        return hasSymmetricKey
            ? (text: 'آماده', color: const Color(0xFF2E7D32))
            : (text: 'نیاز به کلید', color: const Color(0xFFEF6C00));
      case 'asymmetric':
        if (secureState == 'handshake_failed' || verification == 'changed') {
          return (text: 'نیاز به بازیابی', color: const Color(0xFFC62828));
        }
        if (secureState == 'handshake_pending') {
          return (text: 'در حال تبادل', color: const Color(0xFF1565C0));
        }
        if (hasPeerKey &&
            hasSharedKey &&
            verification == 'verified' &&
            secureState == 'ready') {
          return (text: 'آماده', color: const Color(0xFF2E7D32));
        }
        if (hasPeerKey && hasSharedKey) {
          return (text: 'نیاز به تایید', color: const Color(0xFFEF6C00));
        }
        return (text: 'نیاز به ایجاد', color: const Color(0xFFEF6C00));
      default:
        return (text: 'همیشه آماده', color: const Color(0xFF607D8B));
    }
  }

  Future<void> _showSecurityModeSheet() async {
    final selected = await showModalBottomSheet<String>(
      context: context,
      backgroundColor: Colors.transparent,
      builder: (context) {
        final levels = ['normal', 'symmetric', 'asymmetric'];
        return Container(
          decoration: BoxDecoration(
            color: AppTheme.darkCard,
            borderRadius: const BorderRadius.vertical(top: Radius.circular(28)),
            border: Border.all(
                color: Colors.white.withValues(alpha: 0.1), width: 0.5),
          ),
          padding: const EdgeInsets.fromLTRB(18, 18, 18, 24),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Center(
                child: Container(
                  width: 42,
                  height: 4,
                  decoration: BoxDecoration(
                    color: Colors.white.withValues(alpha: 0.2),
                    borderRadius: BorderRadius.circular(999),
                  ),
                ),
              ),
              const SizedBox(height: 16),
              const Text(
                'روش رمزنگاری',
                style: TextStyle(
                    fontSize: 18,
                    fontWeight: FontWeight.bold,
                    color: Colors.white),
              ),
              const SizedBox(height: 6),
              const Text(
                'برای این پیام، حالت مناسب را انتخاب کنید.',
                style: TextStyle(color: Colors.white60, height: 1.4),
              ),
              const SizedBox(height: 16),
              ...levels.map((level) {
                final isSelected = _selectedSecurityLevel == level;
                final accent = _securityAccent(level);
                final badge = _securityModeBadge(level);
                return Padding(
                  padding: const EdgeInsets.only(bottom: 10),
                  child: InkWell(
                    borderRadius: BorderRadius.circular(18),
                    onTap: () => Navigator.of(context).pop(level),
                    child: AnimatedContainer(
                      duration: const Duration(milliseconds: 180),
                      padding: const EdgeInsets.all(14),
                      decoration: BoxDecoration(
                        color: isSelected
                            ? accent.withValues(alpha: 0.15)
                            : Colors.white.withValues(alpha: 0.03),
                        borderRadius: BorderRadius.circular(18),
                        border: Border.all(
                          color: isSelected
                              ? accent.withValues(alpha: 0.6)
                              : Colors.white.withValues(alpha: 0.1),
                          width: isSelected ? 1.6 : 1,
                        ),
                      ),
                      child: Row(
                        children: [
                          Container(
                            width: 42,
                            height: 42,
                            decoration: BoxDecoration(
                              color: accent.withValues(alpha: 0.12),
                              borderRadius: BorderRadius.circular(14),
                            ),
                            child: Icon(_securityIcon(level), color: accent),
                          ),
                          const SizedBox(width: 12),
                          Expanded(
                            child: Column(
                              crossAxisAlignment: CrossAxisAlignment.start,
                              children: [
                                Row(
                                  children: [
                                    Expanded(
                                      child: Text(
                                        _securityLabel(level),
                                        style: const TextStyle(
                                          fontWeight: FontWeight.w700,
                                          color: Colors.white,
                                        ),
                                      ),
                                    ),
                                    Container(
                                      padding: const EdgeInsets.symmetric(
                                        horizontal: 8,
                                        vertical: 4,
                                      ),
                                      decoration: BoxDecoration(
                                        color:
                                            badge.color.withValues(alpha: 0.10),
                                        borderRadius:
                                            BorderRadius.circular(999),
                                      ),
                                      child: Text(
                                        badge.text,
                                        style: TextStyle(
                                          color: badge.color,
                                          fontSize: 11,
                                          fontWeight: FontWeight.w700,
                                        ),
                                      ),
                                    ),
                                  ],
                                ),
                                const SizedBox(height: 4),
                                Text(
                                  _securityDescription(level),
                                  style: const TextStyle(
                                      color: Colors.white38, fontSize: 12),
                                ),
                              ],
                            ),
                          ),
                          const SizedBox(width: 8),
                          Icon(
                            isSelected
                                ? Icons.radio_button_checked_rounded
                                : Icons.radio_button_off_rounded,
                            color:
                                isSelected ? accent : const Color(0xFF97A6B5),
                          ),
                        ],
                      ),
                    ),
                  ),
                );
              }),
            ],
          ),
        );
      },
    );

    if (selected != null && mounted) {
      setState(() => _selectedSecurityLevel = selected);
    }
  }

  String _securityStatusText() {
    final state = contactInfo?['secure_state'] as String? ?? 'none';
    final verification =
        contactInfo?['verification_state'] as String? ?? 'unverified';
    final mode = contactInfo?['mode'] as String? ?? 'normal';

    if (state == 'handshake_pending') {
      return 'در حال تبادل کلید عمومی...';
    }
    if (state == 'handshake_failed') {
      return 'تبادل کلید ناموفق بود؛ دوباره تلاش کنید';
    }
    if (mode == 'asymmetric' &&
        (contactInfo?['peer_public_key'] as String?)?.isNotEmpty == true) {
      if (verification == 'changed') {
        return 'کلید مخاطب تغییر کرده است؛ اثر انگشت را دوباره تطبیق دهید';
      }
      return verification == 'verified' && state == 'ready'
          ? 'ارتباط امن شد و کانال ECC آماده است'
          : 'کلید عمومی دریافت شده؛ برای فعال شدن ECC اثر انگشت را تایید کنید';
    }
    if (mode == 'symmetric' &&
        (contactInfo?['symmetric_key'] as String?)?.isNotEmpty == true) {
      return 'رمزنگاری متقارن آماده است';
    }
    return 'حالت عادی';
  }

  bool get _isAsymmetricReadyNow {
    final mode = contactInfo?['mode'] as String? ?? 'normal';
    final secureState = contactInfo?['secure_state'] as String? ?? 'none';
    final verification =
        contactInfo?['verification_state'] as String? ?? 'unverified';
    final hasPeerKey =
        (contactInfo?['peer_public_key'] as String?)?.isNotEmpty == true;
    final hasSharedKey =
        (contactInfo?['ecc_shared_key'] as String?)?.isNotEmpty == true;
    return mode == 'asymmetric' &&
        hasPeerKey &&
        hasSharedKey &&
        secureState == 'ready' &&
        verification == 'verified';
  }

  Future<void> _startAsymmetricHandshake({bool recovery = false}) async {
    final result = await SecureMessagingService.instance
        .startAsymmetricHandshake(widget.address);
    if (!mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      content: Text(
        recovery
            ? 'بازیابی ارتباط امن شروع شد. ${result['notice']}'
            : (result['notice'] as String),
      ),
    ));
    await loadMessages();
  }

  Future<void> _endAsymmetricSecurity() async {
    await SecureMessagingService.instance
        .resetAsymmetricSecurity(widget.address);
    if (!mounted) return;
    setState(() {
      _dismissedBannerText = null;
    });
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(
        content: Text('ارتباط امن برای این مخاطب پایان یافت.'),
      ),
    );
    await loadMessages();
  }

  Widget _buildAsymmetricActions() {
    if (_selectedSecurityLevel != 'asymmetric') {
      return const SizedBox.shrink();
    }

    final secureState = contactInfo?['secure_state'] as String? ?? 'none';
    final verification =
        contactInfo?['verification_state'] as String? ?? 'unverified';
    final hasPeerKey =
        (contactInfo?['peer_public_key'] as String?)?.isNotEmpty == true;
    final hasSharedKey =
        (contactInfo?['ecc_shared_key'] as String?)?.isNotEmpty == true;
    final needsVerification = hasPeerKey &&
        hasSharedKey &&
        verification != 'verified' &&
        secureState != 'handshake_pending';
    final needsCreate = !needsVerification &&
        !_isAsymmetricReadyNow &&
        secureState != 'handshake_pending' &&
        verification != 'changed';
    final canRecover = _isAsymmetricReadyNow ||
        secureState == 'handshake_failed' ||
        secureState == 'pending_verification' ||
        verification == 'changed';
    final canEnd = secureState == 'handshake_pending' ||
        secureState == 'handshake_failed' ||
        secureState == 'pending_verification' ||
        (contactInfo?['mode'] as String? ?? 'normal') == 'asymmetric' ||
        hasPeerKey;

    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
      child: AppTheme.glassWrapper(
        child: Container(
          width: double.infinity,
          padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 12),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                _isAsymmetricReadyNow
                    ? 'ارتباط امن تایید شده است. حالا می‌توانید پیام‌های ECC بفرستید.'
                    : secureState == 'handshake_pending'
                        ? 'در حال تبادل کلیدهای عمومی هستیم. بعد از دریافت پاسخ، اثر انگشت مخاطب را تایید کنید.'
                        : verification == 'changed'
                            ? 'کلید مخاطب تغییر کرده است. تا زمان تایید اثر انگشت جدید، ارسال ECC غیرفعال می‌ماند.'
                            : needsVerification
                                ? 'کلید عمومی مخاطب دریافت شده است. تا زمان تایید اثر انگشت، ارسال ECC غیرفعال می‌ماند.'
                                : 'برای شروع ارتباط نامتقارن، ابتدا تبادل کلید را انجام دهید.',
                style: const TextStyle(
                    fontSize: 12,
                    fontWeight: FontWeight.w600,
                    color: Colors.white),
              ),
              const SizedBox(height: 14),
              Wrap(
                spacing: 8,
                runSpacing: 8,
                children: [
                  if (needsCreate)
                    ElevatedButton.icon(
                      onPressed: () => _startAsymmetricHandshake(),
                      style: ElevatedButton.styleFrom(
                        backgroundColor:
                            Colors.blueAccent.withValues(alpha: 0.8),
                        foregroundColor: Colors.white,
                        shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(12)),
                      ),
                      icon: const Icon(Icons.security, size: 18),
                      label: const Text('ایجاد ارتباط امن'),
                    ),
                  if (secureState == 'handshake_pending')
                    OutlinedButton.icon(
                      onPressed: null,
                      style: OutlinedButton.styleFrom(
                        foregroundColor: Colors.white60,
                        side: const BorderSide(color: Colors.white24),
                        shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(12)),
                      ),
                      icon: const SizedBox(
                        width: 14,
                        height: 14,
                        child: CircularProgressIndicator(
                            strokeWidth: 2, color: Colors.white60),
                      ),
                      label: const Text('در حال تبادل کلید'),
                    ),
                  if (hasPeerKey)
                    OutlinedButton.icon(
                      onPressed: _showFingerprintSheet,
                      style: OutlinedButton.styleFrom(
                        foregroundColor: Colors.white,
                        side: const BorderSide(color: Colors.white30),
                        shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(12)),
                      ),
                      icon: const Icon(Icons.verified_user_outlined, size: 18),
                      label: Text(verification == 'verified'
                          ? 'اثر انگشت'
                          : 'تایید اثر انگشت'),
                    ),
                  if (canRecover)
                    OutlinedButton.icon(
                      onPressed: () =>
                          _startAsymmetricHandshake(recovery: true),
                      style: OutlinedButton.styleFrom(
                        foregroundColor: Colors.white,
                        side: const BorderSide(color: Colors.white30),
                        shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(12)),
                      ),
                      icon: const Icon(Icons.refresh_rounded, size: 18),
                      label: const Text('بازیابی ارتباط امن'),
                    ),
                  if (canEnd)
                    TextButton.icon(
                      onPressed: _endAsymmetricSecurity,
                      style: TextButton.styleFrom(
                          foregroundColor:
                              Colors.redAccent.withValues(alpha: 0.7)),
                      icon: const Icon(Icons.cancel_outlined, size: 18),
                      label: const Text('پایان ارتباط'),
                    ),
                ],
              ),
            ],
          ),
        ),
      ),
    );
  }

  Future<void> _syncAndLoad() async {
    if (_isLoading) return;
    _isLoading = true;

    try {
      final inbox = await telephony.getInboxSms(columns: [
        SmsColumn.ID,
        SmsColumn.ADDRESS,
        SmsColumn.BODY,
        SmsColumn.DATE,
        SmsColumn.TYPE
      ], filter: SmsFilter.where(SmsColumn.ADDRESS).equals(widget.address));
      final sent = await telephony.getSentSms(columns: [
        SmsColumn.ID,
        SmsColumn.ADDRESS,
        SmsColumn.BODY,
        SmsColumn.DATE,
        SmsColumn.TYPE
      ], filter: SmsFilter.where(SmsColumn.ADDRESS).equals(widget.address));

      final List<Map<String, dynamic>> toCache = [];
      for (final sms in [...inbox, ...sent]) {
        toCache.add({
          'sms_id': sms.id,
          'address': ContactHelper.normalizePhone(sms.address ?? ''),
          'body': sms.body ?? '',
          'date': sms.date ?? 0,
          'type': sms.type?.index ?? 0,
          'is_me': sms.type != SmsType.MESSAGE_TYPE_INBOX ? 1 : 0,
        });
      }

      if (toCache.isNotEmpty) {
        await DatabaseHelper.instance.batchInsertSms(toCache);
      }
    } catch (e) {
      debugPrint('Sync error: $e');
    } finally {
      _isLoading = false;
      loadMessages();
    }
  }

  bool _needsReload = false;

  Future<void> loadMessages({bool isLoadMore = false}) async {
    if (_isLoading) {
      if (!isLoadMore) _needsReload = true;
      return;
    }
    if (isLoadMore && !_hasMore) return;

    _isLoading = true;
    _needsReload = false;
    if (!isLoadMore) {
      _hasMore = true;
    }

    try {
      final cInfo = await DatabaseHelper.instance.getContact(widget.address);
      final totalSmsCount = await DatabaseHelper.instance.getSmsCount(
        widget.address,
      );
      if (mounted) setState(() => contactInfo = cInfo);

      final previousOffset = _offset;
      final fetchOffset = isLoadMore ? previousOffset : 0;
      final rawSms = await DatabaseHelper.instance
          .getPaginatedSms(widget.address, _limit, fetchOffset);

      // 1. Process Database SMS
      final List<ChatModel> processed = await compute(
        (data) => MessageProcessor.processSmsList(
          data['raw'] as List<Map<String, dynamic>>,
          data['address'] as String,
        ),
        {'raw': rawSms, 'address': widget.address},
      );

      // 2. Perform Unified Reconciliation
      final currentMessages = List<ChatModel>.from(messages);
      final baseMessages = isLoadMore
          ? currentMessages
          : currentMessages
              .where(_shouldKeepTransientMessageDuringReload)
              .toList(growable: false);
      final candidates = <_MessageCandidate>[
        ...baseMessages.map(
          (m) => _MessageCandidate(
            m,
            preferCandidate: _shouldPreferInMemoryMessage(m),
          ),
        ),
      ];

      // Add Database Messages
      for (final msg in processed) {
        if (msg.isSecure) {
          final pBody =
              await SecureMessagingService.instance.processIncomingSms(
            widget.address,
            msg.body,
            broadcast: false,
            isMe: msg.isMe,
            isScan: false,
          );
          if (pBody != null && pBody != msg.body) {
            msg.body = pBody;
          }
          _enrichSecureModel(msg);
        }
        candidates.add(_MessageCandidate(msg));
      }

      // Merge Pending Fragments from Cache
      final pendingPacketRows = await SecureMessagingService.instance
          .getPendingPacketsForPhone(widget.address);
      for (final row in pendingPacketRows) {
        final pId = row['msg_id'] as String;
        final pMode = row['packet_mode'] as String? ?? 'SYM';
        candidates.add(
          _MessageCandidate(
            ChatModel(
              body: 'در حال دریافت قطعات...',
              statusLabel:
                  '(${row['received_parts']}/${row['total_parts']}) دریافت قطعات',
              packetId: pId,
              packetMode: pMode,
              date: row['first_seen'] as int? ?? 0,
              isMe: (row['isMe'] as int? ?? 0) == 1,
              status: MessageStatus.received,
              isSecure: true,
              isPendingMultipart: true,
            ),
          ),
        );
      }

      // 3. Finalize List
      final List<ChatModel> updatedList = _reconcileCandidates(candidates);

      final nextOffset = isLoadMore
          ? previousOffset + rawSms.length
          : max(previousOffset, rawSms.length);
      _offset = min(totalSmsCount, nextOffset);
      _hasMore = _offset < totalSmsCount;

      _publishMessages(updatedList);
    } finally {
      _isLoading = false;
      if (_needsReload) loadMessages();
    }
  }

  Future<void> _openContactInfo() async {
    if (!await FlutterContacts.requestPermission(readonly: true) || !mounted) {
      return;
    }

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (_) => const Center(child: CircularProgressIndicator()),
    );

    try {
      final contacts = await FlutterContacts.getContacts(
          withProperties: true, withPhoto: false);
      final currentPhoneNormalized =
          ContactHelper.normalizePhone(widget.address);
      String? contactId;

      for (final contact in contacts) {
        for (final phone in contact.phones) {
          if (ContactHelper.normalizePhone(phone.number) ==
              currentPhoneNormalized) {
            contactId = contact.id;
            break;
          }
        }
        if (contactId != null) break;
      }

      if (mounted) Navigator.pop(context);

      if (contactId != null) {
        await FlutterContacts.openExternalView(contactId);
      } else {
        await FlutterContacts.openExternalInsert(
            Contact(phones: [Phone(widget.address)]));
      }
      if (mounted) {
        setState(() {
          displayName = ContactHelper.getName(widget.address);
        });
      }
    } catch (_) {
      if (mounted && Navigator.canPop(context)) Navigator.pop(context);
    }
  }

  Future<void> _showFingerprintSheet() async {
    final securityContext = await SecureMessagingService.instance
        .getSecurityContext(widget.address);
    if (!mounted || securityContext == null) return;

    showModalBottomSheet(
      context: context,
      backgroundColor: Colors.transparent,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(24)),
      ),
      builder: (context) {
        final peerFingerprint = securityContext['peerFingerprint'] as String?;
        final verificationState =
            securityContext['verificationState'] as String? ?? 'unverified';
        final stateText = verificationState == 'changed'
            ? 'وضعیت: کلید مخاطب تغییر کرده است'
            : verificationState == 'verified'
                ? 'وضعیت: تایید شده'
                : 'وضعیت: هنوز تایید نشده';
        final stateColor = verificationState == 'changed'
            ? Colors.red.shade700
            : verificationState == 'verified'
                ? Colors.green.shade700
                : Colors.orange.shade400;
        return Container(
          decoration: BoxDecoration(
            color: AppTheme.darkCard,
            borderRadius: const BorderRadius.vertical(top: Radius.circular(24)),
            border: Border.all(
                color: Colors.white.withValues(alpha: 0.1), width: 0.5),
          ),
          padding: const EdgeInsets.fromLTRB(20, 20, 20, 32),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              const Text('تایید هویت و اثر انگشت کلید',
                  style: TextStyle(
                      fontSize: 18,
                      fontWeight: FontWeight.bold,
                      color: Colors.white)),
              const SizedBox(height: 12),
              Text('کلید شما:\n${securityContext['localFingerprint']}',
                  style: const TextStyle(color: Colors.white70)),
              const SizedBox(height: 12),
              Text(
                  peerFingerprint == null
                      ? 'هنوز کلید عمومی مخاطب دریافت نشده است.'
                      : 'کلید مخاطب:\n$peerFingerprint',
                  style: const TextStyle(color: Colors.white70)),
              const SizedBox(height: 12),
              const Text(
                'برای جلوگیری از MITM، این اثر انگشت را با تماس تلفنی یا یک کانال امن دیگر با مخاطب تطبیق دهید.',
                style: TextStyle(height: 1.5, color: Colors.white60),
              ),
              const SizedBox(height: 12),
              Text(
                stateText,
                style: TextStyle(
                  color: stateColor,
                  fontWeight: FontWeight.w600,
                ),
              ),
              const SizedBox(height: 16),
              ElevatedButton(
                onPressed: peerFingerprint == null
                    ? null
                    : () async {
                        await SecureMessagingService.instance
                            .markFingerprintVerified(widget.address);
                        if (!mounted) return;
                        Navigator.of(this.context).pop();
                        ScaffoldMessenger.of(this.context).showSnackBar(
                          const SnackBar(
                              content: Text(
                                  'اثر انگشت کلید برای این مخاطب تایید شد.')),
                        );
                        loadMessages();
                      },
                child: Text(verificationState == 'changed'
                    ? 'تایید اثر انگشت جدید'
                    : 'تایید اثر انگشت'),
              ),
            ],
          ),
        );
      },
    );
  }

  void _deleteSmsNative(int messageId) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(15)),
        title: const Text('حذف پیام'),
        content: const Text('آیا از حذف این پیام مطمئن هستید؟'),
        actions: [
          TextButton(
              onPressed: () => Navigator.pop(ctx), child: const Text('لغو')),
          ElevatedButton(
            style: ElevatedButton.styleFrom(
                backgroundColor: Colors.red, foregroundColor: Colors.white),
            onPressed: () async {
              Navigator.pop(ctx);
              try {
                await nativeChannel
                    .invokeMethod('deleteSms', {'id': messageId.toString()});
                if (!mounted) return;
                messages.removeWhere((m) => m.id == messageId);
                _publishMessages(messages);
                Future.delayed(const Duration(seconds: 1), loadMessages);
                ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(content: Text('درخواست حذف ارسال شد')));
              } catch (e) {
                if (!mounted) return;
                ScaffoldMessenger.of(context)
                    .showSnackBar(SnackBar(content: Text('خطا: $e')));
              }
            },
            child: const Text('حذف'),
          ),
        ],
      ),
    );
  }

  Future<void> sendMessage() async {
    final text = _msgController.text.trim();
    if (text.isEmpty) return;

    if (_selectedSecurityLevel == 'symmetric') {
      _showKeyEntryAndSend(text);
      return;
    }

    if (_selectedSecurityLevel == 'asymmetric' && !_isAsymmetricReadyNow) {
      final secureState = contactInfo?['secure_state'] as String? ?? 'none';
      final verification =
          contactInfo?['verification_state'] as String? ?? 'unverified';
      final hasPeerKey =
          (contactInfo?['peer_public_key'] as String?)?.isNotEmpty == true;
      final hasSharedKey =
          (contactInfo?['ecc_shared_key'] as String?)?.isNotEmpty == true;
      final notice = verification == 'changed'
          ? 'کلید مخاطب تغییر کرده است؛ ابتدا اثر انگشت جدید را تایید کنید.'
          : (hasPeerKey && hasSharedKey)
              ? 'کلید مخاطب دریافت شده اما هنوز تایید نشده است؛ ابتدا اثر انگشت را تایید کنید.'
              : secureState == 'handshake_pending'
                  ? 'تبادل کلید هنوز کامل نشده است.'
                  : 'ابتدا روی «ایجاد ارتباط امن» بزنید تا تبادل کلید انجام شود.';
      if (!mounted) return;
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text(notice)));
      return;
    }

    await _executeSendMessage(text, securityLevel: _selectedSecurityLevel);
  }

  void _showKeyEntryAndSend(String text) {
    final keyController =
        TextEditingController(text: contactInfo?['symmetric_key'] ?? '');
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(15)),
        title: const Text('رمزنگاری متقارن'),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Text('کلید متقارن این پیام را وارد یا تایید کنید:'),
            const SizedBox(height: 10),
            TextField(
              controller: keyController,
              decoration: const InputDecoration(
                hintText: 'کلید متقارن',
                border: OutlineInputBorder(),
              ),
            ),
          ],
        ),
        actions: [
          TextButton(
              onPressed: () => Navigator.pop(ctx), child: const Text('لغو')),
          ElevatedButton(
            onPressed: () {
              if (keyController.text.trim().isEmpty) {
                ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(content: Text('لطفاً کلید را وارد کنید')));
                return;
              }
              Navigator.pop(ctx);
              _executeSendMessage(text,
                  securityLevel: 'symmetric',
                  symmetricKey: keyController.text.trim());
            },
            child: const Text('ارسال'),
          ),
        ],
      ),
    );
  }

  Future<void> _executeSendMessage(String text,
      {required String securityLevel, String? symmetricKey}) async {
    final earlyPacketId =
        Random().nextInt(0xFFFFFFFF).toRadixString(16).padLeft(10, '0');
    final tempTimestamp = DateTime.now().millisecondsSinceEpoch;
    final draftLocalId =
        'draft::$tempTimestamp::${Random().nextInt(1 << 32).toRadixString(16)}';

    final tempMsg = ChatModel(
      localId: draftLocalId,
      body: text,
      date: tempTimestamp,
      isMe: true,
      status: MessageStatus.sending,
      isSecure: securityLevel != 'normal',
      packetId: securityLevel == 'normal' ? null : earlyPacketId,
    );
    messages.insert(0, tempMsg);
    _publishMessages(messages);
    _msgController.clear();

    try {
      if (symmetricKey != null) {
        tempMsg.rawBody = await SecureMessagingService.instance
            .getEncryptedPreview(text, symmetricKey);
      }

      final result = await SecureMessagingService.instance.sendMessage(
        widget.address,
        text,
        securityLevel: securityLevel,
        symmetricKey: symmetricKey,
        forcedPacketId: securityLevel == 'normal' ? null : earlyPacketId,
        localTimestamp: tempTimestamp,
      );

      if (!mounted) return;
      if (result['sentText'] == true) {
        tempMsg.packetId = result['packetId'] as String?;
        tempMsg.packetMode = result['packetMode'] as String?;
        tempMsg.rawBody ??= result['protocolBody'] as String?;
        tempMsg.rawViewBody ??= tempMsg.rawBody;
        tempMsg.encryptedPayload ??= result['encryptedPayload'] as String?;
        tempMsg.isPendingMultipart = result['notice'] == 'sent_fragmented';
        tempMsg.status = MessageStatus.sent;
        if (result['notice'] == 'sent') {
          tempMsg.statusLabel = null;
        } else {
          tempMsg.statusLabel = 'ارسال کامل شد';
        }
        _replaceMessagesWithCandidates([
          ...messages.map((m) => _MessageCandidate(m)),
          _MessageCandidate(tempMsg, preferCandidate: true),
        ]);
        Future.delayed(const Duration(milliseconds: 800), loadMessages);
      } else {
        messages.remove(tempMsg);
        _msgController.text = text;
        _msgController.selection = TextSelection.fromPosition(
            TextPosition(offset: _msgController.text.length));
        _publishMessages(messages);
        ScaffoldMessenger.of(context)
            .showSnackBar(SnackBar(content: Text(result['notice'] as String)));
        loadMessages();
      }
    } catch (e) {
      if (!mounted) return;
      setState(() {
        tempMsg.status = MessageStatus.failed;
        tempMsg.statusLabel = 'خطا در ارسال';
      });
      ScaffoldMessenger.of(context)
          .showSnackBar(SnackBar(content: Text('خطا در ارسال: $e')));
    }
  }

  Future<void> _handleRetryDecryption(ChatModel msg) async {
    final source = msg.rawBody ?? msg.body;
    final payload =
        await SecureMessagingService.instance.resolvePayloadForRetry(
      source,
      phone: widget.address,
      hintedPayload: msg.body.contains(' ::PAYLOAD::')
          ? msg.body.split(' ::PAYLOAD::')[1]
          : msg.encryptedPayload,
    );
    if (!mounted) return;
    if (payload == null) {
      ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('payload پیام پیدا نشد.')));
      return;
    }

    final keyController = TextEditingController();
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(15)),
        title: const Text('بازگشایی دستی پیام'),
        content: TextField(
          controller: keyController,
          decoration: const InputDecoration(
            hintText: 'کلید متقارن',
            border: OutlineInputBorder(),
          ),
        ),
        actions: [
          TextButton(
              onPressed: () => Navigator.pop(ctx), child: const Text('لغو')),
          ElevatedButton(
            onPressed: () async {
              if (keyController.text.trim().isEmpty) return;
              Navigator.pop(ctx);
              final messenger = ScaffoldMessenger.of(context);
              final decrypted =
                  await SecureMessagingService.instance.decryptWithKey(
                source,
                keyController.text.trim(),
                phone: widget.address,
                hintedPayload: payload,
              );
              if (!mounted) return;
              if (decrypted != null) {
                final isGroup = msg.rawBody?.contains('@G:') == true ||
                    msg.body.contains('@G:') == true ||
                    (msg.rawBody != null &&
                        ProtocolHelper.parseMessage(msg.rawBody!)['isGroup'] ==
                            true);

                if (isGroup) {
                  final groups = await DatabaseHelper.instance
                      .getGroupsContainingPhone(widget.address);
                  for (final g in groups) {
                    await DatabaseHelper.instance.updateGroupKey(
                        g['id'] as int, keyController.text.trim());
                  }
                } else {
                  await DatabaseHelper.instance.updateContactSecurity(
                    widget.address,
                    symmetricKey: keyController.text.trim(),
                    mode: 'symmetric',
                    state: 'ready',
                  );
                }

                setState(() {
                  msg.body = decrypted;
                  msg.encryptedPayload = payload;
                  msg.rawViewBody = _buildRawViewBody(
                    body: decrypted,
                    rawBody: msg.rawBody,
                    encryptedPayload: payload,
                    packetMode: msg.packetMode ?? 'SYM',
                    isSecure: true,
                  );
                  msg.canRetryDecryption = false;
                  msg.statusLabel = null;
                  msg.isSecure = true;
                  msg.isPendingMultipart = false;
                });
                messenger.showSnackBar(
                    const SnackBar(content: Text('بازگشایی موفقیت‌آمیز بود.')));
                loadMessages();
              } else {
                messenger.showSnackBar(const SnackBar(
                    content: Text(
                        'بازگشایی ناموفق بود. کلید اشتباه است یا دیتا مخدوش شده است.')));
              }
            },
            child: const Text('بازگشایی'),
          ),
        ],
      ),
    );
  }

  Future<void> _makePhoneCall() async {
    try {
      await nativeChannel.invokeMethod('makeCall', {'phone': widget.address});
    } catch (_) {
      if (!mounted) return;
      ScaffoldMessenger.of(context)
          .showSnackBar(const SnackBar(content: Text('خطا در برقراری تماس')));
    }
  }

  Widget _buildSecurityBanner() {
    final status = _securityStatusText();
    if (status.isEmpty || status == _dismissedBannerText) {
      return const SizedBox.shrink();
    }

    final mode = contactInfo?['mode'] as String? ?? 'normal';
    final secureState = contactInfo?['secure_state'] as String? ?? 'none';
    final verification =
        contactInfo?['verification_state'] as String? ?? 'unverified';
    final isAsym =
        mode == 'asymmetric' || _selectedSecurityLevel == 'asymmetric';
    final hasSecurityAlert =
        secureState == 'handshake_failed' || verification == 'changed';
    final hasSecureConnection = isAsym && _isAsymmetricReadyNow;
    final bg = hasSecurityAlert
        ? Colors.red.withValues(alpha: 0.8)
        : (hasSecureConnection
            ? Colors.green.withValues(alpha: 0.8)
            : Colors.blue.withValues(alpha: 0.8));
    final border = Colors.white.withValues(alpha: 0.2);
    const iconColor = Colors.white;
    const textColor = Colors.white;

    return AnimatedSwitcher(
      duration: const Duration(milliseconds: 400),
      transitionBuilder: (Widget child, Animation<double> animation) {
        return FadeTransition(
          opacity: animation,
          child: SlideTransition(
            position: Tween<Offset>(
              begin: const Offset(0, -0.5),
              end: Offset.zero,
            ).animate(animation),
            child: child,
          ),
        );
      },
      child: Container(
        key: ValueKey(status),
        margin: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
        child: ClipRRect(
          borderRadius: BorderRadius.circular(16),
          child: BackdropFilter(
            filter: ImageFilter.blur(sigmaX: 10, sigmaY: 10),
            child: Container(
              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
              decoration: BoxDecoration(
                color: bg.withValues(alpha: 0.2),
                borderRadius: BorderRadius.circular(16),
                border: Border.all(color: border, width: 0.5),
              ),
              child: Row(
                children: [
                  Icon(
                    hasSecurityAlert
                        ? Icons.warning_amber_rounded
                        : (hasSecureConnection
                            ? Icons.verified_user_rounded
                            : Icons.info_outline_rounded),
                    color: iconColor,
                    size: 20,
                  ),
                  const SizedBox(width: 12),
                  Expanded(
                    child: Text(
                      status,
                      style: const TextStyle(
                        color: textColor,
                        fontSize: 13,
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  ),
                  IconButton(
                    onPressed: () =>
                        setState(() => _dismissedBannerText = status),
                    icon: const Icon(Icons.close,
                        color: Colors.white60, size: 18),
                    padding: EdgeInsets.zero,
                    constraints: const BoxConstraints(),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppTheme.darkBg,
      extendBodyBehindAppBar: true,
      resizeToAvoidBottomInset: true,
      appBar: PreferredSize(
        preferredSize: const Size.fromHeight(kToolbarHeight + 8),
        child: AppTheme.glassWrapper(
          radius: 0,
          sigma: 18,
          child: AppBar(
            backgroundColor: Colors.transparent,
            elevation: 0,
            leading: IconButton(
              icon: const Icon(Icons.arrow_back, color: Colors.white),
              onPressed: () => Navigator.of(context).pop(),
            ),
            title: InkWell(
              onTap: _openContactInfo,
              overlayColor: WidgetStateProperty.all(Colors.transparent),
              child: Row(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Hero(
                    tag: 'avatar_${displayName}_ind',
                    child: Container(
                      width: 38,
                      height: 38,
                      decoration: BoxDecoration(
                        shape: BoxShape.circle,
                        gradient: LinearGradient(
                          colors: [
                            Theme.of(context).primaryColor,
                            Theme.of(context)
                                .primaryColor
                                .withValues(alpha: 0.7),
                          ],
                        ),
                      ),
                      child: Center(
                        child: Text(
                          displayName.isNotEmpty ? displayName[0] : '?',
                          style: const TextStyle(
                              color: Colors.white,
                              fontSize: 14,
                              fontWeight: FontWeight.bold),
                        ),
                      ),
                    ),
                  ),
                  const SizedBox(width: 10),
                  Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text(
                        displayName,
                        style: const TextStyle(
                            fontSize: 16,
                            fontWeight: FontWeight.bold,
                            color: Colors.white),
                      ),
                      if (displayName != widget.address)
                        Text(
                          widget.address,
                          style: const TextStyle(
                              fontSize: 11, color: Colors.white70),
                        ),
                    ],
                  ),
                ],
              ),
            ),
            actions: [
              IconButton(
                icon: const Icon(Icons.verified_user_outlined,
                    color: Colors.white, size: 22),
                onPressed: _showFingerprintSheet,
              ),
              IconButton(
                icon: const Icon(Icons.call_outlined,
                    color: Colors.white, size: 22),
                onPressed: _makePhoneCall,
              ),
            ],
          ),
        ),
      ),
      body: Stack(
        children: [
          Positioned.fill(child: CustomPaint(painter: MeshBackgroundPainter())),
          Column(
            children: [
              SizedBox(
                  height:
                      MediaQuery.of(context).padding.top + kToolbarHeight + 8),
              _buildSecurityBanner(),
              Expanded(
                child: ValueListenableBuilder<List<ChatModel>>(
                  valueListenable: _messageNotifier,
                  builder: (context, messages, child) {
                    if (messages.isEmpty) {
                      return Center(
                        child: Column(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: [
                            Icon(Icons.mark_chat_unread_outlined,
                                size: 60,
                                color: Colors.white.withValues(alpha: 0.1)),
                            const SizedBox(height: 10),
                            const Text('آغاز گفتگو...',
                                style: TextStyle(
                                    color: Colors.white38, fontSize: 13)),
                          ],
                        ),
                      );
                    }
                    return ListView.builder(
                      key: const PageStorageKey('chat_list_view'),
                      controller: _scrollController,
                      reverse: true,
                      padding: const EdgeInsets.symmetric(
                          horizontal: 10, vertical: 20),
                      itemCount: messages.length + (_hasMore ? 1 : 0),
                      itemBuilder: (context, index) {
                        if (index == messages.length) {
                          return const Center(
                            child: Padding(
                              padding: EdgeInsets.all(12.0),
                              child: CircularProgressIndicator(strokeWidth: 2),
                            ),
                          );
                        }
                        final msg = messages[index];
                        return GestureDetector(
                          onLongPress: () {
                            if (msg.id != null) {
                              _deleteSmsNative(msg.id!);
                            }
                          },
                          child: MessageBubble(
                            key: ValueKey(
                              msg.localId ??
                                  _packetKey(msg.packetId, msg.packetMode) ??
                                  msg.id?.toString() ??
                                  'temp_${msg.date}',
                            ),
                            body: msg.body,
                            rawBody: msg.rawViewBody ?? msg.rawBody,
                            statusLabel: msg.statusLabel,
                            date: msg.date,
                            isMe: msg.isMe,
                            status: msg.status,
                            isSecure: msg.isSecure,
                            canRetryDecryption: msg.canRetryDecryption,
                            onRetryDecryption: () =>
                                _handleRetryDecryption(msg),
                            packetMode: msg.packetMode,
                            isPendingMultipart: msg.isPendingMultipart,
                          ),
                        );
                      },
                    );
                  },
                ),
              ),
              AppTheme.glassWrapper(
                radius: 0,
                sigma: 15,
                child: Container(
                  padding: const EdgeInsets.fromLTRB(12, 8, 12, 12),
                  decoration: BoxDecoration(
                    color: Colors.white.withValues(alpha: 0.03),
                    border: Border(
                      top: BorderSide(
                          color: Colors.white.withValues(alpha: 0.08),
                          width: 0.5),
                    ),
                  ),
                  child: Column(
                    mainAxisSize: MainAxisSize.min,
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      if (!_loadingSims && _simCards.length > 1)
                        SizedBox(
                          height: 35,
                          child: ListView.builder(
                            scrollDirection: Axis.horizontal,
                            itemCount: _simCards.length,
                            itemBuilder: (context, index) {
                              final sim = _simCards[index];
                              final isSelected = _selectedSim == sim;
                              return Padding(
                                padding: const EdgeInsets.only(right: 8),
                                child: ChoiceChip(
                                  label: Text(sim['displayName']?.toString() ??
                                      'SIM ${index + 1}'),
                                  selected: isSelected,
                                  onSelected: (_) =>
                                      setState(() => _selectedSim = sim),
                                ),
                              );
                            },
                          ),
                        ),
                      const SizedBox(height: 8),
                      Row(
                        children: [
                          InkWell(
                            borderRadius: BorderRadius.circular(18),
                            onTap: _showSecurityModeSheet,
                            child: Container(
                              padding: const EdgeInsets.symmetric(
                                  horizontal: 14, vertical: 12),
                              decoration: BoxDecoration(
                                color: Colors.white.withValues(alpha: 0.05),
                                borderRadius: BorderRadius.circular(18),
                                border: Border.all(
                                    color: Colors.white.withValues(alpha: 0.1),
                                    width: 0.5),
                              ),
                              child: Row(
                                mainAxisSize: MainAxisSize.min,
                                children: [
                                  Container(
                                    width: 32,
                                    height: 32,
                                    decoration: BoxDecoration(
                                      color: _securityAccent(
                                              _selectedSecurityLevel)
                                          .withValues(alpha: 0.15),
                                      borderRadius: BorderRadius.circular(10),
                                    ),
                                    child: Icon(
                                      _securityIcon(_selectedSecurityLevel),
                                      size: 16,
                                      color: _securityAccent(
                                          _selectedSecurityLevel),
                                    ),
                                  ),
                                  const SizedBox(width: 10),
                                  Text(
                                    _securityLabel(_selectedSecurityLevel),
                                    style: const TextStyle(
                                        fontWeight: FontWeight.bold,
                                        fontSize: 14,
                                        color: Colors.white),
                                  ),
                                  const SizedBox(width: 8),
                                  const Icon(Icons.expand_more_rounded,
                                      size: 18, color: Colors.white70),
                                ],
                              ),
                            ),
                          ),
                        ],
                      ),
                      _buildAsymmetricActions(),
                      const SizedBox(height: 10),
                      Row(
                        children: [
                          Expanded(
                            child: TextField(
                              controller: _msgController,
                              minLines: 1,
                              maxLines: 4,
                              style: const TextStyle(color: Colors.white),
                              decoration: InputDecoration(
                                hintText: 'پیام خود را بنویسید...',
                                hintStyle:
                                    const TextStyle(color: Colors.white30),
                                filled: true,
                                fillColor: Colors.white.withValues(alpha: 0.05),
                                contentPadding: const EdgeInsets.symmetric(
                                    horizontal: 16, vertical: 12),
                                border: OutlineInputBorder(
                                  borderRadius: BorderRadius.circular(20),
                                  borderSide: BorderSide.none,
                                ),
                              ),
                            ),
                          ),
                          const SizedBox(width: 10),
                          FloatingActionButton(
                            heroTag: 'send_${widget.address}',
                            mini: true,
                            elevation: 4,
                            backgroundColor: Theme.of(context).primaryColor,
                            onPressed: _selectedSecurityLevel == 'asymmetric' &&
                                    !_isAsymmetricReadyNow
                                ? null
                                : sendMessage,
                            child: const Icon(Icons.send_rounded,
                                color: Colors.white, size: 20),
                          ),
                        ],
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }
}