// ignore_for_file: invalid_use_of_protected_member, invalid_use_of_visible_for_testing_member

part of 'chat_bloc.dart';

extension _ChatBlocSend on ChatBloc {
  Future<void> _sendMessage(String content, {List<XFile>? images}) async {
    final epoch = _sessionEpoch;
    final assistantBaselineAtSend = chatBlocLatestAssistantTimestamp(
      state.items,
    );
    final sendStartedAt = DateTime.now();
    final messageId = 'user-${sendStartedAt.millisecondsSinceEpoch}';
    final localEchoAttachments = (images ?? const <XFile>[])
        .map(
          (image) => <String, dynamic>{
            'path': image.path,
            'mimeType': image.mimeType ?? 'image/jpeg',
            'uploading': true,
          },
        )
        .toList();
    final localEcho = TextMessageItem(
      id: messageId,
      content: content,
      timestamp: sendStartedAt,
      sender: MessageSender.user,
      isLocalEcho: true,
      attachments: localEchoAttachments,
    );

    emit(
      state.copyWith(
        items: [...state.items, localEcho],
        isSending: true,
        isWaitingFirstToken: true,
        isStreaming: false,
        isCancelling: false,
        error: null,
      ),
    );

    try {
      final uploadInputs = await Future.wait(
        (images ?? const <XFile>[]).map(
          (image) async => AttachmentUploadInput(
            name: image.name,
            mimeType: image.mimeType ?? 'image/jpeg',
            bytes: await image.readAsBytes(),
            localPath: image.path,
          ),
        ),
      );
      final sendResult = await _service.sendMessage(
        content,
        attachments: uploadInputs,
      );
      if (epoch != _sessionEpoch) {
        return;
      }
      _logger.info(
        message: 'Chat message sent successfully',
        extra: {'message_id': messageId},
      );
      _syncUploadedAttachments(
        messageId: messageId,
        uploadedAttachments: sendResult.uploadedAttachments,
      );
    } catch (error, stackTrace) {
      _logger.error(
        message: 'Failed to send chat message',
        error: error,
        stackTrace: stackTrace,
        extra: {'message': content},
      );
      if (epoch != _sessionEpoch) {
        return;
      }
      final sseClosedBeforeTerminal = chatBlocIsSseClosedBeforeTerminalError(
        error,
      );
      var recoveredFromHistory = false;
      if (sseClosedBeforeTerminal) {
        recoveredFromHistory = await _recoverFromAbnormalSseClose(
          epoch: epoch,
          localEchoMessage: localEcho,
          sendStartedAt: sendStartedAt,
          assistantBaselineAtSend: assistantBaselineAtSend,
        );
      }
      if (epoch != _sessionEpoch) {
        return;
      }
      _markAttachmentUploadDone(messageId);
      emit(
        state.copyWith(
          isSending: false,
          isWaitingFirstToken: false,
          isStreaming: false,
          isCancelling: false,
          currentStage: null,
          error: sseClosedBeforeTerminal
              ? (recoveredFromHistory
                    ? null
                    : L10n.current.chatSseInterruptedRetry)
              : error.toString(),
        ),
      );
    }
  }

  Future<bool> _recoverFromAbnormalSseClose({
    required int epoch,
    required TextMessageItem localEchoMessage,
    required DateTime sendStartedAt,
    required DateTime? assistantBaselineAtSend,
  }) async {
    try {
      final deadline = DateTime.now().add(_recoveryTimeout);

      while (DateTime.now().isBefore(deadline)) {
        final snapshot = await _service.loadHistory(forceRefresh: true);
        if (epoch != _sessionEpoch) {
          return false;
        }
        final merged = _mergeWithHistory(state.items, snapshot.messages);
        emit(
          state.copyWith(
            items: merged,
            oldestLoadedDate: _extractDateFromItems(merged),
            hasEarlierHistory: snapshot.hasMore,
          ),
        );

        final persistedUserTimestamp = chatBlocFindPersistedUserTimestamp(
          merged,
          localEchoMessage,
          sendStartedAt,
        );
        final assistantCaughtUp = chatBlocHasAssistantAfterBaseline(
          merged,
          assistantBaselineAtSend,
          notBefore: persistedUserTimestamp ?? sendStartedAt,
        );
        if (persistedUserTimestamp != null && assistantCaughtUp) {
          return true;
        }

        final remaining = deadline.difference(DateTime.now());
        if (remaining <= Duration.zero) {
          break;
        }
        await Future<void>.delayed(
          remaining < _recoveryPollInterval ? remaining : _recoveryPollInterval,
        );
      }

      return false;
    } catch (_) {
      return false;
    }
  }

  List<ChatListItem> _mergeWithHistory(
    List<ChatListItem> localItems,
    List<HistoryMessage> historyMessages,
  ) {
    final historyItems = _convertHistoryMessages(historyMessages);
    return ChatTimelineReconciler.merge(
      localItems: localItems,
      remoteItems: historyItems,
    );
  }
}