package com.sshmanager.service;

import com.sshmanager.dto.BackupConnectionDto;
import com.sshmanager.dto.BackupImportResponseDto;
import com.sshmanager.dto.BackupPackageDto;
import com.sshmanager.dto.ConnectionCreateRequest;
import com.sshmanager.dto.ConnectionDto;
import com.sshmanager.dto.SessionTreeLayoutDto;
import com.sshmanager.dto.SessionTreeNodeDto;
import com.sshmanager.entity.Connection;
import com.sshmanager.repository.ConnectionRepository;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.Instant;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Service
public class BackupService {

    private final ConnectionRepository connectionRepository;
    private final ConnectionService connectionService;
    private final SessionTreeLayoutService sessionTreeLayoutService;

    public BackupService(ConnectionRepository connectionRepository,
                         ConnectionService connectionService,
                         SessionTreeLayoutService sessionTreeLayoutService) {
        this.connectionRepository = connectionRepository;
        this.connectionService = connectionService;
        this.sessionTreeLayoutService = sessionTreeLayoutService;
    }

    @Transactional(readOnly = true)
    public BackupPackageDto exportBackup(Long userId) {
        BackupPackageDto backup = new BackupPackageDto();
        backup.setExportedAt(Instant.now());

        List<BackupConnectionDto> exportedConnections = new ArrayList<BackupConnectionDto>();
        for (Connection connection : connectionRepository.findByUserIdOrderByUpdatedAtDesc(userId)) {
            BackupConnectionDto item = new BackupConnectionDto();
            item.setSourceId(connection.getId());
            item.setName(connection.getName());
            item.setHost(connection.getHost());
            item.setPort(connection.getPort());
            item.setUsername(connection.getUsername());
            item.setAuthType(connection.getAuthType());
            item.setPassword(connectionService.getDecryptedPassword(connection));
            item.setPrivateKey(connectionService.getDecryptedPrivateKey(connection));
            item.setPassphrase(connectionService.getDecryptedPassphrase(connection));
            exportedConnections.add(item);
        }

        backup.setConnections(exportedConnections);
        backup.setSessionTree(sessionTreeLayoutService.getLayout(userId));
        return backup;
    }

    @Transactional
    @SuppressWarnings("null")
    public BackupImportResponseDto importBackup(Long userId, BackupPackageDto backupPackage) {
        if (backupPackage == null) {
            throw new IllegalArgumentException("Backup package is required");
        }

        List<BackupConnectionDto> connections = backupPackage.getConnections() == null
            ? new ArrayList<BackupConnectionDto>()
            : backupPackage.getConnections();
        SessionTreeLayoutDto sessionTree = backupPackage.getSessionTree() == null
            ? new SessionTreeLayoutDto()
            : backupPackage.getSessionTree();

        connectionRepository.deleteAll(connectionRepository.findByUserIdOrderByUpdatedAtDesc(userId));

        Map<Long, Long> connectionIdMapping = new HashMap<Long, Long>();
        for (BackupConnectionDto item : connections) {
            ConnectionCreateRequest request = new ConnectionCreateRequest();
            request.setName(item.getName());
            request.setHost(item.getHost());
            request.setPort(item.getPort());
            request.setUsername(item.getUsername());
            request.setAuthType(item.getAuthType());
            request.setPassword(item.getPassword());
            request.setPrivateKey(item.getPrivateKey());
            request.setPassphrase(item.getPassphrase());

            ConnectionDto created = connectionService.create(request, userId);
            if (item.getSourceId() != null) {
                connectionIdMapping.put(item.getSourceId(), created.getId());
            }
        }

        SessionTreeLayoutDto remappedLayout = remapSessionTree(sessionTree, connectionIdMapping);
        sessionTreeLayoutService.saveLayout(userId, remappedLayout);

        int nodeCount = remappedLayout.getNodes() == null ? 0 : remappedLayout.getNodes().size();
        return new BackupImportResponseDto(connections.size(), nodeCount);
    }

    private SessionTreeLayoutDto remapSessionTree(SessionTreeLayoutDto source,
                                                  Map<Long, Long> connectionIdMapping) {
        SessionTreeLayoutDto target = new SessionTreeLayoutDto();
        target.setSortMode(source.getSortMode());

        List<SessionTreeNodeDto> remappedNodes = new ArrayList<SessionTreeNodeDto>();
        if (source.getNodes() != null) {
            for (SessionTreeNodeDto node : source.getNodes()) {
                if (node == null) {
                    continue;
                }
                if ("connection".equals(node.getType())) {
                    Long mappedConnectionId = connectionIdMapping.get(node.getConnectionId());
                    if (mappedConnectionId == null) {
                        continue;
                    }
                    remappedNodes.add(new SessionTreeNodeDto(
                        node.getId(),
                        node.getType(),
                        node.getName(),
                        node.getParentId(),
                        node.getOrder(),
                        mappedConnectionId,
                        node.getExpanded(),
                        node.getCreatedAt(),
                        node.getUpdatedAt()
                    ));
                    continue;
                }

                remappedNodes.add(new SessionTreeNodeDto(
                    node.getId(),
                    node.getType(),
                    node.getName(),
                    node.getParentId(),
                    node.getOrder(),
                    null,
                    node.getExpanded(),
                    node.getCreatedAt(),
                    node.getUpdatedAt()
                ));
            }
        }

        target.setNodes(remappedNodes);
        return target;
    }
}