package de.dlr.shepard.neo4Core.services;
   
   import java.util.ArrayList;
   import java.util.List;
   
   import de.dlr.shepard.neo4Core.dao.PermissionsDAO;
   import de.dlr.shepard.neo4Core.dao.UserDAO;
   import de.dlr.shepard.neo4Core.dao.UserGroupDAO;
   import de.dlr.shepard.neo4Core.entities.Permissions;
  import de.dlr.shepard.neo4Core.entities.User;
  import de.dlr.shepard.neo4Core.entities.UserGroup;
  import de.dlr.shepard.neo4Core.io.PermissionsIO;
  import lombok.extern.slf4j.Slf4j;
  
  @Slf4j
  public class PermissionsService {
  
  	private PermissionsDAO permissionsDAO = new PermissionsDAO();
  	private UserDAO userDAO = new UserDAO();
  	private UserGroupDAO userGroupDAO = new UserGroupDAO();
  
  	/**
  	 * Searches for permissions in Neo4j.
  	 *
  	 * @param entityId identifies the entity that the permissions object belongs to
  	 * @return Permissions with matching entity or null
  	 */
  	public Permissions getPermissionsByEntity(long entityId) {
  		var permissions = permissionsDAO.findByEntity(entityId);
  		if (permissions == null) {
  			log.error("Permissions with entity id {} is null", entityId);
  			return null;
  		}
  		return permissions;
  	}
  
  	/**
  	 * Create Permissions based on an entity and the owner
  	 *
  	 * @param entityId identifies the entity
  	 * @return The created Permissions object
  	 */
  	public Permissions createPermissions(long entityId) {
  		var permissions = new Permissions();
  		return permissionsDAO.createWithEntity(permissions, entityId);
  	}
  
  	/**
  	 * Updates the Permissions in Neo4j
  	 *
  	 * @param permissions the new Permissions object
  	 * @param entityId    identifies the entity
  	 * @return the updated Permissions object
  	 */
  	public Permissions updatePermissions(PermissionsIO permissions, long entityId) {
  		var owner = permissions.getOwner() != null ? userDAO.find(permissions.getOwner()) : null;
  		var permissionType = permissions.getPermissionType();
  		var reader = fetchUsers(permissions.getReader());
  		var writer = fetchUsers(permissions.getWriter());
  		var readerGroups = fetchUserGroups(permissions.getReaderGroupIds());
  		var writerGroups = fetchUserGroups(permissions.getWriterGroupIds());
  		var manager = fetchUsers(permissions.getManager());
  		var old = getPermissionsByEntity(entityId);
  		if (old == null) {
  			// There is no old permissions object
  			var toCreate = new Permissions(owner, reader, writer, readerGroups, writerGroups, manager,
  					permissions.getPermissionType());
  			return permissionsDAO.createWithEntity(toCreate, entityId);
  		}
  		old.setOwner(owner);
  		old.setReader(reader);
  		old.setWriter(writer);
  		old.setReaderGroups(readerGroups);
  		old.setWriterGroups(writerGroups);
  		old.setManager(manager);
  		old.setPermissionType(permissionType);
  		return permissionsDAO.createOrUpdate(old);
  
  	}
  
  	private List<User> fetchUsers(String[] usernames) {
  		var result = new ArrayList<User>(usernames.length);
  		for (var username : usernames) {
  			if (username == null) {
  				continue;
  			}
  
  			var user = userDAO.find(username);
  			if (user != null) {
  				result.add(user);
  			}
  		}
  		return result;
  	}
  
  	private List<UserGroup> fetchUserGroups(long[] userGroupIds) {
  		var result = new ArrayList<UserGroup>(userGroupIds.length);
  		for (var userGroupId : userGroupIds) {
  			var userGroup = userGroupDAO.find(userGroupId);
 			if (userGroup != null) {
 				result.add(userGroup);
 			}
 		}
 		return result;
 	}
 }