/**
 * 
 */
package org.gcube.informationsystem.resourceregistry.contexts.security;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.UUID;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import org.gcube.informationsystem.contexts.reference.entities.Context;
import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
import org.gcube.informationsystem.resourceregistry.contexts.ContextUtility;
import org.gcube.informationsystem.resourceregistry.dbinitialization.DatabaseEnvironment;
import org.gcube.informationsystem.resourceregistry.requests.RequestUtility;
import org.gcube.informationsystem.resourceregistry.utils.DBUtility;
import org.gcube.informationsystem.utils.UUIDManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.arcadedb.database.Document;
import com.arcadedb.database.Identifiable;
import com.arcadedb.database.MutableDocument;
import com.arcadedb.database.RID;
import com.arcadedb.database.Record;
import com.arcadedb.remote.RemoteDatabase;
import com.orientechnologies.orient.core.db.ODatabasePool;
import com.orientechnologies.orient.core.db.document.ODatabaseDocument;
import com.orientechnologies.orient.core.db.record.OIdentifiable;
import com.orientechnologies.orient.core.db.record.ORecordLazySet;
import com.orientechnologies.orient.core.metadata.security.ORestrictedOperation;
import com.orientechnologies.orient.core.metadata.security.ORole;
import com.orientechnologies.orient.core.metadata.security.OSecurity;
import com.orientechnologies.orient.core.metadata.security.OSecurityRole.ALLOW_MODES;
import com.orientechnologies.orient.core.metadata.security.OUser;
import com.orientechnologies.orient.core.record.OElement;
import com.orientechnologies.orient.core.record.ORecord;
import com.orientechnologies.orient.core.record.impl.ODocument;

/**
 * @author Luca Frosini (ISTI - CNR)
 */
public class SecurityContext {
	
	private static Logger logger = LoggerFactory.getLogger(SecurityContext.class);
	
	protected static final String DEFAULT_WRITER_ROLE = "writer";
	protected static final String DEFAULT_READER_ROLE = "reader";
	
	/*
	 * H stand for Hierarchical
	 */
	public static final String H = "H";
	
	protected final boolean hierarchical;
	
	public enum SecurityType {
		ROLE("Role"), USER("User");
		
		private final String name;
		
		private SecurityType(String name) {
			this.name = name;
		}
		
		public String toString() {
			return name;
		}
	}
	
	public enum PermissionMode {
		READER("Reader"), WRITER("Writer");
		
		private final String name;
		
		private PermissionMode(String name) {
			this.name = name;
		}
		
		public String toString() {
			return name;
		}
	}
	
	protected final UUID context;
	
	protected final Map<Boolean,Map<PermissionMode,RemoteDatabase>> databasesMap;
	
	protected SecurityContext parentSecurityContext;
	
	protected Set<SecurityContext> children;
	
	protected boolean isHierarchicalMode() {
		return hierarchical && RequestUtility.getRequestInfo().get().isHierarchicalMode();
	}
	
	public void setParentSecurityContext(SecurityContext parentSecurityContext) {
		if(this.parentSecurityContext!=null) {
			this.parentSecurityContext.getChildren().remove(this);
		}
		
		this.parentSecurityContext = parentSecurityContext;
		if(parentSecurityContext!=null) {
			this.parentSecurityContext.addChild(this);
		}
	}
	
	public SecurityContext getParentSecurityContext() {
		return parentSecurityContext;
	}
	
	private void addChild(SecurityContext child) {
		this.children.add(child);
	}
	
	public Set<SecurityContext> getChildren(){
		return this.children;
	}
	
	protected RemoteDatabase getAdminDatabaseDocument() throws ResourceRegistryException {
		return ContextUtility.getAdminSecurityContext().getRemoteDatabase(PermissionMode.WRITER);
	}
	
	/**
	 * @return a set containing all children and recursively
	 * all children.  
	 */
	private Set<SecurityContext> getAllChildren(){
		Set<SecurityContext> allChildren = new HashSet<>();
		allChildren.add(this);
		for(SecurityContext securityContext : getChildren()) {
			allChildren.addAll(securityContext.getAllChildren());
		}
		return allChildren;
	}
	
	/**
	 * @return 
	 */
	private Set<SecurityContext> getAllParents(){
		Set<SecurityContext> allParents = new HashSet<>();
		SecurityContext parent = getParentSecurityContext();
		while(parent!=null) {
			allParents.add(parent);
			parent = parent.getParentSecurityContext();
		}
		return allParents;
	}
	
	
	/**
	 * Use to change the parent not to set the first time
	 * 
	 * @param newParentSecurityContext
	 * @param orientGraph
	 * @throws ResourceRegistryException 
	 */
	public void changeParentSecurityContext(SecurityContext newParentSecurityContext, RemoteDatabase database) throws ResourceRegistryException {
		if(!hierarchical) {
			StringBuilder errorMessage = new StringBuilder();
			errorMessage.append("Cannot change parent ");
			errorMessage.append(SecurityContext.class.getSimpleName());
			errorMessage.append(" to non hierarchic ");
			errorMessage.append(SecurityContext.class.getSimpleName());
			errorMessage.append(". ");
			errorMessage.append(DBUtility.SHOULD_NOT_OCCUR_ERROR_MESSAGE);
			final String error = errorMessage.toString();
			logger.error(error);
			throw new RuntimeException(error);
		}
		
//		OSecurity oSecurity = getOSecurity(database);
		
		Set<SecurityContext> allChildren = getAllChildren();
		
		Set<SecurityContext> oldParents = getAllParents();
		
		Set<SecurityContext> newParents = new HashSet<>();
		if(newParentSecurityContext!=null) {
			newParents = newParentSecurityContext.getAllParents();
		}
		
		/* 
		 * From old parents I remove the new parents so that oldParents
		 * contains only the parents where I have to remove all 
		 * HReaderRole-UUID e HWriterRole-UUID of allChildren by using 
		 * removeHierarchicRoleFromParent() function
		 * 
		 */
		oldParents.removeAll(newParents);
		removeChildrenHRolesFromParents(database, oldParents, allChildren);
		
		setParentSecurityContext(newParentSecurityContext);
		
		if(newParentSecurityContext!=null){
			for(PermissionMode permissionMode : PermissionMode.values()) {
				List<Role> roles = new ArrayList<>();
				for(SecurityContext child : allChildren) {
					String roleName = child.getSecurityRoleOrUserName(permissionMode, SecurityType.ROLE, true);
					Role role = database.getRole(roleName);
					roles.add(role);
				}
				newParentSecurityContext.addHierarchicalRoleToParent(database, permissionMode, roles.toArray(new Role[allChildren.size()]));
			}
		}
		
	}
	
	protected SecurityContext(UUID context, boolean hierarchical) throws ResourceRegistryException {
		this.context = context;
		this.databasesMap = new HashMap<>();
		this.hierarchical = hierarchical;
		this.children = new HashSet<>(); 
	}
	
	public SecurityContext(UUID context) throws ResourceRegistryException {
		this(context, true);
	}
	
	private synchronized RemoteDatabase getPool(PermissionMode permissionMode, boolean recreate) {
		RemoteDatabase db = null;
		
		Boolean h = isHierarchicalMode();
		
		Map<PermissionMode,RemoteDatabase> databases = databasesMap.get(h);
		if(databases == null) {
			databases = new HashMap<>();
			databasesMap.put(h, databases);
		} else {
			if(recreate) {
				db = databases.get(permissionMode);
				if(db!=null) {
					db.close();
					databases.remove(permissionMode);
				}
			}
		}
		
		db = databases.get(permissionMode);
		
		if(db == null) {
			
			String username = getSecurityRoleOrUserName(permissionMode, SecurityType.USER, h);
			String password = DatabaseEnvironment.DEFAULT_PASSWORDS.get(permissionMode);
			
			db = new RemoteDatabase(DatabaseEnvironment.HOST, DatabaseEnvironment.PORT, DatabaseEnvironment.DB ,username, password);
			
			databases.put(permissionMode, db);
		}
		
		return db;
	}
	
	public UUID getUUID() {
		return context;
	}
	
	public static String getRoleOrUserName(PermissionMode permissionMode, SecurityType securityType) {
		return getRoleOrUserName(permissionMode, securityType, false);
	}
	
	public static String getRoleOrUserName(PermissionMode permissionMode, SecurityType securityType,
			boolean hierarchic) {
		StringBuilder stringBuilder = new StringBuilder();
		if(hierarchic) {
			stringBuilder.append(H);
		}
		stringBuilder.append(permissionMode);
		stringBuilder.append(securityType);
		return stringBuilder.toString();
	}
	
	
	public String getSecurityRoleOrUserName(PermissionMode permissionMode, SecurityType securityType,
			boolean hierarchic) {
		StringBuilder stringBuilder = new StringBuilder();
		stringBuilder.append(getRoleOrUserName(permissionMode, securityType, hierarchic));
		stringBuilder.append("_");
		stringBuilder.append(context.toString());
		return stringBuilder.toString();
	}
	
	public static Set<String> getContexts(Document element) {
		Set<String> contexts = new HashSet<>();
		ORecordLazySet oRecordLazySet = element.getProperty(OSecurity.ALLOW_ALL_FIELD);
		for (Identifiable identifiable : oRecordLazySet) {
			Document oDocument = (Document) identifiable;
			String name = oDocument.getString("name");
			if (name.startsWith(getRoleOrUserName(PermissionMode.WRITER, SecurityType.ROLE))
					|| name.startsWith(getRoleOrUserName(PermissionMode.READER, SecurityType.ROLE))) {
				String[] list = name.split("_");
				if (list.length == 2) {
					String contextUUID = list[1];
					if (!UUIDManager.getInstance().isReservedUUID(contextUUID)) {
						contexts.add(contextUUID);
					}
				}
			}
		}
		return contexts;
	}
	
	
	public void addElement(Document element) throws ResourceRegistryException {
		RemoteDatabase current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		RemoteDatabase adminDatabase = null;
		try {
			adminDatabase = getAdminDatabaseDocument();
			addElement(element, adminDatabase);
		}finally {
			if(adminDatabase!=null) {
				adminDatabase.close();
			}
			
//			if(current!=null) {
//				current.activateOnCurrentThread();
//			}
		}
	}
	
	protected void allow(RemoteDatabase database, Document document, boolean hierarchic) {
		String writerRoleName = getSecurityRoleOrUserName(PermissionMode.WRITER, SecurityType.ROLE, hierarchic);
		
		oSecurity.allowRole(document, RestrictedOperation.ALLOW_ALL, writerRoleName);
		
		String readerRoleName = getSecurityRoleOrUserName(PermissionMode.READER, SecurityType.ROLE, hierarchic);
		
		oSecurity.allowRole(document, RestrictedOperation.ALLOW_READ, readerRoleName);
	}
	
	public boolean isElementInContext(final Document element) throws ResourceRegistryException {
		RID rid = element.getIdentity();
		RemoteDatabase current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		RemoteDatabase database = null;
		
		try {
			database = getRemoteDatabase(PermissionMode.READER);
			
			return database.existsRecord(rid);
			
		} finally {
			if(database!=null) {
				database.close();
			}
			
//			if(current!=null) {
//				current.activateOnCurrentThread();
//			}
		}
		
	}
	
	public void addElement(Document document, RemoteDatabase database) {
		allow(database, document, false);
		if(hierarchical) {
			allow(database, document, true);
		}
//		document.save();
	}
	
	public void removeElement(Document document) throws ResourceRegistryException {
		RemoteDatabase current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		RemoteDatabase adminDatabase = null;
		try {
			adminDatabase = getAdminDatabaseDocument();
			removeElement(document, adminDatabase);
		}finally {
			if(adminDatabase!=null) {
				adminDatabase.close();
			}
			
//			if(current!=null) {
//				current.activateOnCurrentThread();
//			}
		}
	}
	
	protected void deny(RemoteDatabase database, Document document, boolean hierarchical) {
		// The element could be created in such a context so the writerUser for the
		// context is allowed by default because it was the creator
		String writerUserName = getSecurityRoleOrUserName(PermissionMode.WRITER, SecurityType.USER, hierarchical);
		oSecurity.denyUser(document, RestrictedOperation.ALLOW_ALL, writerUserName);
		String readerUserName = getSecurityRoleOrUserName(PermissionMode.WRITER, SecurityType.USER, hierarchical);
		oSecurity.denyUser(document, RestrictedOperation.ALLOW_READ, readerUserName);
		
		String writerRoleName = getSecurityRoleOrUserName(PermissionMode.WRITER, SecurityType.ROLE, hierarchical);
		oSecurity.denyRole(document, RestrictedOperation.ALLOW_ALL, writerRoleName);
		String readerRoleName = getSecurityRoleOrUserName(PermissionMode.READER, SecurityType.ROLE, hierarchical);
		oSecurity.denyRole(document, RestrictedOperation.ALLOW_READ, readerRoleName);
		
	}
	
	public void removeElement(Document document, RemoteDatabase database) {
		deny(database, document, false);
		if(hierarchical) {
			deny(database, document, true);
		}
//		document.save();
	}
	
	protected boolean allowed(final ORole role, final Document document) {
		
		ExecutorService executor = Executors.newSingleThreadExecutor();
		
		Callable<Boolean> callable = new Callable<Boolean>() {
			
			@Override
			public Boolean call() throws Exception {
				RequestUtility.getRequestInfo().get().setHierarchicalMode(false);
				
				RemoteDatabase current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
				RemoteDatabase database = null;
				try {
					database = getRemoteDatabase(PermissionMode.READER);
					// database.activateOnCurrentThread();
					return database.existsRecord(document.getIdentity());
				} catch(Exception e) {
					return false;
				} finally {
					if(database!=null) {
						database.close();
					}
					
//					if(current!=null) {
//						current.activateOnCurrentThread();
//					}
				}
			}
			
		};
		
		Future<Boolean> result = executor.submit(callable);
		try {
			return result.get();
		} catch(Exception e) {
			return false;
		}
	}
	
	public void create() throws ResourceRegistryException {
		RemoteDatabase current = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		RemoteDatabase adminDatabase = null;
		try {
			adminDatabase = getAdminDatabaseDocument();
			
			create(adminDatabase);
			
			adminDatabase.commit();
		} finally {
			if(adminDatabase!=null) {
				adminDatabase.close();
			}
			
//			if(current!=null) {
//				current.activateOnCurrentThread();
//			}
		}
	}
	
	protected Role addExtraRules(Role role, PermissionMode permissionMode) {
		return role;
	}
	
	protected Role getSuperRole(RemoteDatabase database, PermissionMode permissionMode) {
		String superRoleName = permissionMode.name().toLowerCase();
		return database.getRole(superRoleName);
	}
	
	protected void addHierarchicalRoleToParent(RemoteDatabase database, PermissionMode permissionMode, ORole... roles) {
		String userName = getSecurityRoleOrUserName(permissionMode, SecurityType.USER, true);
		User user = database.getUser(userName);
		for(Role role : roles) {
			user.addRole(role);
		}
		user.save();
		
		if(getParentSecurityContext() != null) {
			getParentSecurityContext().addHierarchicalRoleToParent(database, permissionMode, roles);
		}
	}
	
	protected void createRolesAndUsers(RemoteDatabase database) {
		boolean[] booleanArray;
		if(hierarchical) {
			booleanArray = new boolean[] {false, true};
		} else {
			booleanArray = new boolean[] {false};
		}
		
		for(boolean hierarchical : booleanArray) {
			for(PermissionMode permissionMode : PermissionMode.values()) {
				Role superRole = getSuperRole(database, permissionMode);
				
				String roleName = getSecurityRoleOrUserName(permissionMode, SecurityType.ROLE, hierarchical);
				Role role = database.createRole(roleName, superRole, ALLOW_MODES.DENY_ALL_BUT);
				addExtraRules(role, permissionMode);
				role.save();
				logger.trace("{} created", role);
				
				if(hierarchical && getParentSecurityContext() != null) {
					getParentSecurityContext().addHierarchicalRoleToParent(database, permissionMode, role);
				}
				
				String userName = getSecurityRoleOrUserName(permissionMode, SecurityType.USER, hierarchical);
				User user = database.createUser(userName, DatabaseEnvironment.DEFAULT_PASSWORDS.get(permissionMode),
						role);
				user.save();
				logger.trace("{} created", user);
			}
		}
		
	}
	
	public void create(RemoteDatabase database) {
		createRolesAndUsers(database);
		logger.trace("Security Context (roles and users) with UUID {} successfully created", context.toString());
	}
	
	private void drop(RemoteDatabase database, String name, SecurityType securityType) {
		switch(securityType) {
			case ROLE:
				database.dropRole(name);
				break;
			
			case USER:
				database.dropUser(name);
				break;
			
			default:
				break;
		}
		logger.trace("{} successfully dropped", name);
	}
	
	public void delete() throws ResourceRegistryException {
		RemoteDatabase remoteDatabase = ContextUtility.getCurrentODatabaseDocumentFromThreadLocal();
		RemoteDatabase database = null;
		try {
			database = getAdminDatabaseDocument();
			
			delete(database);
			
			database.commit();
		} finally {
			if(database!=null) {
				database.close();
			}
			
//			if(current!=null) {
//				current.activateOnCurrentThread();
//			}
		}
		
	}
	
	protected void removeChildrenHRolesFromParents(RemoteDatabase remoteDatabase) {
		Set<SecurityContext> parents = getAllParents();
		Set<SecurityContext> allChildren = getAllChildren();
		removeChildrenHRolesFromParents(remoteDatabase, parents, allChildren);
	}
	
	protected void removeChildrenHRolesFromParents(RemoteDatabase remoteDatabase, Set<SecurityContext> parents, Set<SecurityContext> children) {
		for(SecurityContext parent : parents) {
			parent.removeChildrenHRolesFromMyHUsers(remoteDatabase, children);
		}
	}
	
	protected void removeChildrenHRolesFromMyHUsers(RemoteDatabase database, Set<SecurityContext> children) {
		for(PermissionMode permissionMode : PermissionMode.values()) {
			String userName = getSecurityRoleOrUserName(permissionMode, SecurityType.USER, true);
			User user = database.getUser(userName);
			for(SecurityContext child : children) {
				String roleName = child.getSecurityRoleOrUserName(permissionMode, SecurityType.ROLE, true);
				logger.debug("Going to remove {} from {}", roleName, userName);
				boolean removed = user.removeRole(roleName);
				logger.trace("{} {} removed from {}", roleName, removed ? "successfully" : "NOT", userName);
			}
			user.save();
		}
		
	}
	
	protected void removeHierarchicRoleFromMyHUser(RemoteDatabase database, PermissionMode permissionMode, String roleName) {
		String userName = getSecurityRoleOrUserName(permissionMode, SecurityType.USER, true);
		User user = database.getUser(userName);
		logger.debug("Going to remove {} from {}", roleName, userName);
		boolean removed = user.removeRole(roleName);
		logger.trace("{} {} removed from {}", roleName, removed ? "successfully" : "NOT", userName);
		user.save();
	}
	
	protected void deleteRolesAndUsers(RemoteDatabase remoteDatabase) {
		boolean[] booleanArray;
		if(hierarchical) {
			booleanArray = new boolean[] {false, true};
		} else {
			booleanArray = new boolean[] {false};
		}
		for(boolean hierarchic : booleanArray) {
			if(hierarchic) {
				removeChildrenHRolesFromParents(remoteDatabase);
			}
			for(PermissionMode permissionMode : PermissionMode.values()) {
				for(SecurityType securityType : SecurityType.values()) {
					String name = getSecurityRoleOrUserName(permissionMode, securityType, hierarchic);
					drop(remoteDatabase, name, securityType);
				}
			}
		}
	}
	
	public void delete(RemoteDatabase remoteDatabase) {
//		OSecurity oSecurity = getOSecurity(orientGraph);
		logger.trace("Going to remove Security Context (roles and users) with UUID {}", context.toString());
		deleteRolesAndUsers(remoteDatabase);
		logger.trace("Security Context (roles and users) with UUID {} successfully removed", context.toString());
	}
	
	public RemoteDatabase getRemoteDatabase(PermissionMode permissionMode) throws ResourceRegistryException {
//		try {
//			ODatabasePool oDatabasePool = getPool(permissionMode, false);
//			ODatabaseSession oDatabaseSession = null;
//			try {
//				oDatabaseSession = oDatabasePool.acquire();
//				if(oDatabaseSession.isClosed()) {
//					// Enforcing pool recreation 
//					throw new Exception();
//				}
//			}catch (Exception e) {
//				oDatabasePool = getPool(permissionMode, true);
//				oDatabaseSession = oDatabasePool.acquire();
//			}
//			oDatabaseSession.activateOnCurrentThread();
//			return oDatabaseSession;
//		}catch (Exception e) {
//			throw new ResourceRegistryException(e);
//		}
		
		return null;
	}
	
	@Override
	public String toString() {
		return String.format("%s %s", Context.NAME, getUUID().toString());
	}
}