EDIT

/**

 * Copyright (C) 2011 EDIT

 * European Distributed Institute of Taxonomy

 * http://www.e-taxonomy.eu

 *

 * The contents of this file are subject to the Mozilla Public License Version 1.1

 * See LICENSE.TXT at the top of this package for the full license terms.

 */

package eu.etaxonomy.cdm.persistence.hibernate;

import java.beans.Introspector;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.Collection;

import java.util.EnumSet;

import java.util.HashMap;

import java.util.HashSet;

import java.util.List;

import java.util.Map;

import java.util.Set;

import org.apache.commons.lang.ArrayUtils;

import org.apache.log4j.Logger;

import org.hibernate.EmptyInterceptor;

import org.hibernate.type.Type;

import org.springframework.security.core.context.SecurityContextHolder;

import org.springframework.stereotype.Component;

import eu.etaxonomy.cdm.database.PermissionDeniedException;

import eu.etaxonomy.cdm.model.CdmBaseType;

import eu.etaxonomy.cdm.model.common.CdmBase;

import eu.etaxonomy.cdm.model.common.IPublishable;

import eu.etaxonomy.cdm.persistence.hibernate.permission.CRUD;

import eu.etaxonomy.cdm.persistence.hibernate.permission.ICdmPermissionEvaluator;

import eu.etaxonomy.cdm.persistence.hibernate.permission.Operation;

import eu.etaxonomy.cdm.persistence.hibernate.permission.Role;

/**

 * @author k.luther

 * @author a.kohlbecker

 *

 */

@Component

public class CdmSecurityHibernateInterceptor extends EmptyInterceptor {

    private static final long serialVersionUID = 8477758472369568074L;

    public static final Logger logger = Logger.getLogger(CdmSecurityHibernateInterceptor.class);

    private ICdmPermissionEvaluator permissionEvaluator;

    public ICdmPermissionEvaluator getPermissionEvaluator() {

        return permissionEvaluator;

    }

    public void setPermissionEvaluator(ICdmPermissionEvaluator permissionEvaluator) {

        this.permissionEvaluator = permissionEvaluator;

    }

    /**

     * The exculdeMap must map every property to the CdmBase type !!!

     */

    public static final Map<Class<? extends CdmBase>, Set<String>> exculdeMap = new HashMap<Class<? extends CdmBase>, Set<String>>();

    static{

//        disabled since no longer needed, see https://dev.e-taxonomy.eu/trac/ticket/4111#comment:8

//        exculdeMap.put(TaxonName.class, new HashSet<String>());

        Set<String> defaultExculdes = new HashSet<String>();

        defaultExculdes.add("createdBy");  //created by is changed by CdmPreDataChangeListener after save. This is handled as a change and therefore throws a security exception during first insert if only CREATE rights exist

        defaultExculdes.add("created");  // same behavior was not yet observed for "created", but to be on the save side we also exclude "created"

        defaultExculdes.add("updatedBy");

        defaultExculdes.add("updated");

        for ( CdmBaseType type: CdmBaseType.values()){

            exculdeMap.put(type.getBaseClass(), new HashSet<String>());

            exculdeMap.get(type.getBaseClass()).addAll(defaultExculdes);

        }

        exculdeMap.put(CdmBase.class, new HashSet<String>());

        exculdeMap.get(CdmBase.class).addAll(defaultExculdes);

        /*

         * default fields required for each type for which excludes are defined

         */

//        exculdeMap.get(TaxonName.class).add("updatedBy");

//        exculdeMap.get(TaxonName.class).add("created");

//        exculdeMap.get(TaxonName.class).add("updated");

        /*

         * the specific excludes

         */

//        exculdeMap.get(TaxonName.class).add("taxonBases");

    }

    @Override

    public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] type) {

        if (SecurityContextHolder.getContext().getAuthentication() == null || !(entity instanceof CdmBase)) {

            return true;

        }

        // evaluate throws EvaluationFailedException

        checkPermissions((CdmBase) entity, Operation.CREATE);

        logger.debug("permission check suceeded - object creation granted");

        return true;

    }

    @Override

    public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, Type[] types) {

        if (SecurityContextHolder.getContext().getAuthentication() == null || !(entity instanceof CdmBase)) {

            return true;

        }

        CdmBase cdmEntity = (CdmBase) entity;

        if (previousState == null){

            return onSave(cdmEntity, id, currentState, propertyNames, null);

        }

        Set<String> excludes = exculdeMap.get(baseType(cdmEntity));

        excludes.addAll(unprotectedCacheFields(currentState, previousState, propertyNames));

        if (isModified(currentState, previousState, propertyNames, excludes)) {

            // evaluate throws EvaluationFailedException

            //if(cdmEntity.getCreated())

            checkPermissions(cdmEntity, Operation.UPDATE);

            logger.debug("Operation.UPDATE permission check suceeded - object update granted");

            if(IPublishable.class.isAssignableFrom(entity.getClass())){

                if(namedPropertyIsModified(currentState, previousState, propertyNames, "publish")){

                    checkRoles(Role.ROLE_PUBLISH, Role.ROLE_ADMIN);

                    logger.debug("Role.ROLE_PUBLISH permission check suceeded - object update granted");

                }

            }

        }

        return true;

    }

    /**

     * Detects all cache fields and the according protection flags. For cache fields which are not

     * protected the name of the cache field and of the protection flag are returned.

     * <p>

     * This method relies on  the convention that the protection flag for cache fields are named like

     * {@code protected{CacheFieldName} } whereas the cache fields a always ending with "Cache"

     *

     * @param currentState

     * @param previousState

     * @param propertyNames

     * @return

     */

    protected Collection<? extends String> unprotectedCacheFields(Object[] currentState, Object[] previousState,

            String[] propertyNames) {

        List<String> excludes = new ArrayList<>();

        for(int i = 0; i < propertyNames.length; i ++){

            if(propertyNames[i].matches("^protected.*Cache$")){

                if(currentState[i] instanceof Boolean && ((Boolean)currentState[i]) == false && currentState[i].equals(previousState[i])){

                    excludes.add(propertyNames[i]);

                    String cacheFieldName = propertyNames[i].replace("protected", "");

                    cacheFieldName = Introspector.decapitalize(cacheFieldName);

                    excludes.add(cacheFieldName);

                }

            }

        }

        return excludes;

    }

    private Class<? extends CdmBase> baseType(CdmBase cdmEntity) {

        Class<? extends CdmBase> basetype = CdmBaseType.baseTypeFor(cdmEntity.getClass());

        return basetype == null ? CdmBase.class : basetype;

    }

    @Override

    public void onDelete(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) {

        if (SecurityContextHolder.getContext().getAuthentication() == null || !(entity instanceof CdmBase)) {

            return;

        }

        CdmBase cdmEntity = (CdmBase) entity;

        // evaluate throws EvaluationFailedException

        checkPermissions(cdmEntity, Operation.DELETE);

        logger.debug("permission check suceeded - object update granted");

        return;

    }

    /**

     * checks if the current authentication has the <code>expectedPermission</code> on the supplied <code>entity</code>.

     * Throws an {@link PermissionDeniedException} if the evaluation fails.

     *

     * @param entity

     * @param expectedOperation

     */

    private void checkPermissions(CdmBase entity, EnumSet<CRUD> expectedOperation) {

        if (!permissionEvaluator.hasPermission(SecurityContextHolder.getContext().getAuthentication(), entity, expectedOperation)){

            throw new PermissionDeniedException(SecurityContextHolder.getContext().getAuthentication(), entity, expectedOperation);

        }

    }

    /**

     * checks if the current authentication has at least one of the <code>roles</code>.

     * Throws an {@link PermissionDeniedException} if the evaluation fails.

     * @param roles

     */

    private void checkRoles(Role ... roles) {

        if (!permissionEvaluator.hasOneOfRoles(SecurityContextHolder.getContext().getAuthentication(), roles)){

            throw new PermissionDeniedException(SecurityContextHolder.getContext().getAuthentication(), roles);

        }

    }

    /**

     * Checks if the CDM entity as been modified by comparing the current with the previous state.

     *

     * @param currentState

     * @param previousState

     * @return true if the currentState and previousState differ.

     */

    private boolean isModified(Object[] currentState, Object[] previousState, String[] propertyNames, Set<String> excludes) {

        Set<Integer> excludeIds = null;

        if(excludes != null && excludes.size() > 0) {

            excludeIds = new HashSet<Integer>(excludes.size());

            int i = 0;

            for(String prop : propertyNames){

                if(excludes.contains(prop)){

                    excludeIds.add(i);

                }

                if(excludeIds.size() == excludes.size()){

                    // all ids found

                    break;

                }

                i++;

            }

        }

        for (int i = 0; i<currentState.length; i++){

            if((excludeIds == null || !excludeIds.contains(i))){

                if(propertyIsModified(currentState, previousState, i)){

                    if(logger.isDebugEnabled()){

                        logger.debug("modified property found: " + propertyNames[i] + ", previousState: " + previousState[i] + ", currentState: " + currentState[i] );

                    }

                    return true;

                }

            }

        }

        return false;

    }

    /**

     * Compares the object states at the property denoted by the key parameter and returns true if they differ in this property

     *

     * @param currentState

     * @param previousState

     * @param isModified

     * @param key

     * @return

     */

    private boolean propertyIsModified(Object[] currentState, Object[] previousState, int key) {

        if (currentState[key]== null ) {

            if ( previousState[key]!= null) {

                return true;

            }

        }

        if (currentState[key]!= null ){

            if (previousState[key] == null){

                return true;

            }

        }

        if (currentState[key]!= null && previousState[key] != null){

            if (!currentState[key].equals(previousState[key])) {

                return true;

            }

        }

        return false;

    }

    private boolean namedPropertyIsModified(Object[] currentState, Object[] previousState, String[] propertyNames, String propertyNameToTest) {

        int key = ArrayUtils.indexOf(propertyNames, propertyNameToTest);

        return propertyIsModified(currentState, previousState, key);

    }

}