/*
 * Copyright (C) 2005 Alfresco, Inc.
 *
 * Licensed under the Mozilla Public License version 1.1 
 * with a permitted attribution clause. You may obtain a
 * copy of the License at
 *
 *   http://www.alfresco.org/legal/license.txt
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the
 * License.
 */
package org.alfresco.repo.lock;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.alfresco.model.ContentModel;
import org.alfresco.repo.policy.JavaBehaviour;
import org.alfresco.repo.policy.PolicyComponent;
import org.alfresco.repo.policy.PolicyScope;
import org.alfresco.repo.security.authentication.AuthenticationUtil;
import org.alfresco.service.cmr.lock.LockService;
import org.alfresco.service.cmr.lock.LockStatus;
import org.alfresco.service.cmr.lock.LockType;
import org.alfresco.service.cmr.lock.NodeLockedException;
import org.alfresco.service.cmr.lock.UnableToAquireLockException;
import org.alfresco.service.cmr.lock.UnableToReleaseLockException;
import org.alfresco.service.cmr.repository.AspectMissingException;
import org.alfresco.service.cmr.repository.ChildAssociationRef;
import org.alfresco.service.cmr.repository.NodeRef;
import org.alfresco.service.cmr.repository.NodeService;
import org.alfresco.service.cmr.repository.StoreRef;
import org.alfresco.service.cmr.search.ResultSet;
import org.alfresco.service.cmr.search.SearchService;
import org.alfresco.service.cmr.security.AuthenticationService;
import org.alfresco.service.cmr.security.OwnableService;
import org.alfresco.service.namespace.NamespaceService;
import org.alfresco.service.namespace.QName;

/**
 * Simple Lock service implementation
 * 
 * @author Roy Wetherall
 */
public class LockServiceImpl implements LockService
{
    /**
     * The node service
     */
    private NodeService nodeService;

    /**
     * The policy component
     */
    private PolicyComponent policyComponent;

    /**
     * List of node ref's to ignore when checking for locks
     */
    private Set<NodeRef> ignoreNodeRefs = new HashSet<NodeRef>();

    /**
     * The authentication service
     */
    private AuthenticationService authenticationService;

    /**
     * The ownable service
     * 
     */
    private OwnableService ownableService;
    
    /**
     * The search service
     */
    private SearchService searchService;

    /**
     * Set the node service
     * 
     * @param nodeService
     *            the node service
     */
    public void setNodeService(NodeService nodeService)
    {
        this.nodeService = nodeService;
    }

    /**
     * Sets the policy component
     * 
     * @param policyComponent
     *            the policy componentO
     */
    public void setPolicyComponent(PolicyComponent policyComponent)
    {
        this.policyComponent = policyComponent;
    }

    /**
     * Sets the authentication service
     * 
     * @param authenticationService
     *            the authentication service
     */
    public void setAuthenticationService(AuthenticationService authenticationService)
    {
        this.authenticationService = authenticationService;
    }

    /**
     * Sets the ownable service
     * 
     * @param ownableService
     *            the ownable service
     */
    public void setOwnableService(OwnableService ownableService)
    {
        this.ownableService = ownableService;
    }
    
    /**
     * Set the search service
     * 
     * @param searchService     the search service
     */
    public void setSearchService(SearchService searchService)
    {
        this.searchService = searchService;
    }

    /**
     * Initialise methods called by Spring framework
     */
    public void initialise()
    {
        // Register the various class behaviours to enable lock checking
        this.policyComponent.bindClassBehaviour(
                QName.createQName(NamespaceService.ALFRESCO_URI, "beforeCreateVersion"), ContentModel.ASPECT_LOCKABLE,
                new JavaBehaviour(this, "checkForLock"));
        this.policyComponent.bindClassBehaviour(QName.createQName(NamespaceService.ALFRESCO_URI, "beforeUpdateNode"),
                ContentModel.ASPECT_LOCKABLE, new JavaBehaviour(this, "checkForLock"));
        this.policyComponent.bindClassBehaviour(QName.createQName(NamespaceService.ALFRESCO_URI, "beforeDeleteNode"),
                ContentModel.ASPECT_LOCKABLE, new JavaBehaviour(this, "checkForLock"));

        // Register onCopy class behaviour
        this.policyComponent.bindClassBehaviour(QName.createQName(NamespaceService.ALFRESCO_URI, "onCopyNode"),
                ContentModel.ASPECT_LOCKABLE, new JavaBehaviour(this, "onCopy"));

        // Register the onCreateVersion behavior for the version aspect
        this.policyComponent.bindClassBehaviour(QName.createQName(NamespaceService.ALFRESCO_URI, "onCreateVersion"),
                ContentModel.ASPECT_LOCKABLE, new JavaBehaviour(this, "onCreateVersion"));
    }
    
    /**
     * @see org.alfresco.service.cmr.lock.LockService#lock(org.alfresco.service.cmr.repository.NodeRef, java.lang.String, org.alfresco.service.cmr.lock.LockType)
     */
    public synchronized void lock(NodeRef nodeRef, LockType lockType)
    {
        // Lock with no expiration
        lock(nodeRef, lockType, 0);
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#lock(org.alfresco.service.cmr.repository.NodeRef, java.lang.String, org.alfresco.service.cmr.lock.LockType, int)
     */
    public synchronized void lock(NodeRef nodeRef, LockType lockType, int timeToExpire)
    {
        // Check for lock aspect
        checkForLockApsect(nodeRef);
        
        // Get the current user name
        String userName = getUserName();

        // Set a default value
        if (lockType == null)
        {
            lockType = LockType.WRITE_LOCK;
        }

        LockStatus currentLockStatus = getLockStatus(nodeRef, userName);
        if (LockStatus.LOCKED.equals(currentLockStatus) == true)
        {
            // Error since we are trying to lock a locked node
            throw new UnableToAquireLockException(nodeRef);
        }
        else if (LockStatus.NO_LOCK.equals(currentLockStatus) == true || 
                 LockStatus.LOCK_EXPIRED.equals(currentLockStatus) == true ||
                 LockStatus.LOCK_OWNER.equals(currentLockStatus) == true)
        {
            this.ignoreNodeRefs.add(nodeRef);
            try
            {
                // Set the current user as the lock owner
                this.nodeService.setProperty(nodeRef, ContentModel.PROP_LOCK_OWNER, userName);
                this.nodeService.setProperty(nodeRef, ContentModel.PROP_LOCK_TYPE, lockType.toString());                
                setExpiryDate(nodeRef, timeToExpire);
            } 
            finally
            {
                this.ignoreNodeRefs.remove(nodeRef);
            }
        }
    }

    /**
     * Helper method to set the expiry date based on the time to expire provided
     * 
     * @param nodeRef       the node reference
     * @param timeToExpire  the time to expire (in seconds)
     */
    private void setExpiryDate(NodeRef nodeRef, int timeToExpire)
    {
        // Set the expiry date
        Date expiryDate = null;
        if (timeToExpire > 0)
        {
            expiryDate = new Date();
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(expiryDate);
            calendar.add(Calendar.SECOND, timeToExpire);
            expiryDate = calendar.getTime();
        }
        
        this.nodeService.setProperty(nodeRef, ContentModel.PROP_EXPIRY_DATE, expiryDate);
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#lock(org.alfresco.service.cmr.repository.NodeRef, java.lang.String, org.alfresco.service.cmr.lock.LockType, int, boolean)
     */
    public synchronized void lock(NodeRef nodeRef, LockType lockType, int timeToExpire, boolean lockChildren)
            throws UnableToAquireLockException
    {
        lock(nodeRef, lockType, timeToExpire);

        if (lockChildren == true)
        {
            Collection<ChildAssociationRef> childAssocRefs = this.nodeService.getChildAssocs(nodeRef);
            for (ChildAssociationRef childAssocRef : childAssocRefs)
            {
                lock(childAssocRef.getChildRef(), lockType, timeToExpire, lockChildren);
            }
        }
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#lock(java.util.Collection, java.lang.String, org.alfresco.service.cmr.lock.LockType, int)
     */
    public synchronized void lock(Collection<NodeRef> nodeRefs, LockType lockType, int timeToExpire)
            throws UnableToAquireLockException
    {
        // Lock each of the specifed nodes
        for (NodeRef nodeRef : nodeRefs)
        {
            lock(nodeRef, lockType, timeToExpire);
        }
    }    

    /**
     * @see org.alfresco.service.cmr.lock.LockService#unlock(NodeRef, String)
     */
    public synchronized void unlock(NodeRef nodeRef) throws UnableToReleaseLockException
    {
        // Check for lock aspect
        checkForLockApsect(nodeRef);
        
        // Get the current user name
        //String userName = getUserName();

        //LockStatus lockStatus = getLockStatus(nodeRef, userName);
        //if (LockStatus.LOCKED.equals(lockStatus) == true)
       // {
        //    // Error since the lock can only be released by the lock owner
        //    throw new UnableToReleaseLockException(nodeRef);
       // }
       // else if (LockStatus.LOCK_OWNER.equals(lockStatus) == true)
       // {
            this.ignoreNodeRefs.add(nodeRef);
            try
            {
                // Clear the lock owner
                this.nodeService.setProperty(nodeRef, ContentModel.PROP_LOCK_OWNER, null);
                this.nodeService.setProperty(nodeRef, ContentModel.PROP_LOCK_TYPE, null);
            } finally
            {
                this.ignoreNodeRefs.remove(nodeRef);
            }
        //}
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#unlock(NodeRef, String,
     *      boolean)
     */
    public synchronized void unlock(NodeRef nodeRef, boolean unlockChildren)
            throws UnableToReleaseLockException
    {
        // Unlock the parent
        unlock(nodeRef);

        if (unlockChildren == true)
        {
            // Get the children and unlock them
            Collection<ChildAssociationRef> childAssocRefs = this.nodeService.getChildAssocs(nodeRef);
            for (ChildAssociationRef childAssocRef : childAssocRefs)
            {
                unlock(childAssocRef.getChildRef(), unlockChildren);
            }
        }
    }

    /**
     * @see org.alfresco.repo.lock.LockService#unlock(Collection<NodeRef>,
     *      String)
     */
    public synchronized void unlock(Collection<NodeRef> nodeRefs) throws UnableToReleaseLockException
    {
        for (NodeRef nodeRef : nodeRefs)
        {
            unlock(nodeRef);
        }
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#getLockStatus(NodeRef)
     */
    public LockStatus getLockStatus(NodeRef nodeRef)
    {
        return getLockStatus(nodeRef, getUserName());
    }

    /**
     * Gets the lock statuc for a node and a user name
     * 
     * @param nodeRef   the node reference
     * @param userName  the user name
     * @return          the lock status
     */
    private LockStatus getLockStatus(NodeRef nodeRef, String userName)
    {
        LockStatus result = LockStatus.NO_LOCK;

        if (this.nodeService.hasAspect(nodeRef, ContentModel.ASPECT_LOCKABLE) == true)

        {
            // Get the current lock owner
            String currentUserRef = (String) this.nodeService.getProperty(nodeRef, ContentModel.PROP_LOCK_OWNER);
            String owner = ownableService.getOwner(nodeRef);
            if (currentUserRef != null)
            {
                Date expiryDate = (Date)this.nodeService.getProperty(nodeRef, ContentModel.PROP_EXPIRY_DATE);
                if (expiryDate != null && expiryDate.before(new Date()) == true)
                {
                    // Indicate that the lock has expired
                    result = LockStatus.LOCK_EXPIRED;
                }
                else
                {
                    if (currentUserRef.equals(userName) == true)
                    {
                        result = LockStatus.LOCK_OWNER;
                    }
                    else if ((owner != null) && owner.equals(userName))
                    {
                        result = LockStatus.LOCK_OWNER;
                    }
                    else
                    {
                        result = LockStatus.LOCKED;
                    }
                }
            }

        }
        return result;

    }

    /**
     * @see LockService#getLockType(NodeRef)
     */
    public LockType getLockType(NodeRef nodeRef)
    {
        LockType result = null;

        if (this.nodeService.hasAspect(nodeRef, ContentModel.ASPECT_LOCKABLE) == true)
        {
            String lockTypeString = (String) this.nodeService.getProperty(nodeRef, ContentModel.PROP_LOCK_TYPE);
            if (lockTypeString != null)
            {
                result = LockType.valueOf(lockTypeString);
            }
        }

        return result;
    }

    /**
     * Checks for the lock aspect. Adds if missing.
     * 
     * @param nodeRef
     *            the node reference
     */
    private void checkForLockApsect(NodeRef nodeRef)
    {
        if (this.nodeService.hasAspect(nodeRef, ContentModel.ASPECT_LOCKABLE) == false)
        {
            this.nodeService.addAspect(nodeRef, ContentModel.ASPECT_LOCKABLE, null);
        }
    }

    /**
     * @see LockService#checkForLock(NodeRef)
     */
    public void checkForLock(NodeRef nodeRef) throws NodeLockedException
    {
        String userName = getUserName();
 
        // Ensure we have found a node reference
        if (nodeRef != null && userName != null)
        {
            // Check to see if should just ignore this node
            if (!(this.ignoreNodeRefs.contains(nodeRef) || userName.equals(AuthenticationUtil.getSystemUserName())))
            {
                try
                {
                    // Get the current lock status on the node ref
                    LockStatus currentLockStatus = getLockStatus(nodeRef, userName);

                    LockType lockType = getLockType(nodeRef);
                    if (LockType.WRITE_LOCK.equals(lockType) == true && 
                        LockStatus.LOCKED.equals(currentLockStatus) == true)
                    {
                        // Error since we are trying to preform an operation
                        // on a locked node
                        throw new NodeLockedException(nodeRef);
                    }
                    else if (LockType.READ_ONLY_LOCK.equals(lockType) == true &&
                             (LockStatus.LOCKED.equals(currentLockStatus) == true || LockStatus.LOCK_OWNER.equals(currentLockStatus) == true))
                    {
                        // Error since there is a read only lock on this object
                        // and all
                        // modifications are prevented
                        throw new NodeLockedException(nodeRef);
                    }
                }
                catch (AspectMissingException exception)
                {
                    // Ignore since this indicates that the node does not have
                    // the lock
                    // aspect applied
                }
            }
        }
    }

    /**
     * OnCopy behaviour implementation for the lock aspect.
     * <p>
     * Ensures that the propety values of the lock aspect are not copied onto
     * the destination node.
     * 
     * @see org.alfresco.repo.copy.CopyServicePolicies.OnCopyNodePolicy#onCopyNode(QName,
     *      NodeRef, StoreRef, boolean, PolicyScope)
     */
    public void onCopy(QName sourceClassRef, NodeRef sourceNodeRef, StoreRef destinationStoreRef,
            boolean copyToNewNode, PolicyScope copyDetails)
    {
        // Add the lock aspect, but do not copy any of the properties
        copyDetails.addAspect(ContentModel.ASPECT_LOCKABLE);
    }

    /**
     * OnCreateVersion behaviour for the lock aspect
     * <p>
     * Ensures that the property valies of the lock aspect are not 'frozen' in
     * the version store.
     * 
     * @param classRef
     *            the class reference
     * @param versionableNode
     *            the versionable node reference
     * @param versionProperties
     *            the version properties
     * @param nodeDetails
     *            the details of the node to be versioned
     */
    public void onCreateVersion(QName classRef, NodeRef versionableNode, Map<String, Serializable> versionProperties,
            PolicyScope nodeDetails)
    {
        // Add the lock aspect, but do not version the property values
        nodeDetails.addAspect(ContentModel.ASPECT_LOCKABLE);
    }

    /**
     * Get the current user reference
     * 
     * @return the current user reference
     */
    private String getUserName()
    {
        return this.authenticationService.getCurrentUserName();
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#getLocks()
     */
    public List<NodeRef> getLocks(StoreRef storeRef)
    {
        return getLocks(
                storeRef,
                "ASPECT:\"" + ContentModel.ASPECT_LOCKABLE.toString() + 
                "\" +@\\{http\\://www.alfresco.org/model/content/1.0\\}" + ContentModel.PROP_LOCK_OWNER.getLocalName() + ":\"" + getUserName() + "\"");
    }
    
    /**
     * Get the locks given a store and query string.
     * 
     * @param storeRef      the store reference
     * @param query         the query string
     * @return              the locked nodes
     */
    private List<NodeRef> getLocks(StoreRef storeRef, String query)
    {
        List<NodeRef> result = new ArrayList<NodeRef>();
        ResultSet resultSet = null;
        try
        {
            resultSet = this.searchService.query(
                    storeRef,
                    SearchService.LANGUAGE_LUCENE, 
                    query);
            result = resultSet.getNodeRefs();
        }
        finally
        {
            if (resultSet != null)
            {
                resultSet.close();
            }
        }
        return result;
    }

    /**
     * @see org.alfresco.service.cmr.lock.LockService#getLocks(org.alfresco.service.cmr.lock.LockType)
     */
    public List<NodeRef> getLocks(StoreRef storeRef, LockType lockType)
    {
        return getLocks(
                storeRef,
                "ASPECT:\"" + ContentModel.ASPECT_LOCKABLE.toString() + 
                "\" +@\\{http\\://www.alfresco.org/model/content/1.0\\}" + ContentModel.PROP_LOCK_OWNER.getLocalName() + ":\"" + getUserName() + "\"" +
                " +@\\{http\\://www.alfresco.org/model/content/1.0\\}" + ContentModel.PROP_LOCK_TYPE.getLocalName() + ":\"" + lockType.toString() + "\"");
    }
}