/*
 * Copyright (C) 2006 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.admin;

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import org.alfresco.error.AlfrescoRuntimeException;
import org.alfresco.i18n.I18NUtil;
import org.alfresco.model.ContentModel;
import org.alfresco.repo.importer.ImporterBootstrap;
import org.alfresco.repo.node.index.FullIndexRecoveryComponent.RecoveryMode;
import org.alfresco.repo.search.impl.lucene.LuceneQueryParser;
import org.alfresco.repo.transaction.TransactionUtil;
import org.alfresco.repo.transaction.TransactionUtil.TransactionWork;
import org.alfresco.service.cmr.repository.ContentReader;
import org.alfresco.service.cmr.repository.ContentService;
import org.alfresco.service.cmr.repository.InvalidStoreRefException;
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.SearchParameters;
import org.alfresco.service.cmr.search.SearchService;
import org.alfresco.service.namespace.NamespaceService;
import org.alfresco.service.transaction.TransactionService;
import org.alfresco.util.AbstractLifecycleBean;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.context.ApplicationEvent;

/**
 * Component to perform a bootstrap check of the alignment of the
 * database, Lucene indexes and content store.
 * <p>
 * The algorithm is:
 * <ul>
 *   <li>Get all stores from the NodeService</li>
 *   <li>Get each root node</li>
 *   <li>Perform a Lucene query for each root node</li>
 *   <li>Query Lucene for a small set of content nodes</li>
 *   <li>Get content readers for each node</li>
 * </ul>
 * If any of the steps fail then the bootstrap bean will fail, except if
 * the indexes are marked for full recovery.  In this case, the Lucene
 * checks are not required as the indexes will be due for a rebuild.  
 * 
 * @author Derek Hulley
 */
public class ConfigurationChecker extends AbstractLifecycleBean
{
    private static Log logger = LogFactory.getLog(ConfigurationChecker.class);
    
    private static final String WARN_RELATIVE_DIR_ROOT = "system.config_check.warn.dir_root";
    private static final String MSG_DIR_ROOT = "system.config_check.msg.dir_root";
    private static final String ERR_DUPLICATE_ROOT_NODE = "system.config_check.err.indexes.duplicate_root_node";
    private static final String ERR_MISSING_INDEXES = "system.config_check.err.missing_index";
    private static final String ERR_MISSING_CONTENT = "system.config_check.err.missing_content";
    private static final String ERR_FIX_DIR_ROOT = "system.config_check.err.fix_dir_root";
    private static final String MSG_HOWTO_INDEX_RECOVER = "system.config_check.msg.howto_index_recover";
    private static final String WARN_STARTING_WITH_ERRORS = "system.config_check.warn.starting_with_errors";

    private boolean strict;
    private RecoveryMode indexRecoveryMode;
    private String dirRoot;

    private ImporterBootstrap systemBootstrap;
    private TransactionService transactionService;
    private NamespaceService namespaceService;
    private NodeService nodeService;
    private SearchService searchService;
    private ContentService contentService;
    
    public ConfigurationChecker()
    {
    }
    
    @Override
    public String toString()
    {
        StringBuilder sb = new StringBuilder(50);
        sb.append("ConfigurationChecker")
          .append("[indexRecoveryMode=").append(indexRecoveryMode)
          .append("]");
        return sb.toString();
    }

    /**
     * This flag controls the behaviour of the component in the event of problems being found.
     * Generally, the system should be <b>strict</b>, but this can be changed if indexes are
     * going to be recovered, or if missing content is acceptable.
     * 
     * @param strict <code>true</code> to prevent system startup if problems are found, otherwise
     *      <code>false</code> to allow the system to startup regardless.
     */
    public void setStrict(boolean strict)
    {
        this.strict = strict;
    }

    /**
     * Set the index recovery mode.  If this is
     * {@link org.alfresco.repo.node.index.FullIndexRecoveryComponent.RecoveryMode#VALIDATE FULL}
     * then the index checks are ignored as the indexes will be scheduled for a rebuild
     * anyway.
     * 
     * @see org.alfresco.repo.node.index.FullIndexRecoveryComponent.RecoveryMode
     */
    public void setIndexRecoveryMode(String indexRecoveryMode)
    {
        this.indexRecoveryMode = RecoveryMode.valueOf(indexRecoveryMode);
    }

    public void setDirRoot(String dirRoot)
    {
        this.dirRoot = dirRoot;
    }

    public void setSystemBootstrap(ImporterBootstrap systemBootstrap)
    {
        this.systemBootstrap = systemBootstrap;
    }

    public void setTransactionService(TransactionService transactionService)
    {
        this.transactionService = transactionService;
    }

    public void setNamespaceService(NamespaceService namespaceService)
    {
        this.namespaceService = namespaceService;
    }

    public void setNodeService(NodeService nodeService)
    {
        this.nodeService = nodeService;
    }

    public void setSearchService(SearchService searchService)
    {
        this.searchService = searchService;
    }

    public void setContentService(ContentService contentService)
    {
        this.contentService = contentService;
    }

    @Override
    protected void onBootstrap(ApplicationEvent event)
    {
        TransactionWork<Object> checkWork = new TransactionWork<Object>()
        {
            public Object doWork() throws Exception
            {
                check();
                return null;
            }
        };
        TransactionUtil.executeInUserTransaction(transactionService, checkWork);
    }
    
    /**
     * Performs the check work.
     */
    private void check()
    {
        if (logger.isDebugEnabled())
        {
            logger.debug("Starting bootstrap configuration check: " + this);
        }
        
        // check the dir.root
        boolean isRelativeRoot = dirRoot.startsWith(".");
        if (isRelativeRoot)
        {
            String msg = I18NUtil.getMessage(WARN_RELATIVE_DIR_ROOT, dirRoot);
            logger.warn(msg);
        }
        File dirRootFile = new File(dirRoot);
        String msgDirRoot = I18NUtil.getMessage(MSG_DIR_ROOT, dirRootFile);
        logger.info(msgDirRoot);

        // get all root nodes from the NodeService, i.e. database
        List<StoreRef> storeRefs = nodeService.getStores();
        List<StoreRef> missingIndexStoreRefs = new ArrayList<StoreRef>(0);
        for (StoreRef storeRef : storeRefs)
        {
            NodeRef rootNodeRef = null;
            try
            {
                rootNodeRef = nodeService.getRootNode(storeRef);
            }
            catch (InvalidStoreRefException e)
            {
                // the store is invalid and will therefore not have a root node entry
                continue;
            }
            if (indexRecoveryMode != RecoveryMode.FULL)
            {
                if (logger.isDebugEnabled())
                {
                    logger.debug("Checking index for store: " + storeRef);
                }
                
                // perform a Lucene query for the root node
                SearchParameters sp = new SearchParameters();
                sp.addStore(storeRef);
                sp.setLanguage(SearchService.LANGUAGE_LUCENE);
                sp.setQuery("ID:" + LuceneQueryParser.escape(rootNodeRef.toString()));
                
                ResultSet results = null;
                int size = 0;
                try
                {
                    results = searchService.query(sp);
                    size = results.length();
                }
                finally
                {
                    try { results.close(); } catch (Throwable e) {}
                }
                
                if (size == 0)
                {
                    // indexes missing for root node
                    missingIndexStoreRefs.add(storeRef);
                    // debug
                    if (logger.isDebugEnabled())
                    {
                        logger.debug("Index missing for store: \n" +
                                "   store: " + storeRef);
                    }
                }
                else if (size > 1)
                {
                    // there are duplicates
                    String msg = I18NUtil.getMessage(ERR_DUPLICATE_ROOT_NODE, storeRef);
                    throw new AlfrescoRuntimeException(msg);
                }
            }
        }
        // check for the system version properties content snippet
        boolean versionPropertiesContentAvailable = true;
        NodeRef descriptorNodeRef = getSystemDescriptor();
        if (descriptorNodeRef != null)
        {
            // get the version properties
            ContentReader reader = contentService.getReader(
                    descriptorNodeRef,
                    ContentModel.PROP_SYS_VERSION_PROPERTIES);
            if (reader != null && !reader.exists())
            {
                // the property is there, but the content is not
                versionPropertiesContentAvailable = false;
            }
        }
            
        // check for missing indexes
        int missingStoreIndexes = missingIndexStoreRefs.size();
        if (missingStoreIndexes > 0)
        {
            String msg = I18NUtil.getMessage(ERR_MISSING_INDEXES, missingStoreIndexes);
            logger.error(msg);
            String msgRecover = I18NUtil.getMessage(MSG_HOWTO_INDEX_RECOVER);
            logger.info(msgRecover);
        }
        // check for missing content
        if (!versionPropertiesContentAvailable)
        {
            String msg = I18NUtil.getMessage(ERR_MISSING_CONTENT);
            logger.error(msg);
        }
        // handle either content or indexes missing
        if (missingStoreIndexes > 0 || !versionPropertiesContentAvailable)
        {
            String msg = I18NUtil.getMessage(ERR_FIX_DIR_ROOT, dirRootFile);
            logger.error(msg);
            
            // Now determine the failure behaviour
            if (strict)
            {
                throw new AlfrescoRuntimeException(msg);
            }
            else
            {
                String warn = I18NUtil.getMessage(WARN_STARTING_WITH_ERRORS);
                logger.warn(warn);
            }
        }
    }
    
    /**
     * @return Returns the system descriptor node or null
     */
    public NodeRef getSystemDescriptor()
    {
        StoreRef systemStoreRef = systemBootstrap.getStoreRef();
        List<NodeRef> nodeRefs = null;
        if (nodeService.exists(systemStoreRef))
        {
            Properties systemProperties = systemBootstrap.getConfiguration();
            String path = systemProperties.getProperty("system.descriptor.current.childname");
            String searchPath = "/" + path;
            NodeRef rootNodeRef = nodeService.getRootNode(systemStoreRef);
            nodeRefs = searchService.selectNodes(rootNodeRef, searchPath, null, namespaceService, false);
            if (nodeRefs.size() > 0)
            {
                NodeRef descriptorNodeRef = nodeRefs.get(0);
                return descriptorNodeRef;
            }
        }
        return null;
    }

    @Override
    protected void onShutdown(ApplicationEvent event)
    {
        // nothing here
    }
}