package org.webslinger.commons.vfs.handlers.cow;

 import java.util.Collection;

 import org.apache.commons.vfs.FileName;

 import org.apache.commons.vfs.FileObject;

 import org.apache.commons.vfs.FileSystemException;

 import org.webslinger.commons.vfs.VFSUtil;

 import org.webslinger.lang.ConcurrentCache;

 public abstract class COWStateXmlStorageHandler implements COWStorageHandler {

     protected final ConcurrentCache<FileName, COWStateXml> states;

     public COWStateXmlStorageHandler() {

         states = new ConcurrentCache<FileName, COWStateXml>(COWStateXmlStorageHandler.class, "states", null, ConcurrentCache.SOFT) {

             protected COWStateXml findIfExists(FileName key) throws Exception {

                 FileObject file = getFile(key);

                 return file.exists() ? new COWStateXml(file) : null;

             }

             protected COWStateXml createValue(FileName key) throws Exception {

                 return new COWStateXml(getFile(key));

             }

         };

     }

     protected abstract FileObject getFile(FileName dir) throws FileSystemException;

     public abstract void excludeNames(Collection<String> names);

     protected COWStateXml getCOWStateXml(FileName name, boolean create) throws FileSystemException {

         name = name.getParent();

         if (name == null) return null;

         try {

             return states.get(name, create);

         } catch (Exception e) {

             throw VFSUtil.makeFileSystemException(e);

         }

     }

     public void removeDeletedChildren(FileName name, Collection<String> names) throws FileSystemException {

         try {

             COWStateXml state = states.get(name, false);

             if (state == null) return;

             state.removeDeletedChildren(names);

         } catch (Exception e) {

             throw VFSUtil.makeFileSystemException(e);

         }

     }

     public Collection<String> loadData(FileName name, boolean[] isDeleted) throws FileSystemException {

         COWStateXml state = getCOWStateXml(name, false);

         if (state == null) return null;

         return state.loadData(name.getBaseName(), isDeleted);

     }

     public boolean submitRequests(FileName name, Request... requests) throws FileSystemException {

         COWStateXml state = getCOWStateXml(name, true);

         if (state == null) return false;

         return state.submitRequests(name.getBaseName(), requests);

     }

 }