
/* ====================================================================
   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
   the License.  You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   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.apache.poi.poifs.filesystem;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.poi.hpsf.ClassID;

/**
 * A DirectoryEntry filter, which exposes another
 *  DirectoryEntry less certain parts.
 * This is typically used when copying or comparing
 *  Filesystems. 
 */
public class FilteringDirectoryNode implements DirectoryEntry
{
   /**
    * The names of our entries to exclude
    */
   private Set<String> excludes;
   /**
    * Excludes of our child directories
    */
   private Map<String,List<String>> childExcludes;
   
   private DirectoryEntry directory;
   
   /**
    * Creates a filter round the specified directory, which
    *  will exclude entries such as "MyNode" and "MyDir/IgnoreNode".
    * The excludes can stretch into children, if they contain a /.
    *  
    * @param directory The Directory to filter
    * @param excludes The Entries to exclude
    */
   public FilteringDirectoryNode(DirectoryEntry directory, Collection<String> excludes) {
      this.directory = directory;
      
      // Process the excludes
      this.excludes = new HashSet<>();
      this.childExcludes = new HashMap<>();
      for (String excl : excludes) {
         int splitAt = excl.indexOf('/');
         if (splitAt == -1) {
            // Applies to us
            this.excludes.add(excl);
         } else {
            // Applies to a child
            String child = excl.substring(0, splitAt);
            String childExcl = excl.substring(splitAt+1);
            if (! this.childExcludes.containsKey(child)) {
               this.childExcludes.put(child, new ArrayList<>());
            }
            this.childExcludes.get(child).add(childExcl);
         }
      }
   }

   public DirectoryEntry createDirectory(String name) throws IOException {
      return directory.createDirectory(name);
   }

   public DocumentEntry createDocument(String name, InputStream stream)
         throws IOException {
      return directory.createDocument(name, stream);
   }

   public DocumentEntry createDocument(String name, int size,
         POIFSWriterListener writer) throws IOException {
      return directory.createDocument(name, size, writer);
   }

   public Iterator<Entry> getEntries() {
      return new FilteringIterator();
   }

   public Iterator<Entry> iterator() {
      return getEntries();
   }
   
   public int getEntryCount() {
      int size = directory.getEntryCount();
      for (String excl : excludes) {
         if (directory.hasEntry(excl)) {
            size--;
         }
      }
      return size;
   }
   
   public Set<String> getEntryNames() {
       Set<String> names = new HashSet<>();
       for (String name : directory.getEntryNames()) {
           if (!excludes.contains(name)) {
               names.add(name);
           }
       }
       return names;
   }

   public boolean isEmpty() {
      return (getEntryCount() == 0);
   }

   public boolean hasEntry(String name) {
      if (excludes.contains(name)) {
         return false;
      }
      return directory.hasEntry(name);
   }

   public Entry getEntry(String name) throws FileNotFoundException {
      if (excludes.contains(name)) {
         throw new FileNotFoundException(name);
      }
      
      Entry entry = directory.getEntry(name);
      return wrapEntry(entry);
   }
   private Entry wrapEntry(Entry entry) {
      String name = entry.getName();
      if (childExcludes.containsKey(name) && entry instanceof DirectoryEntry) {
         return new FilteringDirectoryNode(
               (DirectoryEntry)entry, childExcludes.get(name)); 
      }
      return entry;
   }

   public ClassID getStorageClsid() {
      return directory.getStorageClsid();
   }

   public void setStorageClsid(ClassID clsidStorage) {
      directory.setStorageClsid(clsidStorage);
   }

   public boolean delete() {
      return directory.delete();
   }

   public boolean renameTo(String newName) {
      return directory.renameTo(newName);
   }
   
   public String getName() {
      return directory.getName();
   }

   public DirectoryEntry getParent() {
      return directory.getParent();
   }

   public boolean isDirectoryEntry() {
      return true;
   }

   public boolean isDocumentEntry() {
      return false;
   }
   
   private class FilteringIterator implements Iterator<Entry> {
      private Iterator<Entry> parent;
      private Entry next;
      
      private FilteringIterator() {
         parent = directory.getEntries();
         locateNext();
      }
      private void locateNext() {
         next = null;
         Entry e;
         while (parent.hasNext() && next == null) {
            e = parent.next();
            if (! excludes.contains(e.getName())) {
               next = wrapEntry(e);
            }
         }
      }
      
      public boolean hasNext() {
         return (next != null);
      }
      
      public Entry next() {
         Entry e = next;
         locateNext();
         return e;
      }
      
      public void remove() {
         throw new UnsupportedOperationException("Remove not supported");
      }
   }
}