/*
    * 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.commons.vfs2.provider.zip;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.util.Collection;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.zip.ZipEntry;
  import java.util.zip.ZipFile;
  
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.commons.vfs2.Capability;
  import org.apache.commons.vfs2.FileName;
  import org.apache.commons.vfs2.FileObject;
  import org.apache.commons.vfs2.FileSystemException;
  import org.apache.commons.vfs2.FileSystemOptions;
  import org.apache.commons.vfs2.Selectors;
  import org.apache.commons.vfs2.VfsLog;
  import org.apache.commons.vfs2.provider.AbstractFileName;
  import org.apache.commons.vfs2.provider.AbstractFileSystem;
  import org.apache.commons.vfs2.provider.UriParser;
  
  /**
   * A read-only file system for ZIP and JAR files.
   */
  public class ZipFileSystem extends AbstractFileSystem {
  
      private static final char[] ENC = {'!'};
  
      private static final Log LOG = LogFactory.getLog(ZipFileSystem.class);
  
      private final File file;
      private final Charset charset;
      private ZipFile zipFile;
  
      /**
       * Cache doesn't need to be synchronized since it is read-only.
       */
      private final Map<FileName, FileObject> cache = new HashMap<>();
  
      /**
       * Constructs a new instance.
       *
       * @param rootFileName The root file name of this file system.
       * @param parentLayer The parent layer of this file system.
       * @param fileSystemOptions Options to build this file system.
       * @throws FileSystemException If the parent layer does not exist, or on error replicating the file.
       */
      public ZipFileSystem(final AbstractFileName rootFileName, final FileObject parentLayer, final FileSystemOptions fileSystemOptions)
          throws FileSystemException {
          super(rootFileName, parentLayer, fileSystemOptions);
  
          // Make a local copy of the file
          file = parentLayer.getFileSystem().replicateFile(parentLayer, Selectors.SELECT_SELF);
          charset = ZipFileSystemConfigBuilder.getInstance().getCharset(fileSystemOptions);
  
          // Open the Zip file
          if (!file.exists()) {
              // Don't need to do anything
              zipFile = null;
          }
      }
  
      /**
       * Returns the capabilities of this file system.
       */
      @Override
      protected void addCapabilities(final Collection<Capability> caps) {
          caps.addAll(ZipFileProvider.capabilities);
      }
  
      /**
       * Creates a file object.
       */
      @Override
      protected FileObject createFile(final AbstractFileName name) throws FileSystemException {
          // This is only called for files which do not exist in the Zip file
          return new ZipFileObject(name, null, this, false);
     }
 
     /**
      * Creates a Zip file.
      *
      * @param file the underlying file.
      * @return a Zip file.
      * @throws FileSystemException if a file system error occurs.
      */
     protected ZipFile createZipFile(final File file) throws FileSystemException {
         try {
             return new ZipFile(file, charset);
         } catch (final IOException ioe) {
             throw new FileSystemException("vfs.provider.zip/open-zip-file.error", file, ioe);
         }
     }
 
     /**
      * Creates a new Zip file object.
      *
      * @param fileName the underlying file.
      * @param entry the Zip entry.
      * @return a new ZipFileObject.
      * @throws FileSystemException if a file system error occurs.
      */
     protected ZipFileObject createZipFileObject(final AbstractFileName fileName, final ZipEntry entry) throws FileSystemException {
         return new ZipFileObject(fileName, entry, this, true);
     }
 
     @Override
     protected void doCloseCommunicationLink() {
         // Release the zip file
         try {
             IOUtils.close(zipFile);
             zipFile = null;
         } catch (final IOException e) {
             // getLogger().warn("vfs.provider.zip/close-zip-file.error :" + file, e);
             VfsLog.warn(getLogger(), LOG, "vfs.provider.zip/close-zip-file.error :" + file, e);
         }
     }
 
     /**
      * Gets the Charset, defaults to {@link StandardCharsets#UTF_8}, the value used in {@link ZipFile}.
      *
      * @return the Charset.
      */
     protected Charset getCharset() {
         return charset;
     }
 
     /**
      * Gets a cached file.
      */
     @Override
     protected FileObject getFileFromCache(final FileName name) {
         return cache.get(name);
     }
 
     /**
      * Gets the zip file.
      *
      * @return the zip file.
      * @throws FileSystemException if a file system error occurs.
      */
     protected ZipFile getZipFile() throws FileSystemException {
         if (zipFile == null && file.exists()) {
             zipFile = createZipFile(file);
         }
         return zipFile;
     }
 
     @Override
     public void init() throws FileSystemException {
         super.init();
 
         try {
             // Build the index
             final Enumeration<? extends ZipEntry> entries = getZipFile().entries();
             while (entries.hasMoreElements()) {
                 final ZipEntry entry = entries.nextElement();
                 final AbstractFileName name = (AbstractFileName) getFileSystemManager().resolveName(getRootName(),
                         UriParser.encode(entry.getName(), ENC));
 
                 // Create the file
                 ZipFileObject fileObj;
                 if (entry.isDirectory() && getFileFromCache(name) != null) {
                     fileObj = (ZipFileObject) getFileFromCache(name);
                     fileObj.setZipEntry(entry);
                     continue;
                 }
 
                 fileObj = createZipFileObject(name, entry);
                 putFileToCache(fileObj);
 
                 // Make sure all ancestors exist
                 // TODO - create these on demand
                 ZipFileObject parent;
                 for (AbstractFileName parentName = (AbstractFileName) name
                         .getParent(); parentName != null; fileObj = parent, parentName = (AbstractFileName) parentName
                                 .getParent()) {
                     // Locate the parent
                     parent = (ZipFileObject) getFileFromCache(parentName);
                     if (parent == null) {
                         parent = createZipFileObject(parentName, null);
                         putFileToCache(parent);
                     }
 
                     // Attach child to parent
                     parent.attachChild(fileObj.getName());
                 }
             }
         } finally {
             closeCommunicationLink();
         }
     }
 
     /**
      * Adds a file object to the cache.
      */
     @Override
     protected void putFileToCache(final FileObject file) {
         cache.put(file.getName(), file);
     }
 
     /**
      * remove a cached file.
      */
     @Override
     protected void removeFileFromCache(final FileName name) {
         cache.remove(name);
     }
 
     @Override
     public String toString() {
         return super.toString() + " for " + file;
     }
 
     /*
       will be called after all file-objects closed their streams. protected void notifyAllStreamsClosed() {
       closeCommunicationLink(); }
      */
 }