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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
// *                                                                                                                         *
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package org.apache.juneau.utils;

import java.io.*;
import java.util.*;
import java.util.zip.*;

import org.apache.juneau.*;
import org.apache.juneau.http.*;
import org.apache.juneau.http.annotation.*;

/**
 * Utility class for representing the contents of a zip file as a list of entries whose contents don't resolve until
 * serialization time.
 *
 * <p>
 * Generally associated with <c>RestServlets</c> using the <c>responseHandlers</c> annotation so that
 * REST methods can easily create ZIP file responses by simply returning instances of this class.
 */
@Response
public class ZipFileList extends LinkedList<ZipFileList.ZipFileEntry> implements Streamable {

   private static final long serialVersionUID = 1L;

   /**
    * The name of the zip file.
    */
   public final String fileName;

   @Header("Content-Type")
   @Override /* Streamable */
   public MediaType getMediaType() {
      return MediaType.forString("application/zip");
   }

   /**
    * Returns the value for the <c>Content-Disposition</c> header.
    *
    * @return The value for the <c>Content-Disposition</c> header.
    */
   @Header("Content-Disposition")
   public String getContentDisposition() {
      return "attachment;filename=" + fileName;
   }

   @ResponseBody
   @Override /* Streamable */
   public void streamTo(OutputStream os) throws IOException {
      try (ZipOutputStream zos = new ZipOutputStream(os)) {
         for (ZipFileEntry e : this)
            e.write(zos);
      }
      os.flush();
   }

   /**
    * Constructor.
    *
    * @param fileName The file name of the zip file to create.
    */
   public ZipFileList(String fileName) {
      this.fileName = fileName;
   }

   /**
    * Add an entry to this list.
    *
    * @param e The zip file entry.
    * @return This object (for method chaining).
    */
   public ZipFileList append(ZipFileEntry e) {
      add(e);
      return this;
   }

   /**
    * Interface for ZipFileList entries.
    */
   public static interface ZipFileEntry {
      /**
       * Write this entry to the specified output stream.
       *
       * @param zos The output stream to write to.
       * @throws IOException Thrown by underlying stream.
       */
      void write(ZipOutputStream zos) throws IOException;
   }

   /**
    * ZipFileList entry for File entry types.
    */
   public static class FileEntry implements ZipFileEntry {

      /** The root file to base the entry paths on. */
      protected File root;

      /** The file being zipped. */
      protected File file;

      /**
       * Constructor.
       *
       * @param root The root file that represents the base path.
       * @param file The file to add to the zip file.
       */
      public FileEntry(File root, File file) {
         this.root = root;
         this.file = file;
      }

      /**
       * Constructor.
       *
       * @param file The file to add to the zip file.
       */
      public FileEntry(File file) {
         this.file = file;
         this.root = (file.isDirectory() ? file : file.getParentFile());
      }

      @Override /* ZipFileEntry */
      public void write(ZipOutputStream zos) throws IOException {
         addFile(zos, file);
      }

      /**
       * Subclasses can override this method to customize which files get added to a zip file.
       *
       * @param f The file being added to the zip file.
       * @return Always returns <jk>true</jk>.
       */
      public boolean doAdd(File f) {
         return true;
      }

      /**
       * Adds the specified file to the specified output stream.
       *
       * @param zos The output stream.
       * @param f The file to add.
       * @throws IOException Thrown by underlying stream.
       */
      protected void addFile(ZipOutputStream zos, File f) throws IOException {
         if (doAdd(f)) {
            if (f.isDirectory()) {
               File[] fileList = f.listFiles();
               if (fileList == null)
                  throw new IOException(f.toString());
               for (File fc : fileList)
                  addFile(zos, fc);
            } else if (f.canRead()) {
               String path = f.getAbsolutePath().substring(root.getAbsolutePath().length() + 1).replace('\\', '/');
               ZipEntry e = new ZipEntry(path);
               e.setSize(f.length());
               zos.putNextEntry(e);
               try (FileInputStream fis = new FileInputStream(f)) {
                  IOPipe.create(fis, zos).run();
               }
            }
         }
      }
   }
}