/*
    * 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.fileupload.disk;
  
  import static java.lang.String.format;
  
  import java.io.ByteArrayInputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.UnsupportedEncodingException;
  import java.util.Map;
  import java.util.UUID;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.apache.commons.fileupload.FileItem;
  import org.apache.commons.fileupload.FileItemHeaders;
  import org.apache.commons.fileupload.FileUploadException;
  import org.apache.commons.fileupload.ParameterParser;
  import org.apache.commons.fileupload.util.Streams;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.io.output.DeferredFileOutputStream;
  
  /**
   * <p> The default implementation of the
   * {@link org.apache.commons.fileupload.FileItem FileItem} interface.
   *
   * <p> After retrieving an instance of this class from a {@link
   * DiskFileItemFactory} instance (see
   * {@link org.apache.commons.fileupload.servlet.ServletFileUpload
   * #parseRequest(javax.servlet.http.HttpServletRequest)}), you may
   * either request all contents of file at once using {@link #get()} or
   * request an {@link java.io.InputStream InputStream} with
   * {@link #getInputStream()} and process the file without attempting to load
   * it into memory, which may come handy with large files.
   *
   * <p>Temporary files, which are created for file items, should be
   * deleted later on. The best way to do this is using a
   * {@link org.apache.commons.io.FileCleaningTracker}, which you can set on the
   * {@link DiskFileItemFactory}. However, if you do use such a tracker,
   * then you must consider the following: Temporary files are automatically
   * deleted as soon as they are no longer needed. (More precisely, when the
   * corresponding instance of {@link java.io.File} is garbage collected.)
   * This is done by the so-called reaper thread, which is started and stopped
   * automatically by the {@link org.apache.commons.io.FileCleaningTracker} when
   * there are files to be tracked.
   * It might make sense to terminate that thread, for example, if
   * your web application ends. See the section on "Resource cleanup"
   * in the users guide of commons-fileupload.</p>
   *
   * @since FileUpload 1.1
   */
  public class DiskFileItem
      implements FileItem {
  
      // ----------------------------------------------------- Manifest constants
  
      /**
       * Default content charset to be used when no explicit charset
       * parameter is provided by the sender. Media subtypes of the
       * "text" type are defined to have a default charset value of
       * "ISO-8859-1" when received via HTTP.
       */
      public static final String DEFAULT_CHARSET = "ISO-8859-1";
  
      // ----------------------------------------------------------- Data members
  
      /**
       * UID used in unique file name generation.
       */
      private static final String UID =
              UUID.randomUUID().toString().replace('-', '_');
  
      /**
       * Counter used in unique identifier generation.
       */
      private static final AtomicInteger COUNTER = new AtomicInteger(0);
  
      /**
       * The name of the form field as provided by the browser.
       */
     private String fieldName;
 
     /**
      * The content type passed by the browser, or <code>null</code> if
      * not defined.
      */
     private final String contentType;
 
     /**
      * Whether or not this item is a simple form field.
      */
     private boolean isFormField;
 
     /**
      * The original filename in the user's filesystem.
      */
     private final String fileName;
 
     /**
      * The size of the item, in bytes. This is used to cache the size when a
      * file item is moved from its original location.
      */
     private long size = -1;
 
 
     /**
      * The threshold above which uploads will be stored on disk.
      */
     private final int sizeThreshold;
 
     /**
      * The directory in which uploaded files will be stored, if stored on disk.
      */
     private final File repository;
 
     /**
      * Cached contents of the file.
      */
     private byte[] cachedContent;
 
     /**
      * Output stream for this item.
      */
     private transient DeferredFileOutputStream dfos;
 
     /**
      * The temporary file to use.
      */
     private transient File tempFile;
 
     /**
      * The file items headers.
      */
     private FileItemHeaders headers;
 
     // ----------------------------------------------------------- Constructors
 
     /**
      * Constructs a new <code>DiskFileItem</code> instance.
      *
      * @param fieldName     The name of the form field.
      * @param contentType   The content type passed by the browser or
      *                      <code>null</code> if not specified.
      * @param isFormField   Whether or not this item is a plain form field, as
      *                      opposed to a file upload.
      * @param fileName      The original filename in the user's filesystem, or
      *                      <code>null</code> if not specified.
      * @param sizeThreshold The threshold, in bytes, below which items will be
      *                      retained in memory and above which they will be
      *                      stored as a file.
      * @param repository    The data repository, which is the directory in
      *                      which files will be created, should the item size
      *                      exceed the threshold.
      */
     public DiskFileItem(String fieldName,
             String contentType, boolean isFormField, String fileName,
             int sizeThreshold, File repository) {
         this.fieldName = fieldName;
         this.contentType = contentType;
         this.isFormField = isFormField;
         this.fileName = fileName;
         this.sizeThreshold = sizeThreshold;
         this.repository = repository;
     }
 
     // ------------------------------- Methods from javax.activation.DataSource
 
     /**
      * Returns an {@link java.io.InputStream InputStream} that can be
      * used to retrieve the contents of the file.
      *
      * @return An {@link java.io.InputStream InputStream} that can be
      *         used to retrieve the contents of the file.
      *
      * @throws IOException if an error occurs.
      */
     public InputStream getInputStream()
         throws IOException {
         if (!isInMemory()) {
             return new FileInputStream(dfos.getFile());
         }
 
         if (cachedContent == null) {
             cachedContent = dfos.getData();
         }
         return new ByteArrayInputStream(cachedContent);
     }
 
     /**
      * Returns the content type passed by the agent or <code>null</code> if
      * not defined.
      *
      * @return The content type passed by the agent or <code>null</code> if
      *         not defined.
      */
     public String getContentType() {
         return contentType;
     }
 
     /**
      * Returns the content charset passed by the agent or <code>null</code> if
      * not defined.
      *
      * @return The content charset passed by the agent or <code>null</code> if
      *         not defined.
      */
     public String getCharSet() {
         ParameterParser parser = new ParameterParser();
         parser.setLowerCaseNames(true);
         // Parameter parser can handle null input
         Map<String, String> params = parser.parse(getContentType(), ';');
         return params.get("charset");
     }
 
     /**
      * Returns the original filename in the client's filesystem.
      *
      * @return The original filename in the client's filesystem.
      * @throws org.apache.commons.fileupload.InvalidFileNameException The file name contains a NUL character,
      *   which might be an indicator of a security attack. If you intend to
      *   use the file name anyways, catch the exception and use
      *   {@link org.apache.commons.fileupload.InvalidFileNameException#getName()}.
      */
     public String getName() {
         return Streams.checkFileName(fileName);
     }
 
     // ------------------------------------------------------- FileItem methods
 
     /**
      * Provides a hint as to whether or not the file contents will be read
      * from memory.
      *
      * @return <code>true</code> if the file contents will be read
      *         from memory; <code>false</code> otherwise.
      */
     public boolean isInMemory() {
         if (cachedContent != null) {
             return true;
         }
         return dfos.isInMemory();
     }
 
     /**
      * Returns the size of the file.
      *
      * @return The size of the file, in bytes.
      */
     public long getSize() {
         if (size >= 0) {
             return size;
         } else if (cachedContent != null) {
             return cachedContent.length;
         } else if (dfos.isInMemory()) {
             return dfos.getData().length;
         } else {
             return dfos.getFile().length();
         }
     }
 
     /**
      * Returns the contents of the file as an array of bytes.  If the
      * contents of the file were not yet cached in memory, they will be
      * loaded from the disk storage and cached.
      *
      * @return The contents of the file as an array of bytes
      * or {@code null} if the data cannot be read
      */
     public byte[] get() {
         if (isInMemory()) {
             if (cachedContent == null && dfos != null) {
                 cachedContent = dfos.getData();
             }
             return cachedContent;
         }
 
         byte[] fileData = new byte[(int) getSize()];
         InputStream fis = null;
 
         try {
             fis = new FileInputStream(dfos.getFile());
             IOUtils.readFully(fis, fileData);
         } catch (IOException e) {
             fileData = null;
         } finally {
             IOUtils.closeQuietly(fis);
         }
 
         return fileData;
     }
 
     /**
      * Returns the contents of the file as a String, using the specified
      * encoding.  This method uses {@link #get()} to retrieve the
      * contents of the file.
      *
      * @param charset The charset to use.
      *
      * @return The contents of the file, as a string.
      *
      * @throws UnsupportedEncodingException if the requested character
      *                                      encoding is not available.
      */
     public String getString(final String charset)
         throws UnsupportedEncodingException {
         return new String(get(), charset);
     }
 
     /**
      * Returns the contents of the file as a String, using the default
      * character encoding.  This method uses {@link #get()} to retrieve the
      * contents of the file.
      *
      * <b>TODO</b> Consider making this method throw UnsupportedEncodingException.
      *
      * @return The contents of the file, as a string.
      */
     public String getString() {
         byte[] rawdata = get();
         String charset = getCharSet();
         if (charset == null) {
             charset = DEFAULT_CHARSET;
         }
         try {
             return new String(rawdata, charset);
         } catch (UnsupportedEncodingException e) {
             return new String(rawdata);
         }
     }
 
     /**
      * A convenience method to write an uploaded item to disk. The client code
      * is not concerned with whether or not the item is stored in memory, or on
      * disk in a temporary location. They just want to write the uploaded item
      * to a file.
      * <p>
      * This implementation first attempts to rename the uploaded item to the
      * specified destination file, if the item was originally written to disk.
      * Otherwise, the data will be copied to the specified file.
      * <p>
      * This method is only guaranteed to work <em>once</em>, the first time it
      * is invoked for a particular item. This is because, in the event that the
      * method renames a temporary file, that file will no longer be available
      * to copy or rename again at a later time.
      *
      * @param file The <code>File</code> into which the uploaded item should
      *             be stored.
      *
      * @throws Exception if an error occurs.
      */
     public void write(File file) throws Exception {
         if (isInMemory()) {
             FileOutputStream fout = null;
             try {
                 fout = new FileOutputStream(file);
                 fout.write(get());
                 fout.close();
             } finally {
                 IOUtils.closeQuietly(fout);
             }
         } else {
             File outputFile = getStoreLocation();
             if (outputFile != null) {
                 // Save the length of the file
                 size = outputFile.length();
                 /*
                  * The uploaded file is being stored on disk
                  * in a temporary location so move it to the
                  * desired file.
                  */
                 FileUtils.moveFile(outputFile, file);
             } else {
                 /*
                  * For whatever reason we cannot write the
                  * file to disk.
                  */
                 throw new FileUploadException(
                     "Cannot write uploaded file to disk!");
             }
         }
     }
 
     /**
      * Deletes the underlying storage for a file item, including deleting any
      * associated temporary disk file. Although this storage will be deleted
      * automatically when the <code>FileItem</code> instance is garbage
      * collected, this method can be used to ensure that this is done at an
      * earlier time, thus preserving system resources.
      */
     public void delete() {
         cachedContent = null;
         File outputFile = getStoreLocation();
         if (outputFile != null && outputFile.exists()) {
             outputFile.delete();
         }
     }
 
     /**
      * Returns the name of the field in the multipart form corresponding to
      * this file item.
      *
      * @return The name of the form field.
      *
      * @see #setFieldName(java.lang.String)
      *
      */
     public String getFieldName() {
         return fieldName;
     }
 
     /**
      * Sets the field name used to reference this file item.
      *
      * @param fieldName The name of the form field.
      *
      * @see #getFieldName()
      *
      */
     public void setFieldName(String fieldName) {
         this.fieldName = fieldName;
     }
 
     /**
      * Determines whether or not a <code>FileItem</code> instance represents
      * a simple form field.
      *
      * @return <code>true</code> if the instance represents a simple form
      *         field; <code>false</code> if it represents an uploaded file.
      *
      * @see #setFormField(boolean)
      *
      */
     public boolean isFormField() {
         return isFormField;
     }
 
     /**
      * Specifies whether or not a <code>FileItem</code> instance represents
      * a simple form field.
      *
      * @param state <code>true</code> if the instance represents a simple form
      *              field; <code>false</code> if it represents an uploaded file.
      *
      * @see #isFormField()
      *
      */
     public void setFormField(boolean state) {
         isFormField = state;
     }
 
     /**
      * Returns an {@link java.io.OutputStream OutputStream} that can
      * be used for storing the contents of the file.
      *
      * @return An {@link java.io.OutputStream OutputStream} that can be used
      *         for storing the contents of the file.
      *
      * @throws IOException if an error occurs.
      */
     public OutputStream getOutputStream()
         throws IOException {
         if (dfos == null) {
             File outputFile = getTempFile();
             dfos = new DeferredFileOutputStream(sizeThreshold, outputFile);
         }
         return dfos;
     }
 
     // --------------------------------------------------------- Public methods
 
     /**
      * Returns the {@link java.io.File} object for the <code>FileItem</code>'s
      * data's temporary location on the disk. Note that for
      * <code>FileItem</code>s that have their data stored in memory,
      * this method will return <code>null</code>. When handling large
      * files, you can use {@link java.io.File#renameTo(java.io.File)} to
      * move the file to new location without copying the data, if the
      * source and destination locations reside within the same logical
      * volume.
      *
      * @return The data file, or <code>null</code> if the data is stored in
      *         memory.
      */
     public File getStoreLocation() {
         if (dfos == null) {
             return null;
         }
         if (isInMemory()) {
             return null;
         }
         return dfos.getFile();
     }
 
     // ------------------------------------------------------ Protected methods
 
     /**
      * Removes the file contents from the temporary storage.
      */
     @Override
     protected void finalize() {
         if (dfos == null) {
             return;
         }
         File outputFile = dfos.getFile();
 
         if (outputFile != null && outputFile.exists()) {
             outputFile.delete();
         }
     }
 
     /**
      * Creates and returns a {@link java.io.File File} representing a uniquely
      * named temporary file in the configured repository path. The lifetime of
      * the file is tied to the lifetime of the <code>FileItem</code> instance;
      * the file will be deleted when the instance is garbage collected.
      * <p>
      * <b>Note: Subclasses that override this method must ensure that they return the
      * same File each time.</b>
      *
      * @return The {@link java.io.File File} to be used for temporary storage.
      */
     protected File getTempFile() {
         if (tempFile == null) {
             File tempDir = repository;
             if (tempDir == null) {
                 tempDir = new File(System.getProperty("java.io.tmpdir"));
             }
 
             String tempFileName = format("upload_%s_%s.tmp", UID, getUniqueId());
 
             tempFile = new File(tempDir, tempFileName);
         }
         return tempFile;
     }
 
     // -------------------------------------------------------- Private methods
 
     /**
      * Returns an identifier that is unique within the class loader used to
      * load this class, but does not have random-like appearance.
      *
      * @return A String with the non-random looking instance identifier.
      */
     private static String getUniqueId() {
         final int limit = 100000000;
         int current = COUNTER.getAndIncrement();
         String id = Integer.toString(current);
 
         // If you manage to get more than 100 million of ids, you'll
         // start getting ids longer than 8 characters.
         if (current < limit) {
             id = ("00000000" + id).substring(id.length());
         }
         return id;
     }
 
     /**
      * Returns a string representation of this object.
      *
      * @return a string representation of this object.
      */
     @Override
     public String toString() {
         return format("name=%s, StoreLocation=%s, size=%s bytes, isFormField=%s, FieldName=%s",
                       getName(), getStoreLocation(), Long.valueOf(getSize()),
                       Boolean.valueOf(isFormField()), getFieldName());
     }
 
     /**
      * Returns the file item headers.
      * @return The file items headers.
      */
     public FileItemHeaders getHeaders() {
         return headers;
     }
 
     /**
      * Sets the file item headers.
      * @param pHeaders The file items headers.
      */
     public void setHeaders(FileItemHeaders pHeaders) {
         headers = pHeaders;
     }
 
 }