/*
    * 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
    *
   *   https://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.compress.archivers.ar;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.LinkOption;
  import java.nio.file.Path;
  import java.util.Date;
  import java.util.Objects;
  
  import org.apache.commons.compress.archivers.ArchiveEntry;
  
  /**
   * Represents an archive entry in the "ar" format.
   * <p>
   * Each AR archive starts with "!&lt;arch&gt;" followed by a LF. After these 8 bytes the archive entries are listed. The format of an entry header is as it
   * follows:
   * </p>
   *
   * <pre>
   * START BYTE   END BYTE    NAME                    FORMAT      LENGTH
   * 0            15          File name               ASCII       16
   * 16           27          Modification timestamp  Decimal     12
   * 28           33          Owner ID                Decimal     6
   * 34           39          Group ID                Decimal     6
   * 40           47          File mode               Octal       8
   * 48           57          File size (bytes)       Decimal     10
   * 58           59          File magic              \140\012    2
   * </pre>
   * <p>
   * This specifies that an ar archive entry header contains 60 bytes.
   * </p>
   * <p>
   * Due to the limitation of the file name length to 16 bytes GNU and BSD has their own variants of this format. Currently Commons Compress can read but not
   * write the GNU variant. It fully supports the BSD variant.
   * </p>
   *
   * @see <a href="https://www.freebsd.org/cgi/man.cgi?query=ar&sektion=5">ar man page</a>
   * @Immutable
   */
  public class ArArchiveEntry implements ArchiveEntry {
  
      /** The header for each entry */
      public static final String HEADER = "!<arch>\n";
  
      /** The trailer for each entry {@code 0x60 0x0A} */
      public static final String TRAILER = "`\012";
  
      private static final int DEFAULT_MODE = 33188; // = (octal) 0100644
  
      /**
       * SVR4/GNU adds a trailing / to names; BSD does not. They also vary in how names longer than 16 characters are represented. (Not yet fully supported by
       * this implementation)
       */
      private final String name;
      private final int userId;
      private final int groupId;
      private final int mode;
      private final long lastModified;
      private final long length;
  
      /**
       * Creates a new instance using the attributes of the given file
       *
       * @param inputFile the file to create an entry from
       * @param entryName the name of the entry
       */
      public ArArchiveEntry(final File inputFile, final String entryName) {
          // TODO sort out mode
          this(entryName, inputFile.isFile() ? inputFile.length() : 0, 0, 0, DEFAULT_MODE, inputFile.lastModified() / 1000);
      }
  
      /**
       * Creates a new instance using the attributes of the given file
       *
       * @param inputPath the file to create an entry from
       * @param entryName the name of the entry
       * @param options   options indicating how symbolic links are handled.
       * @throws IOException if an I/O error occurs.
       * @since 1.21
       */
     public ArArchiveEntry(final Path inputPath, final String entryName, final LinkOption... options) throws IOException {
         this(entryName, Files.isRegularFile(inputPath, options) ? Files.size(inputPath) : 0, 0, 0, DEFAULT_MODE,
                 Files.getLastModifiedTime(inputPath, options).toMillis() / 1000);
     }
 
     /**
      * Constructs a new instance using a couple of default values.
      *
      * <p>
      * Sets userId and groupId to 0, the octal file mode to 644 and the last modified time to the current time.
      * </p>
      *
      * @param name   name of the entry
      * @param length length of the entry in bytes
      */
     public ArArchiveEntry(final String name, final long length) {
         this(name, length, 0, 0, DEFAULT_MODE, System.currentTimeMillis() / 1000);
     }
 
     /**
      * Constructs a new instance.
      *
      * @param name         name of the entry
      * @param length       length of the entry in bytes
      * @param userId       numeric user id
      * @param groupId      numeric group id
      * @param mode         file mode
      * @param lastModified last modified time in seconds since the epoch
      */
     public ArArchiveEntry(final String name, final long length, final int userId, final int groupId, final int mode, final long lastModified) {
         this.name = name;
         if (length < 0) {
             throw new IllegalArgumentException("length must not be negative");
         }
         this.length = length;
         this.userId = userId;
         this.groupId = groupId;
         this.mode = mode;
         this.lastModified = lastModified;
     }
 
     @Override
     public boolean equals(final Object obj) {
         if (this == obj) {
             return true;
         }
         if (obj == null || getClass() != obj.getClass()) {
             return false;
         }
         final ArArchiveEntry other = (ArArchiveEntry) obj;
         return Objects.equals(name, other.name);
     }
 
     /**
      * Gets the group ID.
      *
      * @return the group ID.
      */
     public int getGroupId() {
         return groupId;
     }
 
     /**
      * Gets the last modified time in seconds since the epoch.
      *
      * @return the last modified date.
      */
     public long getLastModified() {
         return lastModified;
     }
 
     @Override
     public Date getLastModifiedDate() {
         return new Date(1000 * getLastModified());
     }
 
     /**
      * Gets the length.
      *
      * @return the length.
      */
     public long getLength() {
         return length;
     }
 
     /**
      * Gets the mode.
      *
      * @return the mode.
      */
     public int getMode() {
         return mode;
     }
 
     @Override
     public String getName() {
         return name;
     }
 
     @Override
     public long getSize() {
         return getLength();
     }
 
     /**
      * Gets the user ID.
      *
      * @return the user ID.
      */
     public int getUserId() {
         return userId;
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(name);
     }
 
     @Override
     public boolean isDirectory() {
         return false;
     }
 }