/**
 * 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.hadoop.fs;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputValidation;
import java.io.Serializable;
import java.util.Collections;
import java.util.EnumSet;
import java.util.Set;

import org.apache.hadoop.fs.FSProtos.FileStatusProto;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.fs.protocolPB.PBHelper;
import org.apache.hadoop.io.Writable;

/** Interface that represents the client side information for a file.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class FileStatus implements Writable, Comparable<Object>,
    Serializable, ObjectInputValidation {

  private static final long serialVersionUID = 0x13caeae8;

  private Path path;
  private long length;
  private Boolean isdir;
  private short block_replication;
  private long blocksize;
  private long modification_time;
  private long access_time;
  private FsPermission permission;
  private String owner;
  private String group;
  private Path symlink;
  private Set<AttrFlags> attr;

  /**
   * Flags for entity attributes.
   */
  public enum AttrFlags {
    /** ACL information available for this entity. */
    HAS_ACL,
    /** Entity is encrypted. */
    HAS_CRYPT,
    /** Entity is stored erasure-coded. */
    HAS_EC,
    /** Snapshot capability enabled. */
    SNAPSHOT_ENABLED,
  }

  /**
   * Shared, empty set of attributes (a common case for FileStatus).
   */
  public static final Set<AttrFlags> NONE = Collections.<AttrFlags>emptySet();

  /**
   * Convert boolean attributes to a set of flags.
   * @param acl   See {@link AttrFlags#HAS_ACL}.
   * @param crypt See {@link AttrFlags#HAS_CRYPT}.
   * @param ec    See {@link AttrFlags#HAS_EC}.
   * @param sn    See {@link AttrFlags#SNAPSHOT_ENABLED}.
   * @return converted set of flags.
   */
  public static Set<AttrFlags> attributes(boolean acl, boolean crypt,
                                          boolean ec, boolean sn) {
    if (!(acl || crypt || ec || sn)) {
      return NONE;
    }
    EnumSet<AttrFlags> ret = EnumSet.noneOf(AttrFlags.class);
    if (acl) {
      ret.add(AttrFlags.HAS_ACL);
    }
    if (crypt) {
      ret.add(AttrFlags.HAS_CRYPT);
    }
    if (ec) {
      ret.add(AttrFlags.HAS_EC);
    }
    if (sn) {
      ret.add(AttrFlags.SNAPSHOT_ENABLED);
    }
    return ret;
  }

  public FileStatus() { this(0, false, 0, 0, 0, 0, null, null, null, null); }
  
  //We should deprecate this soon?
  public FileStatus(long length, boolean isdir, int block_replication,
                    long blocksize, long modification_time, Path path) {

    this(length, isdir, block_replication, blocksize, modification_time,
         0, null, null, null, path);
  }

  /**
   * Constructor for file systems on which symbolic links are not supported
   */
  public FileStatus(long length, boolean isdir,
                    int block_replication,
                    long blocksize, long modification_time, long access_time,
                    FsPermission permission, String owner, String group, 
                    Path path) {
    this(length, isdir, block_replication, blocksize, modification_time,
         access_time, permission, owner, group, null, path);
  }

  public FileStatus(long length, boolean isdir,
                    int block_replication,
                    long blocksize, long modification_time, long access_time,
                    FsPermission permission, String owner, String group, 
                    Path symlink,
                    Path path) {
    this(length, isdir, block_replication, blocksize, modification_time,
        access_time, permission, owner, group, symlink, path,
        false, false, false);
  }

  public FileStatus(long length, boolean isdir, int block_replication,
      long blocksize, long modification_time, long access_time,
      FsPermission permission, String owner, String group, Path symlink,
      Path path, boolean hasAcl, boolean isEncrypted, boolean isErasureCoded) {
    this(length, isdir, block_replication, blocksize, modification_time,
        access_time, permission, owner, group, symlink, path,
        attributes(hasAcl, isEncrypted, isErasureCoded, false));
  }

  public FileStatus(long length, boolean isdir, int block_replication,
      long blocksize, long modification_time, long access_time,
      FsPermission permission, String owner, String group, Path symlink,
      Path path, Set<AttrFlags> attr) {
    this.length = length;
    this.isdir = isdir;
    this.block_replication = (short)block_replication;
    this.blocksize = blocksize;
    this.modification_time = modification_time;
    this.access_time = access_time;
    if (permission != null) {
      this.permission = permission;
    } else if (isdir) {
      this.permission = FsPermission.getDirDefault();
    } else if (symlink != null) {
      this.permission = FsPermission.getDefault();
    } else {
      this.permission = FsPermission.getFileDefault();
    }
    this.owner = (owner == null) ? "" : owner;
    this.group = (group == null) ? "" : group;
    this.symlink = symlink;
    this.path = path;
    this.attr = attr;

    // The variables isdir and symlink indicate the type:
    // 1. isdir implies directory, in which case symlink must be null.
    // 2. !isdir implies a file or symlink, symlink != null implies a
    //    symlink, otherwise it's a file.
    assert (isdir && symlink == null) || !isdir;
  }

  /**
   * Copy constructor.
   *
   * @param other FileStatus to copy
   */
  public FileStatus(FileStatus other) throws IOException {
    // It's important to call the getters here instead of directly accessing the
    // members.  Subclasses like ViewFsFileStatus can override the getters.
    this(other.getLen(), other.isDirectory(), other.getReplication(),
      other.getBlockSize(), other.getModificationTime(), other.getAccessTime(),
      other.getPermission(), other.getOwner(), other.getGroup(),
      (other.isSymlink() ? other.getSymlink() : null),
      other.getPath());
  }

  /**
   * Get the length of this file, in bytes.
   * @return the length of this file, in bytes.
   */
  public long getLen() {
    return length;
  }

  /**
   * Is this a file?
   * @return true if this is a file
   */
  public boolean isFile() {
    return !isDirectory() && !isSymlink();
  }

  /**
   * Is this a directory?
   * @return true if this is a directory
   */
  public boolean isDirectory() {
    return isdir;
  }

  /**
   * Old interface, instead use the explicit {@link FileStatus#isFile()},
   * {@link FileStatus#isDirectory()}, and {@link FileStatus#isSymlink()}
   * @return true if this is a directory.
   * @deprecated Use {@link FileStatus#isFile()},
   * {@link FileStatus#isDirectory()}, and {@link FileStatus#isSymlink()}
   * instead.
   */
  @Deprecated
  public final boolean isDir() {
    return isDirectory();
  }

  /**
   * Is this a symbolic link?
   * @return true if this is a symbolic link
   */
  public boolean isSymlink() {
    return symlink != null;
  }

  /**
   * Get the block size of the file.
   * @return the number of bytes
   */
  public long getBlockSize() {
    return blocksize;
  }

  /**
   * Get the replication factor of a file.
   * @return the replication factor of a file.
   */
  public short getReplication() {
    return block_replication;
  }

  /**
   * Get the modification time of the file.
   * @return the modification time of file in milliseconds since January 1, 1970 UTC.
   */
  public long getModificationTime() {
    return modification_time;
  }

  /**
   * Get the access time of the file.
   * @return the access time of file in milliseconds since January 1, 1970 UTC.
   */
  public long getAccessTime() {
    return access_time;
  }

  /**
   * Get FsPermission associated with the file.
   * @return permission. If a filesystem does not have a notion of permissions
   *         or if permissions could not be determined, then default 
   *         permissions equivalent of "rwxrwxrwx" is returned.
   */
  public FsPermission getPermission() {
    return permission;
  }

  /**
   * Tell whether the underlying file or directory has ACLs set.
   *
   * @return true if the underlying file or directory has ACLs set.
   */
  public boolean hasAcl() {
    return attr.contains(AttrFlags.HAS_ACL);
  }

  /**
   * Tell whether the underlying file or directory is encrypted or not.
   *
   * @return true if the underlying file is encrypted.
   */
  public boolean isEncrypted() {
    return attr.contains(AttrFlags.HAS_CRYPT);
  }

  /**
   * Tell whether the underlying file or directory is erasure coded or not.
   *
   * @return true if the underlying file or directory is erasure coded.
   */
  public boolean isErasureCoded() {
    return attr.contains(AttrFlags.HAS_EC);
  }

  /**
   * Check if directory is Snapshot enabled or not.
   *
   * @return true if directory is snapshot enabled
   */
  public boolean isSnapshotEnabled() {
    return attr.contains(AttrFlags.SNAPSHOT_ENABLED);
  }

  /**
   * Get the owner of the file.
   * @return owner of the file. The string could be empty if there is no
   *         notion of owner of a file in a filesystem or if it could not 
   *         be determined (rare).
   */
  public String getOwner() {
    return owner;
  }
  
  /**
   * Get the group associated with the file.
   * @return group for the file. The string could be empty if there is no
   *         notion of group of a file in a filesystem or if it could not 
   *         be determined (rare).
   */
  public String getGroup() {
    return group;
  }
  
  public Path getPath() {
    return path;
  }
  
  public void setPath(final Path p) {
    path = p;
  }

  /* These are provided so that these values could be loaded lazily 
   * by a filesystem (e.g. local file system).
   */
  
  /**
   * Sets permission.
   * @param permission if permission is null, default value is set
   */
  protected void setPermission(FsPermission permission) {
    this.permission = (permission == null) ? 
                      FsPermission.getFileDefault() : permission;
  }
  
  /**
   * Sets owner.
   * @param owner if it is null, default value is set
   */  
  protected void setOwner(String owner) {
    this.owner = (owner == null) ? "" : owner;
  }
  
  /**
   * Sets group.
   * @param group if it is null, default value is set
   */  
  protected void setGroup(String group) {
    this.group = (group == null) ? "" :  group;
  }

  /**
   * @return The contents of the symbolic link.
   */
  public Path getSymlink() throws IOException {
    if (!isSymlink()) {
      throw new IOException("Path " + path + " is not a symbolic link");
    }
    return symlink;
  }

  public void setSymlink(final Path p) {
    symlink = p;
  }

  /**
   * Compare this FileStatus to another FileStatus
   * @param   o the FileStatus to be compared.
   * @return  a negative integer, zero, or a positive integer as this object
   *   is less than, equal to, or greater than the specified object.
   */
  public int compareTo(FileStatus o) {
    return this.getPath().compareTo(o.getPath());
  }

  /**
   * Compare this FileStatus to another FileStatus.
   * This method was added back by HADOOP-14683 to keep binary compatibility.
   *
   * @param   o the FileStatus to be compared.
   * @return  a negative integer, zero, or a positive integer as this object
   *   is less than, equal to, or greater than the specified object.
   * @throws ClassCastException if the specified object is not FileStatus
   */
  @Override
  public int compareTo(Object o) {
    FileStatus other = (FileStatus) o;
    return compareTo(other);
  }

  /** Compare if this object is equal to another object
   * @param   o the object to be compared.
   * @return  true if two file status has the same path name; false if not.
   */
  @Override
  public boolean equals(Object o) {
    if (!(o instanceof FileStatus)) {
      return false;
    }
    if (this == o) {
      return true;
    }
    FileStatus other = (FileStatus)o;
    return this.getPath().equals(other.getPath());
  }
  
  /**
   * Returns a hash code value for the object, which is defined as
   * the hash code of the path name.
   *
   * @return  a hash code value for the path name.
   */
  @Override
  public int hashCode() {
    return getPath().hashCode();
  }
  
  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append(getClass().getSimpleName())
        .append("{")
        .append("path=" + path)
        .append("; isDirectory=" + isdir);
    if(!isDirectory()){
      sb.append("; length=" + length)
          .append("; replication=" + block_replication)
          .append("; blocksize=" + blocksize);
    }
    sb.append("; modification_time=" + modification_time)
        .append("; access_time=" + access_time)
        .append("; owner=" + owner)
        .append("; group=" + group)
        .append("; permission=" + permission)
        .append("; isSymlink=" + isSymlink());
    if(isSymlink()) {
      try {
        sb.append("; symlink=" + getSymlink());
      } catch (IOException e) {
        throw new RuntimeException("Unexpected exception", e);
      }
    }
    sb.append("; hasAcl=" + hasAcl())
        .append("; isEncrypted=" + isEncrypted())
        .append("; isErasureCoded=" + isErasureCoded())
        .append("}");
    return sb.toString();
  }

  /**
   * Read instance encoded as protobuf from stream.
   * @param in Input stream
   * @see PBHelper#convert(FileStatus)
   * @deprecated Use the {@link PBHelper} and protobuf serialization directly.
   */
  @Override
  @Deprecated
  public void readFields(DataInput in) throws IOException {
    int size = in.readInt();
    if (size < 0) {
      throw new IOException("Can't read FileStatusProto with negative " +
          "size of " + size);
    }
    byte[] buf = new byte[size];
    in.readFully(buf);
    FileStatusProto proto = FileStatusProto.parseFrom(buf);
    FileStatus other = PBHelper.convert(proto);
    isdir = other.isDirectory();
    length = other.getLen();
    block_replication = other.getReplication();
    blocksize = other.getBlockSize();
    modification_time = other.getModificationTime();
    access_time = other.getAccessTime();
    setPermission(other.getPermission());
    setOwner(other.getOwner());
    setGroup(other.getGroup());
    setSymlink((other.isSymlink() ? other.getSymlink() : null));
    setPath(other.getPath());
    attr = attributes(other.hasAcl(), other.isEncrypted(),
        other.isErasureCoded(), other.isSnapshotEnabled());
    assert !(isDirectory() && isSymlink()) : "A directory cannot be a symlink";
  }

  /**
   * Write instance encoded as protobuf to stream.
   * @param out Output stream
   * @see PBHelper#convert(FileStatus)
   * @deprecated Use the {@link PBHelper} and protobuf serialization directly.
   */
  @Override
  @Deprecated
  public void write(DataOutput out) throws IOException {
    FileStatusProto proto = PBHelper.convert(this);
    int size = proto.getSerializedSize();
    out.writeInt(size);
    out.write(proto.toByteArray());
  }

  @Override
  public void validateObject() throws InvalidObjectException {
    if (null == path) {
      throw new InvalidObjectException("No Path in deserialized FileStatus");
    }
    if (null == isdir) {
      throw new InvalidObjectException("No type in deserialized FileStatus");
    }
  }


}