/**
 * 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.hive.ql.hooks;

import java.io.Serializable;
import java.net.URI;
import java.util.Map;

import org.apache.hadoop.hive.ql.metadata.Partition;
import org.apache.hadoop.hive.ql.metadata.DummyPartition;
import org.apache.hadoop.hive.ql.metadata.Table;

/**
 * This class encapsulates an object that is being read or written to by the
 * query. This object may be a table, partition, dfs directory or a local
 * directory.
 */
public class Entity implements Serializable {
  private static final long serialVersionUID = 1L;

  /**
   * The type of the entity.
   */
  public static enum Type {
    TABLE, PARTITION, DUMMYPARTITION, DFS_DIR, LOCAL_DIR
  };

  /**
   * The type.
   */
  private Type typ;

  /**
   * The table. This is null if this is a directory.
   */
  private Table t;

  /**
   * The partition.This is null if this object is not a partition.
   */
  private Partition p;

  /**
   * The directory if this is a directory.
   */
  private String d;

  /**
   * This is derived from t and p, but we need to serialize this field to make
   * sure Entity.hashCode() does not need to recursively read into t and p.
   */
  private String name;

  /**
   * Whether the output is complete or not. For eg, for dynamic partitions, the
   * complete output may not be known
   */
  private boolean complete;

  public boolean isComplete() {
    return complete;
  }

  public void setComplete(boolean complete) {
    this.complete = complete;;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public Type getTyp() {
    return typ;
  }

  public void setTyp(Type typ) {
    this.typ = typ;
  }

  public Table getT() {
    return t;
  }

  public void setT(Table t) {
    this.t = t;
  }

  public Partition getP() {
    return p;
  }

  public void setP(Partition p) {
    this.p = p;
  }

  public String getD() {
    return d;
  }

  public void setD(String d) {
    this.d = d;
  }

  /**
   * Only used by serialization.
   */
  public Entity() {
  }

  /**
   * Constructor for a table.
   *
   * @param t
   *          Table that is read or written to.
   */
  public Entity(Table t) {
    this(t, true);
  }

  public Entity(Table t, boolean complete) {
    d = null;
    p = null;
    this.t = t;
    typ = Type.TABLE;
    name = computeName();
    this.complete = complete;
  }

  /**
   * Constructor for a partition.
   *
   * @param p
   *          Partition that is read or written to.
   */
  public Entity(Partition p) {
    this(p, true);
  }

  public Entity(Partition p, boolean complete) {
    d = null;
    this.p = p;
    t = p.getTable();
    typ = Type.PARTITION;
    name = computeName();
    this.complete = complete;
  }

  public Entity(DummyPartition p, boolean complete) {
    d = null;
    this.p = p;
    t = p.getTable();
    typ = Type.DUMMYPARTITION;
    name = computeName();
    this.complete = complete;
  }

  /**
   * Constructor for a file.
   *
   * @param d
   *          The name of the directory that is being read or written to.
   * @param islocal
   *          Flag to decide whether this directory is local or in dfs.
   */
  public Entity(String d, boolean islocal) {
    this(d, islocal, true);
  }

  public Entity(String d, boolean islocal, boolean complete) {
    this.d = d;
    p = null;
    t = null;
    if (islocal) {
      typ = Type.LOCAL_DIR;
    } else {
      typ = Type.DFS_DIR;
    }
    name = computeName();
    this.complete = complete;
  }

  /**
   * Get the parameter map of the Entity.
   */
  public Map<String, String> getParameters() {
    if (p != null) {
      return p.getParameters();
    } else {
      return t.getParameters();
    }
  }

  /**
   * Get the type of the entity.
   */
  public Type getType() {
    return typ;
  }

  /**
   * Get the location of the entity.
   */
  public URI getLocation() throws Exception {
    if (typ == Type.TABLE) {
      return t.getDataLocation();
    }

    if (typ == Type.PARTITION) {
      return p.getDataLocation();
    }

    if (typ == Type.DFS_DIR || typ == Type.LOCAL_DIR) {
      return new URI(d);
    }

    return null;
  }

  /**
   * Get the partition associated with the entity.
   */
  public Partition getPartition() {
    return p;
  }

  /**
   * Get the table associated with the entity.
   */
  public Table getTable() {
    return t;
  }

  /**
   * toString function.
   */
  @Override
  public String toString() {
    return name;
  }

  private String computeName() {
    switch (typ) {
    case TABLE:
      return t.getDbName() + "@" + t.getTableName();
    case PARTITION:
      return t.getDbName() + "@" + t.getTableName() + "@" + p.getName();
    case DUMMYPARTITION:
      return p.getName();
    default:
      return d;
    }
  }

  /**
   * Equals function.
   */
  @Override
  public boolean equals(Object o) {
    if (o == null) {
      return false;
    }

    if (o instanceof Entity) {
      Entity ore = (Entity) o;
      return (toString().equalsIgnoreCase(ore.toString()));
    } else {
      return false;
    }
  }

  /**
   * Hashcode function.
   */
  @Override
  public int hashCode() {
    return toString().hashCode();
  }

}