/*
 * 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.phoenix.parse;

import org.apache.phoenix.compile.ColumnResolver;
import org.apache.phoenix.schema.types.PInteger;

/**
 * Node representing an ORDER BY clause (including asc/desc and nulls first/last) in SQL
 * @since 0.1
 */
public final class OrderByNode {
  private final ParseNode child;
  private final boolean nullsLast;
  private final boolean orderAscending;

  OrderByNode(ParseNode child, boolean nullsLast, boolean orderAscending) {
    this.child = child;
    this.nullsLast = nullsLast;
    this.orderAscending = orderAscending;
  }

  public boolean isNullsLast() {
    return nullsLast;
  }

  public boolean isAscending() {
    return orderAscending;
  }

  public ParseNode getNode() {
    return child;
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((child == null) ? 0 : child.hashCode());
    result = prime * result + (nullsLast ? 1231 : 1237);
    result = prime * result + (orderAscending ? 1231 : 1237);
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null) return false;
    if (getClass() != obj.getClass()) return false;
    OrderByNode other = (OrderByNode) obj;
    if (child == null) {
      if (other.child != null) return false;
    } else if (!child.equals(other.child)) return false;
    if (nullsLast != other.nullsLast) return false;
    if (orderAscending != other.orderAscending) return false;
    return true;
  }

  @Override
  public String toString() {
    return child.toString() + (orderAscending ? " asc" : " desc") + " nulls "
      + (nullsLast ? "last" : "first");
  }

  public void toSQL(ColumnResolver resolver, StringBuilder buf) {
    child.toSQL(resolver, buf);
    if (!orderAscending) buf.append(" DESC");
    if (nullsLast) buf.append(" NULLS LAST ");
  }

  public boolean isIntegerLiteral() {
    return child instanceof LiteralParseNode
      && ((LiteralParseNode) child).getType() == PInteger.INSTANCE;
  }

  public Integer getValueIfIntegerLiteral() {
    if (!isIntegerLiteral()) {
      return null;
    }
    return (Integer) ((LiteralParseNode) child).getValue();
  }
}
