/*
 * 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.expression;

import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.visitor.ExpressionVisitor;
import org.apache.phoenix.schema.TypeMismatchException;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PBoolean;
import org.apache.phoenix.schema.types.PDataType;

/**
 * Implementation of the NOT operator that negates it's single boolean child expression.
 * @since 0.1
 */
public class NotExpression extends BaseSingleExpression {

  public static Expression create(Expression child, ImmutableBytesWritable ptr)
    throws SQLException {
    if (child.getDataType() != PBoolean.INSTANCE) {
      throw TypeMismatchException.newException(child.getDataType(), PBoolean.INSTANCE, "NOT");
    }
    if (child.isStateless()) {
      if (!child.evaluate(null, ptr) || ptr.getLength() == 0) {
        return LiteralExpression.newConstant(null, PBoolean.INSTANCE, child.getDeterminism());
      }
      return LiteralExpression.newConstant(!(Boolean) PBoolean.INSTANCE.toObject(ptr),
        PBoolean.INSTANCE, child.getDeterminism());
    }
    return new NotExpression(child);
  }

  public NotExpression() {
  }

  public NotExpression(Expression expression) {
    super(expression);
  }

  public NotExpression(List<Expression> l) {
    super(l);
  }

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    if (!getChild().evaluate(tuple, ptr)) {
      return false;
    }
    if (ptr.getLength() == 0) {
      return true;
    }

    ptr.set(Boolean.TRUE.equals(PBoolean.INSTANCE.toObject(ptr))
      ? PDataType.FALSE_BYTES
      : PDataType.TRUE_BYTES);
    return true;
  }

  @Override
  public PDataType getDataType() {
    return PBoolean.INSTANCE;
  }

  @Override
  public final <T> T accept(ExpressionVisitor<T> visitor) {
    List<T> l = acceptChildren(visitor, visitor.visitEnter(this));
    T t = visitor.visitLeave(this, l);
    if (t == null) {
      t = visitor.defaultReturn(this, l);
    }
    return t;
  }

  @Override
  public String toString() {
    StringBuilder buf = new StringBuilder("NOT (");
    buf.append(children.get(0).toString());
    buf.append(")");
    return buf.toString();
  }
}
