/*
 * 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.io.DataOutput;
import java.io.IOException;
import java.sql.SQLException;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.execute.RuntimeContext;
import org.apache.phoenix.expression.visitor.ExpressionVisitor;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;

public class CorrelateVariableFieldAccessExpression extends BaseTerminalExpression {
  private final RuntimeContext runtimeContext;
  private final String variableId;
  private final Expression fieldAccessExpression;

  public CorrelateVariableFieldAccessExpression(RuntimeContext context, String variableId,
    Expression fieldAccessExpression) {
    super();
    this.runtimeContext = context;
    this.variableId = variableId;
    this.fieldAccessExpression = fieldAccessExpression;
  }

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    Tuple variable = runtimeContext.getCorrelateVariableValue(variableId);
    if (variable == null) throw new RuntimeException("Variable '" + variableId + "' not set.");

    return fieldAccessExpression.evaluate(variable, ptr);
  }

  @Override
  public <T> T accept(ExpressionVisitor<T> visitor) {
    return visitor.visit(this);
  }

  @Override
  public void write(DataOutput output) throws IOException {
    ImmutableBytesWritable ptr = new ImmutableBytesWritable();
    boolean success = evaluate(null, ptr);
    Object value = success ? getDataType().toObject(ptr) : null;
    try {
      LiteralExpression expr = LiteralExpression.newConstant(value, getDataType());
      expr.write(output);
    } catch (SQLException e) {
      throw new IOException(e);
    }
  }

  @SuppressWarnings("rawtypes")
  @Override
  public PDataType getDataType() {
    return this.fieldAccessExpression.getDataType();
  }

}
