/*
 * 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 java.sql.SQLException;
import java.util.List;
import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.function.FloorDateExpression;
import org.apache.phoenix.expression.function.FloorDecimalExpression;
import org.apache.phoenix.expression.function.FloorFunction;
import org.apache.phoenix.schema.TypeMismatchException;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PDecimal;
import org.apache.phoenix.schema.types.PTimestamp;

/**
 * Parse node corresponding to {@link FloorFunction}. It also acts as a factory for creating the
 * right kind of floor expression according to the data type of the first child.
 * @since 3.0.0
 */
public class FloorParseNode extends FunctionParseNode {

  FloorParseNode(String name, List<ParseNode> children, BuiltInFunctionInfo info) {
    super(name, children, info);
  }

  @Override
  public Expression create(List<Expression> children, StatementContext context)
    throws SQLException {
    return getFloorExpression(children);
  }

  public static Expression getFloorExpression(List<Expression> children) throws SQLException {
    final Expression firstChild = children.get(0);
    final PDataType firstChildDataType = firstChild.getDataType();

    // FLOOR on timestamp doesn't really care about the nanos part i.e. it just sets it to zero.
    // Which is exactly what FloorDateExpression does too.
    if (firstChildDataType.isCoercibleTo(PTimestamp.INSTANCE)) {
      return FloorDateExpression.create(children);
    } else if (firstChildDataType.isCoercibleTo(PDecimal.INSTANCE)) {
      return FloorDecimalExpression.create(children);
    } else {
      throw TypeMismatchException.newException(firstChildDataType, "1");
    }
  }

  /**
   * When rounding off decimals, user need not specify the scale. In such cases, we need to prevent
   * the function from getting evaluated as null. This is really a hack. A better way would have
   * been if {@link org.apache.phoenix.parse.FunctionParseNode.BuiltInFunctionInfo} provided a way
   * of associating default values for each permissible data type. Something like: @
   * Argument(allowedTypes={PDataType.VARCHAR, PDataType.INTEGER}, defaultValues = {"null", "1"}
   * isConstant=true) Till then, this will have to do.
   */
  @Override
  public boolean evalToNullIfParamIsNull(StatementContext context, int index) throws SQLException {
    return index == 0;
  }

}
