/*
 * 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.function;

import java.io.DataInput;
import java.io.IOException;
import java.sql.SQLException;
import java.util.List;
import java.util.Locale;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.parse.FunctionParseNode;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PVarchar;
import org.apache.phoenix.util.i18n.LocaleUtils;

@FunctionParseNode.BuiltInFunction(name = LowerFunction.NAME,
    args = { @FunctionParseNode.Argument(allowedTypes = { PVarchar.class }),
      @FunctionParseNode.Argument(allowedTypes = { PVarchar.class }, defaultValue = "null",
          isConstant = true) })
public class LowerFunction extends ScalarFunction {
  public static final String NAME = "LOWER";

  private Locale locale = null;

  public LowerFunction() {
  }

  public LowerFunction(List<Expression> children) throws SQLException {
    super(children);
    initialize();
  }

  private void initialize() {
    if (children.size() > 1) {
      String localeISOCode = getLiteralValue(1, String.class);
      locale = LocaleUtils.get().getLocaleByIsoCode(localeISOCode);
    }
  }

  @Override
  public void readFields(DataInput input) throws IOException {
    super.readFields(input);
    initialize();
  }

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

    String sourceStr = (String) PVarchar.INSTANCE.toObject(ptr, getStrExpression().getSortOrder());

    if (sourceStr == null) {
      return true;
    }

    String resultStr = locale == null ? sourceStr.toLowerCase() : sourceStr.toLowerCase(locale);

    ptr.set(PVarchar.INSTANCE.toBytes(resultStr));
    return true;
  }

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

  @Override
  public Integer getMaxLength() {
    return getStrExpression().getMaxLength();
  }

  @Override
  public boolean isNullable() {
    return getStrExpression().isNullable();
  }

  @Override
  public String getName() {
    return NAME;
  }

  private Expression getStrExpression() {
    return children.get(0);
  }
}
