/*
 * 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.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.parse.FunctionParseNode.Argument;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.schema.SortOrder;
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.ByteUtil;
import org.apache.phoenix.util.StringUtil;

/**
 * Implementation of the {@code Trim(<string>) } build-in function. It removes from both end of
 * {@code <string> } space character and other function bytes in single byte utf8 characters set.
 * @since 0.1
 */
@BuiltInFunction(name = TrimFunction.NAME, args = { @Argument(allowedTypes = { PVarchar.class }) })
public class TrimFunction extends ScalarFunction {
  public static final String NAME = "TRIM";

  private Integer maxLength;

  public TrimFunction() {
  }

  public TrimFunction(List<Expression> children) throws SQLException {
    super(children);
    if (getStringExpression().getDataType().isFixedWidth()) {
      maxLength = getStringExpression().getMaxLength();
    }
  }

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

  @Override
  public SortOrder getSortOrder() {
    return children.get(0).getSortOrder();
  }

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    if (!getStringExpression().evaluate(tuple, ptr)) {
      return false;
    }
    if (ptr.getLength() == 0) {
      ptr.set(ByteUtil.EMPTY_BYTE_ARRAY);
      return true;
    }
    byte[] string = ptr.get();
    int offset = ptr.getOffset();
    int length = ptr.getLength();

    SortOrder sortOrder = getSortOrder();
    int end = StringUtil.getFirstNonBlankCharIdxFromEnd(string, offset, length, sortOrder);
    if (end == offset - 1) {
      ptr.set(ByteUtil.EMPTY_BYTE_ARRAY);
      return true;
    }
    int head = StringUtil.getFirstNonBlankCharIdxFromStart(string, offset, length, sortOrder);
    ptr.set(string, head, end - head + 1);
    return true;
  }

  @Override
  public Integer getMaxLength() {
    return maxLength;
  }

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

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

}
