/*
 * 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.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Determinism;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.util.regex.AbstractBaseSplitter;
import org.apache.phoenix.parse.FunctionParseNode;
import org.apache.phoenix.parse.RegexpSplitParseNode;
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.schema.types.PVarcharArray;
import org.apache.phoenix.util.ByteUtil;

/**
 * Function to split a string value into a {@code VARCHAR_ARRAY}.
 * <p>
 * Usage: {@code REGEXP_SPLIT(&lt;source_str&gt;, &lt;split_pattern&gt;)}
 * <p>
 * {@code source_str} is the string in which we want to split. {@code split_pattern} is a Java
 * compatible regular expression string to split the source string. The function returns a
 * {@link org.apache.phoenix.schema.types.PVarcharArray}
 */
@FunctionParseNode.BuiltInFunction(name = RegexpSplitFunction.NAME,
    nodeClass = RegexpSplitParseNode.class,
    args = { @FunctionParseNode.Argument(allowedTypes = { PVarchar.class }),
      @FunctionParseNode.Argument(allowedTypes = { PVarchar.class }) },
    classType = FunctionParseNode.FunctionClassType.ABSTRACT,
    derivedFunctions = { ByteBasedRegexpSplitFunction.class, StringBasedRegexpSplitFunction.class })
public abstract class RegexpSplitFunction extends ScalarFunction {

  public static final String NAME = "REGEXP_SPLIT";

  private static final PVarchar TYPE = PVarchar.INSTANCE;

  private AbstractBaseSplitter initializedSplitter = null;

  public RegexpSplitFunction() {
  }

  public RegexpSplitFunction(List<Expression> children) {
    super(children);
    init();
  }

  private void init() {
    ImmutableBytesWritable ptr = new ImmutableBytesWritable();
    Expression e = getPatternStrExpression();
    if (e.isStateless() && e.getDeterminism() == Determinism.ALWAYS && e.evaluate(null, ptr)) {
      String pattern = (String) TYPE.toObject(ptr, TYPE, e.getSortOrder());
      if (pattern != null) {
        initializedSplitter = compilePatternSpec(pattern);
      }
    }
  }

  protected abstract AbstractBaseSplitter compilePatternSpec(String value);

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

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

  @Override
  public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    AbstractBaseSplitter splitter = initializedSplitter;
    if (splitter == null) {
      Expression e = getPatternStrExpression();
      if (e.evaluate(tuple, ptr)) {
        String pattern = (String) TYPE.toObject(ptr, TYPE, e.getSortOrder());
        if (pattern != null) {
          splitter = compilePatternSpec(pattern);
        } else {
          ptr.set(ByteUtil.EMPTY_BYTE_ARRAY); // set ptr to null
          return true;
        }
      } else {
        return false;
      }
    }

    Expression e = getSourceStrExpression();
    if (!e.evaluate(tuple, ptr)) {
      return false;
    }
    TYPE.coerceBytes(ptr, TYPE, e.getSortOrder(), SortOrder.ASC);

    return splitter.split(ptr);
  }

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

  private Expression getPatternStrExpression() {
    return children.get(1);
  }

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