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/*
 * 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}.
 * 
 * Usage:
 * {@code REGEXP_SPLIT(<source_str>, <split_pattern>)}
 * 
 * {@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 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;
    }
}