/*
 * 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.hyracks.storage.am.lsm.invertedindex.ondisk;

import org.apache.hyracks.api.dataflow.value.ITypeTraits;
import org.apache.hyracks.api.exceptions.HyracksDataException;
import org.apache.hyracks.storage.am.lsm.invertedindex.api.IInvertedListTupleReference;

public abstract class AbstractInvertedListTupleReference implements IInvertedListTupleReference {

    protected final ITypeTraits[] typeTraits;
    protected final int[] fieldStartOffsets;
    protected byte[] data;
    protected int startOff;

    // check if the type trait is fixed-size or variable-size
    // throws an IllegalArgument exception if get unexpected traits
    protected abstract void verifyTypeTrait() throws HyracksDataException;

    public AbstractInvertedListTupleReference(ITypeTraits[] typeTraits) throws HyracksDataException {
        this.typeTraits = typeTraits;
        this.fieldStartOffsets = new int[typeTraits.length];
        this.fieldStartOffsets[0] = 0;

        verifyTypeTrait();
    }

    protected abstract void calculateFieldStartOffsets();

    @Override
    public void reset(byte[] data, int startOff) {
        this.data = data;
        this.startOff = startOff;
        calculateFieldStartOffsets();
    }

    @Override
    public int getFieldCount() {
        return typeTraits.length;
    }

    @Override
    public byte[] getFieldData(int fIdx) {
        return data;
    }

    @Override
    public int getFieldStart(int fIdx) {
        return startOff + fieldStartOffsets[fIdx];
    }
}
