/*
 * 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.jena.dboe.base.buffer;

import static java.lang.String.format;

import java.nio.ByteBuffer;
import java.nio.IntBuffer;

import org.apache.jena.dboe.base.record.RecordException;
import org.apache.jena.dboe.sys.SysDB;
import org.apache.jena.dboe.sys.SystemIndex;

/** An IntBuffer with extra operations */

final public class PtrBuffer extends BufferBase {
    private IntBuffer iBuff;

    private PtrBuffer(int maxRec) {
        this(ByteBuffer.allocate(SystemIndex.SizeOfPointer * maxRec), 0);
    }

    public PtrBuffer(ByteBuffer bb, int num) {
        super(bb, SystemIndex.SizeOfPointer, num);
        iBuff = bb.asIntBuffer();

        if ( CheckBuffer ) {
            // It is a IntBuffer with associated ByteBuffer
            if ( iBuff.position() != 0 || bb.order() != SysDB.NetworkOrder )
                throw new RecordException("Duff pointer buffer");
        }
    }

    public int get(int idx) {
        checkBounds(idx, numSlot);
        return _get(idx);
    }

    public int getHigh() {
        if ( numSlot == 0 )
            throw new IllegalArgumentException("Empty PtrBuffer");
        return _get(numSlot - 1);
    }

    public int getLow() {
        if ( numSlot == 0 )
            throw new IllegalArgumentException("Empty PtrBuffer");
        return _get(0);
    }

    public void add(int val) {
        add(numSlot, val);
    }

    public void add(int idx, int val) {
        if ( idx != numSlot ) {
            checkBounds(idx, numSlot);
            shiftUp(idx);
        } else {
            if ( numSlot >= maxSlot )
                throw new BufferException(format("Out of bounds: idx=%d, ptrs=%d", idx, maxSlot));
            numSlot++;
        }
        // Add right at the top.
        _set(idx, val);
    }

    public void set(int idx, int val) {
        checkBounds(idx, numSlot);
        _set(idx, val);
    }

    private final int _get(int idx) {
        return iBuff.get(idx);
    }

    private final void _set(int idx, int val) {
        iBuff.put(idx, val);
    }

    @Override
    public String toString() {
        StringBuilder str = new StringBuilder();
        str.append(format("Len=%d Max=%d ", numSlot, maxSlot));

        for ( int i = 0; i < numSlot ; i++ ) {
            if ( i != 0 )
                str.append(" ");
            int x = _get(i);
            str.append(format("%04d", x));
        }
        return str.toString();
    }

    private static void checkBounds(int idx, int len) {
        if ( idx < 0 || idx >= len )
            throw new BufferException(format("Out of bounds: idx=%d, ptrs=%d", idx, len));
    }

    /**
     * A duplicate which does not share anything with the original - for testing
     */
    public PtrBuffer duplicate() {
        PtrBuffer n = new PtrBuffer(maxSlot);
        copy(0, n, 0, maxSlot); // numSlot
        n.numSlot = numSlot; // Reset
        return n;
    }
}
