/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2010-2011 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * http://glassfish.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
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 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
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 * If you wish your version of this file to be governed by only the CDDL or
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 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
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package com.sun.jersey.json.impl;

import java.io.IOException;
import java.io.InputStream;

/**
 *
 * @author Jakub.Podlesak@Sun.COM
 */
public abstract class FilteringInputStream extends InputStream {

    private byte[] currentBuffer;
    private int cursor;

    protected abstract byte[] nextBytes() throws IOException;


    @Override
    public int available() throws IOException {

        if (currentBuffer == null) {
            return 0;
        }

        return currentBuffer.length - cursor;
    }


    @Override
    public synchronized void mark(int readlimit) {
        throw new UnsupportedOperationException();
    }

    @Override
    public boolean markSupported() {
        return false;
    }


    private void getNextBytesIfNothingAvailable() throws IOException {
        if (available() < 1) {
            currentBuffer = nextBytes();
            cursor = 0;
        }

    }


    public int read() throws IOException {

        getNextBytesIfNothingAvailable();

        if((currentBuffer == null) || (currentBuffer.length == 0)) {
            return -1;
        }

        return currentBuffer[cursor++];
    }


    @Override
    public int read(byte[] b) throws IOException {
        return this.read(b, 0, b.length);
    }


    @Override
    public int read(byte[] b, int off, int len) throws IOException {

        getNextBytesIfNothingAvailable();

        if (currentBuffer == null) {
            return -1;
        }

        int availableBytes = currentBuffer.length - cursor;

        if (len >= availableBytes) {
            System.arraycopy(currentBuffer, cursor, b, off, availableBytes);
            currentBuffer = null;
            return availableBytes;
        } else {
            System.arraycopy(currentBuffer, cursor, b, off, len);
            cursor += len;
            return len;
        }
    }


    @Override
    public synchronized void reset() throws IOException {
        throw new IOException();
    }

    @Override
    public long skip(long n) throws IOException {
        return super.skip(n);
    }

    @Override
    public String toString() {
        return super.toString();
    }
}
