/*
 * 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.
 */

/* $Id$ */

package org.apache.pdfbox.io;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * This class contains various I/O-related methods.
 * @version $Revision$
 */
public class IOUtils
{

    //TODO PDFBox should really use Apache Commons IO.

    private IOUtils()
    {
        //Utility class. Don't instantiate.
    }

    /**
     * Reads the input stream and returns its contents as a byte array.
     * @param in the input stream to read from.
     * @return the byte array
     * @throws IOException if an I/O error occurs
     */
    public static byte[] toByteArray(InputStream in) throws IOException
    {
        ByteArrayOutputStream baout = new ByteArrayOutputStream();
        copy(in, baout);
        return baout.toByteArray();
    }

    /**
     * Copies all the contents from the given input stream to the given output stream.
     * @param input the input stream
     * @param output the output stream
     * @return the number of bytes that have been copied
     * @throws IOException if an I/O error occurs
     */
    public static long copy(InputStream input, OutputStream output) throws IOException
    {
        byte[] buffer = new byte[4096];
        long count = 0;
        int n = 0;
        while (-1 != (n = input.read(buffer)))
        {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }

    /**
     * Populates the given buffer with data read from the input stream. If the data doesn't
     * fit the buffer, only the data that fits in the buffer is read. If the data is less than
     * fits in the buffer, the buffer is not completely filled.
     * @param in the input stream to read from
     * @param buffer the buffer to fill
     * @return the number of bytes written to the buffer
     * @throws IOException if an I/O error occurs
     */
    public static long populateBuffer(InputStream in, byte[] buffer) throws IOException
    {
        int remaining = buffer.length;
        while (remaining > 0)
        {
            int bufferWritePos = buffer.length - remaining;
            int bytesRead = in.read(buffer, bufferWritePos, remaining);
            if (bytesRead < 0)
            {
                break; //EOD
            }
            remaining -= bytesRead;
        }
        return buffer.length - remaining;
    }


}