/*
 * Copyright 1998-2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package sun.misc;

import java.net.URL;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.io.InputStream;
import java.security.CodeSigner;
import java.util.jar.Manifest;
import java.util.jar.Attributes;
import java.nio.ByteBuffer;
import sun.nio.ByteBuffered;

/**
 * This class is used to represent a Resource that has been loaded
 * from the class path.
 *
 * @author  David Connelly
 * @since   1.2
 */
public abstract class Resource {
    /**
     * Returns the name of the Resource.
     */
    public abstract String getName();

    /**
     * Returns the URL of the Resource.
     */
    public abstract URL getURL();

    /**
     * Returns the CodeSource URL for the Resource.
     */
    public abstract URL getCodeSourceURL();

    /**
     * Returns an InputStream for reading the Resource data.
     */
    public abstract InputStream getInputStream() throws IOException;

    /**
     * Returns the length of the Resource data, or -1 if unknown.
     */
    public abstract int getContentLength() throws IOException;

    private InputStream cis;

    /* Cache result in case getBytes is called after getByteBuffer. */
    private synchronized InputStream cachedInputStream() throws IOException {
        if (cis == null) {
            cis = getInputStream();
        }
        return cis;
    }

    /**
     * Returns the Resource data as an array of bytes.
     */
    public byte[] getBytes() throws IOException {
        byte[] b;
        // Get stream before content length so that a FileNotFoundException
        // can propagate upwards without being caught too early
        InputStream in = cachedInputStream();

        // This code has been uglified to protect against interrupts.
        // Even if a thread has been interrupted when loading resources,
        // the IO should not abort, so must carefully retry, failing only
        // if the retry leads to some other IO exception.

        boolean isInterrupted = Thread.interrupted();
        int len;
        for (;;) {
            try {
                len = getContentLength();
                break;
            } catch (InterruptedIOException iioe) {
                Thread.interrupted();
                isInterrupted = true;
            }
        }

        try {
            if (len != -1) {
                // Read exactly len bytes from the input stream
                b = new byte[len];
                while (len > 0) {
                    int n = 0;
                    try {
                        n = in.read(b, b.length - len, len);
                    } catch (InterruptedIOException iioe) {
                        Thread.interrupted();
                        isInterrupted = true;
                    }
                    if (n == -1) {
                        throw new IOException("unexpected EOF");
                    }
                    len -= n;
                }
            } else {
                // Read until end of stream is reached
                b = new byte[1024];
                int total = 0;
                for (;;) {
                    len = 0;
                    try {
                        len = in.read(b, total, b.length - total);
                        if (len == -1)
                            break;
                    } catch (InterruptedIOException iioe) {
                        Thread.interrupted();
                        isInterrupted = true;
                    }
                    total += len;
                    if (total >= b.length) {
                        byte[] tmp = new byte[total * 2];
                        System.arraycopy(b, 0, tmp, 0, total);
                        b = tmp;
                    }
                }
                // Trim array to correct size, if necessary
                if (total != b.length) {
                    byte[] tmp = new byte[total];
                    System.arraycopy(b, 0, tmp, 0, total);
                    b = tmp;
                }
            }
        } finally {
            try {
                in.close();
            } catch (InterruptedIOException iioe) {
                isInterrupted = true;
            } catch (IOException ignore) {}

            if (isInterrupted) {
                Thread.currentThread().interrupt();
            }
        }
        return b;
    }

    /**
     * Returns the Resource data as a ByteBuffer, but only if the input stream
     * was implemented on top of a ByteBuffer. Return <tt>null</tt> otherwise.
     */
    public ByteBuffer getByteBuffer() throws IOException {
        InputStream in = cachedInputStream();
        if (in instanceof ByteBuffered) {
            return ((ByteBuffered)in).getByteBuffer();
        }
        return null;
    }

    /**
     * Returns the Manifest for the Resource, or null if none.
     */
    public Manifest getManifest() throws IOException {
        return null;
    }

    /**
     * Returns theCertificates for the Resource, or null if none.
     */
    public java.security.cert.Certificate[] getCertificates() {
        return null;
    }

    /**
     * Returns the code signers for the Resource, or null if none.
     */
    public CodeSigner[] getCodeSigners() {
        return null;
    }
}