/*
 * Copyright (c) 2015, 2017, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.svm.core.jdk;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.graalvm.nativeimage.hosted.Feature;
import org.graalvm.nativeimage.ImageSingletons;
import org.graalvm.nativeimage.Platform;
import org.graalvm.nativeimage.Platforms;

import com.oracle.svm.core.annotate.AutomaticFeature;
import com.oracle.svm.core.hub.DynamicHub;
import com.oracle.svm.core.util.VMError;

Support for resources on Substrate VM. All resources that need to be available at run time need to be added explicitly during native image generation using registerResource. Registered resources are then available from classes and class loaders. /**
 * Support for resources on Substrate VM. All resources that need to be available at run time need
 * to be added explicitly during native image generation using {@link #registerResource}.
 *
 * Registered resources are then available from {@link DynamicHub#getResource classes} and
 * {@link Target_java_lang_ClassLoader class loaders}.
 */
public final class Resources {

    static class ResourcesSupport {
        final Map<String, List<byte[]>> resources = new HashMap<>();
    }

    @AutomaticFeature
    static class ResourcesFeature implements Feature {
        @Override
        public void afterRegistration(AfterRegistrationAccess access) {
            ImageSingletons.add(ResourcesSupport.class, new ResourcesSupport());
        }

        @Override
        public void afterCompilation(AfterCompilationAccess access) {
            /*
             * The resources embedded in the image heap are read-only at run time. Note that we do
             * not mark the collection data structures as read-only because Java collections have
             * all sorts of lazily initialized fields. Only the byte[] arrays themselves can be
             * safely made read-only.
             */
            for (List<byte[]> resourceList : ImageSingletons.lookup(ResourcesSupport.class).resources.values()) {
                for (byte[] resource : resourceList) {
                    access.registerAsImmutable(resource);
                }
            }
        }
    }

    private Resources() {
    }

    @Platforms(Platform.HOSTED_ONLY.class)
    public static void registerResource(String name, InputStream is) {
        ResourcesSupport support = ImageSingletons.lookup(ResourcesSupport.class);

        byte[] arr = new byte[4096];
        int pos = 0;
        try {
            for (;;) {
                if (pos == arr.length) {
                    byte[] tmp = new byte[arr.length * 2];
                    System.arraycopy(arr, 0, tmp, 0, arr.length);
                    arr = tmp;
                }
                int len = is.read(arr, pos, arr.length - pos);
                if (len == -1) {
                    break;
                }
                pos += len;
            }
        } catch (IOException ex) {
            throw VMError.shouldNotReachHere(ex);
        }

        byte[] res = new byte[pos];
        System.arraycopy(arr, 0, res, 0, pos);

        List<byte[]> list = support.resources.get(name);
        if (list == null) {
            list = new ArrayList<>();
            support.resources.put(name, list);
        }
        list.add(res);
    }

    @Platforms(Platform.HOSTED_ONLY.class)
    public static void registerDirectoryResource(String dir, String content) {
        /*
         * A directory content represents the names of all files and subdirectories located in the
         * specified directory, separated with new line delimiter and joined into one string which
         * is later converted into a byte array and placed into the resources map.
         */
        ResourcesSupport support = ImageSingletons.lookup(ResourcesSupport.class);

        byte[] arr = content.getBytes();
        List<byte[]> list = support.resources.get(dir);
        if (list == null) {
            list = new ArrayList<>();
            support.resources.put(dir, list);
        }
        list.add(arr);
    }

    public static List<byte[]> get(String name) {
        return ImageSingletons.lookup(ResourcesSupport.class).resources.get(name);
    }

    public static URL createURL(String name, byte[] resourceBytes) {
        class Conn extends URLConnection {
            Conn(URL url) {
                super(url);
            }

            @Override
            public void connect() throws IOException {
            }

            @Override
            public InputStream getInputStream() throws IOException {
                return new ByteArrayInputStream(resourceBytes);
            }

            @Override
            public long getContentLengthLong() {
                return resourceBytes.length;
            }
        }

        try {
            return new URL("resource", null, -1, name, new URLStreamHandler() {
                @Override
                protected URLConnection openConnection(URL u) throws IOException {
                    return new Conn(u);
                }
            });
        } catch (MalformedURLException ex) {
            throw new IllegalStateException(ex);
        }
    }
}