/*

 * Copyright (c) 2014, 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 jdk.internal.jimage;

import java.nio.ByteBuffer;

import java.util.Objects;

/**

 * @implNote This class needs to maintain JDK 8 source compatibility.

 *

 * It is used internally in the JDK to implement jimage/jrtfs access,

 * but also compiled and delivered as part of the jrtfs.jar to support access

 * to the jimage file provided by the shipped JDK by tools running on JDK 8.

 */

public class ImageLocation {

    public static final int ATTRIBUTE_END = 0;

    public static final int ATTRIBUTE_MODULE = 1;

    public static final int ATTRIBUTE_PARENT = 2;

    public static final int ATTRIBUTE_BASE = 3;

    public static final int ATTRIBUTE_EXTENSION = 4;

    public static final int ATTRIBUTE_OFFSET = 5;

    public static final int ATTRIBUTE_COMPRESSED = 6;

    public static final int ATTRIBUTE_UNCOMPRESSED = 7;

    public static final int ATTRIBUTE_COUNT = 8;

    protected final long[] attributes;

    protected final ImageStrings strings;

    public ImageLocation(long[] attributes, ImageStrings strings) {

        this.attributes = Objects.requireNonNull(attributes);

        this.strings = Objects.requireNonNull(strings);

    }

    ImageStrings getStrings() {

        return strings;

    }

    static long[] decompress(ByteBuffer bytes) {

        Objects.requireNonNull(bytes);

        long[] attributes = new long[ATTRIBUTE_COUNT];

        if (bytes != null) {

            while (bytes.hasRemaining()) {

                int data = bytes.get() & 0xFF;

                int kind = data >>> 3;

                if (kind == ATTRIBUTE_END) {

                    break;

                }

                if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {

                    throw new InternalError(

                        "Invalid jimage attribute kind: " + kind);

                }

                int length = (data & 0x7) + 1;

                long value = 0;

                for (int j = 0; j < length; j++) {

                    value <<= 8;

                    if (!bytes.hasRemaining()) {

                        throw new InternalError("Missing jimage attribute data");

                    }

                    value |= bytes.get() & 0xFF;

                }

                 attributes[kind] = value;

            }

        }

        return attributes;

    }

    public static byte[] compress(long[] attributes) {

        Objects.requireNonNull(attributes);

        ImageStream stream = new ImageStream(16);

        for (int kind = ATTRIBUTE_END + 1; kind < ATTRIBUTE_COUNT; kind++) {

            long value = attributes[kind];

            if (value != 0) {

                int n = (63 - Long.numberOfLeadingZeros(value)) >> 3;

                stream.put((kind << 3) | n);

                for (int i = n; i >= 0; i--) {

                    stream.put((int)(value >> (i << 3)));

                }

            }

        }

        stream.put(ATTRIBUTE_END << 3);

        return stream.toArray();

     }

    public boolean verify(String name) {

        return verify(name, attributes, strings);

    }

    /**

     * A simpler verification would be {@code name.equals(getFullName())}, but

     * by not creating the full name and enabling early returns we allocate

     * fewer objects. Could possibly be made allocation free by extending

     * ImageStrings to test if strings at an offset match the name region.

     */

    static boolean verify(String name, long[] attributes, ImageStrings strings) {

        Objects.requireNonNull(name);

        final int length = name.length();

        int index = 0;

        int moduleOffset = (int)attributes[ATTRIBUTE_MODULE];

        if (moduleOffset != 0) {

            String module = strings.get(moduleOffset);

            final int moduleLen = module.length();

            index = moduleLen + 1;

            if (length <= index

                    || name.charAt(0) != '/'

                    || !name.regionMatches(1, module, 0, moduleLen)

                    || name.charAt(index++) != '/') {

                return false;

            }

        }

        return verifyName(name, index, length, attributes, strings);

    }

    static boolean verify(String module, String name, long[] attributes,

            ImageStrings strings) {

        Objects.requireNonNull(module);

        Objects.requireNonNull(name);

        int moduleOffset = (int)attributes[ATTRIBUTE_MODULE];

        if (moduleOffset != 0) {

            if (!module.equals(strings.get(moduleOffset))) {

                return false;

            }

        }

        return verifyName(name, 0, name.length(), attributes, strings);

    }

    private static boolean verifyName(String name, int index, int length,

            long[] attributes, ImageStrings strings) {

        int parentOffset = (int) attributes[ATTRIBUTE_PARENT];

        if (parentOffset != 0) {

            String parent = strings.get(parentOffset);

            final int parentLen = parent.length();

            if (!name.regionMatches(index, parent, 0, parentLen)) {

                return false;

            }

            index += parentLen;

            if (length <= index || name.charAt(index++) != '/') {

                return false;

            }

        }

        String base = strings.get((int) attributes[ATTRIBUTE_BASE]);

        final int baseLen = base.length();

        if (!name.regionMatches(index, base, 0, baseLen)) {

            return false;

        }

        index += baseLen;

        int extOffset = (int) attributes[ATTRIBUTE_EXTENSION];

        if (extOffset != 0) {

            String extension = strings.get(extOffset);

            int extLen = extension.length();

            if (length <= index

                    || name.charAt(index++) != '.'

                    || !name.regionMatches(index, extension, 0, extLen)) {

                return false;

            }

            index += extLen;

        }

        return length == index;

    }

    long getAttribute(int kind) {

        if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {

            throw new InternalError(

                "Invalid jimage attribute kind: " + kind);

        }

        return attributes[kind];

    }

    String getAttributeString(int kind) {

        if (kind < ATTRIBUTE_END || ATTRIBUTE_COUNT <= kind) {

            throw new InternalError(

                "Invalid jimage attribute kind: " + kind);

        }

        return getStrings().get((int)attributes[kind]);

    }

    public String getModule() {

        return getAttributeString(ATTRIBUTE_MODULE);

    }

    public int getModuleOffset() {

        return (int)getAttribute(ATTRIBUTE_MODULE);

    }

    public String getBase() {

        return getAttributeString(ATTRIBUTE_BASE);

    }

    public int getBaseOffset() {

        return (int)getAttribute(ATTRIBUTE_BASE);

    }

    public String getParent() {

        return getAttributeString(ATTRIBUTE_PARENT);

    }

    public int getParentOffset() {

        return (int)getAttribute(ATTRIBUTE_PARENT);

    }

    public String getExtension() {

        return getAttributeString(ATTRIBUTE_EXTENSION);

    }

    public int getExtensionOffset() {

        return (int)getAttribute(ATTRIBUTE_EXTENSION);

    }

    public String getFullName() {

        return getFullName(false);

    }

    public String getFullName(boolean modulesPrefix) {

        StringBuilder builder = new StringBuilder();

        if (getModuleOffset() != 0) {

            if (modulesPrefix) {

                builder.append("/modules");

            }

            builder.append('/');

            builder.append(getModule());

            builder.append('/');

        }

        if (getParentOffset() != 0) {

            builder.append(getParent());

            builder.append('/');

        }

        builder.append(getBase());

        if (getExtensionOffset() != 0) {

            builder.append('.');

            builder.append(getExtension());

        }

        return builder.toString();

    }

    String buildName(boolean includeModule, boolean includeParent,

            boolean includeName) {

        StringBuilder builder = new StringBuilder();

        if (includeModule && getModuleOffset() != 0) {

            builder.append("/modules/");

            builder.append(getModule());

         }

        if (includeParent && getParentOffset() != 0) {

            builder.append('/');

            builder.append(getParent());

        }

        if (includeName) {

            if (includeModule || includeParent) {

                builder.append('/');

            }

            builder.append(getBase());

            if (getExtensionOffset() != 0) {

                builder.append('.');

                builder.append(getExtension());

            }

        }

        return builder.toString();

   }

    public long getContentOffset() {

        return getAttribute(ATTRIBUTE_OFFSET);

    }

    public long getCompressedSize() {

        return getAttribute(ATTRIBUTE_COMPRESSED);

    }

    public long getUncompressedSize() {

        return getAttribute(ATTRIBUTE_UNCOMPRESSED);

    }

    static ImageLocation readFrom(BasicImageReader reader, int offset) {

        Objects.requireNonNull(reader);

        long[] attributes = reader.getAttributes(offset);

        ImageStringsReader strings = reader.getStrings();

        return new ImageLocation(attributes, strings);

    }

}