/*

 * 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 sun.security.util;

import java.util.ArrayList;

import java.util.HashMap;

import java.io.ByteArrayOutputStream;

import java.util.List;

import static java.nio.charset.StandardCharsets.UTF_8;

/**

 * This class is used to compute digests on sections of the Manifest.

 * Please note that multiple sections might have the same name, and they

 * all belong to a single Entry.

 */

public class ManifestDigester {

    public static final String MF_MAIN_ATTRS = "Manifest-Main-Attributes";

    /** the raw bytes of the manifest */

    /** state returned by findSection */

    static class Position {

        int endOfFirstLine; // not including newline character

        int endOfSection; // end of section, not including the blank line

                          // between sections

        int startOfNext;  // the start of the next section

    }

    /**

     * find a section in the manifest.

     *

     * @param offset should point to the starting offset with in the

     * raw bytes of the next section.

     *

     * @pos set by

     *

     * @return false if end of bytes has been reached, otherwise returns

     *          true

     */

    @SuppressWarnings("fallthrough")

    private boolean findSection(int offset, Position pos)

    {

        int i = offset, len = rawBytes.length;

        int next;

        boolean allBlank = true;

        while (i < len) {

            byte b = rawBytes[i];

            switch(b) {

            case '\r':

                    pos.endOfFirstLine = i-1;

                    i++;

                /* fall through */

            case '\n':

                    pos.endOfFirstLine = i-1;

                if (allBlank || (i == len-1)) {

                    pos.startOfNext = i+1;

                    return true;

                }

                else {

                    // start of a new line

                    last = i;

                    allBlank = true;

                }

                break;

            default:

                allBlank = false;

                break;

            }

            i++;

        }

        return false;

    }

    public ManifestDigester(byte[] bytes)

    {

        rawBytes = bytes;

        Position pos = new Position();

            return; // XXX: exception?

        // create an entry for main attributes

        int start = pos.startOfNext;

        while(findSection(start, pos)) {

            int len = pos.endOfFirstLine-start+1;

            int sectionLen = pos.endOfSection-start+1;

            int sectionLenWithBlank = pos.startOfNext-start;

                if (isNameAttr(bytes, start)) {

                    ByteArrayOutputStream nameBuf = new ByteArrayOutputStream();

                    nameBuf.write(bytes, start+6, len-6);

                    int i = start + len;

                    if ((i-start) < sectionLen) {

                            i += 2;

                        } else {

                            i += 1;

                        }

                    }

                    while ((i-start) < sectionLen) {

                        if (bytes[i++] == ' ') {

                            // name is wrapped

                            int wrapStart = i;

                            while (((i-start) < sectionLen)

                            nameBuf.write(bytes, wrapStart, wrapLen);

                        } else {

                            break;

                        }

                    }

                                            dummy -> new Entry())

                            .addSection(new Section(start, sectionLen,

                                    sectionLenWithBlank, rawBytes));

                }

            }

            start = pos.startOfNext;

        }

    }

    private boolean isNameAttr(byte[] bytes, int start)

    {

        return ((bytes[start] == 'N') || (bytes[start] == 'n')) &&

               ((bytes[start+1] == 'a') || (bytes[start+1] == 'A')) &&

               ((bytes[start+2] == 'm') || (bytes[start+2] == 'M')) &&

               ((bytes[start+3] == 'e') || (bytes[start+3] == 'E')) &&

               (bytes[start+4] == ':') &&

               (bytes[start+5] == ' ');

    }

    public static class Entry {

        // One Entry for one name, and one name can have multiple sections.

        // According to the JAR File Specification: "If there are multiple

        // individual sections for the same file entry, the attributes in

        // these sections are merged."

        private List<Section> sections = new ArrayList<>();

        boolean oldStyle;

        private Entry addSection(Section sec)

        {

            sections.add(sec);

            return this;

        }

        public byte[] digest(MessageDigest md)

        {

            md.reset();

            for (Section sec : sections) {

                if (oldStyle) {

                    Section.doOldStyle(md, sec.rawBytes, sec.offset, sec.lengthWithBlankLine);

                } else {

                    md.update(sec.rawBytes, sec.offset, sec.lengthWithBlankLine);

                }

            }

            return md.digest();

        }

        /** Netscape doesn't include the new line. Intel and JavaSoft do */

        public byte[] digestWorkaround(MessageDigest md)

        {

            md.reset();

            for (Section sec : sections) {

                md.update(sec.rawBytes, sec.offset, sec.length);

            }

            return md.digest();

        }

    }

    private static class Section {

        int offset;

        int length;

        int lengthWithBlankLine;

        byte[] rawBytes;

        public Section(int offset, int length,

                     int lengthWithBlankLine, byte[] rawBytes)

        {

            this.offset = offset;

            this.length = length;

            this.lengthWithBlankLine = lengthWithBlankLine;

            this.rawBytes = rawBytes;

        }

        private static void doOldStyle(MessageDigest md,

                                byte[] bytes,

                                int offset,

                                int length)

        {

            // this is too gross to even document, but here goes

            // the 1.1 jar verification code ignored spaces at the

            // end of lines when calculating digests, so that is

            // what this code does. It only gets called if we

            // are parsing a 1.1 signed signature file

            int i = offset;

            int start = offset;

            int max = offset + length;

            int prev = -1;

            while(i <max) {

                if ((bytes[i] == '\r') && (prev == ' ')) {

                    md.update(bytes, start, i-start-1);

                    start = i;

                }

                prev = bytes[i];

                i++;

            }

            md.update(bytes, start, i-start);

        }

    }

    public Entry get(String name, boolean oldStyle) {

            e.oldStyle = oldStyle;

        return e;

    }

    public byte[] manifestDigest(MessageDigest md) {

        md.reset();

        md.update(rawBytes, 0, rawBytes.length);

        return md.digest();

    }

}