/*

 * Copyright (c) 2008, 2013, 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

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package sun.invoke.anon;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Arrays;

import java.util.HashSet;

import java.util.IdentityHashMap;

import java.util.Map;

import static sun.invoke.anon.ConstantPoolVisitor.*;

/** A class and its patched constant pool.

 *

 *  This class allow to modify (patch) a constant pool

 *  by changing the value of its entry.

 *  Entry are referenced using index that can be get

 *  by parsing the constant pool using

 *  {@link ConstantPoolParser#parse(ConstantPoolVisitor)}.

 *

 * @see ConstantPoolVisitor

 * @see ConstantPoolParser#createPatch()

 */

public class ConstantPoolPatch {

    final ConstantPoolParser outer;

    final Object[] patchArray;

    ConstantPoolPatch(ConstantPoolParser outer) {

        this.outer      = outer;

        this.patchArray = new Object[outer.getLength()];

    }

    /** Create a {@link ConstantPoolParser} and

     *  a {@link ConstantPoolPatch} in one step.

     *  Equivalent to {@code new ConstantPoolParser(classFile).createPatch()}.

     *

     * @param classFile an array of bytes containing a class.

     * @see #ConstantPoolParser(Class)

     */

    public ConstantPoolPatch(byte[] classFile) throws InvalidConstantPoolFormatException {

        this(new ConstantPoolParser(classFile));

    }

    /** Create a {@link ConstantPoolParser} and

     *  a {@link ConstantPoolPatch} in one step.

     *  Equivalent to {@code new ConstantPoolParser(templateClass).createPatch()}.

     *

     * @param templateClass the class to parse.

     * @see #ConstantPoolParser(Class)

     */

    public ConstantPoolPatch(Class<?> templateClass) throws IOException, InvalidConstantPoolFormatException {

        this(new ConstantPoolParser(templateClass));

    }

    /** Creates a patch from an existing patch.

     *  All changes are copied from that patch.

     * @param patch a patch

     *

     * @see ConstantPoolParser#createPatch()

     */

    public ConstantPoolPatch(ConstantPoolPatch patch) {

        outer      = patch.outer;

        patchArray = patch.patchArray.clone();

    }

    /** Which parser built this patch? */

    public ConstantPoolParser getParser() {

        return outer;

    }

    /** Report the tag at the given index in the constant pool. */

    public byte getTag(int index) {

        return outer.getTag(index);

    }

    /** Report the current patch at the given index of the constant pool.

     *  Null means no patch will be made.

     *  To observe the unpatched entry at the given index, use

     *  {@link #getParser()}{@code .}@link ConstantPoolParser#parse(ConstantPoolVisitor)}

     */

    public Object getPatch(int index) {

        Object value = patchArray[index];

        if (value == null)  return null;

        switch (getTag(index)) {

        case CONSTANT_Fieldref:

        case CONSTANT_Methodref:

        case CONSTANT_InterfaceMethodref:

            if (value instanceof String)

                value = stripSemis(2, (String) value);

            break;

        case CONSTANT_NameAndType:

            if (value instanceof String)

                value = stripSemis(1, (String) value);

            break;

        }

        return value;

    }

    /** Clear all patches. */

    public void clear() {

        Arrays.fill(patchArray, null);

    }

    /** Clear one patch. */

    public void clear(int index) {

        patchArray[index] = null;

    }

    /** Produce the patches as an array. */

    public Object[] getPatches() {

        return patchArray.clone();

    }

    /** Produce the original constant pool as an array. */

    public Object[] getOriginalCP() throws InvalidConstantPoolFormatException {

        return getOriginalCP(0, patchArray.length, -1);

    }

    /** Walk the constant pool, applying patches using the given map.

     *

     * @param utf8Map Utf8 strings to modify, if encountered

     * @param classMap Classes (or their names) to modify, if encountered

     * @param valueMap Constant values to modify, if encountered

     * @param deleteUsedEntries if true, delete map entries that are used

     */

    public void putPatches(final Map<String,String> utf8Map,

                           final Map<String,Object> classMap,

                           final Map<Object,Object> valueMap,

                           boolean deleteUsedEntries) throws InvalidConstantPoolFormatException {

        final HashSet<String> usedUtf8Keys;

        final HashSet<String> usedClassKeys;

        final HashSet<Object> usedValueKeys;

        if (deleteUsedEntries) {

            usedUtf8Keys  = (utf8Map  == null) ? null : new HashSet<String>();

            usedClassKeys = (classMap == null) ? null : new HashSet<String>();

            usedValueKeys = (valueMap == null) ? null : new HashSet<Object>();

        } else {

            usedUtf8Keys = null;

            usedClassKeys = null;

            usedValueKeys = null;

        }

        outer.parse(new ConstantPoolVisitor() {

            @Override

            public void visitUTF8(int index, byte tag, String utf8) {

                putUTF8(index, utf8Map.get(utf8));

                if (usedUtf8Keys != null)  usedUtf8Keys.add(utf8);

            }

            @Override

            public void visitConstantValue(int index, byte tag, Object value) {

                putConstantValue(index, tag, valueMap.get(value));

                if (usedValueKeys != null)  usedValueKeys.add(value);

            }

            @Override

            public void visitConstantString(int index, byte tag, String name, int nameIndex) {

                if (tag == CONSTANT_Class) {

                    putConstantValue(index, tag, classMap.get(name));

                    if (usedClassKeys != null)  usedClassKeys.add(name);

                } else {

                    assert(tag == CONSTANT_String);

                    visitConstantValue(index, tag, name);

                }

            }

        });

        if (usedUtf8Keys != null)   utf8Map.keySet().removeAll(usedUtf8Keys);

        if (usedClassKeys != null)  classMap.keySet().removeAll(usedClassKeys);

        if (usedValueKeys != null)  valueMap.keySet().removeAll(usedValueKeys);

    }

    Object[] getOriginalCP(final int startIndex,

                           final int endIndex,

                           final int tagMask) throws InvalidConstantPoolFormatException {

        final Object[] cpArray = new Object[endIndex - startIndex];

        outer.parse(new ConstantPoolVisitor() {

            void show(int index, byte tag, Object value) {

                if (index < startIndex || index >= endIndex)  return;

                if (((1 << tag) & tagMask) == 0)  return;

                cpArray[index - startIndex] = value;

            }

            @Override

            public void visitUTF8(int index, byte tag, String utf8) {

                show(index, tag, utf8);

            }

            @Override

            public void visitConstantValue(int index, byte tag, Object value) {

                assert(tag != CONSTANT_String);

                show(index, tag, value);

            }

            @Override

            public void visitConstantString(int index, byte tag,

                                            String value, int j) {

                show(index, tag, value);

            }

            @Override

            public void visitMemberRef(int index, byte tag,

                    String className, String memberName,

                    String signature,

                    int j, int k) {

                show(index, tag, new String[]{ className, memberName, signature });

            }

            @Override

            public void visitDescriptor(int index, byte tag,

                    String memberName, String signature,

                    int j, int k) {

                show(index, tag, new String[]{ memberName, signature });

            }

        });

        return cpArray;

    }

    /** Write the head (header plus constant pool)

     *  of the patched class file to the indicated stream.

     */

    void writeHead(OutputStream out) throws IOException {

        outer.writePatchedHead(out, patchArray);

    }

    /** Write the tail (everything after the constant pool)

     *  of the patched class file to the indicated stream.

     */

    void writeTail(OutputStream out) throws IOException {

        outer.writeTail(out);

    }

    private void checkConstantTag(byte tag, Object value) {

        if (value == null)

            throw new IllegalArgumentException(

                    "invalid null constant value");

        if (classForTag(tag) != value.getClass())

            throw new IllegalArgumentException(

                    "invalid constant value"

                    + (tag == CONSTANT_None ? ""

                        : " for tag "+tagName(tag))

                    + " of class "+value.getClass());

    }

    private void checkTag(int index, byte putTag) {

        byte tag = outer.tags[index];

        if (tag != putTag)

            throw new IllegalArgumentException(

                "invalid put operation"

                + " for " + tagName(putTag)

                + " at index " + index + " found " + tagName(tag));

    }

    private void checkTagMask(int index, int tagBitMask) {

        byte tag = outer.tags[index];

        int tagBit = ((tag & 0x1F) == tag) ? (1 << tag) : 0;

        if ((tagBit & tagBitMask) == 0)

            throw new IllegalArgumentException(

                "invalid put operation"

                + " at index " + index + " found " + tagName(tag));

    }

    private static void checkMemberName(String memberName) {

        if (memberName.indexOf(';') >= 0)

            throw new IllegalArgumentException("memberName " + memberName + " contains a ';'");

    }

    /** Set the entry of the constant pool indexed by index to

     *  a new string.

     *

     * @param index an index to a constant pool entry containing a

     *        {@link ConstantPoolVisitor#CONSTANT_Utf8} value.

     * @param utf8 a string

     *

     * @see ConstantPoolVisitor#visitUTF8(int, byte, String)

     */

    public void putUTF8(int index, String utf8) {

        if (utf8 == null) { clear(index); return; }

        checkTag(index, CONSTANT_Utf8);

        patchArray[index] = utf8;

    }

    /** Set the entry of the constant pool indexed by index to

     *  a new value, depending on its dynamic type.

     *

     * @param index an index to a constant pool entry containing a

     *        one of the following structures:

     *        {@link ConstantPoolVisitor#CONSTANT_Integer},

     *        {@link ConstantPoolVisitor#CONSTANT_Float},

     *        {@link ConstantPoolVisitor#CONSTANT_Long},

     *        {@link ConstantPoolVisitor#CONSTANT_Double},

     *        {@link ConstantPoolVisitor#CONSTANT_String}, or

     *        {@link ConstantPoolVisitor#CONSTANT_Class}

     * @param value a boxed int, float, long or double; or a string or class object

     * @throws IllegalArgumentException if the type of the constant does not

     *         match the constant pool entry type,

     *         as reported by {@link #getTag(int)}

     *

     * @see #putConstantValue(int, byte, Object)

     * @see ConstantPoolVisitor#visitConstantValue(int, byte, Object)

     * @see ConstantPoolVisitor#visitConstantString(int, byte, String, int)

     */

    public void putConstantValue(int index, Object value) {

        if (value == null) { clear(index); return; }

        byte tag = tagForConstant(value.getClass());

        checkConstantTag(tag, value);

        checkTag(index, tag);

        patchArray[index] = value;

    }

    /** Set the entry of the constant pool indexed by index to

     *  a new value.

     *

     * @param index an index to a constant pool entry matching the given tag

     * @param tag one of the following values:

     *        {@link ConstantPoolVisitor#CONSTANT_Integer},

     *        {@link ConstantPoolVisitor#CONSTANT_Float},

     *        {@link ConstantPoolVisitor#CONSTANT_Long},

     *        {@link ConstantPoolVisitor#CONSTANT_Double},

     *        {@link ConstantPoolVisitor#CONSTANT_String}, or

     *        {@link ConstantPoolVisitor#CONSTANT_Class}

     * @param value a boxed number, string, or class object

     * @throws IllegalArgumentException if the type of the constant does not

     *         match the constant pool entry type, or if a class name contains

     *         '/' or ';'

     *

     * @see #putConstantValue(int, Object)

     * @see ConstantPoolVisitor#visitConstantValue(int, byte, Object)

     * @see ConstantPoolVisitor#visitConstantString(int, byte, String, int)

     */

    public void putConstantValue(int index, byte tag, Object value) {

        if (value == null) { clear(index); return; }

        checkTag(index, tag);

        if (tag == CONSTANT_Class && value instanceof String) {

            checkClassName((String) value);

        } else if (tag == CONSTANT_String) {

            // the JVM accepts any object as a patch for a string

        } else {

            // make sure the incoming value is the right type

            checkConstantTag(tag, value);

        }

        checkTag(index, tag);

        patchArray[index] = value;

    }

    /** Set the entry of the constant pool indexed by index to

     *  a new {@link ConstantPoolVisitor#CONSTANT_NameAndType} value.

     *

     * @param index an index to a constant pool entry containing a

     *        {@link ConstantPoolVisitor#CONSTANT_NameAndType} value.

     * @param memberName a memberName

     * @param signature a signature

     * @throws IllegalArgumentException if memberName contains the character ';'

     *

     * @see ConstantPoolVisitor#visitDescriptor(int, byte, String, String, int, int)

     */

    public void putDescriptor(int index, String memberName, String signature) {

        checkTag(index, CONSTANT_NameAndType);

        checkMemberName(memberName);

        patchArray[index] = addSemis(memberName, signature);

    }

    /** Set the entry of the constant pool indexed by index to

     *  a new {@link ConstantPoolVisitor#CONSTANT_Fieldref},

     *  {@link ConstantPoolVisitor#CONSTANT_Methodref}, or

     *  {@link ConstantPoolVisitor#CONSTANT_InterfaceMethodref} value.

     *

     * @param index an index to a constant pool entry containing a member reference

     * @param className a class name

     * @param memberName a field or method name

     * @param signature a field or method signature

     * @throws IllegalArgumentException if memberName contains the character ';'

     *             or signature is not a correct signature

     *

     * @see ConstantPoolVisitor#visitMemberRef(int, byte, String, String, String, int, int)

     */

    public void putMemberRef(int index, byte tag,

                    String className, String memberName, String signature) {

        checkTagMask(tag, CONSTANT_MemberRef_MASK);

        checkTag(index, tag);

        checkClassName(className);

        checkMemberName(memberName);

        if (signature.startsWith("(") == (tag == CONSTANT_Fieldref))

            throw new IllegalArgumentException("bad signature: "+signature);

        patchArray[index] = addSemis(className, memberName, signature);

    }

              CONSTANT_Fieldref

            | CONSTANT_Methodref

            | CONSTANT_InterfaceMethodref;

    private static final Map<Class<?>, Byte> CONSTANT_VALUE_CLASS_TAG

        = new IdentityHashMap<Class<?>, Byte>(6);

    private static final Class<?>[] CONSTANT_VALUE_CLASS = new Class<?>[16];

    static {

        Object[][] values = {

            {Integer.class, CONSTANT_Integer},

            {Long.class, CONSTANT_Long},

            {Float.class, CONSTANT_Float},

            {Double.class, CONSTANT_Double},

            {String.class, CONSTANT_String},

            {Class.class, CONSTANT_Class}

        };

        for (Object[] value : values) {

            Class<?> cls = (Class<?>)value[0];

            Byte     tag = (Byte) value[1];

            CONSTANT_VALUE_CLASS_TAG.put(cls, tag);

            CONSTANT_VALUE_CLASS[(byte)tag] = cls;

        }

    }

    static Class<?> classForTag(byte tag) {

        if ((tag & 0xFF) >= CONSTANT_VALUE_CLASS.length)

            return null;

        return CONSTANT_VALUE_CLASS[tag];

    }

    static byte tagForConstant(Class<?> cls) {

        Byte tag = CONSTANT_VALUE_CLASS_TAG.get(cls);

        return (tag == null) ? CONSTANT_None : (byte)tag;

    }

    private static void checkClassName(String className) {

        if (className.indexOf('/') >= 0 || className.indexOf(';') >= 0)

            throw new IllegalArgumentException("invalid class name " + className);

    }

    static String addSemis(String name, String... names) {

        StringBuilder buf = new StringBuilder(name.length() * 5);

        buf.append(name);

        for (String name2 : names) {

            buf.append(';').append(name2);

        }

        String res = buf.toString();

        assert(stripSemis(names.length, res)[0].equals(name));

        assert(stripSemis(names.length, res)[1].equals(names[0]));

        assert(names.length == 1 ||

               stripSemis(names.length, res)[2].equals(names[1]));

        return res;

    }

    static String[] stripSemis(int count, String string) {

        String[] res = new String[count+1];

        int pos = 0;

        for (int i = 0; i < count; i++) {

            int pos2 = string.indexOf(';', pos);

            if (pos2 < 0)  pos2 = string.length();  // yuck

            res[i] = string.substring(pos, pos2);

            pos = pos2;

        }

        res[count] = string.substring(pos);

        return res;

    }

    public String toString() {

        StringBuilder buf = new StringBuilder(this.getClass().getName());

        buf.append("{");

        Object[] origCP = null;

        for (int i = 0; i < patchArray.length; i++) {

            if (patchArray[i] == null)  continue;

            if (origCP != null) {

                buf.append(", ");

            } else {

                try {

                    origCP = getOriginalCP();

                } catch (InvalidConstantPoolFormatException ee) {

                    origCP = new Object[0];

                }

            }

            Object orig = (i < origCP.length) ? origCP[i] : "?";

            buf.append(orig).append("=").append(patchArray[i]);

        }

        buf.append("}");

        return buf.toString();

    }

}