/*

 * Copyright (c) 1999, 2015, 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.sun.tools.javac.jvm;

import java.io.*;

import java.util.LinkedHashMap;

import java.util.Map;

import java.util.Set;

import java.util.HashSet;

import javax.tools.JavaFileManager;

import javax.tools.FileObject;

import javax.tools.JavaFileObject;

import com.sun.tools.javac.code.*;

import com.sun.tools.javac.code.Attribute.RetentionPolicy;

import com.sun.tools.javac.code.Symbol.*;

import com.sun.tools.javac.code.Type.*;

import com.sun.tools.javac.code.Types.UniqueType;

import com.sun.tools.javac.file.BaseFileObject;

import com.sun.tools.javac.jvm.Pool.DynamicMethod;

import com.sun.tools.javac.jvm.Pool.Method;

import com.sun.tools.javac.jvm.Pool.MethodHandle;

import com.sun.tools.javac.jvm.Pool.Variable;

import com.sun.tools.javac.util.*;

import static com.sun.tools.javac.code.Flags.*;

import static com.sun.tools.javac.code.Kinds.Kind.*;

import static com.sun.tools.javac.code.Scope.LookupKind.NON_RECURSIVE;

import static com.sun.tools.javac.code.TypeTag.*;

import static com.sun.tools.javac.main.Option.*;

import static javax.tools.StandardLocation.CLASS_OUTPUT;

/** This class provides operations to map an internal symbol table graph

 *  rooted in a ClassSymbol into a classfile.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 */

public class ClassWriter extends ClassFile {

    protected static final Context.Key<ClassWriter> classWriterKey = new Context.Key<>();

    private final Options options;

    /** Switch: verbose output.

     */

    private boolean verbose;

    /** Switch: scramble private field names.

     */

    private boolean scramble;

    /** Switch: scramble all field names.

     */

    private boolean scrambleAll;

    /** Switch: retrofit mode.

     */

    private boolean retrofit;

    /** Switch: emit source file attribute.

     */

    private boolean emitSourceFile;

    /** Switch: generate CharacterRangeTable attribute.

     */

    private boolean genCrt;

    /** Switch: describe the generated stackmap.

     */

    boolean debugstackmap;

    /**

     * Target class version.

     */

    private Target target;

    /**

     * Source language version.

     */

    private Source source;

    /** Type utilities. */

    private Types types;

    /** The initial sizes of the data and constant pool buffers.

     *  Sizes are increased when buffers get full.

     */

    static final int DATA_BUF_SIZE = 0x0fff0;

    static final int POOL_BUF_SIZE = 0x1fff0;

    /** An output buffer for member info.

     */

    ByteBuffer databuf = new ByteBuffer(DATA_BUF_SIZE);

    /** An output buffer for the constant pool.

     */

    ByteBuffer poolbuf = new ByteBuffer(POOL_BUF_SIZE);

    /** The constant pool.

     */

    Pool pool;

    /** The inner classes to be written, as a set.

     */

    Set<ClassSymbol> innerClasses;

    /** The inner classes to be written, as a queue where

     *  enclosing classes come first.

     */

    ListBuffer<ClassSymbol> innerClassesQueue;

    /** The bootstrap methods to be written in the corresponding class attribute

     *  (one for each invokedynamic)

     */

    /** The log to use for verbose output.

     */

    private final Log log;

    /** The name table. */

    private final Names names;

    /** Access to files. */

    private final JavaFileManager fileManager;

    /** Sole signature generator */

    private final CWSignatureGenerator signatureGen;

    /** The tags and constants used in compressed stackmap. */

    static final int SAME_FRAME_SIZE = 64;

    static final int SAME_LOCALS_1_STACK_ITEM_EXTENDED = 247;

    static final int SAME_FRAME_EXTENDED = 251;

    static final int FULL_FRAME = 255;

    static final int MAX_LOCAL_LENGTH_DIFF = 4;

    /** Get the ClassWriter instance for this context. */

    public static ClassWriter instance(Context context) {

        ClassWriter instance = context.get(classWriterKey);

        if (instance == null)

            instance = new ClassWriter(context);

        return instance;

    }

    /** Construct a class writer, given an options table.

     */

    protected ClassWriter(Context context) {

        context.put(classWriterKey, this);

        log = Log.instance(context);

        names = Names.instance(context);

        options = Options.instance(context);

        target = Target.instance(context);

        source = Source.instance(context);

        types = Types.instance(context);

        fileManager = context.get(JavaFileManager.class);

        signatureGen = new CWSignatureGenerator(types);

        verbose        = options.isSet(VERBOSE);

        scramble       = options.isSet("-scramble");

        scrambleAll    = options.isSet("-scrambleAll");

        retrofit       = options.isSet("-retrofit");

        genCrt         = options.isSet(XJCOV);

        debugstackmap  = options.isSet("debugstackmap");

        emitSourceFile = options.isUnset(G_CUSTOM) ||

                            options.isSet(G_CUSTOM, "source");

        String dumpModFlags = options.get("dumpmodifiers");

        dumpClassModifiers =

            (dumpModFlags != null && dumpModFlags.indexOf('c') != -1);

        dumpFieldModifiers =

            (dumpModFlags != null && dumpModFlags.indexOf('f') != -1);

        dumpInnerClassModifiers =

            (dumpModFlags != null && dumpModFlags.indexOf('i') != -1);

        dumpMethodModifiers =

            (dumpModFlags != null && dumpModFlags.indexOf('m') != -1);

    }

/******************************************************************

 * Diagnostics: dump generated class names and modifiers

 ******************************************************************/

    /** Value of option 'dumpmodifiers' is a string

     *  indicating which modifiers should be dumped for debugging:

     *    'c' -- classes

     *    'f' -- fields

     *    'i' -- innerclass attributes

     *    'm' -- methods

     *  For example, to dump everything:

     *    javac -XDdumpmodifiers=cifm MyProg.java

     */

    private final boolean dumpClassModifiers; // -XDdumpmodifiers=c

    private final boolean dumpFieldModifiers; // -XDdumpmodifiers=f

    private final boolean dumpInnerClassModifiers; // -XDdumpmodifiers=i

    private final boolean dumpMethodModifiers; // -XDdumpmodifiers=m

    /** Return flags as a string, separated by " ".

     */

    public static String flagNames(long flags) {

        StringBuilder sbuf = new StringBuilder();

        int i = 0;

        long f = flags & StandardFlags;

        while (f != 0) {

            if ((f & 1) != 0) {

                sbuf.append(" ");

                sbuf.append(flagName[i]);

            }

            f = f >> 1;

            i++;

        }

        return sbuf.toString();

    }

    //where

        private final static String[] flagName = {

            "PUBLIC", "PRIVATE", "PROTECTED", "STATIC", "FINAL",

            "SUPER", "VOLATILE", "TRANSIENT", "NATIVE", "INTERFACE",

            "ABSTRACT", "STRICTFP"};

/******************************************************************

 * Output routines

 ******************************************************************/

    /** Write a character into given byte buffer;

     *  byte buffer will not be grown.

     */

    void putChar(ByteBuffer buf, int op, int x) {

        buf.elems[op  ] = (byte)((x >>  8) & 0xFF);

        buf.elems[op+1] = (byte)((x      ) & 0xFF);

    }

    /** Write an integer into given byte buffer;

     *  byte buffer will not be grown.

     */

    void putInt(ByteBuffer buf, int adr, int x) {

        buf.elems[adr  ] = (byte)((x >> 24) & 0xFF);

        buf.elems[adr+1] = (byte)((x >> 16) & 0xFF);

        buf.elems[adr+2] = (byte)((x >>  8) & 0xFF);

        buf.elems[adr+3] = (byte)((x      ) & 0xFF);

    }

    /**

     * Signature Generation

     */

    private class CWSignatureGenerator extends Types.SignatureGenerator {

        /**

         * An output buffer for type signatures.

         */

        ByteBuffer sigbuf = new ByteBuffer();

        CWSignatureGenerator(Types types) {

            super(types);

        }

        /**

         * Assemble signature of given type in string buffer.

         * Check for uninitialized types before calling the general case.

         */

        @Override

        public void assembleSig(Type type) {

            switch (type.getTag()) {

                case UNINITIALIZED_THIS:

                case UNINITIALIZED_OBJECT:

                    // we don't yet have a spec for uninitialized types in the

                    // local variable table

                    assembleSig(types.erasure(((UninitializedType)type).qtype));

                    break;

                default:

                    super.assembleSig(type);

            }

        }

        @Override

        protected void append(char ch) {

            sigbuf.appendByte(ch);

        }

        @Override

        protected void append(byte[] ba) {

            sigbuf.appendBytes(ba);

        }

        @Override

        protected void append(Name name) {

            sigbuf.appendName(name);

        }

        @Override

        protected void classReference(ClassSymbol c) {

            enterInner(c);

        }

        private void reset() {

            sigbuf.reset();

        }

        private Name toName() {

            return sigbuf.toName(names);

        }

        private boolean isEmpty() {

            return sigbuf.length == 0;

        }

    }

    /**

     * Return signature of given type

     */

    Name typeSig(Type type) {

        Assert.check(signatureGen.isEmpty());

        //- System.out.println(" ? " + type);

        signatureGen.assembleSig(type);

        Name n = signatureGen.toName();

        signatureGen.reset();

        //- System.out.println("   " + n);

        return n;

    }

    /** Given a type t, return the extended class name of its erasure in

     *  external representation.

     */

    public Name xClassName(Type t) {

        if (t.hasTag(CLASS)) {

            return names.fromUtf(externalize(t.tsym.flatName()));

        } else if (t.hasTag(ARRAY)) {

            return typeSig(types.erasure(t));

        } else {

            throw new AssertionError("xClassName expects class or array type, got " + t);

        }

    }

/******************************************************************

 * Writing the Constant Pool

 ******************************************************************/

    /** Thrown when the constant pool is over full.

     */

    public static class PoolOverflow extends Exception {

        private static final long serialVersionUID = 0;

        public PoolOverflow() {}

    }

    public static class StringOverflow extends Exception {

        private static final long serialVersionUID = 0;

        public final String value;

        public StringOverflow(String s) {

            value = s;

        }

    }

    /** Write constant pool to pool buffer.

     *  Note: during writing, constant pool

     *  might grow since some parts of constants still need to be entered.

     */

    void writePool(Pool pool) throws PoolOverflow, StringOverflow {

        int poolCountIdx = poolbuf.length;

        poolbuf.appendChar(0);

        int i = 1;

        while (i < pool.pp) {

            Object value = pool.pool[i];

            Assert.checkNonNull(value);

            if (value instanceof Method || value instanceof Variable)

                value = ((DelegatedSymbol)value).getUnderlyingSymbol();

            if (value instanceof MethodSymbol) {

                MethodSymbol m = (MethodSymbol)value;

                if (!m.isDynamic()) {

                    poolbuf.appendByte((m.owner.flags() & INTERFACE) != 0

                              ? CONSTANT_InterfaceMethodref

                              : CONSTANT_Methodref);

                    poolbuf.appendChar(pool.put(m.owner));

                    poolbuf.appendChar(pool.put(nameType(m)));

                } else {

                    //invokedynamic

                    DynamicMethodSymbol dynSym = (DynamicMethodSymbol)m;

                    MethodHandle handle = new MethodHandle(dynSym.bsmKind, dynSym.bsm, types);

                    //init cp entries

                    pool.put(names.BootstrapMethods);

                    pool.put(handle);

                    for (Object staticArg : dynSym.staticArgs) {

                        pool.put(staticArg);

                    }

                    poolbuf.appendByte(CONSTANT_InvokeDynamic);

                    poolbuf.appendChar(bootstrapMethods.size() - 1);

                    poolbuf.appendChar(pool.put(nameType(dynSym)));

                }

            } else if (value instanceof VarSymbol) {

                VarSymbol v = (VarSymbol)value;

                poolbuf.appendByte(CONSTANT_Fieldref);

                poolbuf.appendChar(pool.put(v.owner));

                poolbuf.appendChar(pool.put(nameType(v)));

            } else if (value instanceof Name) {

                poolbuf.appendByte(CONSTANT_Utf8);

                byte[] bs = ((Name)value).toUtf();

                poolbuf.appendChar(bs.length);

                poolbuf.appendBytes(bs, 0, bs.length);

                if (bs.length > Pool.MAX_STRING_LENGTH)

                    throw new StringOverflow(value.toString());

            } else if (value instanceof ClassSymbol) {

                ClassSymbol c = (ClassSymbol)value;

                if (c.owner.kind == TYP) pool.put(c.owner);

                poolbuf.appendByte(CONSTANT_Class);

                if (c.type.hasTag(ARRAY)) {

                    poolbuf.appendChar(pool.put(typeSig(c.type)));

                } else {

                    poolbuf.appendChar(pool.put(names.fromUtf(externalize(c.flatname))));

                    enterInner(c);

                }

            } else if (value instanceof NameAndType) {

                NameAndType nt = (NameAndType)value;

                poolbuf.appendByte(CONSTANT_NameandType);

                poolbuf.appendChar(pool.put(nt.name));

                poolbuf.appendChar(pool.put(typeSig(nt.uniqueType.type)));

            } else if (value instanceof Integer) {

                poolbuf.appendByte(CONSTANT_Integer);

                poolbuf.appendInt(((Integer)value).intValue());

            } else if (value instanceof Long) {

                poolbuf.appendByte(CONSTANT_Long);

                poolbuf.appendLong(((Long)value).longValue());

                i++;

            } else if (value instanceof Float) {

                poolbuf.appendByte(CONSTANT_Float);

                poolbuf.appendFloat(((Float)value).floatValue());

            } else if (value instanceof Double) {

                poolbuf.appendByte(CONSTANT_Double);

                poolbuf.appendDouble(((Double)value).doubleValue());

                i++;

            } else if (value instanceof String) {

                poolbuf.appendByte(CONSTANT_String);

                poolbuf.appendChar(pool.put(names.fromString((String)value)));

            } else if (value instanceof UniqueType) {

                Type type = ((UniqueType)value).type;

                if (type.hasTag(METHOD)) {

                    poolbuf.appendByte(CONSTANT_MethodType);

                    poolbuf.appendChar(pool.put(typeSig((MethodType)type)));

                } else {

                    Assert.check(type.hasTag(ARRAY));

                    poolbuf.appendByte(CONSTANT_Class);

                    poolbuf.appendChar(pool.put(xClassName(type)));

                }

            } else if (value instanceof MethodHandle) {

                MethodHandle ref = (MethodHandle)value;

                poolbuf.appendByte(CONSTANT_MethodHandle);

                poolbuf.appendByte(ref.refKind);

                poolbuf.appendChar(pool.put(ref.refSym));

            } else {

                Assert.error("writePool " + value);

            }

            i++;

        }

        if (pool.pp > Pool.MAX_ENTRIES)

            throw new PoolOverflow();

        putChar(poolbuf, poolCountIdx, pool.pp);

    }

    /** Given a field, return its name.

     */

    Name fieldName(Symbol sym) {

        if (scramble && (sym.flags() & PRIVATE) != 0 ||

            scrambleAll && (sym.flags() & (PROTECTED | PUBLIC)) == 0)

            return names.fromString("_$" + sym.name.getIndex());

        else

            return sym.name;

    }

    /** Given a symbol, return its name-and-type.

     */

    NameAndType nameType(Symbol sym) {

        return new NameAndType(fieldName(sym),

                               retrofit

                               ? sym.erasure(types)

                               : sym.externalType(types), types);

        // if we retrofit, then the NameAndType has been read in as is

        // and no change is necessary. If we compile normally, the

        // NameAndType is generated from a symbol reference, and the

        // adjustment of adding an additional this$n parameter needs to be made.

    }

/******************************************************************

 * Writing Attributes

 ******************************************************************/