/*

 * Copyright (c) 1999, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.lang.reflect;

import java.io.ByteArrayOutputStream;

import java.io.DataOutputStream;

import java.io.File;

import java.io.IOException;

import java.io.OutputStream;

import java.lang.reflect.Array;

import java.lang.reflect.Method;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.LinkedList;

import java.util.List;

import java.util.ListIterator;

import java.util.Map;

import sun.security.action.GetBooleanAction;

/**

 * ProxyGenerator contains the code to generate a dynamic proxy class

 * for the java.lang.reflect.Proxy API.

 *

 * The external interfaces to ProxyGenerator is the static

 * "generateProxyClass" method.

 *

 * @author      Peter Jones

 * @since       1.3

 */

class ProxyGenerator {

    /*

     * In the comments below, "JVMS" refers to The Java Virtual Machine

     * Specification Second Edition and "JLS" refers to the original

     * version of The Java Language Specification, unless otherwise

     * specified.

     */

    /* generate 1.5-era class file version */

    private static final int CLASSFILE_MAJOR_VERSION = 49;

    private static final int CLASSFILE_MINOR_VERSION = 0;

    /*

     * beginning of constants copied from

     * sun.tools.java.RuntimeConstants (which no longer exists):

     */

    /* constant pool tags */

    private static final int CONSTANT_UTF8              = 1;

    private static final int CONSTANT_UNICODE           = 2;

    private static final int CONSTANT_INTEGER           = 3;

    private static final int CONSTANT_FLOAT             = 4;

    private static final int CONSTANT_LONG              = 5;

    private static final int CONSTANT_DOUBLE            = 6;

    private static final int CONSTANT_CLASS             = 7;

    private static final int CONSTANT_STRING            = 8;

    private static final int CONSTANT_FIELD             = 9;

    private static final int CONSTANT_METHOD            = 10;

    private static final int CONSTANT_INTERFACEMETHOD   = 11;

    private static final int CONSTANT_NAMEANDTYPE       = 12;

    /* access and modifier flags */

    private static final int ACC_PUBLIC                 = 0x00000001;

    private static final int ACC_PRIVATE                = 0x00000002;

//  private static final int ACC_PROTECTED              = 0x00000004;

    private static final int ACC_STATIC                 = 0x00000008;

    private static final int ACC_FINAL                  = 0x00000010;

//  private static final int ACC_SYNCHRONIZED           = 0x00000020;

//  private static final int ACC_VOLATILE               = 0x00000040;

//  private static final int ACC_TRANSIENT              = 0x00000080;

//  private static final int ACC_NATIVE                 = 0x00000100;

//  private static final int ACC_INTERFACE              = 0x00000200;

//  private static final int ACC_ABSTRACT               = 0x00000400;

    private static final int ACC_SUPER                  = 0x00000020;

//  private static final int ACC_STRICT                 = 0x00000800;

    /* opcodes */

//  private static final int opc_nop                    = 0;

    private static final int opc_aconst_null            = 1;

//  private static final int opc_iconst_m1              = 2;

    private static final int opc_iconst_0               = 3;

//  private static final int opc_iconst_1               = 4;

//  private static final int opc_iconst_2               = 5;

//  private static final int opc_iconst_3               = 6;

//  private static final int opc_iconst_4               = 7;

//  private static final int opc_iconst_5               = 8;

//  private static final int opc_lconst_0               = 9;

//  private static final int opc_lconst_1               = 10;

//  private static final int opc_fconst_0               = 11;

//  private static final int opc_fconst_1               = 12;

//  private static final int opc_fconst_2               = 13;

//  private static final int opc_dconst_0               = 14;

//  private static final int opc_dconst_1               = 15;

    private static final int opc_bipush                 = 16;

    private static final int opc_sipush                 = 17;

    private static final int opc_ldc                    = 18;

    private static final int opc_ldc_w                  = 19;

//  private static final int opc_ldc2_w                 = 20;

    private static final int opc_iload                  = 21;

    private static final int opc_lload                  = 22;

    private static final int opc_fload                  = 23;

    private static final int opc_dload                  = 24;

    private static final int opc_aload                  = 25;

    private static final int opc_iload_0                = 26;

//  private static final int opc_iload_1                = 27;

//  private static final int opc_iload_2                = 28;

//  private static final int opc_iload_3                = 29;

    private static final int opc_lload_0                = 30;

//  private static final int opc_lload_1                = 31;

//  private static final int opc_lload_2                = 32;

//  private static final int opc_lload_3                = 33;

    private static final int opc_fload_0                = 34;

//  private static final int opc_fload_1                = 35;

//  private static final int opc_fload_2                = 36;

//  private static final int opc_fload_3                = 37;

    private static final int opc_dload_0                = 38;

//  private static final int opc_dload_1                = 39;

//  private static final int opc_dload_2                = 40;

//  private static final int opc_dload_3                = 41;

    private static final int opc_aload_0                = 42;

//  private static final int opc_aload_1                = 43;

//  private static final int opc_aload_2                = 44;

//  private static final int opc_aload_3                = 45;

//  private static final int opc_iaload                 = 46;

//  private static final int opc_laload                 = 47;

//  private static final int opc_faload                 = 48;

//  private static final int opc_daload                 = 49;

//  private static final int opc_aaload                 = 50;

//  private static final int opc_baload                 = 51;

//  private static final int opc_caload                 = 52;

//  private static final int opc_saload                 = 53;

//  private static final int opc_istore                 = 54;

//  private static final int opc_lstore                 = 55;

//  private static final int opc_fstore                 = 56;

//  private static final int opc_dstore                 = 57;

    private static final int opc_astore                 = 58;

//  private static final int opc_istore_0               = 59;

//  private static final int opc_istore_1               = 60;

//  private static final int opc_istore_2               = 61;

//  private static final int opc_istore_3               = 62;

//  private static final int opc_lstore_0               = 63;

//  private static final int opc_lstore_1               = 64;

//  private static final int opc_lstore_2               = 65;

//  private static final int opc_lstore_3               = 66;

//  private static final int opc_fstore_0               = 67;

//  private static final int opc_fstore_1               = 68;

//  private static final int opc_fstore_2               = 69;

//  private static final int opc_fstore_3               = 70;

//  private static final int opc_dstore_0               = 71;

//  private static final int opc_dstore_1               = 72;

//  private static final int opc_dstore_2               = 73;

//  private static final int opc_dstore_3               = 74;

    private static final int opc_astore_0               = 75;

//  private static final int opc_astore_1               = 76;

//  private static final int opc_astore_2               = 77;

//  private static final int opc_astore_3               = 78;

//  private static final int opc_iastore                = 79;

//  private static final int opc_lastore                = 80;

//  private static final int opc_fastore                = 81;

//  private static final int opc_dastore                = 82;

    private static final int opc_aastore                = 83;

//  private static final int opc_bastore                = 84;

//  private static final int opc_castore                = 85;

//  private static final int opc_sastore                = 86;

    private static final int opc_pop                    = 87;

//  private static final int opc_pop2                   = 88;

    private static final int opc_dup                    = 89;

//  private static final int opc_dup_x1                 = 90;

//  private static final int opc_dup_x2                 = 91;

//  private static final int opc_dup2                   = 92;

//  private static final int opc_dup2_x1                = 93;

//  private static final int opc_dup2_x2                = 94;

//  private static final int opc_swap                   = 95;

//  private static final int opc_iadd                   = 96;

//  private static final int opc_ladd                   = 97;

//  private static final int opc_fadd                   = 98;

//  private static final int opc_dadd                   = 99;

//  private static final int opc_isub                   = 100;

//  private static final int opc_lsub                   = 101;

//  private static final int opc_fsub                   = 102;

//  private static final int opc_dsub                   = 103;

//  private static final int opc_imul                   = 104;

//  private static final int opc_lmul                   = 105;

//  private static final int opc_fmul                   = 106;

//  private static final int opc_dmul                   = 107;

//  private static final int opc_idiv                   = 108;

//  private static final int opc_ldiv                   = 109;

//  private static final int opc_fdiv                   = 110;

//  private static final int opc_ddiv                   = 111;

//  private static final int opc_irem                   = 112;

//  private static final int opc_lrem                   = 113;

//  private static final int opc_frem                   = 114;

//  private static final int opc_drem                   = 115;

//  private static final int opc_ineg                   = 116;

//  private static final int opc_lneg                   = 117;

//  private static final int opc_fneg                   = 118;

//  private static final int opc_dneg                   = 119;

//  private static final int opc_ishl                   = 120;

//  private static final int opc_lshl                   = 121;

//  private static final int opc_ishr                   = 122;

//  private static final int opc_lshr                   = 123;

//  private static final int opc_iushr                  = 124;

//  private static final int opc_lushr                  = 125;

//  private static final int opc_iand                   = 126;

//  private static final int opc_land                   = 127;

//  private static final int opc_ior                    = 128;

//  private static final int opc_lor                    = 129;

//  private static final int opc_ixor                   = 130;

//  private static final int opc_lxor                   = 131;

//  private static final int opc_iinc                   = 132;

//  private static final int opc_i2l                    = 133;

//  private static final int opc_i2f                    = 134;

//  private static final int opc_i2d                    = 135;

//  private static final int opc_l2i                    = 136;

//  private static final int opc_l2f                    = 137;

//  private static final int opc_l2d                    = 138;

//  private static final int opc_f2i                    = 139;

//  private static final int opc_f2l                    = 140;

//  private static final int opc_f2d                    = 141;

//  private static final int opc_d2i                    = 142;

//  private static final int opc_d2l                    = 143;

//  private static final int opc_d2f                    = 144;

//  private static final int opc_i2b                    = 145;

//  private static final int opc_i2c                    = 146;

//  private static final int opc_i2s                    = 147;

//  private static final int opc_lcmp                   = 148;

//  private static final int opc_fcmpl                  = 149;

//  private static final int opc_fcmpg                  = 150;

//  private static final int opc_dcmpl                  = 151;

//  private static final int opc_dcmpg                  = 152;

//  private static final int opc_ifeq                   = 153;

//  private static final int opc_ifne                   = 154;

//  private static final int opc_iflt                   = 155;

//  private static final int opc_ifge                   = 156;

//  private static final int opc_ifgt                   = 157;

//  private static final int opc_ifle                   = 158;

//  private static final int opc_if_icmpeq              = 159;

//  private static final int opc_if_icmpne              = 160;

//  private static final int opc_if_icmplt              = 161;

//  private static final int opc_if_icmpge              = 162;

//  private static final int opc_if_icmpgt              = 163;

//  private static final int opc_if_icmple              = 164;

//  private static final int opc_if_acmpeq              = 165;

//  private static final int opc_if_acmpne              = 166;

//  private static final int opc_goto                   = 167;

//  private static final int opc_jsr                    = 168;

//  private static final int opc_ret                    = 169;

//  private static final int opc_tableswitch            = 170;

//  private static final int opc_lookupswitch           = 171;

    private static final int opc_ireturn                = 172;

    private static final int opc_lreturn                = 173;

    private static final int opc_freturn                = 174;

    private static final int opc_dreturn                = 175;

    private static final int opc_areturn                = 176;

    private static final int opc_return                 = 177;

    private static final int opc_getstatic              = 178;

    private static final int opc_putstatic              = 179;

    private static final int opc_getfield               = 180;

//  private static final int opc_putfield               = 181;

    private static final int opc_invokevirtual          = 182;

    private static final int opc_invokespecial          = 183;

    private static final int opc_invokestatic           = 184;

    private static final int opc_invokeinterface        = 185;

    private static final int opc_new                    = 187;

//  private static final int opc_newarray               = 188;

    private static final int opc_anewarray              = 189;

//  private static final int opc_arraylength            = 190;

    private static final int opc_athrow                 = 191;

    private static final int opc_checkcast              = 192;

//  private static final int opc_instanceof             = 193;

//  private static final int opc_monitorenter           = 194;

//  private static final int opc_monitorexit            = 195;

    private static final int opc_wide                   = 196;

//  private static final int opc_multianewarray         = 197;

//  private static final int opc_ifnull                 = 198;

//  private static final int opc_ifnonnull              = 199;

//  private static final int opc_goto_w                 = 200;

//  private static final int opc_jsr_w                  = 201;

    // end of constants copied from sun.tools.java.RuntimeConstants

    /** name of the superclass of proxy classes */

    private static final String superclassName = "java/lang/reflect/Proxy";

    /** name of field for storing a proxy instance's invocation handler */

    private static final String handlerFieldName = "h";

    /** debugging flag for saving generated class files */

    private static final boolean saveGeneratedFiles =

        java.security.AccessController.doPrivileged(

            new GetBooleanAction(

                "jdk.proxy.ProxyGenerator.saveGeneratedFiles")).booleanValue();

    /**

     * Generate a public proxy class given a name and a list of proxy interfaces.

     */

    static byte[] generateProxyClass(final String name,

                                     Class<?>[] interfaces) {

        return generateProxyClass(name, interfaces, (ACC_PUBLIC | ACC_FINAL | ACC_SUPER));

    }

    /**

     * Generate a proxy class given a name and a list of proxy interfaces.

     *

     * @param name        the class name of the proxy class

     * @param interfaces  proxy interfaces

     * @param accessFlags access flags of the proxy class

    */

    static byte[] generateProxyClass(final String name,

                                     Class<?>[] interfaces,

                                     int accessFlags)

    {

        ProxyGenerator gen = new ProxyGenerator(name, interfaces, accessFlags);

        final byte[] classFile = gen.generateClassFile();

        if (saveGeneratedFiles) {

            java.security.AccessController.doPrivileged(

            new java.security.PrivilegedAction<Void>() {

                public Void run() {

                    try {

                        int i = name.lastIndexOf('.');

                        Path path;

                        if (i > 0) {

                            Path dir = Paths.get(name.substring(0, i).replace('.', File.separatorChar));

                            Files.createDirectories(dir);

                            path = dir.resolve(name.substring(i+1, name.length()) + ".class");

                        } else {

                            path = Paths.get(name + ".class");

                        }

                        Files.write(path, classFile);

                        return null;

                    } catch (IOException e) {

                        throw new InternalError(

                            "I/O exception saving generated file: " + e);

                    }

                }

            });

        }

        return classFile;

    }

    /* preloaded Method objects for methods in java.lang.Object */

    private static Method hashCodeMethod;

    private static Method equalsMethod;

    private static Method toStringMethod;

    static {

        try {

            hashCodeMethod = Object.class.getMethod("hashCode");

            equalsMethod =

                Object.class.getMethod("equals", new Class<?>[] { Object.class });

            toStringMethod = Object.class.getMethod("toString");

        } catch (NoSuchMethodException e) {

            throw new NoSuchMethodError(e.getMessage());

        }

    }

    /** name of proxy class */

    private String className;

    /** proxy interfaces */

    private Class<?>[] interfaces;

    /** proxy class access flags */

    private int accessFlags;

    /** constant pool of class being generated */

    private ConstantPool cp = new ConstantPool();

    /** FieldInfo struct for each field of generated class */

    private List<FieldInfo> fields = new ArrayList<>();

    /** MethodInfo struct for each method of generated class */

    private List<MethodInfo> methods = new ArrayList<>();

    /**

     * maps method signature string to list of ProxyMethod objects for

     * proxy methods with that signature

     */

    private Map<String, List<ProxyMethod>> proxyMethods = new HashMap<>();

    /** count of ProxyMethod objects added to proxyMethods */

    private int proxyMethodCount = 0;

    /**

     * Construct a ProxyGenerator to generate a proxy class with the

     * specified name and for the given interfaces.

     *

     * A ProxyGenerator object contains the state for the ongoing

     * generation of a particular proxy class.

     */

    private ProxyGenerator(String className, Class<?>[] interfaces, int accessFlags) {

        this.className = className;

        this.interfaces = interfaces;

        this.accessFlags = accessFlags;

    }

    /**

     * Generate a class file for the proxy class.  This method drives the

     * class file generation process.

     */

    private byte[] generateClassFile() {

        /* ============================================================

         * Step 1: Assemble ProxyMethod objects for all methods to

         * generate proxy dispatching code for.

         */

        /*

         * Record that proxy methods are needed for the hashCode, equals,

         * and toString methods of java.lang.Object.  This is done before

         * the methods from the proxy interfaces so that the methods from

         * java.lang.Object take precedence over duplicate methods in the

         * proxy interfaces.

         */

        addProxyMethod(hashCodeMethod, Object.class);

        addProxyMethod(equalsMethod, Object.class);

        addProxyMethod(toStringMethod, Object.class);

        /*

         * Now record all of the methods from the proxy interfaces, giving

         * earlier interfaces precedence over later ones with duplicate

         * methods.

         */

        for (Class<?> intf : interfaces) {

            for (Method m : intf.getMethods()) {

                if (!Modifier.isStatic(m.getModifiers())) {

                    addProxyMethod(m, intf);

                }

            }

        }

        /*

         * For each set of proxy methods with the same signature,

         * verify that the methods' return types are compatible.

         */

        for (List<ProxyMethod> sigmethods : proxyMethods.values()) {

            checkReturnTypes(sigmethods);

        }

        /* ============================================================

         * Step 2: Assemble FieldInfo and MethodInfo structs for all of

         * fields and methods in the class we are generating.

         */

        try {

            methods.add(generateConstructor());

            for (List<ProxyMethod> sigmethods : proxyMethods.values()) {

                for (ProxyMethod pm : sigmethods) {

                    // add static field for method's Method object

                    fields.add(new FieldInfo(pm.methodFieldName,

                        "Ljava/lang/reflect/Method;",

                         ACC_PRIVATE | ACC_STATIC));

                    // generate code for proxy method and add it

                    methods.add(pm.generateMethod());

                }

            }

            methods.add(generateStaticInitializer());

        } catch (IOException e) {

            throw new InternalError("unexpected I/O Exception", e);

        }

        if (methods.size() > 65535) {

            throw new IllegalArgumentException("method limit exceeded");

        }

        if (fields.size() > 65535) {

            throw new IllegalArgumentException("field limit exceeded");

        }

        /* ============================================================

         * Step 3: Write the final class file.

         */

        /*

         * Make sure that constant pool indexes are reserved for the

         * following items before starting to write the final class file.

         */

        cp.getClass(dotToSlash(className));

        cp.getClass(superclassName);

        for (Class<?> intf: interfaces) {

            cp.getClass(dotToSlash(intf.getName()));

        }

        /*

         * Disallow new constant pool additions beyond this point, since

         * we are about to write the final constant pool table.

         */

        cp.setReadOnly();

        ByteArrayOutputStream bout = new ByteArrayOutputStream();

        DataOutputStream dout = new DataOutputStream(bout);