/*

 * Copyright (c) 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.

 *

 * 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.

 */

import java.io.*;

import com.sun.tools.classfile.*;

/**

 * The {@code ClassFileVisitor} reads a class file using the

 * {@code com.sun.tools.classfile} library. It iterates over the methods

 * in a class, and checks MethodParameters attributes against JLS

 * requirements, as well as assumptions about the javac implementations.

 * <p>

 * It enforces the following rules:

 * <ul>

 * <li>All non-synthetic methods with arguments must have the

 * MethodParameters attribute. </li>

 * <li>At most one MethodParameters attribute per method.</li>

 * <li>An empty MethodParameters attribute is not allowed (i.e. no

 * attribute for methods taking no parameters).</li>

 * <li>The number of recorded parameter names much equal the number

 * of parameters, including any implicit or synthetic parameters generated

 * by the compiler.</li>

 * <li>Although the spec allow recording parameters with no name, the javac

 * implementation is assumed to record a name for all parameters. That is,

 * the Methodparameters attribute must record a non-zero, valid constant

 * pool index for each parameter.</li>

 * <li>Check presence, expected names (e.g. this$N, $enum$name, ...) and flags

 * (e.g. ACC_SYNTHETIC, ACC_MANDATED) for compiler generated parameters.</li>

 * <li>Names of explicit parameters must reflect the names in the Java source.

 * This is checked by assuming a design pattern where any name is permitted

 * for the first explicit parameter. For subsequent parameters the following

 * rule is checked: <i>param[n] == ++param[n-1].charAt(0) + param[n-1]</i>

 * </ul>

 */

class ClassFileVisitor extends Tester.Visitor {

    Tester tester;

    public String cname;

    public boolean isEnum;

    public boolean isInterface;

    public boolean isInner;

    public boolean isPublic;

    public boolean isStatic;

    public boolean isAnon;

    public ClassFile classFile;

    public ClassFileVisitor(Tester tester) {

        super(tester);

    }

    public void error(String msg) {

        super.error("classfile: " + msg);

    }

    public void warn(String msg) {

        super.warn("classfile: " + msg);

    }

    /**

     * Read the class and determine some key characteristics, like if it's

     * an enum, or inner class, etc.

     */

    void visitClass(final String cname, final File cfile, final StringBuilder sb) throws Exception {

        this.cname = cname;

        classFile = ClassFile.read(cfile);

        isEnum = classFile.access_flags.is(AccessFlags.ACC_ENUM);

        isInterface = classFile.access_flags.is(AccessFlags.ACC_INTERFACE);

        isPublic = classFile.access_flags.is(AccessFlags.ACC_PUBLIC);

        isInner = false;

        isStatic = false;

        isAnon = false;

        Attribute attr = classFile.getAttribute("InnerClasses");

        if (attr != null) attr.accept(new InnerClassVisitor(), null);

        isAnon = isInner & isAnon;

        sb.append(isStatic ? "static " : "")

            .append(isPublic ? "public " : "")

            .append(isEnum ? "enum " : isInterface ? "interface " : "class ")

            .append(cname).append(" -- ");

        if (isInner) {

            sb.append(isAnon ? "anon" : "inner");

        }

        sb.append("\n");

        for (Method method : classFile.methods) {

            new MethodVisitor().visitMethod(method, sb);

        }

    }

    /**

     * Used to visit InnerClasses_attribute of a class,

     * to determne if this class is an local class, and anonymous

     * inner class or a none-static member class. These types of

     * classes all have an containing class instances field that

     * requires an implicit or synthetic constructor argument.

     */

    class InnerClassVisitor extends AttributeVisitor<Void, Void> {

        public Void visitInnerClasses(InnerClasses_attribute iattr, Void v) {

            try{

                for (InnerClasses_attribute.Info info : iattr.classes) {

                    if (info.getInnerClassInfo(classFile.constant_pool) == null) continue;

                    String in = info.getInnerClassInfo(classFile.constant_pool).getName();

                    if (in == null || !cname.equals(in)) continue;

                    isInner = true;

                    isAnon = null == info.getInnerName(classFile.constant_pool);

                    isStatic = info.inner_class_access_flags.is(AccessFlags.ACC_STATIC);

                    break;

                }

            } catch(Exception e) {

                throw new IllegalStateException(e);

            }

            return null;

        }

    }

    /**

     * Check the MethodParameters attribute of a method.

     */

    class MethodVisitor extends AttributeVisitor<Void, StringBuilder> {

        public String mName;

        public Descriptor mDesc;

        public int mParams;

        public int mAttrs;

        public int mNumParams;

        public boolean mSynthetic;

        public boolean mIsConstructor;

        public boolean mIsClinit;

        public boolean mIsBridge;

        public boolean isFinal;

        public String prefix;

        void visitMethod(Method method, StringBuilder sb) throws Exception {

            mName = method.getName(classFile.constant_pool);

            mDesc = method.descriptor;

            mParams =  mDesc.getParameterCount(classFile.constant_pool);

            mAttrs = method.attributes.attrs.length;

            mNumParams = -1; // no MethodParameters attribute found

            mSynthetic = method.access_flags.is(AccessFlags.ACC_SYNTHETIC);

            mIsConstructor = mName.equals("<init>");

            mIsClinit = mName.equals("<clinit>");

            prefix = cname + "." + mName + "() - ";

            mIsBridge = method.access_flags.is(AccessFlags.ACC_BRIDGE);

            if (mIsClinit) {

                sb = new StringBuilder(); // Discard output

            }

            sb.append(cname).append(".").append(mName).append("(");

            for (Attribute a : method.attributes) {

                a.accept(this, sb);

            }

            if (mNumParams == -1) {

                if (mSynthetic) {

                    // We don't generate MethodParameters attribute for synthetic

                    // methods, so we are creating a parameter pattern to match

                    // ReflectionVisitor API output.

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

                        if (i == 0)

                            sb.append("arg").append(i);

                        else

                            sb.append(", arg").append(i);

                    }

                    sb.append(")/*synthetic*/");

                } else {

                    sb.append(")");

                }

            }

            sb.append("\n");

            // IMPL: methods with arguments must have a MethodParameters

            // attribute, except possibly some synthetic methods.

            if (mNumParams == -1 && mParams > 0 && ! mSynthetic) {

                error(prefix + "missing MethodParameters attribute");

            }

        }

        public Void visitMethodParameters(MethodParameters_attribute mp,

                                          StringBuilder sb) {

            // SPEC: At most one MethodParameters attribute allowed

            if (mNumParams != -1) {

                error(prefix + "Multiple MethodParameters attributes");

                return null;

            }

            mNumParams = mp.method_parameter_table_length;

            // SPEC: An empty attribute is not allowed!

            if (mNumParams == 0) {

                error(prefix + "0 length MethodParameters attribute");

                return null;

            }

            // SPEC: one name per parameter.

            if (mNumParams != mParams) {

                error(prefix + "found " + mNumParams +

                      " parameters, expected " + mParams);

                return null;

            }

            // IMPL: Whether MethodParameters attributes will be generated

            // for some synthetics is unresolved. For now, assume no.

            if (mSynthetic) {

                warn(prefix + "synthetic has MethodParameter attribute");

            }

            String sep = "";

            String userParam = null;

            for (int x = 0; x <  mNumParams; x++) {

                isFinal = (mp.method_parameter_table[x].flags & AccessFlags.ACC_FINAL) != 0;

                // IMPL: Assume all parameters are named, something.

                int cpi = mp.method_parameter_table[x].name_index;

                if (cpi == 0) {

                    error(prefix + "name expected, param[" + x + "]");

                    return null;

                }

                // SPEC: a non 0 index, must be valid!

                String param = null;

                try {

                    param = classFile.constant_pool.getUTF8Value(cpi);

                    if (isFinal)

                        param = "final " + param;

                    sb.append(sep).append(param);

                    sep = ", ";

                } catch(ConstantPoolException e) {

                    error(prefix + "invalid index " + cpi + " for param["

                          + x + "]");

                    return null;

                }

                // Check availability, flags and special names

                int check = checkParam(mp, param, x, sb, isFinal);

                if (check < 0) {

                    return null;

                }

                // TEST: check test assumptions about parameter name.

                // Expected names are calculated starting with the

                // 2nd explicit (user given) parameter.

                // param[n] == ++param[n-1].charAt(0) + param[n-1]

                String expect = null;

                if (userParam != null) {

                    char c = userParam.charAt(0);

                    expect =  (++c) + userParam;

                }

                if(isFinal && expect != null)

                    expect = "final " + expect;

                if (check > 0) {

                    if(isFinal) {

                        userParam = param.substring(6);

                    } else {

                    userParam = param;

                }

                }

                if (expect != null && !param.equals(expect)) {

                    error(prefix + "param[" + x + "]='"

                          + param + "' expected '" + expect + "'");

                    return null;

                }

            }

            if (mSynthetic) {

                sb.append(")/*synthetic*/");

            } else {

                sb.append(")");

            }

            return null;

        }

        /*

         * Check a parameter for conformity to JLS and javac specific

         * assumptions.

         * Return -1, if an error is detected. Otherwise, return 0, if

         * the parameter is compiler generated, or 1 for an (presumably)

         * explicitly declared parameter.

         */

        int checkParam(MethodParameters_attribute mp, String param, int index,

                       StringBuilder sb, boolean isFinal) {

            boolean synthetic = (mp.method_parameter_table[index].flags

                                 & AccessFlags.ACC_SYNTHETIC) != 0;

            boolean mandated = (mp.method_parameter_table[index].flags

                                & AccessFlags.ACC_MANDATED) != 0;

            // Setup expectations for flags and special names

            String expect = null;

            boolean allowMandated = false;

            boolean allowSynthetic = false;

            if (mSynthetic || synthetic) {

                // not an implementation gurantee, but okay for now

                expect = "arg" + index; // default

            }

            if (mIsConstructor) {

                if (isEnum) {

                    if (index == 0) {

                        expect = "\\$enum\\$name";

                        allowSynthetic = true;

                    } else if(index == 1) {

                        expect = "\\$enum\\$ordinal";

                        allowSynthetic = true;

                    }

                } else if (index == 0) {

                    if (isAnon) {

                        expect = "this\\$[0-9]+";

                        allowMandated = true;

                        if (isFinal) {

                            expect = "final this\\$[0-9]+";

                        }

                    } else if (isInner && !isStatic) {

                        expect = "this\\$[0-9]+";

                        allowMandated = true;

                        if (!isPublic) {

                            // some but not all non-public inner classes

                            // have synthetic argument. For now we give

                            // the test a bit of slack and allow either.

                            allowSynthetic = true;

                        }

                        if (isFinal) {

                            expect = "final this\\$[0-9]+";

                        }

                    }

                }

            } else if (isEnum && mNumParams == 1 && index == 0 && mName.equals("valueOf")) {

                expect = "name";

                allowMandated = true;

            } else if (mIsBridge) {

                allowSynthetic = true;

                /*  you can't expect an special name for bridges' parameters.

                 *  The name of the original parameters are now copied.

                 */

                expect = null;

            }

            if (mandated) sb.append("/*implicit*/");

            if (synthetic) sb.append("/*synthetic*/");

            // IMPL: our rules a somewhat fuzzy, sometimes allowing both mandated

            // and synthetic. However, a parameters cannot be both.

            if (mandated && synthetic) {

                error(prefix + "param[" + index + "] == \"" + param

                      + "\" ACC_SYNTHETIC and ACC_MANDATED");

                return -1;

            }

            // ... but must be either, if both "allowed".

            if (!(mandated || synthetic) && allowMandated && allowSynthetic) {

                error(prefix + "param[" + index + "] == \"" + param

                      + "\" expected ACC_MANDATED or ACC_SYNTHETIC");

                return -1;

            }

            // ... if only one is "allowed", we meant "required".

            if (!mandated && allowMandated && !allowSynthetic) {

                error(prefix + "param[" + index + "] == \"" + param

                      + "\" expected ACC_MANDATED");

                return -1;

            }

            if (!synthetic && !allowMandated && allowSynthetic) {

                error(prefix + "param[" + index + "] == \"" + param

                      + "\" expected ACC_SYNTHETIC");

                return -1;

            }

            // ... and not "allowed", means prohibited.

            if (mandated && !allowMandated) {

                error(prefix + "param[" + index + "] == \"" + param

                      + "\" unexpected, is ACC_MANDATED");

                return -1;

            }

            if (synthetic && !allowSynthetic) {

                error(prefix + "param[" + index + "] == \"" + param

                      + "\" unexpected, is ACC_SYNTHETIC");

                return -1;

            }

            // Test special name expectations

            if (expect != null) {

                if (param.matches(expect)) {

                    return 0;

                }

                error(prefix + "param[" + index + "]='" + param +

                      "' expected '" + expect + "'");

                return -1;

            }

            // No further checking for synthetic methods.

            if (mSynthetic) {

                return 0;

            }

            // Otherwise, do check test parameter naming convention.

            return 1;

        }

    }

}