/*
 * 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.
 */

/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file:
 *
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

package jdk.internal.org.objectweb.asm.tree.analysis;

import java.util.List;
import jdk.internal.org.objectweb.asm.Opcodes;
import jdk.internal.org.objectweb.asm.Type;

/**
 * An extended {@link BasicVerifier} that performs more precise verifications. This verifier
 * computes exact class types, instead of using a single "object reference" type (as done in {@link
 * BasicVerifier}).
 *
 * @author Eric Bruneton
 * @author Bing Ran
 */
public class SimpleVerifier extends BasicVerifier {

    /** The type of the class that is verified. */
    private final Type currentClass;

    /** The type of the super class of the class that is verified. */
    private final Type currentSuperClass;

    /** The types of the interfaces directly implemented by the class that is verified. */
    private final List<Type> currentClassInterfaces;

    /** Whether the class that is verified is an interface. */
    private final boolean isInterface;

    /** The loader to use to load the referenced classes. */
    private ClassLoader loader = getClass().getClassLoader();

    /**
      * Constructs a new {@link SimpleVerifier}. <i>Subclasses must not use this constructor</i>.
      * Instead, they must use the {@link #SimpleVerifier(int, Type, Type, List, boolean)} version.
      */
    public SimpleVerifier() {
        this(null, null, false);
    }

    /**
      * Constructs a new {@link SimpleVerifier} to verify a specific class. This class will not be
      * loaded into the JVM since it may be incorrect. <i>Subclasses must not use this constructor</i>.
      * Instead, they must use the {@link #SimpleVerifier(int, Type, Type, List, boolean)} version.
      *
      * @param currentClass the type of the class to be verified.
      * @param currentSuperClass the type of the super class of the class to be verified.
      * @param isInterface whether the class to be verifier is an interface.
      */
    public SimpleVerifier(
            final Type currentClass, final Type currentSuperClass, final boolean isInterface) {
        this(currentClass, currentSuperClass, null, isInterface);
    }

    /**
      * Constructs a new {@link SimpleVerifier} to verify a specific class. This class will not be
      * loaded into the JVM since it may be incorrect. <i>Subclasses must not use this constructor</i>.
      * Instead, they must use the {@link #SimpleVerifier(int, Type, Type, List, boolean)} version.
      *
      * @param currentClass the type of the class to be verified.
      * @param currentSuperClass the type of the super class of the class to be verified.
      * @param currentClassInterfaces the types of the interfaces directly implemented by the class to
      *     be verified.
      * @param isInterface whether the class to be verifier is an interface.
      */
    public SimpleVerifier(
            final Type currentClass,
            final Type currentSuperClass,
            final List<Type> currentClassInterfaces,
            final boolean isInterface) {
        this(
                /* latest api = */ ASM9,
                currentClass,
                currentSuperClass,
                currentClassInterfaces,
                isInterface);
        if (getClass() != SimpleVerifier.class) {
            throw new IllegalStateException();
        }
    }

    /**
      * Constructs a new {@link SimpleVerifier} to verify a specific class. This class will not be
      * loaded into the JVM since it may be incorrect.
      *
      * @param api the ASM API version supported by this verifier. Must be one of the {@code
      *     ASM}<i>x</i> values in {@link Opcodes}.
      * @param currentClass the type of the class to be verified.
      * @param currentSuperClass the type of the super class of the class to be verified.
      * @param currentClassInterfaces the types of the interfaces directly implemented by the class to
      *     be verified.
      * @param isInterface whether the class to be verifier is an interface.
      */
    protected SimpleVerifier(
            final int api,
            final Type currentClass,
            final Type currentSuperClass,
            final List<Type> currentClassInterfaces,
            final boolean isInterface) {
        super(api);
        this.currentClass = currentClass;
        this.currentSuperClass = currentSuperClass;
        this.currentClassInterfaces = currentClassInterfaces;
        this.isInterface = isInterface;
    }

    /**
      * Sets the <code>ClassLoader</code> to be used in {@link #getClass}.
      *
      * @param loader the <code>ClassLoader</code> to use.
      */
    public void setClassLoader(final ClassLoader loader) {
        this.loader = loader;
    }

    @Override
    public BasicValue newValue(final Type type) {
        if (type == null) {
            return BasicValue.UNINITIALIZED_VALUE;
        }

        boolean isArray = type.getSort() == Type.ARRAY;
        if (isArray) {
            switch (type.getElementType().getSort()) {
                case Type.BOOLEAN:
                case Type.CHAR:
                case Type.BYTE:
                case Type.SHORT:
                    return new BasicValue(type);
                default:
                    break;
            }
        }

        BasicValue value = super.newValue(type);
        if (BasicValue.REFERENCE_VALUE.equals(value)) {
            if (isArray) {
                value = newValue(type.getElementType());
                StringBuilder descriptor = new StringBuilder();
                for (int i = 0; i < type.getDimensions(); ++i) {
                    descriptor.append('[');
                }
                descriptor.append(value.getType().getDescriptor());
                value = new BasicValue(Type.getType(descriptor.toString()));
            } else {
                value = new BasicValue(type);
            }
        }
        return value;
    }

    @Override
    protected boolean isArrayValue(final BasicValue value) {
        Type type = value.getType();
        return type != null && (type.getSort() == Type.ARRAY || type.equals(NULL_TYPE));
    }

    @Override
    protected BasicValue getElementValue(final BasicValue objectArrayValue) throws AnalyzerException {
        Type arrayType = objectArrayValue.getType();
        if (arrayType != null) {
            if (arrayType.getSort() == Type.ARRAY) {
                return newValue(Type.getType(arrayType.getDescriptor().substring(1)));
            } else if (arrayType.equals(NULL_TYPE)) {
                return objectArrayValue;
            }
        }
        throw new AssertionError();
    }

    @Override
    protected boolean isSubTypeOf(final BasicValue value, final BasicValue expected) {
        Type expectedType = expected.getType();
        Type type = value.getType();
        switch (expectedType.getSort()) {
            case Type.INT:
            case Type.FLOAT:
            case Type.LONG:
            case Type.DOUBLE:
                return type.equals(expectedType);
            case Type.ARRAY:
            case Type.OBJECT:
                if (type.equals(NULL_TYPE)) {
                    return true;
                } else if (type.getSort() == Type.OBJECT || type.getSort() == Type.ARRAY) {
                    if (isAssignableFrom(expectedType, type)) {
                        return true;
                    } else if (getClass(expectedType).isInterface()) {
                        // The merge of class or interface types can only yield class types (because it is not
                        // possible in general to find an unambiguous common super interface, due to multiple
                        // inheritance). Because of this limitation, we need to relax the subtyping check here
                        // if 'value' is an interface.
                        return Object.class.isAssignableFrom(getClass(type));
                    } else {
                        return false;
                    }
                } else {
                    return false;
                }
            default:
                throw new AssertionError();
        }
    }

    @Override
    public BasicValue merge(final BasicValue value1, final BasicValue value2) {
        if (!value1.equals(value2)) {
            Type type1 = value1.getType();
            Type type2 = value2.getType();
            if (type1 != null
                    && (type1.getSort() == Type.OBJECT || type1.getSort() == Type.ARRAY)
                    && type2 != null
                    && (type2.getSort() == Type.OBJECT || type2.getSort() == Type.ARRAY)) {
                if (type1.equals(NULL_TYPE)) {
                    return value2;
                }
                if (type2.equals(NULL_TYPE)) {
                    return value1;
                }
                if (isAssignableFrom(type1, type2)) {
                    return value1;
                }
                if (isAssignableFrom(type2, type1)) {
                    return value2;
                }
                int numDimensions = 0;
                if (type1.getSort() == Type.ARRAY
                        && type2.getSort() == Type.ARRAY
                        && type1.getDimensions() == type2.getDimensions()
                        && type1.getElementType().getSort() == Type.OBJECT
                        && type2.getElementType().getSort() == Type.OBJECT) {
                    numDimensions = type1.getDimensions();
                    type1 = type1.getElementType();
                    type2 = type2.getElementType();
                }
                while (true) {
                    if (type1 == null || isInterface(type1)) {
                        return newArrayValue(Type.getObjectType("java/lang/Object"), numDimensions);
                    }
                    type1 = getSuperClass(type1);
                    if (isAssignableFrom(type1, type2)) {
                        return newArrayValue(type1, numDimensions);
                    }
                }
            }
            return BasicValue.UNINITIALIZED_VALUE;
        }
        return value1;
    }

    private BasicValue newArrayValue(final Type type, final int dimensions) {
        if (dimensions == 0) {
            return newValue(type);
        } else {
            StringBuilder descriptor = new StringBuilder();
            for (int i = 0; i < dimensions; ++i) {
                descriptor.append('[');
            }
            descriptor.append(type.getDescriptor());
            return newValue(Type.getType(descriptor.toString()));
        }
    }

    /**
      * Returns whether the given type corresponds to the type of an interface. The default
      * implementation of this method loads the class and uses the reflection API to return its result
      * (unless the given type corresponds to the class being verified).
      *
      * @param type a type.
      * @return whether 'type' corresponds to an interface.
      */
    protected boolean isInterface(final Type type) {
        if (currentClass != null && currentClass.equals(type)) {
            return isInterface;
        }
        return getClass(type).isInterface();
    }

    /**
      * Returns the type corresponding to the super class of the given type. The default implementation
      * of this method loads the class and uses the reflection API to return its result (unless the
      * given type corresponds to the class being verified).
      *
      * @param type a type.
      * @return the type corresponding to the super class of 'type'.
      */
    protected Type getSuperClass(final Type type) {
        if (currentClass != null && currentClass.equals(type)) {
            return currentSuperClass;
        }
        Class<?> superClass = getClass(type).getSuperclass();
        return superClass == null ? null : Type.getType(superClass);
    }

    /**
      * Returns whether the class corresponding to the first argument is either the same as, or is a
      * superclass or superinterface of the class corresponding to the second argument. The default
      * implementation of this method loads the classes and uses the reflection API to return its
      * result (unless the result can be computed from the class being verified, and the types of its
      * super classes and implemented interfaces).
      *
      * @param type1 a type.
      * @param type2 another type.
      * @return whether the class corresponding to 'type1' is either the same as, or is a superclass or
      *     superinterface of the class corresponding to 'type2'.
      */
    protected boolean isAssignableFrom(final Type type1, final Type type2) {
        if (type1.equals(type2)) {
            return true;
        }
        if (currentClass != null && currentClass.equals(type1)) {
            if (getSuperClass(type2) == null) {
                return false;
            } else {
                if (isInterface) {
                    return type2.getSort() == Type.OBJECT || type2.getSort() == Type.ARRAY;
                }
                return isAssignableFrom(type1, getSuperClass(type2));
            }
        }
        if (currentClass != null && currentClass.equals(type2)) {
            if (isAssignableFrom(type1, currentSuperClass)) {
                return true;
            }
            if (currentClassInterfaces != null) {
                for (Type currentClassInterface : currentClassInterfaces) {
                    if (isAssignableFrom(type1, currentClassInterface)) {
                        return true;
                    }
                }
            }
            return false;
        }
        return getClass(type1).isAssignableFrom(getClass(type2));
    }

    /**
      * Loads the class corresponding to the given type. The class is loaded with the class loader
      * specified with {@link #setClassLoader}, or with the class loader of this class if no class
      * loader was specified.
      *
      * @param type a type.
      * @return the class corresponding to 'type'.
      */
    protected Class<?> getClass(final Type type) {
        try {
            if (type.getSort() == Type.ARRAY) {
                return Class.forName(type.getDescriptor().replace('/', '.'), false, loader);
            }
            return Class.forName(type.getClassName(), false, loader);
        } catch (ClassNotFoundException e) {
            throw new TypeNotPresentException(e.toString(), e);
        }
    }
}
