/*

 * Copyright (c) 2009, 2019, 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.

 *

 */

package invokevirtual;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

public class Checker extends shared.Checker {

    public Checker(Class staticTargetClass, Class dynamicTargetClass) {

        super(staticTargetClass, dynamicTargetClass);

    }

    public String check (Class callerClass) {

        Method m;

        try {

            // May cause java.lang.VerifyError

            m = getOverriddenMethod();

        } catch (Throwable e) {

            return e.getClass().getName();

        }

        // Check method accessibility (it's a static property, according to JLS #6.6: Access Control)

        if (m != null) {

            Method staticTargetMethod = getDeclaredMethod(staticTargetClass);

            if (checkAccess(staticTargetMethod, callerClass)) {

                // Can't invoke abstract method

                if ( Modifier.isAbstract(m.getModifiers())) {

                    return "java.lang.AbstractMethodError";

                }

                return String.format("%s.%s"

                        , m.getDeclaringClass().getSimpleName()

                        , methodName

                        );

            } else {

                // if method isn't accessible, IllegalAccessError is thrown

                return "java.lang.IllegalAccessError";

            }

        } else {

            // if method == null, NoSuchMethodError is thrown

            return "java.lang.NoSuchMethodError";

        }

    }

    public Method getOverriddenMethod() {

        return getOverriddenMethod(staticTargetClass, dynamicTargetClass);

    }

    public Method getOverriddenMethod(Class staticTarget, Class dynamicTarget) {

        // Assertion #1. C is a subclass of A

        if (!staticTarget.isAssignableFrom(dynamicTarget)) {

            return null;

        }

        Method staticTargetMethod = getDeclaredMethod(staticTarget);

        Method dynamicTargetMethod = getDeclaredMethod(dynamicTarget);

        if (staticTarget.equals(dynamicTarget)) {

            return staticTargetMethod;

        }

        // TODO: ? need to find out the right behavior

        if (staticTargetMethod == null) {

            return null;

        }

        // Dynamic target doesn't have desired method, so check its superclass

        if (dynamicTargetMethod == null) {

            return getOverriddenMethod(staticTarget, dynamicTarget.getSuperclass());

        } else {

            // Private method can't override anything

            if (Modifier.isPrivate(dynamicTargetMethod.getModifiers())) {

                return getOverriddenMethod(staticTarget, dynamicTarget.getSuperclass());

            }

        }

        // TODO: abstract methods

        //Assertion #3.a: A.m2 is PUB || PROT || (PP && PKG(A) == PKG(C))

        int staticTargetModifiers = staticTargetMethod.getModifiers();

        {

            boolean isPublic = Modifier.isPublic(staticTargetModifiers);

            boolean isProtected = Modifier.isProtected(staticTargetModifiers);

            boolean isPrivate = Modifier.isPrivate(staticTargetModifiers) ;

            String staticTargetPkg = getClassPackageName(staticTarget);

            String dynamicTargetPkg = getClassPackageName(dynamicTarget);

            if (isPublic || isProtected

                || (!isPublic && !isProtected && !isPrivate

                    && staticTargetPkg.equals(dynamicTargetPkg))) {

                return dynamicTargetMethod;

            }

        }

        // OR

        //Assertion #3.b: exists m3: C.m1 != B.m3, A.m2 != B.m3, B.m3 overrides A.m2, C.m1 overrides B.m3

        Class ancestor = dynamicTarget.getSuperclass();

        while (ancestor != staticTarget) {

            Method OverriddenM2 = getOverriddenMethod(staticTarget, ancestor);

            Method m3 = getDeclaredMethod(ancestor);

            Method m1 = getOverriddenMethod(ancestor, dynamicTarget);

            if (m1 != null && m3 != null) {

                if (m1.equals(dynamicTargetMethod) && m3.equals(OverriddenM2)) {

                    return dynamicTargetMethod;

                }

            } else {

                if (m1 == null && dynamicTargetMethod == null

                    && m3 == null && OverriddenM2 == null)

                {

                    return null;

                }

            }

            ancestor = ancestor.getSuperclass();

        }

        return getOverriddenMethod(staticTarget, dynamicTarget.getSuperclass());

    }

}