//////////////////////////////////////////////////////////////////////////////
// Clirr: compares two versions of a java library for binary compatibility
// Copyright (C) 2003 - 2005  Lars Kühne
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//////////////////////////////////////////////////////////////////////////////

package net.sf.clirr.core.internal.checks;

import net.sf.clirr.core.Severity;
import net.sf.clirr.core.Message;
import net.sf.clirr.core.internal.AbstractDiffReporter;
import net.sf.clirr.core.internal.ApiDiffDispatcher;
import net.sf.clirr.core.internal.ClassChangeCheck;
import net.sf.clirr.core.spi.JavaType;
import net.sf.clirr.core.spi.Method;
import net.sf.clirr.core.spi.Scope;

/**
 * Detects changes in class modifiers (abstract, final).
 *
 * @author lkuehne
 */
public final class ClassModifierCheck
    extends AbstractDiffReporter
    implements ClassChangeCheck
{
    private static final Message MSG_MODIFIER_UNABLE_TO_DETERMINE_CLASS_SCOPE = new Message(3000);
    private static final Message MSG_MODIFIER_REMOVED_FINAL = new Message(3001);
    private static final Message MSG_MODIFIER_ADDED_FINAL_TO_EFFECTIVE_FINAL = new Message(3002);
    private static final Message MSG_MODIFIER_ADDED_FINAL = new Message(3003);
    private static final Message MSG_MODIFIER_REMOVED_ABSTRACT = new Message(3004);
    private static final Message MSG_MODIFIER_ADDED_ABSTRACT = new Message(3005);

    /**
     * Create a new instance of this check.
     * @param dispatcher the diff dispatcher that distributes the detected changes to the listeners.
     */
    public ClassModifierCheck(ApiDiffDispatcher dispatcher)
    {
        super(dispatcher);
    }

    /** {@inheritDoc} */
    public boolean check(JavaType compatBaseLine, JavaType currentVersion)
    {
        final String className = compatBaseLine.getName();

        Scope currentScope = currentVersion.getEffectiveScope();
        if (currentScope.isLessVisibleThan(Scope.PACKAGE))
        {
            // for private classes, we don't care if they are now final,
            // or now abstract, or now an interface.
            return true;
        }

        final boolean currentIsFinal = currentVersion.isFinal();
        final boolean compatIsFinal = compatBaseLine.isFinal();
        final boolean currentIsAbstract = currentVersion.isAbstract();
        final boolean compatIsAbstract = compatBaseLine.isAbstract();
        final boolean currentIsInterface = currentVersion.isInterface();
        final boolean compatIsInterface = compatBaseLine.isInterface();

        if (compatIsFinal && !currentIsFinal)
        {
            log(MSG_MODIFIER_REMOVED_FINAL,
                    Severity.INFO, className, null, null, null);
        }
        else if (!compatIsFinal && currentIsFinal)
        {
            if (isEffectivelyFinal(compatBaseLine))
            {
                log(MSG_MODIFIER_ADDED_FINAL_TO_EFFECTIVE_FINAL,
                        Severity.INFO, className, null, null, null);
            }
            else
            {
                log(MSG_MODIFIER_ADDED_FINAL,
                        getSeverity(compatBaseLine, Severity.ERROR),
                        className, null, null, null);
            }
        }

        // interfaces are always abstract, don't report gender change here
        if (compatIsAbstract && !currentIsAbstract && !compatIsInterface)
        {
            log(MSG_MODIFIER_REMOVED_ABSTRACT,
                    Severity.INFO, className, null, null, null);
        }
        else if (!compatIsAbstract && currentIsAbstract && !currentIsInterface)
        {
            log(MSG_MODIFIER_ADDED_ABSTRACT,
                    getSeverity(compatBaseLine, Severity.ERROR),
                    className, null, null, null);
        }

        return true;
    }

    /**
     * There are cases where nonfinal classes are effectively final
     * because they do not have public or protected ctors. For such
     * classes we should not emit errors when a final modifier is
     * introduced.
     */
    private boolean isEffectivelyFinal(JavaType clazz)
    {
        if (clazz.isFinal())
        {
            return true;
        }

        // iterate over all constructors, and detect whether any are
        // public or protected. If so, return false.
        Method[] methods = clazz.getMethods();
        for (int i = 0; i < methods.length; ++i)
        {
            Method method = methods[i];
            final String methodName = method.getName();
            if (methodName.equals("<init>"))
            {
                if (method.getEffectiveScope().isMoreVisibleThan(Scope.PACKAGE))
                {
                    return false;
                }
            }
        }

        // no public or protected constructor found
        return true;
    }
}
