/*
 * Bytecode analysis framework
 * Copyright (C) 2005, University of Maryland
 *
 * 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 edu.umd.cs.findbugs.ba.type;

import java.util.HashSet;
import java.util.Iterator;

import org.apache.bcel.classfile.ClassFormatException;
import org.apache.bcel.generic.ReferenceType;
import org.apache.bcel.generic.Type;

import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.Hierarchy;
import edu.umd.cs.findbugs.ba.ch.Subtypes2;

/**
 * Field property storing the types of values stored in a field. The idea is
 * that we may be able to determine a more precise type for values loaded from
 * the field than the field type alone would indicate.
 * 
 * @author David Hovemeyer
 */
public class FieldStoreType {
    private HashSet<String> typeSignatureSet;

    private ReferenceType loadType;

    public FieldStoreType() {
        this.typeSignatureSet = new HashSet<String>();
    }

    // TODO: type may be exact
    public void addTypeSignature(String signature) {
        loadType = null;
        typeSignatureSet.add(signature);
    }

    public Iterator<String> signatureIterator() {
        return typeSignatureSet.iterator();
    }

    public ReferenceType getLoadType(ReferenceType fieldType) {
        if (loadType == null) {
            computeLoadType(fieldType);
        }
        return loadType;
    }

    private void computeLoadType(ReferenceType fieldType) {
        ReferenceType leastSupertype = null;

        for (Iterator<String> i = signatureIterator(); i.hasNext();) {
            try {
                String signature = i.next();
                Type type = Type.getType(signature);
                if (!(type instanceof ReferenceType))
                    continue;

                // FIXME: this will mangle interface types, since
                // getFirstCommonSuperclass() ignores interfaces.
                /*
                 * leastSupertype = (leastSupertype == null) ? (ReferenceType)
                 * type :
                 * leastSupertype.getFirstCommonSuperclass((ReferenceType)
                 * type);
                 */
                if (leastSupertype == null) {
                    leastSupertype = (ReferenceType) type;
                } else {
                    if (Subtypes2.ENABLE_SUBTYPES2_FOR_COMMON_SUPERCLASS_QUERIES) {
                        leastSupertype = AnalysisContext.currentAnalysisContext().getSubtypes2()
                                .getFirstCommonSuperclass(leastSupertype, (ReferenceType) type);
                    } else {
                        leastSupertype = leastSupertype.getFirstCommonSuperclass((ReferenceType) type);
                    }
                }

            } catch (ClassFormatException e) {
                // Bad signature: ignore
            } catch (ClassNotFoundException e) {
                AnalysisContext.reportMissingClass(e);
            }
        }

        try {
            if (leastSupertype != null && Hierarchy.isSubtype(leastSupertype, fieldType))
                loadType = leastSupertype;
        } catch (ClassNotFoundException e) {
            AnalysisContext.reportMissingClass(e);
        }

        if (loadType == null)
            loadType = fieldType;
    }
}
