/*
 * Copyright (c) 2003, 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.  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.
 */

package sun.reflect.generics.repository;

import java.lang.reflect.Type;
import java.util.IdentityHashMap;
import java.util.Map;
import java.util.function.Function;

import sun.reflect.generics.factory.GenericsFactory;
import sun.reflect.generics.tree.ClassSignature;
import sun.reflect.generics.tree.TypeTree;
import sun.reflect.generics.visitor.Reifier;
import sun.reflect.generics.parser.SignatureParser;


/**
 * This class represents the generic type information for a class.
 * The code is not dependent on a particular reflective implementation.
 * It is designed to be used unchanged by at least core reflection and JDI.
 */
public class ClassRepository extends GenericDeclRepository<ClassSignature> {

    public static final ClassRepository NONE = ClassRepository.make("Ljava/lang/Object;", null);

    /** The generic superclass info.  Lazily initialized. */
    private volatile Type superclass;

    /** The generic superinterface info.  Lazily initialized. */
    private volatile Type[] superInterfaces;

 // private, to enforce use of static factory
    private ClassRepository(String rawSig, GenericsFactory f) {
        super(rawSig, f);
    }

    protected ClassSignature parse(String s) {
        return SignatureParser.make().parseClassSig(s);
    }

    /**
     * Static factory method.
     * @param rawSig - the generic signature of the reflective object
     * that this repository is servicing
     * @param f - a factory that will provide instances of reflective
     * objects when this repository converts its AST
     * @return a <tt>ClassRepository</tt> that manages the generic type
     * information represented in the signature <tt>rawSig</tt>
     */
    public static ClassRepository make(String rawSig, GenericsFactory f) {
        return new ClassRepository(rawSig, f);
    }

 /*
 * When queried for a particular piece of type information, the
 * general pattern is to consult the corresponding cached value.
 * If the corresponding field is non-null, it is returned.
 * If not, it is created lazily. This is done by selecting the appropriate
 * part of the tree and transforming it into a reflective object
 * using a visitor, which is created by feeding it the factory
 * with which the repository was created.
 */

    public Type getSuperclass() {
        Type value = superclass;
        if (value == null) {
            value = computeSuperclass();
            superclass = value;
        }
        return value;
    }

    public Type[] getSuperInterfaces() {
        Type[] value = superInterfaces;
        if (value == null) {
            value = computeSuperInterfaces();
            superInterfaces = value;
        }
        return value.clone();
    }

    private volatile Map<Object, Object> derivatives;
    private static final Object nullDerivative = new Object();

    public <D> D getDerivative(Class<?> clazz, Object key,
                               Function<Class<?>, ? extends D> function) {
        Map<Object, Object> dm = derivatives;
        Object d = (dm == null) ? null : dm.get(key);
        if (d == null) {
            d = function.apply(clazz);
            if (d == null) d = nullDerivative;
            // re-read derivatives reference to minimize the chance of
            // loosing concurrent updates...
            dm = derivatives;
            Map<Object, Object> newDm = new IdentityHashMap<>(
                (dm == null) ? 1 : dm.size() + 1);
            newDm.put(key, d);
            if (dm != null) newDm.putAll(dm);
            derivatives = newDm;
        }
        @SuppressWarnings("unchecked")
        D derivative = (d == nullDerivative) ? null : (D) d;
        return derivative;
    }

    private Type computeSuperclass() {
        Reifier r = getReifier(); // obtain visitor
        // Extract superclass subtree from AST and reify
        getTree().getSuperclass().accept(r);
        return r.getResult();
    }

    private Type[] computeSuperInterfaces() {
        // first, extract super interface subtree(s) from AST
        TypeTree[] ts = getTree().getSuperInterfaces();
        // create array to store reified subtree(s)
        int length = ts.length;
        Type[] superInterfaces = new Type[length];
        // reify all subtrees
        for (int i = 0; i < length; i++) {
            Reifier r = getReifier(); // obtain visitor
            ts[i].accept(r);// reify subtree
            // extract result from visitor and store it
            superInterfaces[i] = r.getResult();
        }
        return superInterfaces;
    }
}