/*

 * Copyright (c) 2018, 2020, 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

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 */

package java.lang.constant;

import java.lang.invoke.MethodHandles;

import static java.lang.constant.ConstantUtils.dropFirstAndLastChar;

import static java.lang.constant.ConstantUtils.internalToBinary;

import static java.util.Objects.requireNonNull;

/**

 * A <a href="package-summary.html#nominal">nominal descriptor</a> for a class,

 * interface, or array type.  A {@linkplain ReferenceClassDescImpl} corresponds to a

 * {@code Constant_Class_info} entry in the constant pool of a classfile.

 */

final class ReferenceClassDescImpl implements ClassDesc {

    private final String descriptor;

    /**

     * Creates a {@linkplain ClassDesc} from a descriptor string for a class or

     * interface type

     *

     * @param descriptor a field descriptor string for a class or interface type

     * @throws IllegalArgumentException if the descriptor string is not a valid

     * field descriptor string, or does not describe a class or interface type

     * @jvms 4.3.2 Field Descriptors

     */

    ReferenceClassDescImpl(String descriptor) {

        requireNonNull(descriptor);

        int len = ConstantUtils.skipOverFieldSignature(descriptor, 0, descriptor.length(), false);

        if (len == 0 || len == 1

            || len != descriptor.length())

            throw new IllegalArgumentException(String.format("not a valid reference type descriptor: %s", descriptor));

        this.descriptor = descriptor;

    }

    @Override

    public String descriptorString() {

        return descriptor;

    }

    @Override

    public Class<?> resolveConstantDesc(MethodHandles.Lookup lookup)

            throws ReflectiveOperationException {

        ClassDesc c = this;

        int depth = ConstantUtils.arrayDepth(descriptorString());

        for (int i=0; i<depth; i++)

            c = c.componentType();

        if (c.isPrimitive())

            return lookup.findClass(descriptorString());

        else {

            Class<?> clazz = lookup.findClass(internalToBinary(dropFirstAndLastChar(c.descriptorString())));

            for (int i = 0; i < depth; i++)

                clazz = clazz.arrayType();

            return clazz;

        }

    }

    /**

     * Returns {@code true} if this {@linkplain ReferenceClassDescImpl} is

     * equal to another {@linkplain ReferenceClassDescImpl}.  Equality is

     * determined by the two class descriptors having equal class descriptor

     * strings.

     *

     * @param o the {@code ClassDesc} to compare to this

     *       {@code ClassDesc}

     * @return {@code true} if the specified {@code ClassDesc}

     *      is equal to this {@code ClassDesc}.

     */

    @Override

    public boolean equals(Object o) {

        if (this == o) return true;

        if (o == null || getClass() != o.getClass()) return false;

        ClassDesc constant = (ClassDesc) o;

        return descriptor.equals(constant.descriptorString());

    }

    @Override

    public int hashCode() {

        return descriptor.hashCode();

    }

    @Override

    public String toString() {

        return String.format("ClassDesc[%s]", displayName());

    }

}