/*

 * Copyright (c) 2016, 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.module;

import java.util.Objects;

import java.util.Set;

/**

 * A module in a graph of <em>resolved modules</em>.

 *

 * <p> {@code ResolvedModule} defines the {@link #configuration configuration}

 * method to get the configuration that the resolved module is in. It defines

 * the {@link #reference() reference} method to get the reference to the

 * module's content.

 *

 * @since 9

 * @see Configuration#modules()

 */

public final class ResolvedModule {

    private final Configuration cf;

    private final ModuleReference mref;

    ResolvedModule(Configuration cf, ModuleReference mref) {

        this.cf = Objects.requireNonNull(cf);

        this.mref = Objects.requireNonNull(mref);

    }

    /**

     * Returns the configuration that this resolved module is in.

     *

     * @return The configuration that this resolved module is in

     */

    public Configuration configuration() {

        return cf;

    }

    /**

     * Returns the reference to the module's content.

     *

     * @return The reference to the module's content

     */

    public ModuleReference reference() {

        return mref;

    }

    /**

     * Returns the module descriptor.

     *

     * This convenience method is the equivalent to invoking:

     * <pre> {@code

     *     reference().descriptor()

     * }</pre>

     *

     * @return The module descriptor

     */

    ModuleDescriptor descriptor() {

        return mref.descriptor();

    }

    /**

     * Returns the module name.

     *

     * This convenience method is the equivalent to invoking:

     * <pre> {@code

     *     reference().descriptor().name()

     * }</pre>

     *

     * @return The module name

     */

    public String name() {

        return mref.descriptor().name();

    }

    /**

     * Returns the set of resolved modules that this resolved module reads.

     *

     * @return A possibly-empty unmodifiable set of resolved modules that

     *         this resolved module reads

     */

    public Set<ResolvedModule> reads() {

        return cf.reads(this);

    }

    /**

     * Computes a hash code for this resolved module.

     *

     * <p> The hash code is based upon the components of the resolved module

     * and satisfies the general contract of the {@link Object#hashCode

     * Object.hashCode} method. </p>

     *

     * @return The hash-code value for this resolved module

     */

    @Override

    public int hashCode() {

        return cf.hashCode() ^ mref.hashCode();

    }

    /**

     * Tests this resolved module for equality with the given object.

     *

     * <p> If the given object is not a {@code ResolvedModule} then this

     * method returns {@code false}. Two {@code ResolvedModule} objects are

     * equal if they are in the same configuration and have equal references

     * to the module content. </p>

     *

     * <p> This method satisfies the general contract of the {@link

     * java.lang.Object#equals(Object) Object.equals} method. </p>

     *

     * @param   ob

     *          the object to which this object is to be compared

     *

     * @return  {@code true} if, and only if, the given object is a module

     *          reference that is equal to this module reference

     */

    @Override

    public boolean equals(Object ob) {

        return (ob instanceof ResolvedModule that)

            && Objects.equals(this.cf, that.cf)

            && Objects.equals(this.mref, that.mref);

    }

    /**

     * Returns a string describing this resolved module.

     *

     * @return A string describing this resolved module

     */

    @Override

    public String toString() {

        return System.identityHashCode(cf) + "/" + name();

    }

}