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/*
 * Copyright (c) 2010, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package jakarta.ws.rs.core;

import java.io.StringWriter;
import java.util.List;
import java.util.Locale;
import java.util.Objects;

import jakarta.ws.rs.ext.RuntimeDelegate;

/**
 * Abstraction for a resource representation variant.
 *
 * Contains information about media type, language and encoding of the resource representation.
 *
 * @author Paul Sandoz
 * @author Marc Hadley
 * @since 1.0
 */
public class Variant {

    private Locale language;
    private MediaType mediaType;
    private String encoding;

    /**
     * Create a new instance of Variant.
     *
     * @param mediaType the media type of the variant - may be {@code null}.
     * @param language the language of the variant (two-letter ISO-639 code); may be {@code null}.
     * @param encoding the content encoding of the variant - may be {@code null}.
     * @throws java.lang.IllegalArgumentException if all the parameters are {@code null}.
     * @since 2.0
     */
    public Variant(final MediaType mediaType, final String language, final String encoding) {
        if (mediaType == null && language == null && encoding == null) {
            throw new IllegalArgumentException("mediaType, language, encoding all null");
        }
        this.encoding = encoding;
        this.language = (language == null) ? null : new Locale(language);
        this.mediaType = mediaType;
    }

    /**
     * Create a new instance of Variant.
     *
     * @param mediaType the media type of the variant - may be {@code null}.
     * @param language the language of the variant (two-letter ISO-639 code); may be {@code null}.
     * @param country uppercase two-letter ISO-3166 language code of the variant; may be {@code null} provided
     * {@code language} is {@code null} too.
     * @param encoding the content encoding of the variant - may be {@code null}.
     * @throws java.lang.IllegalArgumentException if all the parameters are {@code null}.
     * @since 2.0
     */
    public Variant(final MediaType mediaType, final String language, final String country, final String encoding) {
        if (mediaType == null && language == null && encoding == null) {
            throw new IllegalArgumentException("mediaType, language, encoding all null");
        }
        this.encoding = encoding;
        this.language = (language == null) ? null : new Locale(language, country);
        this.mediaType = mediaType;
    }

    /**
     * Create a new instance of Variant.
     *
     * @param mediaType the media type of the variant - may be {@code null}.
     * @param language the language of the variant (two-letter ISO-639 code); may be {@code null}.
     * @param country uppercase two-letter ISO-3166 language code of the variant; may be {@code null} provided
     * {@code language} is {@code null} too.
     * @param languageVariant vendor and browser specific language code of the variant (see also {@link Locale} class
     * description); may be {@code null} provided {@code language} and {@code country} are {@code null} too.
     * @param encoding the content encoding of the variant - may be {@code null}.
     * @throws java.lang.IllegalArgumentException if all the parameters are {@code null}.
     * @since 2.0
     */
    public Variant(final MediaType mediaType, final String language, final String country, final String languageVariant, final String encoding) {
        if (mediaType == null && language == null && encoding == null) {
            throw new IllegalArgumentException("mediaType, language, encoding all null");
        }
        this.encoding = encoding;
        this.language = (language == null) ? null : new Locale(language, country, languageVariant);
        this.mediaType = mediaType;
    }

    /**
     * Create a new instance of Variant.
     *
     * @param mediaType the media type of the variant - may be {@code null}.
     * @param language the language of the variant - may be {@code null}.
     * @param encoding the content encoding of the variant - may be {@code null}.
     * @throws java.lang.IllegalArgumentException if all the parameters are {@code null}.
     */
    public Variant(final MediaType mediaType, final Locale language, final String encoding) {
        if (mediaType == null && language == null && encoding == null) {
            throw new IllegalArgumentException("mediaType, language, encoding all null");
        }
        this.encoding = encoding;
        this.language = language;
        this.mediaType = mediaType;
    }

    /**
     * Get the language of the variant.
     *
     * @return the language or {@code null} if none set.
     */
    public Locale getLanguage() {
        return language;
    }

    /**
     * Get the string representation of the variant language, or {@code null} if no language has been set.
     *
     * @return the string representing variant language or {@code null} if none set.
     * @since 2.0
     */
    public String getLanguageString() {
        return (language == null) ? null : language.toString();
    }

    /**
     * Get the media type of the variant.
     *
     * @return the media type or {@code null} if none set.
     */
    public MediaType getMediaType() {
        return mediaType;
    }

    /**
     * Get the encoding of the variant.
     *
     * @return the encoding or {@code null} if none set.
     */
    public String getEncoding() {
        return encoding;
    }

    /**
     * Create a {@link VariantListBuilder} initialized with a set of supported media types.
     *
     * @param mediaTypes the available mediaTypes. If specific char-sets are supported they should be included as parameters
     * of the respective media type.
     * @return the initialized builder.
     * @throws java.lang.IllegalArgumentException if mediaTypes is null or contains no elements.
     */
    public static VariantListBuilder mediaTypes(final MediaType... mediaTypes) {
        VariantListBuilder b = VariantListBuilder.newInstance();
        b.mediaTypes(mediaTypes);
        return b;
    }

    /**
     * Create a {@link VariantListBuilder} initialized with a set of supported languages.
     *
     * @param languages the available languages.
     * @return the initialized builder.
     * @throws java.lang.IllegalArgumentException if languages is null or contains no elements.
     */
    public static VariantListBuilder languages(final Locale... languages) {
        VariantListBuilder b = VariantListBuilder.newInstance();
        b.languages(languages);
        return b;
    }

    /**
     * Create a {@link VariantListBuilder} initialized with a set of supported encodings.
     *
     * @param encodings the available encodings.
     * @return the initialized builder.
     * @throws java.lang.IllegalArgumentException if encodings is null or contains no elements.
     */
    public static VariantListBuilder encodings(final String... encodings) {
        VariantListBuilder b = VariantListBuilder.newInstance();
        b.encodings(encodings);
        return b;
    }

    /**
     * Generate hash code from variant properties.
     *
     * @return the hash code.
     */
    @Override
    public int hashCode() {
        return Objects.hash(this.language, this.mediaType, this.encoding);
    }

    /**
     * Compares obj to this variant to see if they are the same considering all property values.
     *
     * @param obj the object to compare to.
     * @return true if the two variants are the same, false otherwise.
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final Variant other = (Variant) obj;
        if (!Objects.equals(this.language, other.language)) {
            return false;
        }
        if (!Objects.equals(this.mediaType, other.mediaType)) {
            return false;
        }
        return Objects.equals(this.encoding, other.encoding);
    }

    @Override
    public String toString() {
        StringWriter w = new StringWriter();
        w.append("Variant[mediaType=");
        w.append(mediaType == null ? "null" : mediaType.toString());
        w.append(", language=");
        w.append(language == null ? "null" : language.toString());
        w.append(", encoding=");
        w.append(encoding == null ? "null" : encoding);
        w.append("]");
        return w.toString();
    }

    /**
     * A builder for a list of representation variants.
     */
    public abstract static class VariantListBuilder {

        /**
         * Protected constructor, use the static {@code newInstance} method to obtain an instance.
         */
        protected VariantListBuilder() {
        }

        /**
         * Create a new builder instance.
         *
         * @return a new builder instance.
         */
        public static VariantListBuilder newInstance() {
            return RuntimeDelegate.getInstance().createVariantListBuilder();
        }

        /**
         * Add the current combination of metadata to the list of supported variants (provided the current combination of
         * metadata is not empty) and build a list of representation variants from the current state of the builder. After this
         * method is called the builder is reset to an empty state.
         *
         * @return a list of representation variants.
         */
        public abstract List build();

        /**
         * Add the current combination of metadata to the list of supported variants, after this method is called the current
         * combination of metadata is emptied.
         * 

* If more than one value is supplied for one or more of the variant properties then a variant will be generated for * each possible combination. E.g. in the following {@code list} would have five (4 + 1) members: *

* *
         * List<Variant> list = VariantListBuilder.newInstance()
         *         .languages(Locale.ENGLISH, Locale.FRENCH).encodings("zip", "identity").add()
         *         .languages(Locale.GERMAN).mediaTypes(MediaType.TEXT_PLAIN_TYPE).add()
         *         .build()
         * 
*

* Note that it is not necessary to call the {@code add()} method immediately before the build method is called. E.g. * the resulting list produced in the example above would be identical to the list produced by the following code: *

* *
         * List<Variant> list = VariantListBuilder.newInstance()
         *         .languages(Locale.ENGLISH, Locale.FRENCH).encodings("zip", "identity").add()
         *         .languages(Locale.GERMAN).mediaTypes(MediaType.TEXT_PLAIN_TYPE)
         *         .build()
         * 
* * @return the updated builder. * @throws IllegalStateException if there is not at least one mediaType, language or encoding set for the current * variant. */ public abstract VariantListBuilder add(); /** * Set the language(s) for this variant. * * @param languages the available languages. * @return the updated builder. */ public abstract VariantListBuilder languages(Locale... languages); /** * Set the encoding(s) for this variant. * * @param encodings the available encodings. * @return the updated builder. */ public abstract VariantListBuilder encodings(String... encodings); /** * Set the media type(s) for this variant. * * @param mediaTypes the available mediaTypes. If specific charsets are supported they should be included as parameters * of the respective media type. * @return the updated builder. */ public abstract VariantListBuilder mediaTypes(MediaType... mediaTypes); } }




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