/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2010-2017 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://oss.oracle.com/licenses/CDDL+GPL-1.1
 * or LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package org.glassfish.jersey.message.internal;

import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.ws.rs.core.Link;

import javax.inject.Singleton;

import org.glassfish.jersey.internal.LocalizationMessages;
import org.glassfish.jersey.internal.util.Tokenizer;
import org.glassfish.jersey.spi.HeaderDelegateProvider;

import static org.glassfish.jersey.message.internal.Utils.throwIllegalArgumentExceptionIfNull;

/**
 * Provider for Link Headers.
 *
 * @author Santiago Pericas-Geertsen
 * @author Marek Potociar (marek.potociar at oracle.com)
 */
@Singleton
public class LinkProvider implements HeaderDelegateProvider<Link> {

    private static final Logger LOGGER = Logger.getLogger(LinkProvider.class.getName());

    @Override
    public boolean supports(final Class<?> type) {
        return Link.class.isAssignableFrom(type);
    }

    @Override
    public Link fromString(final String value) throws IllegalArgumentException {
        return initBuilder(new JerseyLink.Builder(), value).build();
    }

    /**
     * Initialize an existing Jersey link builder with the link data provided in a form of a string.
     *
     * @param lb    link builder to be initialized.
     * @param value link data as a string.
     * @return initialized link builder.
     */
    static JerseyLink.Builder initBuilder(JerseyLink.Builder lb, String value) {
        throwIllegalArgumentExceptionIfNull(value, LocalizationMessages.LINK_IS_NULL());
        try {
            value = value.trim();
            final String params;
            if (value.startsWith("<")) {
                final int gtIndex = value.indexOf('>');
                if (gtIndex != -1) {
                    lb.uri(value.substring(1, gtIndex).trim());
                    params = value.substring(gtIndex + 1).trim();
                } else {
                    throw new IllegalArgumentException("Missing token > in " + value);
                }
            } else {
                throw new IllegalArgumentException("Missing starting token < in " + value);
            }

            final StringTokenizer st = new StringTokenizer(params, ";=\"", true);
            while (st.hasMoreTokens()) {
                checkToken(st, ";");
                final String n = st.nextToken().trim();
                checkToken(st, "=");

                String v = nextNonEmptyToken(st);
                if (v.equals("\"")) {
                    v = st.nextToken();
                    checkToken(st, "\"");
                }

                lb.param(n, v);
            }
        } catch (final Throwable e) {
            if (LOGGER.isLoggable(Level.FINER)) {
                LOGGER.log(Level.FINER, "Error parsing link value '" + value + "'", e);
            }
            lb = null;
        }
        if (lb == null) {
            throw new IllegalArgumentException("Unable to parse link " + value);
        }
        return lb;
    }

    private static String nextNonEmptyToken(final StringTokenizer st) throws IllegalArgumentException {
        String token;
        do {
            token = st.nextToken().trim();
        } while (token.length() == 0);

        return token;
    }

    private static void checkToken(final StringTokenizer st, final String expected) throws IllegalArgumentException {
        String token;
        do {
            token = st.nextToken().trim();
        } while (token.length() == 0);
        if (!token.equals(expected)) {
            throw new IllegalArgumentException("Expected token " + expected + " but found " + token);
        }
    }

    @Override
    public String toString(final Link value) {
        return stringfy(value);
    }

    /**
     * Convert {@link Link} instance to a string version.
     *
     * @param value link instance to be stringified.
     * @return string version of a given link instance.
     */
    static String stringfy(final Link value) {
        throwIllegalArgumentExceptionIfNull(value, LocalizationMessages.LINK_IS_NULL());

        final Map<String, String> map = value.getParams();
        final StringBuilder sb = new StringBuilder();
        sb.append('<').append(value.getUri()).append('>');

        for (final Map.Entry<String, String> entry : map.entrySet()) {
            sb.append("; ").append(entry.getKey()).append("=\"").append(entry.getValue()).append("\"");
        }
        return sb.toString();
    }

    /**
     * Extract the list of link relations from the string value of a {@link Link#REL} attribute.
     *
     * @param rel string value of the link {@code "rel"} attribute.
     * @return list of relations in the {@code "rel"} attribute string value.
     */
    static List<String> getLinkRelations(final String rel) {
        return (rel == null) ? null : Arrays.asList(Tokenizer.tokenize(rel, "\" "));
    }
}
