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/*
 * Copyright 2012 Guido Steinacker
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.otto.jsonhome.model;

import java.net.URI;
import java.util.*;

import static java.util.Arrays.asList;
import static java.util.Collections.unmodifiableMap;

/**
 * Immutable container of {@link ResourceLink resource links}, representing a json-home document.
 * 
 * This implementation is immutable.
 *
 * @see http://tools.ietf.org/html/draft-nottingham-json-home-02
 * @author Guido Steinacker
 * @since 15.09.12
 */
public final class JsonHome {

    private final Map resources;

    private JsonHome(final Map resources) {
        this.resources = unmodifiableMap(new HashMap(resources));
    }

    public static JsonHome emptyJsonHome() {
        return new JsonHome(Collections.emptyMap());

    }

    /**
     * Creates a JsonHome document from one or more ResourceLinks. The link-relation types of the resources
     * must be unique, otherwise an IllegalArgumentException is thrown.
     *
     * @param resources collection of resource links.
     * @return JsonHome
     */
    public static JsonHome jsonHome(final ResourceLink resourceLink, final ResourceLink... resources) {
        final List resourceLinks = new ArrayList();
        resourceLinks.add(resourceLink);
        resourceLinks.addAll(asList(resources));
        return jsonHome(resourceLinks);
    }

    /**
     * Creates a JsonHome document from a collection of ResourceLinks. The link-relation types of the resources
     * must be unique, otherwise an IllegalArgumentException is thrown.
     *
     * @param resources collection of resource links.
     * @return JsonHome
     */
    public static JsonHome jsonHome(final Collection resources) {
        final Map resourceMap = new HashMap(resources.size());
        for (final ResourceLink resource : resources) {
            if (resourceMap.containsKey(resource.getLinkRelationType())) {
                throw new IllegalArgumentException("Unable to construct JsonHome. Link-relation types must be unique.");
            }
            resourceMap.put(resource.getLinkRelationType(), resource);
        }
        return new JsonHome(resourceMap);
    }

    /**
     * Returns an unmodifiable map containing the resources of this json-home document.
     *
     * @return mapping of link-relation types to resource links.
     */
    public Map getResources() {
        return resources;
    }

    public boolean hasResourceFor(final URI relationTypeURI) {
        return resources.containsKey(relationTypeURI);
    }

    public ResourceLink getResourceFor(final URI relationTypeURI) {
        return resources.get(relationTypeURI);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        JsonHome jsonHome = (JsonHome) o;

        if (resources != null ? !resources.equals(jsonHome.resources) : jsonHome.resources != null) return false;

        return true;
    }

    @Override
    public int hashCode() {
        return resources != null ? resources.hashCode() : 0;
    }

    @Override
    public String toString() {
        return "JsonHome{" +
                "resources=" + resources.values() +
                '}';
    }
}