001/*
002 * Licensed to DuraSpace under one or more contributor license agreements.
003 * See the NOTICE file distributed with this work for additional information
004 * regarding copyright ownership.
005 *
006 * DuraSpace licenses this file to you under the Apache License,
007 * Version 2.0 (the "License"); you may not use this file except in
008 * compliance with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.fcrepo.http.commons.exceptionhandlers;
019
020import static org.fcrepo.kernel.api.RdfLexicon.CONSTRAINED_BY;
021
022import javax.servlet.ServletContext;
023import javax.ws.rs.core.Link;
024import javax.ws.rs.core.UriInfo;
025import javax.ws.rs.ext.ExceptionMapper;
026
027import org.fcrepo.kernel.api.exception.ConstraintViolationException;
028
029/**
030 * Abstract class for constraint violation subclasses
031 *
032 * @author whikloj
033 * @since 2015-06-24
034 * @param <T> Throwable subclass of ConstraintViolationException
035 */
036public abstract class ConstraintExceptionMapper<T extends ConstraintViolationException> implements ExceptionMapper<T> {
037
038    /**
039     * Where the RDF exception files sit.
040     */
041    private static final String CONSTRAINT_DIR = "/static/constraints/";
042
043    /**
044     * Creates a constrainedBy link header with the appropriate RDF URL for the exception.
045     *
046     * @param e ConstraintViolationException Exception which implements the buildContraintUri method.
047     * @param context ServletContext ServletContext that we're running in.
048     * @param uriInfo UriInfo UriInfo from the ExceptionMapper.
049     * @return Link A http://www.w3.org/ns/ldp#constrainedBy link header
050     */
051    public static Link buildConstraintLink(final ConstraintViolationException e,
052                                           final ServletContext context,
053                                           final UriInfo uriInfo) {
054
055        String path = context.getContextPath();
056        if (path.equals("/")) {
057            path = "";
058        }
059
060        final String constraintURI = uriInfo == null ? "" : String.format("%s://%s%s%s%s.rdf",
061                uriInfo.getBaseUri().getScheme(), uriInfo.getBaseUri().getAuthority(), path,
062                CONSTRAINT_DIR, e.getClass().toString().substring(e.getClass().toString().lastIndexOf('.') + 1));
063        return Link.fromUri(constraintURI).rel(CONSTRAINED_BY.getURI()).build();
064    }
065
066}