001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.rest.server.arg;
018
019import static org.apache.juneau.commons.utils.StringUtils.*;
020
021import org.apache.juneau.commons.reflect.*;
022import org.apache.juneau.rest.server.*;
023import org.apache.juneau.rest.server.httppart.*;
024
025/**
026 * Resolves method parameters and parameter types annotated with {@link Attr} on {@link RestOp}-annotated Java methods.
027 *
028 * <p>
029 * The parameter value is resolved using:
030 * <p class='bjava'>
031 *    <jv>opSession</jv>
032 *       .{@link RestOpSession#getRequest() getRequest}()
033 *       .{@link RestRequest#getAttributes() getAttributes}()
034 *       .{@link RequestAttributes#get(String) get}(<jv>name</jv>)
035 *       .{@link RequestAttribute#as(Class) as}(<jv>type</jv>);
036 * </p>
037 *
038 * <h5 class='section'>See Also:</h5><ul>
039 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JavaMethodParameters">Java Method Parameters</a>
040 * </ul>
041 */
042public class AttributeArg implements RestOpArg {
043
044   private static final AnnotationProvider AP = AnnotationProvider.INSTANCE;
045
046   /**
047    * Static creator.
048    *
049    * @param paramInfo The Java method parameter being resolved. Must not be <jk>null</jk>.
050    * @return A new {@link AttributeArg}, or <jk>null</jk> if the parameter is not annotated with {@link Attr}.
051    */
052   public static AttributeArg create(ParameterInfo paramInfo) {
053      if (AP.has(Attr.class, paramInfo))
054         return new AttributeArg(paramInfo);
055      return null;
056   }
057
058   private final String name;
059
060   private final Class<?> type;
061
062   /**
063    * Constructor.
064    *
065    * @param paramInfo The Java method parameter being resolved. Must not be <jk>null</jk>.
066    */
067   protected AttributeArg(ParameterInfo paramInfo) {
068      this.name = getName(paramInfo);
069      this.type = paramInfo.getParameterType().inner();
070   }
071
072   @Override /* Overridden from RestOpArg */
073   public Object resolve(RestOpSession opSession) throws Exception {
074      return opSession.getRequest().getAttribute(name).as(type).orElse(null);
075   }
076
077   private static String getName(ParameterInfo paramInfo) {
078      // @formatter:off
079      return AP.find(Attr.class, paramInfo)
080         .stream()
081         .map(AnnotationInfo::inner)
082         .filter(x -> isAnyNotBlank(x.value(), x.name()))
083         .findFirst()
084         .map(x -> firstNonBlank(x.name(), x.value()))
085         .orElseThrow(() -> new ArgException(paramInfo, "@Attr used without name or value"));
086      // @formatter:on
087   }
088}