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.arg;
018
019import static org.apache.juneau.commons.utils.StringUtils.*;
020
021import org.apache.juneau.commons.reflect.*;
022import org.apache.juneau.rest.*;
023import org.apache.juneau.rest.annotation.*;
024import org.apache.juneau.rest.httppart.*;
025
026/**
027 * Resolves method parameters and parameter types annotated with {@link Attr} on {@link RestOp}-annotated Java methods.
028 *
029 * <p>
030 * The parameter value is resolved using:
031 * <p class='bjava'>
032 *    <jv>opSession</jv>
033 *       .{@link RestOpSession#getRequest() getRequest}()
034 *       .{@link RestRequest#getAttributes() getAttributes}()
035 *       .{@link RequestAttributes#get(String) get}(<jv>name</jv>)
036 *       .{@link RequestAttribute#as(Class) as}(<jv>type</jv>);
037 * </p>
038 *
039 * <h5 class='section'>See Also:</h5><ul>
040 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JavaMethodParameters">Java Method Parameters</a>
041 * </ul>
042 */
043public class AttributeArg implements RestOpArg {
044
045   private static final AnnotationProvider AP = AnnotationProvider.INSTANCE;
046
047   /**
048    * Static creator.
049    *
050    * @param paramInfo The Java method parameter being resolved.
051    * @return A new {@link AttributeArg}, or <jk>null</jk> if the parameter is not annotated with {@link Attr}.
052    */
053   public static AttributeArg create(ParameterInfo paramInfo) {
054      if (AP.has(Attr.class, paramInfo))
055         return new AttributeArg(paramInfo);
056      return null;
057   }
058
059   private final String name;
060
061   private final Class<?> type;
062
063   /**
064    * Constructor.
065    *
066    * @param paramInfo The Java method parameter being resolved.
067    */
068   protected AttributeArg(ParameterInfo paramInfo) {
069      this.name = getName(paramInfo);
070      this.type = paramInfo.getParameterType().inner();
071   }
072
073   @Override /* Overridden from RestOpArg */
074   public Object resolve(RestOpSession opSession) throws Exception {
075      return opSession.getRequest().getAttribute(name).as(type).orElse(null);
076   }
077
078   private static String getName(ParameterInfo paramInfo) {
079      // @formatter:off
080      return AP.find(Attr.class, paramInfo)
081         .stream()
082         .map(AnnotationInfo::inner)
083         .filter(x -> isAnyNotBlank(x.value(), x.name()))
084         .findFirst()
085         .map(x -> firstNonBlank(x.name(), x.value()))
086         .orElseThrow(() -> new ArgException(paramInfo, "@Attr used without name or value"));
087      // @formatter:on
088   }
089}