001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.http;
014
015import static org.apache.juneau.internal.CollectionUtils.*;
016
017import java.util.*;
018import java.util.Map.*;
019import java.util.concurrent.*;
020
021import org.apache.juneau.annotation.*;
022import org.apache.juneau.internal.*;
023
024/**
025 * Describes a single type used in content negotiation between an HTTP client and server, as described in
026 * Section 14.1 and 14.7 of RFC2616 (the HTTP/1.1 specification).
027 *
028 * <ul class='seealso'>
029 *    <li class='extlink'>{@doc RFC2616}
030 * </ul>
031 */
032@BeanIgnore
033public final class MediaTypeRange implements Comparable<MediaTypeRange>  {
034
035   private static final MediaTypeRange[] DEFAULT = new MediaTypeRange[]{new MediaTypeRange("*/*")};
036   private static final boolean NOCACHE = Boolean.getBoolean("juneau.nocache");
037   private static final ConcurrentHashMap<String,MediaTypeRange[]> CACHE = new ConcurrentHashMap<>();
038
039   private final MediaType mediaType;
040   private final Float qValue;
041   private final Map<String,Set<String>> extensions;
042
043   /**
044    * Parses an <c>Accept</c> header value into an array of media ranges.
045    *
046    * <p>
047    * The returned media ranges are sorted such that the most acceptable media is available at ordinal position
048    * <js>'0'</js>, and the least acceptable at position n-1.
049    *
050    * <p>
051    * The syntax expected to be found in the referenced <c>value</c> complies with the syntax described in
052    * RFC2616, Section 14.1, as described below:
053    * <p class='bcode w800'>
054    *    Accept         = "Accept" ":"
055    *                      #( media-range [ accept-params ] )
056    *
057    *    media-range    = ( "*\/*"
058    *                      | ( type "/" "*" )
059    *                      | ( type "/" subtype )
060    *                      ) *( ";" parameter )
061    *    accept-params  = ";" "q" "=" qvalue *( accept-extension )
062    *    accept-extension = ";" token [ "=" ( token | quoted-string ) ]
063    * </p>
064    *
065    * @param value
066    *    The value to parse.
067    *    If <jk>null</jk> or empty, returns a single <c>MediaTypeRange</c> is returned that represents all types.
068    * @return
069    *    The media ranges described by the string.
070    *    The ranges are sorted such that the most acceptable media is available at ordinal position <js>'0'</js>, and
071    *    the least acceptable at position n-1.
072    */
073   public static MediaTypeRange[] parse(String value) {
074
075      if (value == null || value.length() == 0)
076         return DEFAULT;
077
078      MediaTypeRange[] mtr = CACHE.get(value);
079      if (mtr != null)
080         return mtr;
081
082      if (value.indexOf(',') == -1) {
083         mtr = new MediaTypeRange[]{new MediaTypeRange(value)};
084      } else {
085         Set<MediaTypeRange> ranges = new TreeSet<>();
086         for (String r : StringUtils.split(value)) {
087            r = r.trim();
088            if (r.isEmpty())
089               continue;
090            ranges.add(new MediaTypeRange(r));
091         }
092         mtr = ranges.toArray(new MediaTypeRange[ranges.size()]);
093      }
094      if (NOCACHE)
095         return mtr;
096      CACHE.putIfAbsent(value, mtr);
097      return CACHE.get(value);
098   }
099
100   private MediaTypeRange(String token) {
101      Builder b = new Builder(token);
102      this.mediaType = b.mediaType;
103      this.qValue = b.qValue;
104      this.extensions = unmodifiableMap(b.extensions);
105   }
106
107   static final class Builder {
108      MediaType mediaType;
109      Float qValue = 1f;
110      Map<String,Set<String>> extensions;
111
112      Builder(String token) {
113
114         token = token.trim();
115
116         int i = token.indexOf(";q=");
117
118         if (i == -1) {
119            mediaType = MediaType.forString(token);
120            return;
121         }
122
123         mediaType = MediaType.forString(token.substring(0, i));
124
125         String[] tokens = token.substring(i+1).split(";");
126
127         // Only the type of the range is specified
128         if (tokens.length > 0) {
129            boolean isInExtensions = false;
130            for (int j = 0; j < tokens.length; j++) {
131               String[] parm = tokens[j].split("=");
132               if (parm.length == 2) {
133                  String k = parm[0], v = parm[1];
134                  if (isInExtensions) {
135                     if (extensions == null)
136                        extensions = new TreeMap<>();
137                     if (! extensions.containsKey(k))
138                        extensions.put(k, new TreeSet<String>());
139                     extensions.get(k).add(v);
140                  } else if (k.equals("q")) {
141                     qValue = new Float(v);
142                     isInExtensions = true;
143                  }
144               }
145            }
146         }
147      }
148   }
149
150   /**
151    * Returns the media type enclosed by this media range.
152    *
153    * <h5 class='section'>Examples:</h5>
154    * <ul>
155    *    <li><js>"text/html"</js>
156    *    <li><js>"text/*"</js>
157    *    <li><js>"*\/*"</js>
158    * </ul>
159    *
160    * @return The media type of this media range, lowercased, never <jk>null</jk>.
161    */
162   public MediaType getMediaType() {
163      return mediaType;
164   }
165
166   /**
167    * Returns the <js>'q'</js> (quality) value for this type, as described in Section 3.9 of RFC2616.
168    *
169    * <p>
170    * The quality value is a float between <c>0.0</c> (unacceptable) and <c>1.0</c> (most acceptable).
171    *
172    * <p>
173    * If 'q' value doesn't make sense for the context (e.g. this range was extracted from a <js>"content-*"</js>
174    * header, as opposed to <js>"accept-*"</js> header, its value will always be <js>"1"</js>.
175    *
176    * @return The 'q' value for this type, never <jk>null</jk>.
177    */
178   public Float getQValue() {
179      return qValue;
180   }
181
182   /**
183    * Returns the optional set of custom extensions defined for this type.
184    *
185    * <p>
186    * Values are lowercase and never <jk>null</jk>.
187    *
188    * @return The optional list of extensions, never <jk>null</jk>.
189    */
190   public Map<String,Set<String>> getExtensions() {
191      return extensions;
192   }
193
194   /**
195    * Provides a string representation of this media range, suitable for use as an <c>Accept</c> header value.
196    *
197    * <p>
198    * The literal text generated will be all lowercase.
199    *
200    * @return A media range suitable for use as an Accept header value, never <c>null</c>.
201    */
202   @Override /* Object */
203   public String toString() {
204      StringBuffer sb = new StringBuffer().append(mediaType);
205
206      // '1' is equivalent to specifying no qValue. If there's no extensions, then we won't include a qValue.
207      if (qValue.floatValue() == 1.0) {
208         if (! extensions.isEmpty()) {
209            sb.append(";q=").append(qValue);
210            for (Entry<String,Set<String>> e : extensions.entrySet()) {
211               String k = e.getKey();
212               for (String v : e.getValue())
213                  sb.append(';').append(k).append('=').append(v);
214            }
215         }
216      } else {
217         sb.append(";q=").append(qValue);
218         for (Entry<String,Set<String>> e : extensions.entrySet()) {
219            String k = e.getKey();
220            for (String v : e.getValue())
221               sb.append(';').append(k).append('=').append(v);
222         }
223      }
224      return sb.toString();
225   }
226
227   /**
228    * Returns <jk>true</jk> if the specified object is also a <c>MediaType</c>, and has the same qValue, type,
229    * parameters, and extensions.
230    *
231    * @return <jk>true</jk> if object is equivalent.
232    */
233   @Override /* Object */
234   public boolean equals(Object o) {
235
236      if (o == null || !(o instanceof MediaTypeRange))
237         return false;
238
239      if (this == o)
240         return true;
241
242      MediaTypeRange o2 = (MediaTypeRange) o;
243      return qValue.equals(o2.qValue)
244         && mediaType.equals(o2.mediaType)
245         && extensions.equals(o2.extensions);
246   }
247
248   /**
249    * Returns a hash based on this instance's <c>media-type</c>.
250    *
251    * @return A hash based on this instance's <c>media-type</c>.
252    */
253   @Override /* Object */
254   public int hashCode() {
255      return mediaType.hashCode();
256   }
257
258   /**
259    * Compares two MediaRanges for equality.
260    *
261    * <p>
262    * The values are first compared according to <c>qValue</c> values.
263    * Should those values be equal, the <c>type</c> is then lexicographically compared (case-insensitive) in
264    * ascending order, with the <js>"*"</js> type demoted last in that order.
265    * <c>MediaRanges</c> with the same type but different sub-types are compared - a more specific subtype is
266    * promoted over the 'wildcard' subtype.
267    * <c>MediaRanges</c> with the same types but with extensions are promoted over those same types with no
268    * extensions.
269    *
270    * @param o The range to compare to.  Never <jk>null</jk>.
271    */
272   @Override /* Comparable */
273   public int compareTo(MediaTypeRange o) {
274
275      // Compare q-values.
276      int qCompare = Float.compare(o.qValue, qValue);
277      if (qCompare != 0)
278         return qCompare;
279
280      // Compare media-types.
281      // Note that '*' comes alphabetically before letters, so just do a reverse-alphabetical comparison.
282      int i = o.mediaType.toString().compareTo(mediaType.toString());
283      return i;
284   }
285}