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// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
// * to you 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                                                              *
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// *  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  *
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// * specific language governing permissions and limitations under the License.                                              *
// ***************************************************************************************************************************
package org.apache.juneau.http;

import static org.apache.juneau.http.Constants.*;
import static org.apache.juneau.internal.StringUtils.*;
import static org.apache.juneau.internal.ObjectUtils.*;

import java.util.*;

import org.apache.http.*;
import org.apache.http.message.*;
import org.apache.juneau.annotation.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.json.*;


/**
 * Describes a single media type used in content negotiation between an HTTP client and server, as described in
 * Section 14.1 and 14.7 of RFC2616 (the HTTP/1.1 specification).
 *
 * <ul class='seealso'>
 *    <li class='extlink'>{@doc ExtRFC2616}
 * </ul>
 */
@BeanIgnore
public class MediaType implements Comparable<MediaType>  {

   private static final Cache<String,MediaType> CACHE = new Cache<>(NOCACHE, CACHE_MAX_SIZE);

   /** Reusable predefined media type */
   @SuppressWarnings("javadoc")
   public static final MediaType
      CSV = of("text/csv"),
      HTML = of("text/html"),
      JSON = of("application/json"),
      MSGPACK = of("octal/msgpack"),
      PLAIN = of("text/plain"),
      UON = of("text/uon"),
      URLENCODING = of("application/x-www-form-urlencoded"),
      XML = of("text/xml"),
      XMLSOAP = of("text/xml+soap"),

      RDF = of("text/xml+rdf"),
      RDFABBREV = of("text/xml+rdf+abbrev"),
      NTRIPLE = of("text/n-triple"),
      TURTLE = of("text/turtle"),
      N3 = of("text/n3")
   ;

   private final String string;                          // The entire unparsed value.
   private final String mediaType;                      // The "type/subtype" portion of the media type..
   private final String type;                           // The media type (e.g. "text" for Accept, "utf-8" for Accept-Charset)
   private final String subType;                        // The media sub-type (e.g. "json" for Accept, not used for Accept-Charset)
   private final String[] subTypes;                     // The media sub-type (e.g. "json" for Accept, not used for Accept-Charset)
   private final String[] subTypesSorted;               // Same as subTypes, but sorted so that it can be used for comparison.
   private final boolean hasSubtypeMeta;                // The media subtype contains meta-character '*'.

   private final NameValuePair[] parameters;            // The media type parameters (e.g. "text/html;level=1").  Does not include q!

   /**
    * Returns the media type for the specified string.
    * The same media type strings always return the same objects so that these objects
    * can be compared for equality using '=='.
    *
    * <ul class='notes'>
    *    <li>
    *       Spaces are replaced with <js>'+'</js> characters.
    *       This gets around the issue where passing media type strings with <js>'+'</js> as HTTP GET parameters
    *       get replaced with spaces by your browser.  Since spaces aren't supported by the spec, this
    *       is doesn't break anything.
    *    <li>
    *       Anything including and following the <js>';'</js> character is ignored (e.g. <js>";charset=X"</js>).
    * </ul>
    *
    * @param value
    *    The media type string.
    *    Will be lowercased.
    *    Returns <jk>null</jk> if input is null or empty.
    * @return A cached media type object.
    */
   public static MediaType of(String value) {
      if (isEmpty(value))
         return null;
      MediaType x = CACHE.get(value);
      if (x == null)
         x = CACHE.put(value, new MediaType(value));
      return x;
   }

   /**
    * Same as {@link #of(String)} but allows you to construct an array of <c>MediaTypes</c> from an
    * array of strings.
    *
    * @param values
    *    The media type strings.
    * @return
    *    An array of <c>MediaType</c> objects.
    *    <br>Always the same length as the input string array.
    */
   public static MediaType[] ofAll(String...values) {
      MediaType[] mt = new MediaType[values.length];
      for (int i = 0; i < values.length; i++)
         mt[i] = of(values[i]);
      return mt;
   }

   /**
    * Constructor.
    *
    * @param mt The media type string.
    */
   public MediaType(String mt) {
      this(parse(mt));
   }

   /**
    * Constructor.
    *
    * @param e The parsed media type string.
    */
   public MediaType(HeaderElement e) {
      mediaType = e.getName();

      List<NameValuePair> parameters = AList.of();
      for (NameValuePair p : e.getParameters()) {
         if (p.getName().equals("q"))
            break;
         parameters.add(BasicNameValuePair.of(p.getName(), p.getValue()));
      }
      this.parameters= parameters.toArray(new NameValuePair[parameters.size()]);

      String x = mediaType.replace(' ', '+');
      int i = x.indexOf('/');
      type = (i == -1 ? x : x.substring(0, i));
      subType = (i == -1 ? "*" : x.substring(i+1));

      subTypes = StringUtils.split(subType, '+');
      subTypesSorted = Arrays.copyOf(subTypes, subTypes.length);
      Arrays.sort(this.subTypesSorted);
      hasSubtypeMeta = ArrayUtils.contains("*", this.subTypes);

      StringBuilder sb = new StringBuilder();
      sb.append(mediaType);
      for (NameValuePair p : parameters)
         sb.append(';').append(p.getName()).append('=').append(p.getValue());
      this.string = sb.toString();
   }

   /**
    * Returns the <js>'type'</js> fragment of the <js>'type/subType'</js> string.
    *
    * @return The media type.
    */
   public final String getType() {
      return type;
   }

   /**
    * Returns the <js>'subType'</js> fragment of the <js>'type/subType'</js> string.
    *
    * @return The media subtype.
    */
   public final String getSubType() {
      return subType;
   }

   /**
    * Returns <jk>true</jk> if the subtype contains the specified <js>'+'</js> delimited subtype value.
    *
    * @param st
    *    The subtype string.
    *    Case is ignored.
    * @return <jk>true</jk> if the subtype contains the specified subtype string.
    */
   public final boolean hasSubType(String st) {
      if (st != null)
         for (String s : subTypes)
            if (st.equalsIgnoreCase(s))
               return true;
      return false;
   }

   /**
    * Returns the subtypes broken down by fragments delimited by <js>"'"</js>.
    *
    * <P>
    * For example, the media type <js>"text/foo+bar"</js> will return a list of
    * <code>[<js>'foo'</js>,<js>'bar'</js>]</code>
    *
    * @return An unmodifiable list of subtype fragments.  Never <jk>null</jk>.
    */
   public final List<String> getSubTypes() {
      return Collections.unmodifiableList(Arrays.asList(subTypes));
   }

   /**
    * Returns <jk>true</jk> if this media type subtype contains the <js>'*'</js> meta character.
    *
    * @return <jk>true</jk> if this media type subtype contains the <js>'*'</js> meta character.
    */
   public final boolean isMetaSubtype() {
      return hasSubtypeMeta;
   }

   /**
    * Returns a match metric against the specified media type where a larger number represents a better match.
    *
    * <p>
    * This media type can contain <js>'*'</js> metacharacters.
    * <br>The comparison media type must not.
    *
    * <ul>
    *    <li>Exact matches (e.g. <js>"text/json"</js>/</js>"text/json"</js>) should match
    *       better than meta-character matches (e.g. <js>"text/*"</js>/</js>"text/json"</js>)
    *    <li>The comparison media type can have additional subtype tokens (e.g. <js>"text/json+foo"</js>)
    *       that will not prevent a match if the <c>allowExtraSubTypes</c> flag is set.
    *       The reverse is not true, e.g. the comparison media type must contain all subtype tokens found in the
    *       comparing media type.
    *       <ul>
    *          <li>We want the {@link JsonSerializer} (<js>"text/json"</js>) class to be able to handle requests for <js>"text/json+foo"</js>.
    *          <li>We want to make sure {@link org.apache.juneau.json.SimpleJsonSerializer} (<js>"text/json+simple"</js>) does not handle
    *             requests for <js>"text/json"</js>.
    *       </ul>
    *       More token matches should result in a higher match number.
    * </ul>
    *
    * The formula is as follows for <c>type/subTypes</c>:
    * <ul>
    *    <li>An exact match is <c>100,000</c>.
    *    <li>Add the following for type (assuming subtype match is &lt;0):
    *    <ul>
    *       <li><c>10,000</c> for an exact match (e.g. <js>"text"</js>==<js>"text"</js>).
    *       <li><c>5,000</c> for a meta match (e.g. <js>"*"</js>==<js>"text"</js>).
    *    </ul>
    *    <li>Add the following for subtype (assuming type match is &lt;0):
    *    <ul>
    *       <li><c>7,500</c> for an exact match (e.g. <js>"json+foo"</js>==<js>"json+foo"</js> or <js>"json+foo"</js>==<js>"foo+json"</js>)
    *       <li><c>100</c> for every subtype entry match (e.g. <js>"json"</js>/<js>"json+foo"</js>)
    *    </ul>
    * </ul>
    *
    * @param o The media type to compare with.
    * @param allowExtraSubTypes If <jk>true</jk>,
    * @return <jk>true</jk> if the media types match.
    */
   public final int match(MediaType o, boolean allowExtraSubTypes) {

      if (o == null)
         return -1;

      // Perfect match
      if (this == o || (type.equals(o.type) && subType.equals(o.subType)))
         return 100000;

      int c = 0;

      if (type.equals(o.type))
         c += 10000;
      else if ("*".equals(type) || "*".equals(o.type))
         c += 5000;

      if (c == 0)
         return 0;

      // Subtypes match but are ordered different
      if (ArrayUtils.equals(subTypesSorted, o.subTypesSorted))
         return c + 7500;

      for (String st1 : subTypes) {
         if ("*".equals(st1))
            c += 0;
         else if (ArrayUtils.contains(st1, o.subTypes))
            c += 100;
         else if (o.hasSubtypeMeta)
            c += 0;
         else
            return 0;
      }
      for (String st2 : o.subTypes) {
         if ("*".equals(st2))
            c += 0;
         else if (ArrayUtils.contains(st2, subTypes))
            c += 100;
         else if (hasSubtypeMeta)
            c += 0;
         else if (! allowExtraSubTypes)
            return 0;
         else
            c += 10;
      }

      return c;
   }

   /**
    * Returns the additional parameters on this media type.
    *
    * <p>
    * For example, given the media type string <js>"text/html;level=1"</js>, will return a map
    * with the single entry <code>{level:[<js>'1'</js>]}</code>.
    *
    * @return The map of additional parameters, or an empty map if there are no parameters.
    */
   public List<NameValuePair> getParameters() {
      return Collections.unmodifiableList(Arrays.asList(parameters));
   }

   /**
    * Returns the additional parameter on this media type.
    *
    * @param name The additional parameter name.
    * @return The parameter value, or <jk>null</jk> if not found.
    */
   public String getParameter(String name) {
      for (NameValuePair p : parameters)
         if (eq(name, p.getName()))
            return p.getValue();
      return null;
   }

   private static HeaderElement parse(String value) {
      HeaderElement[] elements = BasicHeaderValueParser.parseElements(emptyIfNull(trim(value)), null);
      return (elements.length > 0 ? elements[0] : new BasicHeaderElement("", ""));
   }

   @Override /* Object */
   public String toString() {
      return string;
   }

   @Override /* Object */
   public int hashCode() {
      return string.hashCode();
   }

   @Override /* Object */
   public boolean equals(Object o) {
      return (o instanceof MediaType) && eq(this, (MediaType)o, (x,y)->eq(x.string, y.string));
   }

   @Override
   public final int compareTo(MediaType o) {
      return toString().compareTo(o.toString());
   }
}