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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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// ***************************************************************************************************************************
package org.apache.juneau.http.header;

import java.net.*;
import java.util.function.*;

import org.apache.juneau.http.annotation.*;

/**
 * Represents a parsed <l>Referer</l> HTTP request header.
 *
 * <p>
 * This is the address of the previous web page from which a link to the currently requested page was followed.
 * (The word “referrer” has been misspelled in the RFC as well as in most implementations to the point that it has
 * become standard usage and is considered correct terminology)
 *
 * <h5 class='figure'>Example</h5>
 * <p class='bcode'>
 *    Referer: http://en.wikipedia.org/wiki/Main_Page
 * </p>
 *
 * <h5 class='topic'>RFC2616 Specification</h5>
 *
 * The Referer[sic] request-header field allows the client to specify, for the server's benefit, the address (URI) of
 * the resource from which the Request-URI was obtained (the "referrer", although the header field is misspelled.)
 * The Referer request-header allows a server to generate lists of back-links to resources for interest, logging,
 * optimized caching, etc.
 * It also allows obsolete or mistyped links to be traced for maintenance.
 * The Referer field MUST NOT be sent if the Request-URI was obtained from a source that does not have its own URI,
 * such as input from the user keyboard.
 *
 * <p class='bcode'>
 *    Referer        = "Referer" ":" ( absoluteURI | relativeURI )
 * </p>
 *
 * <p>
 * Example:
 * <p class='bcode'>
 *    Referer: http://www.w3.org/hypertext/DataSources/Overview.html
 * </p>
 *
 * <p>
 * If the field value is a relative URI, it SHOULD be interpreted relative to the Request-URI.
 * The URI MUST NOT include a fragment. See section 15.1.3 for security considerations.
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="../../../../../index.html#juneau-rest-common">juneau-rest-common</a>
 *    <li class='extlink'><a class="doclink" href="https://www.w3.org/Protocols/rfc2616/rfc2616.html">Hypertext Transfer Protocol -- HTTP/1.1</a>
 * </ul>
 *
 * @serial exclude
 */
@Header("Referer")
public class Referer extends BasicUriHeader {

   //-----------------------------------------------------------------------------------------------------------------
   // Static
   //-----------------------------------------------------------------------------------------------------------------

   private static final long serialVersionUID = 1L;
   private static final String NAME = "Referer";

   /**
    * Static creator.
    *
    * @param value
    *    The header value.
    *    <br>Must be parsable by {@link URI#create(String)}.
    *    <br>Can be <jk>null</jk>.
    * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
    */
   public static Referer of(String value) {
      return value == null ? null : new Referer(value);
   }

   /**
    * Static creator.
    *
    * @param value
    *    The header value.
    *    <br>Can be <jk>null</jk>.
    * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
    */
   public static Referer of(URI value) {
      return value == null ? null : new Referer(value);
   }

   /**
    * Static creator with delayed value.
    *
    * <p>
    * Header value is re-evaluated on each call to {@link #getValue()}.
    *
    * @param value
    *    The supplier of the header value.
    *    <br>Can be <jk>null</jk>.
    * @return A new header bean, or <jk>null</jk> if the value is <jk>null</jk>.
    */
   public static Referer of(Supplier<URI> value) {
      return value == null ? null : new Referer(value);
   }

   //-----------------------------------------------------------------------------------------------------------------
   // Instance
   //-----------------------------------------------------------------------------------------------------------------

   /**
    * Constructor.
    *
    * @param value
    *    The header value.
    *    <br>Must be parsable by {@link URI#create(String)}.
    *    <br>Can be <jk>null</jk>.
    */
   public Referer(String value) {
      super(NAME, value);
   }

   /**
    * Constructor.
    *
    * @param value
    *    The header value.
    *    <br>Can be <jk>null</jk>.
    */
   public Referer(URI value) {
      super(NAME, value);
   }

   /**
    * Constructor with delayed value.
    *
    * <p>
    * Header value is re-evaluated on each call to {@link #getValue()}.
    *
    * @param value
    *    The supplier of the header value.
    *    <br>Can be <jk>null</jk>.
    */
   public Referer(Supplier<URI> value) {
      super(NAME, value);
   }
}