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

import static org.apache.juneau.internal.StringUtils.*;

import java.lang.reflect.*;
import java.util.*;
import java.util.function.*;

import org.apache.juneau.collections.*;
import org.apache.juneau.http.*;
import org.apache.juneau.internal.*;

/**
 * Category of headers that consist of a comma-delimited list of entity validator values.
 *
 * <p>
 * <h5 class='figure'>Example</h5>
 * <p class='bcode w800'>
 *    If-Match: "xyzzy"
 *    If-Match: "xyzzy", "r2d2xxxx", "c3piozzzz"
 *    If-Match: *
 * </p>
 *
 * <ul class='seealso'>
 *    <li class='extlink'>{@doc ExtRFC2616}
 * </ul>
 */
public class BasicEntityTagArrayHeader extends BasicHeader {

   private static final long serialVersionUID = 1L;

   /**
    * Convenience creator.
    *
    * @param name The header name.
    * @param value
    *    The header value.
    *    <br>Can be any of the following:
    *    <ul>
    *       <li><c>String</c> - A comma-delimited list of entity validator values (e.g. <js>"\"xyzzy\", \"r2d2xxxx\", \"c3piozzzz\""</js>).
    *       <li>A collection or array of {@link EntityTag} objects.
    *       <li>A collection or array of anything else - Converted to Strings.
    *       <li>Anything else - Converted to <c>String</c>.
    *    </ul>
    * @return A new {@link BasicEntityTagArrayHeader} object, or <jk>null</jk> if the name or value is <jk>null</jk>.
    */
   public static BasicEntityTagArrayHeader of(String name, Object value) {
      if (isEmpty(name) || value == null)
         return null;
      return new BasicEntityTagArrayHeader(name, value);
   }

   /**
    * Convenience creator using supplier.
    *
    * <p>
    * Header value is re-evaluated on each call to {@link #getValue()}.
    *
    * @param name The header name.
    * @param value
    *    The header value supplier.
    *    <br>Can be any of the following:
    *    <ul>
    *       <li><c>String</c> - A comma-delimited list of entity validator values (e.g. <js>"\"xyzzy\", \"r2d2xxxx\", \"c3piozzzz\""</js>).
    *       <li>A collection or array of {@link EntityTag} objects.
    *       <li>A collection or array of anything else - Converted to Strings.
    *       <li>Anything else - Converted to <c>String</c>.
    *    </ul>
    * @return A new {@link BasicEntityTagArrayHeader} object, or <jk>null</jk> if the name or value is <jk>null</jk>.
    */
   public static BasicEntityTagArrayHeader of(String name, Supplier<?> value) {
      if (isEmpty(name) || value == null)
         return null;
      return new BasicEntityTagArrayHeader(name, value);
   }

   private List<EntityTag> parsed;

   /**
    * Constructor.
    *
    * @param name The header name.
    * @param value
    *    The header value.
    *    <br>Can be any of the following:
    *    <ul>
    *       <li><c>String</c> - A comma-delimited list of entity validator values (e.g. <js>"\"xyzzy\", \"r2d2xxxx\", \"c3piozzzz\""</js>).
    *       <li>A collection or array of {@link EntityTag} objects.
    *       <li>A collection or array of anything else - Converted to Strings.
    *       <li>Anything else - Converted to <c>String</c>.
    *       <li>A {@link Supplier} of anything on this list.
    *    </ul>
    */
   public BasicEntityTagArrayHeader(String name, Object value) {
      super(name, value);
      if (! isSupplier(value))
         parsed = getParsedValue();
   }

   @Override /* Header */
   public String getValue() {
      Object o = getRawValue();
      if (o instanceof String)
         return (String)o;
      return StringUtils.join(asEntityTags(), ',');
   }

   /**
    * Returns this header value as an array of {@link EntityTag} objects.
    *
    * @return this header value as an array of {@link EntityTag} objects.
    */
   public List<EntityTag> asEntityTags() {
      return getParsedValue();
   }

   private List<EntityTag> getParsedValue() {
      if (parsed != null)
         return parsed;
      Object o = getRawValue();
      if (o == null)
         return null;
      if (o instanceof EntityTag[])
         return AList.of((EntityTag[])o).unmodifiable();

      AList<EntityTag> l = AList.of();
      if (o instanceof Collection) {
         for (Object o2 : (Collection<?>)o)
            l.add(EntityTag.of(o2));
      } else if (o.getClass().isArray()) {
         for (int i = 0; i < Array.getLength(o); i++)
            l.add(EntityTag.of(Array.get(o, i)));
      } else {
         for (String s : split(o.toString()))
            l.add(EntityTag.of(s));
      }
      return l.unmodifiable();
   }
}