/*
 * 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
 *
 *      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 "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.juneau.rest.server.httppart;

import static org.apache.juneau.commons.utils.Shorts.*;
import static org.apache.juneau.commons.utils.StringUtils.*;

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

import org.apache.juneau.marshall.*;
import org.apache.juneau.bct.assertions.*;

/**
 * Implementation of a named object.
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/RestServerHttpParts">HTTP parts in REST servers</a>
 * </ul>
 */
@Marshalled(as=MarshalledAs.STRING)
public class BasicNamedAttribute implements NamedAttribute {

   /**
    * Static creator.
    *
    * @param name The parameter name.
    * @param value The parameter value.
    * @return A new {@link BasicNamedAttribute} object.
    */
   public static BasicNamedAttribute of(String name, Object value) {
      return new BasicNamedAttribute(name, value);
   }

   /**
    * Static creator with delayed value.
    *
    * <p>
    * Value is re-evaluated on each call to {@link #getValue()}.
    *
    * @param name The parameter name.
    * @param value The parameter value supplier.
    * @return A new {@link BasicNamedAttribute} object.
    */
   public static BasicNamedAttribute of(String name, Supplier<?> value) {
      return new BasicNamedAttribute(name, value);
   }

   /**
    * Creates a {@link BasicNamedAttribute} from a name/value pair string (e.g. <js>"Foo: bar"</js>)
    *
    * @param pair The pair string.  Can be <jk>null</jk>, in which case <jk>null</jk> is returned.
    * @return A new {@link BasicNamedAttribute} object, or <jk>null</jk> if the pair string was <jk>null</jk>.
    */
   public static BasicNamedAttribute ofPair(String pair) {
      if (pair == null)
         return null;
      var i = pair.indexOf(':');
      if (i == -1)
         i = pair.indexOf('=');
      if (i == -1)
         return of(pair, "");
      return of(pair.substring(0, i).trim(), pair.substring(i + 1).trim());
   }

   private final String name;
   private final Object value;

   /**
    * Constructor.
    *
    * @param name The parameter name.
    * @param value The POJO to serialize to the parameter value.
    */
   public BasicNamedAttribute(String name, Object value) {
      this.name = name;
      this.value = value;
   }

   /**
    * Copy constructor.
    *
    * @param copyOf The object to copy.
    */
   protected BasicNamedAttribute(BasicNamedAttribute copyOf) {
      this.name = copyOf.name;
      this.value = copyOf.value;
   }

   /**
    * Provides an object for performing assertions against the name of this pair.
    *
    * @return An object for performing assertions against the name of this pair.
    */
   public FluentStringAssertion<BasicNamedAttribute> assertName() {
      return new FluentStringAssertion<>(getName(), this);
   }

   /**
    * Provides an object for performing assertions against the value of this pair.
    *
    * @return An object for performing assertions against the value of this pair.
    */
   public FluentObjectAssertion<Object,BasicNamedAttribute> assertValue() {
      return new FluentObjectAssertion<>(getValue(), this);
   }

   /**
    * If a value is present, returns the value, otherwise throws {@link NoSuchElementException}.
    *
    * <p>
    * This is a shortcut for calling <c>asString().get()</c>.
    *
    * @return The value if present.
    */
   public Object get() {
      Object o = getValue();
      if (o == null)
         throw new NoSuchElementException();
      return o;
   }

   @Override /* Overridden from NamedAttribute */
   public String getName() { return name; }

   @Override /* Overridden from NamedAttribute */
   public Object getValue() { return unwrap(value); }

   /**
    * Returns <jk>true</jk> if the value exists.
    *
    * <p>
    * This is a shortcut for calling <c>asString().isPresent()</c>.
    *
    * @return <jk>true</jk> if the value exists.
    */
   public boolean isPresent() { return nn(getValue()); }

   /**
    * If a value is present, returns the value, otherwise returns other.
    *
    * <p>
    * This is a shortcut for calling <c>asString().orElse(<jv>other</jv>)</c>.
    *
    * @param other The other value.
    * @return The value if present or the other value if not.
    */
   public Object orElse(Object other) {
      Object o = getValue();
      return nn(o) ? o : other;
   }

   @Override /* Overridden from Object */
   public String toString() {
      return urlEncode(getName()) + "=" + getValue();
   }

   private static Object unwrap(Object o) {
      while (o instanceof Supplier)
         o = ((Supplier<?>)o).get();
      return o;
   }
}