/*
 * 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.http.part;

import static org.apache.juneau.commons.utils.AssertionUtils.*;
import static org.apache.juneau.commons.utils.ThrowableUtils.*;
import static org.apache.juneau.commons.utils.Utils.*;

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

import org.apache.http.*;
import org.apache.juneau.annotation.*;
import org.apache.juneau.assertions.*;
import org.apache.juneau.commons.reflect.*;
import org.apache.juneau.http.header.*;

/**
 * Implementation of {@link NameValuePair} for serializing POJOs as URL-encoded form post entries.
 *
 * Provides the following features:
 * <ul class='spaced-list'>
 *    <li>
 *       Values from {@link Supplier Suppliers}.
 *    <li>
 *       Caching.
 *    <li>
 *       Fluent setters.
 *    <li>
 *       Fluent assertions.
 * </ul>
 *
 * <h5 class='section'>See Also:</h5><ul>
 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/JuneauRestCommonBasics">juneau-rest-common Basics</a>
 * </ul>
 */
@BeanIgnore
public class BasicPart implements NameValuePair, Headerable {
   /**
    * Returns <jk>true</jk> if the {@link #cast(Object)} method can be used on the specified object.
    *
    * @param o The object to check.
    * @return <jk>true</jk> if the {@link #cast(Object)} method can be used on the specified object.
    */
   public static boolean canCast(Object o) {
      if (o == null)
         return false;
      var ci = ClassInfo.of(o);
      return nn(ci) && ci.isChildOfAny(Headerable.class, NameValuePair.class, NameValuePairable.class, Map.Entry.class);
   }

   /**
    * Utility method for converting an arbitrary object to a {@link NameValuePair}.
    *
    * @param o
    *    The object to cast or convert to a {@link NameValuePair}.
    * @return Either the same object cast as a {@link NameValuePair} or converted to a {@link NameValuePair}.
    */
   public static NameValuePair cast(Object o) {
      if (o instanceof NameValuePair o2)
         return o2;
      if (o instanceof NameValuePairable o3)
         return o3.asNameValuePair();
      if (o instanceof NameValuePair o2) {
         return BasicPart.of(o2.getName(), o2.getValue());
      }
      if (o instanceof Headerable o2) {
         var x = o2.asHeader();
         return BasicPart.of(x.getName(), x.getValue());
      }
      if (o instanceof Map.Entry e) {
         return BasicPart.of(s(e.getKey()), e.getValue());
      }
      throw rex("Object of type {0} could not be converted to a Part.", cn(o));
   }

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

   /**
    * Creates a {@link NameValuePair} from a name/value pair string (e.g. <js>"Foo: bar"</js>)
    *
    * @param pair The pair string.
    * @return A new {@link NameValuePair} object.
    */
   public static BasicPart 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 part name.
    * @param value The POJO to serialize to The part value.
    */
   public BasicPart(String name, Object value) {
      this.name = name;
      this.value = value;
   }

   /**
    * Copy constructor.
    *
    * @param copyFrom The object to copy.
    */
   protected BasicPart(BasicPart copyFrom) {
      assertArgNotNull("copyFrom", copyFrom);
      this.name = copyFrom.name;
      this.value = copyFrom.value;
   }

   @Override /* Overridden from Headerable */
   public BasicHeader asHeader() {
      return BasicHeader.of(name, s(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<BasicPart> 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 FluentStringAssertion<BasicPart> assertValue() {
      return new FluentStringAssertion<>(getValue(), this);
   }

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

   /**
    * Returns the raw value of the part.
    *
    * @return The raw value of the part.
    */
   public Object getRawValue() { return unwrap(value); }

   @Override /* Overridden from NameValuePair */
   public String getValue() { return s(unwrap(value)); }

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

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