/*
 * 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.common.utils.StringUtils.*;
import static org.apache.juneau.common.utils.Utils.*;
import static org.apache.juneau.internal.ConsumerUtils.*;

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

import org.apache.http.*;
import org.apache.http.util.*;
import org.apache.juneau.collections.*;
import org.apache.juneau.common.utils.*;
import org.apache.juneau.http.annotation.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.svl.*;

/**
 * An simple list of HTTP parts (form-data, query-parameters, path-parameters).
 *
 * <h5 class='figure'>Example</h5>
 * <p class='bjava'>
 *    PartList <jv>parts</jv> = PartList
 *       .<jsm>create</jsm>()
 *       .append(MyPart.<jsm>of</jsm>(<js>"foo"</js>))
 *       .append(<js>"Bar"</js>, ()-&gt;<jsm>getDynamicValueFromSomewhere</jsm>());
 * </p>
 *
 * <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>
 */
public class PartList extends ControlledArrayList<NameValuePair> {

   private static final long serialVersionUID = 1L;

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

   /** Represents no part list in annotations. */
   public static final class Void extends PartList {
      private static final long serialVersionUID = 1L;
   }

   /**
    * Instantiates a new part list.
    *
    * @return A new part list.
    */
   public static PartList create() {
      return new PartList();
   }

   /**
    * Creates a new {@link PartList} initialized with the specified parts.
    *
    * @param parts
    *    The parts to add to the list.
    *    <br>Can be <jk>null</jk>.
    *    <br><jk>null</jk> entries are ignored.
    * @return A new unmodifiable instance, never <jk>null</jk>.
    */
   public static PartList of(List<NameValuePair> parts) {
      return new PartList().append(parts);
   }

   /**
    * Creates a new {@link PartList} initialized with the specified parts.
    *
    * @param parts
    *    The parts to add to the list.
    *    <br><jk>null</jk> entries are ignored.
    * @return A new unmodifiable instance, never <jk>null</jk>.
    */
   public static PartList of(NameValuePair...parts) {
      return new PartList().append(parts);
   }

   /**
    * Creates a new {@link PartList} initialized with the specified name/value pairs.
    *
    * <h5 class='figure'>Example</h5>
    * <p class='bjava'>
    *    PartList <jv>parts</jv> = PartList.<jsm>ofPairs</jsm>(<js>"foo"</js>, 1, <js>"bar"</js>, <jk>true</jk>);
    * </p>
    *
    * @param pairs
    *    Initial list of pairs.
    *    <br>Must be an even number of parameters representing key/value pairs.
    * @throws RuntimeException If odd number of parameters were specified.
    * @return A new instance.
    */
   public static PartList ofPairs(String... pairs) {
      PartList x = new PartList();
      if (pairs == null)
         pairs = new String[0];
      if (pairs.length % 2 != 0)
         throw new IllegalArgumentException("Odd number of parameters passed into PartList.ofPairs()");
      for (int i = 0; i < pairs.length; i+=2)
         x.add(BasicPart.of(pairs[i], pairs[i+1]));
      return x;
   }

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

   private VarResolver varResolver;
   boolean caseInsensitive;

   /**
    * Constructor.
    */
   public PartList() {
      super(false);
   }

   /**
    * Copy constructor.
    *
    * @param copyFrom The bean to copy.
    */
   protected PartList(PartList copyFrom) {
      super(false, copyFrom);
      caseInsensitive = copyFrom.caseInsensitive;
   }

   /**
    * Makes a copy of this list.
    *
    * @return A new copy of this list.
    */
   public PartList copy() {
      return new PartList(this);
   }

   /**
    * Adds a collection of default parts.
    *
    * <p>
    * Default parts are set if they're not already in the list.
    *
    * @param parts The list of default parts.
    * @return This object.
    */
   public PartList setDefault(List<NameValuePair> parts) {
      if (parts != null)
         parts.stream().filter(x -> x != null && ! contains(x.getName())).forEach(this::set);
      return this;
   }

   /**
    * Makes a copy of this list of parts and adds a collection of default parts.
    *
    * <p>
    * Default parts are set if they're not already in the list.
    *
    * @param parts The list of default parts.
    * @return A new list, or the same list if the parts were empty.
    */
   public PartList setDefault(NameValuePair...parts) {
      if (parts != null)
         setDefault(Arrays.asList(parts));
      return this;
   }

   /**
    * Replaces the first occurrence of the part with the same name.
    *
    * @param name The header name.
    * @param value The header value.
    * @return This object.
    */
   public PartList setDefault(String name, Object value) {
      return setDefault(createPart(name, value));
   }

   /**
    * Replaces the first occurrence of the headers with the same name.
    *
    * @param name The header name.
    * @param value The header value.
    * @return This object.
    */
   public PartList setDefault(String name, Supplier<?> value) {
      return setDefault(createPart(name, value));
   }

   //-------------------------------------------------------------------------------------------------------------
   // Properties
   //-------------------------------------------------------------------------------------------------------------

   /**
    * Allows part values to contain SVL variables.
    *
    * <p>
    * Resolves variables in part values when using the following methods:
    * <ul>
    *    <li class='jm'>{@link #append(String, Object) append(String,Object)}
    *    <li class='jm'>{@link #append(String, Supplier) append(String,Supplier&lt;?&gt;)}
    *    <li class='jm'>{@link #prepend(String, Object) prepend(String,Object)}
    *    <li class='jm'>{@link #prepend(String, Supplier) prepend(String,Supplier&lt;?&gt;)}
    *    <li class='jm'>{@link #set(String, Object) set(String,Object)}
    *    <li class='jm'>{@link #set(String, Supplier) set(String,Supplier&lt;?&gt;)}
    * </ul>
    *
    * <p>
    * Uses {@link VarResolver#DEFAULT} to resolve variables.
    *
    * @return This object.
    */
   public PartList resolving() {
      return resolving(VarResolver.DEFAULT);
   }

   /**
    * Allows part values to contain SVL variables.
    *
    * <p>
    * Resolves variables in part values when using the following methods:
    * <ul>
    *    <li class='jm'>{@link #append(String, Object) append(String,Object)}
    *    <li class='jm'>{@link #append(String, Supplier) append(String,Supplier&lt;?&gt;)}
    *    <li class='jm'>{@link #prepend(String, Object) prepend(String,Object)}
    *    <li class='jm'>{@link #prepend(String, Supplier) prepend(String,Supplier&lt;?&gt;)}
    *    <li class='jm'>{@link #set(String, Object) set(String,Object)}
    *    <li class='jm'>{@link #set(String, Supplier) set(String,Supplier&lt;?&gt;)}
    * </ul>
    *
    * @param varResolver The variable resolver to use for resolving variables.
    * @return This object.
    */
   public PartList resolving(VarResolver varResolver) {
      assertModifiable();
      this.varResolver = varResolver;
      return this;
   }

   /**
    * Specifies that the parts in this list should be treated as case-sensitive.
    *
    * <p>
    * The default behavior is case-sensitive.
    *
    * @param value The new value for this setting.
    * @return This object.
    */
   public PartList caseInsensitive(boolean value) {
      assertModifiable();
      caseInsensitive = value;
      return this;
   }

   /**
    * Adds the specified part to the end of the parts in this list.
    *
    * @param value The part to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList append(NameValuePair value) {
      if (value != null)
         add(value);
      return this;
   }

   /**
    * Appends the specified part to the end of this list.
    *
    * <p>
    * The part is added as a {@link BasicPart}.
    *
    * @param name The part name.
    * @param value The part value.
    * @return This object.
    */
   public PartList append(String name, Object value) {
      return append(createPart(name, value));
   }

   /**
    * Appends the specified part to the end of this list using a value supplier.
    *
    * <p>
    * The part is added as a {@link BasicPart}.
    *
    * <p>
    * Value is re-evaluated on each call to {@link BasicPart#getValue()}.
    *
    * @param name The part name.
    * @param value The part value supplier.
    * @return This object.
    */
   public PartList append(String name, Supplier<?> value) {
      return append(createPart(name, value));
   }

   /**
    * Adds the specified parts to the end of the parts in this list.
    *
    * @param values The parts to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList append(NameValuePair...values) {
      if (values != null)
            for (NameValuePair value : values)
                append(value);
      return this;
   }

   /**
    * Adds the specified parts to the end of the parts in this list.
    *
    * @param values The parts to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList append(List<NameValuePair> values) {
      if (values != null)
         values.forEach(this::append);
      return this;
   }

   /**
    * Adds the specified part to the beginning of the parts in this list.
    *
    * @param value The part to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList prepend(NameValuePair value) {
      if (value != null)
         add(0, value);
      return this;
   }

   /**
    * Appends the specified part to the beginning of this list.
    *
    * <p>
    * The part is added as a {@link BasicPart}.
    *
    * @param name The part name.
    * @param value The part value.
    * @return This object.
    */
   public PartList prepend(String name, Object value) {
      return prepend(createPart(name, value));
   }

   /**
    * Appends the specified part to the beginning of this list using a value supplier.
    *
    * <p>
    * The part is added as a {@link BasicPart}.
    *
    * <p>
    * Value is re-evaluated on each call to {@link BasicPart#getValue()}.
    *
    * @param name The part name.
    * @param value The part value supplier.
    * @return This object.
    */
   public PartList prepend(String name, Supplier<?> value) {
      return prepend(createPart(name, value));
   }

   /**
    * Adds the specified parts to the beginning of the parts in this list.
    *
    * @param values The parts to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList prepend(NameValuePair...values) {
      if (values != null)
         prepend(alist(values));
      return this;
   }

   /**
    * Adds the specified parts to the beginning of the parts in this list.
    *
    * @param values The parts to add.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList prepend(List<NameValuePair> values) {
      if (values != null)
         addAll(0, values);
      return this;
   }

   /**
    * Removes the specified part from this list.
    *
    * @param value The part to remove.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList remove(NameValuePair value) {
      if (value != null)
         removeIf(x -> eq(x.getName(), value.getName()) && eq(x.getValue(), value.getValue()));
      return this;
   }

   /**
    * Removes the specified parts from this list.
    *
    * @param values The parts to remove.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList remove(NameValuePair...values) {
      for (NameValuePair value : values)
            remove(value);
      return this;
   }

   /**
    * Removes the specified parts from this list.
    *
    * @param values The parts to remove.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList remove(List<NameValuePair> values) {
      if (values != null)
         values.forEach(this::remove);
      return this;
   }

   /**
    * Removes the part with the specified name from this list.
    *
    * @param name The part name.
    * @return This object.
    */
   public PartList remove(String name) {
      removeIf(x -> eq(x.getName(), name));
      return this;
   }

   /**
    * Removes the part with the specified name from this list.
    *
    * @param names The part name.
    * @return This object.
    */
   public PartList remove(String...names) {
      if (names != null)
            for (String name : names)
                remove(name);
      return this;
   }

   /**
    * Adds or replaces the part(s) with the same name.
    *
    * <p>
    * If no part with the same name is found the given part is added to the end of the list.
    *
    * @param value The part to replace.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList set(NameValuePair value) {
      if (value != null) {
         boolean replaced = false;
         for (int i = 0, j = size(); i < j; i++) {
            NameValuePair x = get(i);
            if (eq(x.getName(), value.getName())) {
               if (replaced) {
                  remove(i);
                  j--;
               } else {
                  set(i, value);
                  replaced = true;
               }
            }
         }

         if (! replaced)
            add(value);
      }

      return this;
   }

   /**
    * Adds or replaces the part(s) with the same name.
    *
    * <p>
    * If no part with the same name is found the given part is added to the end of the list.
    *
    * @param values The part to replace.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList set(NameValuePair...values) {
      if (values != null)
         set(alist(values));
      return this;
   }

   /**
    * Replaces the first occurrence of the parts with the same name.
    *
    * @param name The part name.
    * @param value The part value.
    * @return This object.
    */
   public PartList set(String name, Object value) {
      return set(createPart(name, value));
   }

   /**
    * Replaces the first occurrence of the parts with the same name.
    *
    * @param name The part name.
    * @param value The part value.
    * @return This object.
    */
   public PartList set(String name, Supplier<?> value) {
      return set(createPart(name, value));
   }

   /**
    * Replaces the first occurrence of the parts with the same name.
    *
    * <p>
    * If no part with the same name is found the given part is added to the end of the list.
    *
    * @param values The parts to replace.  <jk>null</jk> values are ignored.
    * @return This object.
    */
   public PartList set(List<NameValuePair> values) {

      if (values != null) {
         for (NameValuePair h : values) {
            if (h != null) {
               for (int i2 = 0, j2 = size(); i2 < j2; i2++) {
                  NameValuePair x = get(i2);
                  if (eq(x.getName(), h.getName())) {
                     remove(i2);
                     j2--;
                  }
               }
            }
         }

         for (NameValuePair x : values) {
            if (x != null) {
               add(x);
            }
         }
      }

      return this;
   }

   /**
    * Gets the first part with the given name.
    *
    * <p>
    * Part name comparison is case sensitive by default.
    *
    * @param name The part name.
    * @return The first matching part, or {@link Optional#empty()} if not found.
    */
   public Optional<NameValuePair> getFirst(String name) {
      for (int i = 0; i < size(); i++) {
         NameValuePair x = get(i);
         if (eq(x.getName(), name))
            return Utils.opt(x);
      }
      return opte();
   }

   /**
    * Gets the last part with the given name.
    *
    * <p>
    * Part name comparison is case sensitive by default.
    *
    * @param name The part name.
    * @return The last matching part, or {@link Optional#empty()} if not found.
    */
   public Optional<NameValuePair> getLast(String name) {
      for (int i = size() - 1; i >= 0; i--) {
         NameValuePair x = get(i);
         if (eq(x.getName(), name))
            return Utils.opt(x);
      }
      return opte();
   }

   /**
    * Gets a part representing all of the part values with the given name.
    *
    * <p>
    * If more that one part with the given name exists the values will be combined with <js>", "</js> as per
    * <a href='https://tools.ietf.org/html/rfc2616#section-4.2'>RFC 2616 Section 4.2</a>.
    *
    * @param name The part name.
    * @return A part with a condensed value, or {@link Optional#empty()} if no parts by the given name are present
    */
   public Optional<NameValuePair> get(String name) {

      NameValuePair first = null;
      List<NameValuePair> rest = null;
      for (NameValuePair x : this) {
         if (eq(x.getName(), name)) {
            if (first == null)
               first = x;
            else {
               if (rest == null)
                  rest = Utils.list();
               rest.add(x);
            }
         }
      }

      if (first == null)
         return opte();

      if (rest == null)
         return Utils.opt(first);

      CharArrayBuffer sb = new CharArrayBuffer(128);
      sb.append(first.getValue());
      for (NameValuePair element : rest) {
         sb.append(',');
         sb.append(element.getValue());
      }

      return Utils.opt(new BasicStringPart(name, sb.toString()));
   }

   /**
    * Gets a part representing all of the part values with the given name.
    *
    * <p>
    * If more that one part with the given name exists the values will be combined with <js>", "</js> as per
    * <a href='https://tools.ietf.org/html/rfc2616#section-4.2'>RFC 2616 Section 4.2</a>.
    *
    * <p>
    * The implementation class must have a public constructor taking in one of the following argument lists:
    * <ul>
    *    <li><c>X(String <jv>value</jv>)</c>
    *    <li><c>X(Object <jv>value</jv>)</c>
    *    <li><c>X(String <jv>name</jv>, String <jv>value</jv>)</c>
    *    <li><c>X(String <jv>name</jv>, Object <jv>value</jv>)</c>
    * </ul>
    *
    * <h5 class='figure'>Example</h5>
    * <p class='bjava'>
    *    BasicIntegerPart <jv>age</jv> = <jv>partList</jv>.get(<js>"age"</js>, BasicIntegerPart.<jk>class</jk>);
    * </p>
    *
    * @param <T> The part implementation class.
    * @param name The part name.
    * @param type The part implementation class.
    * @return A part with a condensed value or <jk>null</jk> if no parts by the given name are present
    */
   public <T> Optional<T> get(String name, Class<T> type) {

      NameValuePair first = null;
      List<NameValuePair> rest = null;
      for (NameValuePair x : this) {
         if (eq(x.getName(), name)) {
            if (first == null)
               first = x;
            else {
               if (rest == null)
                  rest = Utils.list();
               rest.add(x);
            }
         }
      }

      if (first == null)
         return opte();

      if (rest == null)
         return opt(PartBeanMeta.of(type).construct(name, first.getValue()));

      CharArrayBuffer sb = new CharArrayBuffer(128);
      sb.append(first.getValue());
      for (NameValuePair element : rest) {
         sb.append(',');
         sb.append(element.getValue());
      }

      return Utils.opt(PartBeanMeta.of(type).construct(name, sb.toString()));
   }

   /**
    * Gets a part representing all of the part values with the given name.
    *
    * <p>
    * Same as {@link #get(String, Class)} but the part name is pulled from the name or value attribute of the {@link FormData}/{@link Query}/{@link Path} annotation.
    *
    * <h5 class='figure'>Example</h5>
    * <p class='bjava'>
    *    Age <jv>age</jv> = <jv>partList</jv>.get(Age.<jk>class</jk>);
    * </p>
    *
    * @param <T> The part implementation class.
    * @param type The part implementation class.
    * @return A part with a condensed value or <jk>null</jk> if no parts by the given name are present
    */
   public <T> Optional<T> get(Class<T> type) {
      Utils.assertArgNotNull("type", type);

      String name = PartBeanMeta.of(type).getSchema().getName();
      Utils.assertArg(name != null, "Part name could not be found on bean type ''{0}''", type.getName());

      return get(name, type);
   }

   /**
    * Gets all of the parts.
    *
    * <p>
    * The returned array maintains the relative order in which the parts were added.
    * Each call creates a new array not backed by this list.
    *
    * <p>
    * As a general rule, it's more efficient to use the other methods with consumers to
    * get parts.
    *
    * @return An array containing all parts, never <jk>null</jk>.
    */
   public NameValuePair[] getAll() {
      return stream().toArray(NameValuePair[]::new);
   }

   /**
    * Gets all of the parts with the given name.
    *
    * <p>
    * The returned array maintains the relative order in which the parts were added.
    * Part name comparison is case sensitive by default.
    * Parts with null values are ignored.
    * Each call creates a new array not backed by this list.
    *
    * <p>
    * As a general rule, it's more efficient to use the other methods with consumers to
    * get parts.
    *
    * @param name The part name.
    *
    * @return An array containing all matching parts, never <jk>null</jk>.
    */
   public NameValuePair[] getAll(String name) {
      return stream().filter(x -> eq(x.getName(), name)).toArray(NameValuePair[]::new);
   }

   /**
    * Performs an action on the values for all matching parts in this list.
    *
    * @param filter A predicate to apply to each element to determine if it should be included.  Can be <jk>null</jk>.
    * @param action An action to perform on each element.
    * @return This object.
    */
   public PartList forEachValue(Predicate<NameValuePair> filter, Consumer<String> action) {
      return forEach(filter, x -> action.accept(x.getValue()));
   }

   /**
    * Performs an action on the values of all matching parts in this list.
    *
    * @param name The part name.
    * @param action An action to perform on each element.
    * @return This object.
    */
   public PartList forEachValue(String name, Consumer<String> action) {
      return forEach(name, x -> action.accept(x.getValue()));
   }

   /**
    * Returns all the string values for all parts with the specified name.
    *
    * @param name The part name.
    * @return An array containing all values.  Never <jk>null</jk>.
    */
   public String[] getValues(String name) {
      return stream().filter(x -> eq(x.getName(), name)).map(NameValuePair::getValue).toArray(String[]::new);
   }

   /**
    * Tests if parts with the given name are contained within this list.
    *
    * <p>
    * Part name comparison is case insensitive.
    *
    * @param name The part name.
    * @return <jk>true</jk> if at least one part with the name is present.
    */
   public boolean contains(String name) {
      return stream().anyMatch(x -> eq(x.getName(), name));
   }

   /**
    * Returns an iterator over this list of parts.
    *
    * @return A new iterator over this list of parts.
    */
   public PartIterator partIterator() {
      return new BasicPartIterator(toArray(new NameValuePair[0]), null, caseInsensitive);
   }

   /**
    * Returns an iterator over the parts with a given name in this list.
    *
    * @param name The name of the parts over which to iterate, or <jk>null</jk> for all parts
    *
    * @return A new iterator over the matching parts in this list.
    */
   public PartIterator partIterator(String name) {
      return new BasicPartIterator(getAll(name), name, caseInsensitive);
   }

   /**
    * Performs an action on all parts in this list with the specified name.
    *
    * <p>
    * This is the preferred method for iterating over parts as it does not involve
    * creation or copy of lists/arrays.
    *
    * @param name The parts name.
    * @param action An action to perform on each element.
    * @return This object.
    */
   public PartList forEach(String name, Consumer<NameValuePair> action) {
      return forEach(x -> eq(name, x.getName()), action);
   }

   /**
    * Performs an action on all the matching parts in this list.
    *
    * <p>
    * This is the preferred method for iterating over parts as it does not involve
    * creation or copy of lists/arrays.
    *
    * @param filter A predicate to apply to each element to determine if it should be included.  Can be <jk>null</jk>.
    * @param action An action to perform on each element.
    * @return This object.
    */
   public PartList forEach(Predicate<NameValuePair> filter, Consumer<NameValuePair> action) {
      forEach(x -> consume(filter, action, x));
      return this;
   }

   /**
    * Returns a stream of the parts in this list with the specified name.
    *
    * <p>
    * This does not involve a copy of the underlying array of <c>NameValuePair</c> objects so should perform well.
    *
    * @param name The part name.
    * @return This object.
    */
   public Stream<NameValuePair> stream(String name) {
      return stream().filter(x->eq(name, x.getName()));
   }

   //-------------------------------------------------------------------------------------------------------------
   // Other methods
   //-------------------------------------------------------------------------------------------------------------

   private NameValuePair createPart(String name, Object value) {
      boolean isResolving = varResolver != null;

      if (value instanceof Supplier<?>) {
         Supplier<?> value2 = (Supplier<?>)value;
         return isResolving ? new BasicPart(name, resolver(value2)) : new BasicPart(name, value2);
      }
      return isResolving ? new BasicPart(name, resolver(value)) : new BasicPart(name, value);
   }

   private Supplier<Object> resolver(Object input) {
      return ()->varResolver.resolve(Utils.s(unwrap(input)));
   }

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

   private boolean eq(String s1, String s2) {
      return caseInsensitive ? Utils.eqic(s1, s2) : Utils.eq(s1, s2);
   }

   /**
    * Returns this list as a URL-encoded custom query.
    */
   @Override /* Object */
   public String toString() {
      StringBuilder sb = new StringBuilder();
      forEach(p -> {
         if (p != null) {
            String v = p.getValue();
            if (v != null) {
               if (sb.length() > 0)
                  sb.append("&");
               sb.append(urlEncode(p.getName())).append('=').append(urlEncode(p.getValue()));
            }
         }
      });
      return sb.toString();
   }
   @Override /* Overridden from ControlledArrayList */
   public PartList setUnmodifiable() {
      super.setUnmodifiable();
      return this;
   }
}