//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.client.util;
  
  import java.io.UnsupportedEncodingException;
  import java.net.URLEncoder;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.nio.charset.UnsupportedCharsetException;
  
  import org.eclipse.jetty.client.api.ContentProvider;
  import org.eclipse.jetty.util.Fields;
  
  /**
   * A {@link ContentProvider} for form uploads with the
   * "application/x-www-form-urlencoded" content type.
   */
  public class FormContentProvider extends StringContentProvider
  {
      public FormContentProvider(Fields fields)
      {
          this(fields, StandardCharsets.UTF_8);
      }
  
      public FormContentProvider(Fields fields, Charset charset)
      {
          super("application/x-www-form-urlencoded", convert(fields, charset), charset);
      }
  
      public static String convert(Fields fields)
      {
          return convert(fields, StandardCharsets.UTF_8);
      }
  
      public static String convert(Fields fields, Charset charset)
      {
          // Assume 32 chars between name and value.
          StringBuilder builder = new StringBuilder(fields.getSize() * 32);
          for (Fields.Field field : fields)
          {
              for (String value : field.getValues())
              {
                  if (builder.length() > 0)
                      builder.append("&");
                  builder.append(encode(field.getName(), charset)).append("=").append(encode(value, charset));
              }
          }
          return builder.toString();
      }
  
      private static String encode(String value, Charset charset)
      {
          try
          {
              return URLEncoder.encode(value, charset.name());
          }
          catch (UnsupportedEncodingException x)
          {
              throw new UnsupportedCharsetException(charset.name());
          }
      }
  }