/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.core5.http.message;
  
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.http.HeaderElement;
  import org.apache.hc.core5.http.NameValuePair;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.CharArrayBuffer;
  
  /**
   * Default {@link org.apache.hc.core5.http.message.HeaderValueFormatter} implementation.
   *
   * @since 4.0
   */
  @Contract(threading = ThreadingBehavior.IMMUTABLE)
  public class BasicHeaderValueFormatter implements HeaderValueFormatter {
  
      public final static BasicHeaderValueFormatterrValueFormatter.html#BasicHeaderValueFormatter">BasicHeaderValueFormatter INSTANCE = new BasicHeaderValueFormatter();
  
      private final static String SEPARATORS = " ;,:@()<>\\\"/[]?={}\t";
      private final static String UNSAFE_CHARS = "\"\\";
  
      public BasicHeaderValueFormatter() {
          super();
      }
  
      @Override
      public void formatElements(
              final CharArrayBuffer buffer, final HeaderElement[] elems, final boolean quote) {
          Args.notNull(buffer, "Char array buffer");
          Args.notNull(elems, "Header element array");
  
          for (int i = 0; i < elems.length; i++) {
              if (i > 0) {
                  buffer.append(", ");
              }
              formatHeaderElement(buffer, elems[i], quote);
          }
      }
  
      @Override
      public void formatHeaderElement(
              final CharArrayBuffer buffer, final HeaderElement elem, final boolean quote) {
          Args.notNull(buffer, "Char array buffer");
          Args.notNull(elem, "Header element");
  
          buffer.append(elem.getName());
          final String value = elem.getValue();
          if (value != null) {
              buffer.append('=');
              formatValue(buffer, value, quote);
          }
  
          final int c = elem.getParameterCount();
          if (c > 0) {
              for (int i = 0; i < c; i++) {
                  buffer.append("; ");
                  formatNameValuePair(buffer, elem.getParameter(i), quote);
              }
          }
      }
  
      @Override
      public void formatParameters(
              final CharArrayBuffer buffer, final NameValuePair[] nvps, final boolean quote) {
          Args.notNull(buffer, "Char array buffer");
          Args.notNull(nvps, "Header parameter array");
  
          for (int i = 0; i < nvps.length; i++) {
              if (i > 0) {
                  buffer.append("; ");
              }
             formatNameValuePair(buffer, nvps[i], quote);
         }
     }
 
     @Override
     public void formatNameValuePair(
             final CharArrayBuffer buffer, final NameValuePair nvp, final boolean quote) {
         Args.notNull(buffer, "Char array buffer");
         Args.notNull(nvp, "Name / value pair");
 
         buffer.append(nvp.getName());
         final String value = nvp.getValue();
         if (value != null) {
             buffer.append('=');
             formatValue(buffer, value, quote);
         }
     }
 
     void formatValue(final CharArrayBuffer buffer, final String value, final boolean quote) {
 
         boolean quoteFlag = quote;
         if (!quoteFlag) {
             for (int i = 0; (i < value.length()) && !quoteFlag; i++) {
                 quoteFlag = isSeparator(value.charAt(i));
             }
         }
 
         if (quoteFlag) {
             buffer.append('"');
         }
         for (int i = 0; i < value.length(); i++) {
             final char ch = value.charAt(i);
             if (isUnsafe(ch)) {
                 buffer.append('\\');
             }
             buffer.append(ch);
         }
         if (quoteFlag) {
             buffer.append('"');
         }
     }
 
     boolean isSeparator(final char ch) {
         return SEPARATORS.indexOf(ch) >= 0;
     }
 
     boolean isUnsafe(final char ch) {
         return UNSAFE_CHARS.indexOf(ch) >= 0;
     }
 
 }