/*
    * ====================================================================
    * 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.client5.http.ssl;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.hc.core5.http.NameValuePair;
  import org.apache.hc.core5.http.message.BasicNameValuePair;
  import org.apache.hc.core5.util.CharArrayBuffer;
  import org.apache.hc.core5.util.Tokenizer;
  
  final class DistinguishedNameParser {
  
      /**
       * Default instance of {@link DistinguishedNameParser}.
       */
      public final static DistinguishedNameParser INSTANCE = new DistinguishedNameParser();
  
      private static final Tokenizer.Delimiter EQUAL_OR_COMMA_OR_PLUS = Tokenizer.delimiters('=', ',', '+');
      private static final Tokenizer.Delimiter COMMA_OR_PLUS = Tokenizer.delimiters(',', '+');
  
      private final Tokenizer tokenParser = new InternalTokenParser();
  
      private DistinguishedNameParser() {
          // empty
      }
  
      private String parseToken(final CharArrayBuffer buf, final Tokenizer.Cursor cursor, final Tokenizer.Delimiter delimiters) {
          return tokenParser.parseToken(buf, cursor, delimiters);
      }
  
      private String parseValue(final CharArrayBuffer buf, final Tokenizer.Cursor cursor, final Tokenizer.Delimiter delimiters) {
          return tokenParser.parseValue(buf, cursor, delimiters);
      }
  
      private NameValuePair parseParameter(final CharArrayBuffer buf, final Tokenizer.Cursor cursor) {
          final String name = parseToken(buf, cursor, EQUAL_OR_COMMA_OR_PLUS);
          if (cursor.atEnd()) {
              return new BasicNameValuePair(name, null);
          }
          final int delim = buf.charAt(cursor.getPos());
          cursor.updatePos(cursor.getPos() + 1);
          if (delim == ',') {
              return new BasicNameValuePair(name, null);
          }
          final String value = parseValue(buf, cursor, COMMA_OR_PLUS);
          if (!cursor.atEnd()) {
              cursor.updatePos(cursor.getPos() + 1);
          }
          return new BasicNameValuePair(name, value);
      }
  
      List<NameValuePair> parse(final CharArrayBuffer buf, final Tokenizer.Cursor cursor) {
          final List<NameValuePair> params = new ArrayList<>();
          tokenParser.skipWhiteSpace(buf, cursor);
          while (!cursor.atEnd()) {
              final NameValuePair param = parseParameter(buf, cursor);
              params.add(param);
          }
          return params;
      }
  
      List<NameValuePair> parse(final String s) {
          if (s == null) {
              return null;
          }
          final CharArrayBuffer buffer = new CharArrayBuffer(s.length());
          buffer.append(s);
          final Tokenizer.Cursor cursor = new Tokenizer.Cursor(0, s.length());
          return parse(buffer, cursor);
      }
  
      static class InternalTokenParser extends Tokenizer {
 
         @Override
         public void copyUnquotedContent(
                 final CharSequence buf,
                 final Tokenizer.Cursor cursor,
                 final Tokenizer.Delimiter delimiters,
                 final StringBuilder dst) {
             int pos = cursor.getPos();
             final int indexFrom = cursor.getPos();
             final int indexTo = cursor.getUpperBound();
             boolean escaped = false;
             for (int i = indexFrom; i < indexTo; i++, pos++) {
                 final char current = buf.charAt(i);
                 if (escaped) {
                     dst.append(current);
                     escaped = false;
                 } else {
                     if ((delimiters != null && delimiters.test(current))
                             || Tokenizer.isWhitespace(current) || current == '\"') {
                         break;
                     } else if (current == '\\') {
                         escaped = true;
                     } else {
                         dst.append(current);
                     }
                 }
             }
             cursor.updatePos(pos);
         }
     }
 
 }