/*
    * ====================================================================
    * 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 java.io.Serializable;
  
  import org.apache.hc.core5.http.Chars;
  import org.apache.hc.core5.http.FormattedHeader;
  import org.apache.hc.core5.http.ParseException;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.CharArrayBuffer;
  import org.apache.hc.core5.util.Tokenizer;
  
  /**
   * This class represents a raw HTTP header whose content is parsed 'on demand'
   * only when the header value needs to be consumed.
   *
   * @since 4.0
   */
  public class BufferedHeader implements FormattedHeader, Serializable {
  
      private static final long serialVersionUID = -2768352615787625448L;
  
      /**
       * Header name.
       */
      private final String name;
  
      /**
       * The buffer containing the entire header line.
       */
      private final CharArrayBuffer buffer;
  
      /**
       * The beginning of the header value in the buffer
       */
      private final int valuePos;
  
      private String value;
  
      /**
       * @since 5.0
       */
      public static BufferedHeader create(final CharArrayBuffer buffer) {
          try {
              return new BufferedHeader(buffer);
          } catch (final ParseException ex) {
              throw new IllegalArgumentException(ex.getMessage());
          }
      }
  
      /**
       * Creates a new header from a buffer.
       * The name of the header will be parsed immediately,
       * the value only if it is accessed.
       *
       * @param buffer    the buffer containing the header to represent
       *
       * @throws ParseException   in case of a parse error
       */
      public BufferedHeader(final CharArrayBuffer buffer) throws ParseException {
          this(buffer, true);
      }
  
      BufferedHeader(final CharArrayBuffer buffer, final boolean strict) throws ParseException {
          super();
          Args.notNull(buffer, "Char array buffer");
          final int colon = buffer.indexOf(':');
          if (colon <= 0) {
              throw new ParseException("Invalid header", buffer, 0, buffer.length());
          }
          if (strict && Tokenizer.isWhitespace(buffer.charAt(colon - 1))) {
              throw new ParseException("Invalid header", buffer, 0, buffer.length(), colon - 1);
          }
         final String s = buffer.substringTrimmed(0, colon);
         if (s.isEmpty()) {
             throw new ParseException("Invalid header", buffer, 0, buffer.length(), colon);
         }
         this.buffer = buffer;
         this.name = s;
         this.valuePos = colon + 1;
     }
 
     @Override
     public String getName() {
         return this.name;
     }
 
     @Override
     public String getValue() {
         if (value == null) {
             int beginIdx = valuePos;
             int endIdx = buffer.length();
             while (beginIdx < buffer.length() && Tokenizer.isWhitespace(buffer.charAt(beginIdx))) {
                 beginIdx++;
             }
             while (endIdx > beginIdx && Tokenizer.isWhitespace(buffer.charAt(endIdx - 1))) {
                 endIdx--;
             }
             final StringBuilder buf = new StringBuilder(endIdx - beginIdx);
             for (int i = beginIdx; i < endIdx; i++) {
                 final char ch = buffer.charAt(i);
                 if (ch == Chars.CR || ch == Chars.LF || ch == Chars.NULL) {
                     buf.append((char) Chars.SP);
                 } else {
                     buf.append(ch);
                 }
             }
             value = buf.toString();
         }
         return value;
     }
 
     @Override
     public boolean isSensitive() {
         return false;
     }
 
     @Override
     public int getValuePos() {
         return this.valuePos;
     }
 
     @Override
     public CharArrayBuffer getBuffer() {
         return this.buffer;
     }
 
     @Override
     public String toString() {
         return this.buffer.toString();
     }
 
 }