/*
    * 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.commons.imaging.formats.pnm;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  import org.apache.commons.imaging.ImagingException;
  
  final class WhiteSpaceReader {
      private final InputStream is;
  
      WhiteSpaceReader(final InputStream is) {
          this.is = is;
      }
  
      public char nextChar() throws IOException {
          char c = read();
  
          if (c == '#') {
              while (c != '\n' && c != '\r') {
                  c = read();
              }
          }
          return c;
      }
  
      private char read() throws IOException {
          final int result = is.read();
          if (result < 0) {
              throw new ImagingException("PNM: Unexpected EOF");
          }
          return (char) result;
      }
  
      public String readLine() throws IOException {
          final StringBuilder buffer = new StringBuilder();
          for (char c = read(); c != '\n' && c != '\r'; c = read()) {
              buffer.append(c);
          }
          return buffer.length() > 0 ? buffer.toString() : null;
      }
  
      public String readtoWhiteSpace() throws IOException {
          char c = nextChar();
  
          while (Character.isWhitespace(c)) {
              c = nextChar();
          }
  
          final StringBuilder buffer = new StringBuilder();
  
          while (!Character.isWhitespace(c)) {
              buffer.append(c);
              c = nextChar();
          }
  
          return buffer.toString();
      }
  }