/*
    *  Licensed 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.
   *  under the License.
   */
  
  package org.apache.commons.imaging.formats.pcx;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.Arrays;
  
  import org.apache.commons.imaging.ImagingException;
  import org.apache.commons.imaging.common.BinaryFunctions;
  
  final class RleReader {
      private final boolean isCompressed;
      private int count;
      private byte sample;
  
      RleReader(final boolean isCompressed) {
          this.isCompressed = isCompressed;
      }
  
      void read(final InputStream is, final byte[] samples) throws IOException, ImagingException {
          if (isCompressed) {
              final int prefill = Math.min(count, samples.length);
              Arrays.fill(samples, 0, prefill, sample);
              count -= prefill;
  
              for (int bytesRead = prefill; bytesRead < samples.length;) {
                  final byte b = BinaryFunctions.readByte("RleByte", is, "Error reading image data");
                  if ((b & 0xc0) == 0xc0) {
                      count = b & 0x3f;
                      sample = BinaryFunctions.readByte("RleValue", is, "Error reading image data");
                  } else {
                      count = 1;
                      sample = b;
                  }
                  final int samplesToAdd = Math.min(count, samples.length - bytesRead);
                  Arrays.fill(samples, bytesRead, bytesRead + samplesToAdd, sample);
                  bytesRead += samplesToAdd;
                  count -= samplesToAdd;
              }
          } else {
              int r;
              for (int bytesRead = 0; bytesRead < samples.length; bytesRead += r) {
                  r = is.read(samples, bytesRead, samples.length - bytesRead);
                  if (r < 0) {
                      throw new ImagingException("Premature end of file reading image data");
                  }
              }
          }
      }
  }