/*
    * 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.awt.image.BufferedImage;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.charset.StandardCharsets;
  
  import org.apache.commons.imaging.ImagingException;
  
  final class PbmWriter implements PnmWriter {
  
      private final boolean rawBits;
  
      PbmWriter(final boolean rawBits) {
          this.rawBits = rawBits;
      }
  
      @Override
      public void writeImage(final BufferedImage src, final OutputStream os, final PnmImagingParameters params) throws ImagingException, IOException {
          os.write(PnmConstants.PNM_PREFIX_BYTE);
          os.write(rawBits ? PnmConstants.PBM_RAW_CODE : PnmConstants.PBM_TEXT_CODE);
          os.write(PnmConstants.PNM_SEPARATOR);
  
          final int width = src.getWidth();
          final int height = src.getHeight();
  
          os.write(Integer.toString(width).getBytes(StandardCharsets.US_ASCII));
          os.write(PnmConstants.PNM_SEPARATOR);
  
          os.write(Integer.toString(height).getBytes(StandardCharsets.US_ASCII));
          os.write(PnmConstants.PNM_NEWLINE);
  
          int bitcache = 0;
          int bitsInCache = 0;
  
          for (int y = 0; y < height; y++) {
              for (int x = 0; x < width; x++) {
                  final int argb = src.getRGB(x, y);
                  final int red = 0xff & argb >> 16;
                  final int green = 0xff & argb >> 8;
                  final int blue = 0xff & argb >> 0;
                  int sample = (red + green + blue) / 3;
                  if (sample > 127) {
                      sample = 0;
                  } else {
                      sample = 1;
                  }
  
                  if (rawBits) {
                      bitcache = bitcache << 1 | 0x1 & sample;
                      bitsInCache++;
  
                      if (bitsInCache >= 8) {
                          os.write((byte) bitcache);
                          bitcache = 0;
                          bitsInCache = 0;
                      }
                  } else {
                      os.write(Integer.toString(sample).getBytes(StandardCharsets.US_ASCII)); // max
                      // component
                      // value
                      os.write(PnmConstants.PNM_SEPARATOR);
                  }
              }
  
              if (rawBits && bitsInCache > 0) {
                  bitcache = bitcache << 8 - bitsInCache;
                  os.write((byte) bitcache);
                  bitcache = 0;
                  bitsInCache = 0;
              }
          }
      }
  }