/*
    * 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.bmp;
  
  import static org.apache.commons.imaging.common.BinaryFunctions.read2Bytes;
  import static org.apache.commons.imaging.common.BinaryFunctions.readByte;
  
  import java.io.IOException;
  import java.nio.ByteOrder;
  
  import org.apache.commons.imaging.ImagingException;
  
  final class PixelParserRgb extends AbstractPixelParserSimple {
      private int byteCount;
      private int cachedBitCount;
      private int cachedByte;
  
      PixelParserRgb(final BmpHeaderInfo bhi, final byte[] colorTable, final byte[] imageData) {
          super(bhi, colorTable, imageData);
  
      }
  
      @Override
      public int getNextRgb() throws ImagingException, IOException {
  
          switch (bhi.bitsPerPixel) {
          case 1:
          case 4: {
              if (cachedBitCount < bhi.bitsPerPixel) {
                  if (cachedBitCount != 0) {
                      throw new ImagingException("Unexpected leftover bits: " + cachedBitCount + "/" + bhi.bitsPerPixel);
                  }
  
                  cachedBitCount += 8;
                  cachedByte = 0xff & imageData[byteCount];
                  byteCount++;
              }
              final int cacheMask = (1 << bhi.bitsPerPixel) - 1;
              final int sample = cacheMask & cachedByte >> 8 - bhi.bitsPerPixel;
              cachedByte = 0xff & cachedByte << bhi.bitsPerPixel;
              cachedBitCount -= bhi.bitsPerPixel;
              return getColorTableRgb(sample);
          }
          case 8: {
              final int sample = 0xff & imageData[byteCount + 0];
              final int rgb = getColorTableRgb(sample);
              byteCount += 1;
              return rgb;
          }
          case 16: {
              final int data = read2Bytes("Pixel", is, "BMP Image Data", ByteOrder.LITTLE_ENDIAN);
              final int blue = (0x1f & data >> 0) << 3;
              final int green = (0x1f & data >> 5) << 3;
              final int red = (0x1f & data >> 10) << 3;
              final int alpha = 0xff;
              final int rgb = alpha << 24 | red << 16 | green << 8 | blue << 0;
              byteCount += 2;
              return rgb;
          }
          case 24: {
              final int blue = 0xff & imageData[byteCount + 0];
              final int green = 0xff & imageData[byteCount + 1];
              final int red = 0xff & imageData[byteCount + 2];
              final int alpha = 0xff;
              final int rgb = alpha << 24 | red << 16 | green << 8 | blue << 0;
              byteCount += 3;
              return rgb;
          }
          case 32: {
              final int blue = 0xff & imageData[byteCount + 0];
              final int green = 0xff & imageData[byteCount + 1];
              final int red = 0xff & imageData[byteCount + 2];
              final int alpha = 0xff;
              final int rgb = alpha << 24 | red << 16 | green << 8 | blue << 0;
              byteCount += 4;
              return rgb;
          }
          default:
              break;
          }
  
          throw new ImagingException("Unknown BitsPerPixel: " + bhi.bitsPerPixel);
      }
  
      @Override
     public void newline() throws ImagingException, IOException {
         cachedBitCount = 0;
 
         while (byteCount % 4 != 0) {
             readByte("Pixel", is, "BMP Image Data");
             byteCount++;
         }
     }
 }