/*
    * 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.palette;
  
  import java.util.Collections;
  import java.util.List;
  
  import org.apache.commons.imaging.ImagingException;
  import org.apache.commons.imaging.common.Allocator;
  
  public class QuantizedPalette implements Palette {
  
      private final int precision;
      private final List<ColorSpaceSubset> subsets;
      private final ColorSpaceSubset[] straight;
  
      public QuantizedPalette(final List<ColorSpaceSubset> subsets, final int precision) {
          this.subsets = subsets == null ? Collections.emptyList() : Collections.unmodifiableList(subsets);
          this.precision = precision;
  
          straight = Allocator.array(1 << precision * 3, ColorSpaceSubset[]::new, ColorSpaceSubset.SHALLOW_SIZE);
  
          for (int i = 0; i < this.subsets.size(); i++) {
              final ColorSpaceSubset subset = this.subsets.get(i);
              subset.setIndex(i);
  
              for (int u = subset.mins[0]; u <= subset.maxs[0]; u++) {
                  for (int j = subset.mins[1]; j <= subset.maxs[1]; j++) {
                      for (int k = subset.mins[2]; k <= subset.maxs[2]; k++) {
                          final int index = u << precision * 2 | j << precision * 1 | k << precision * 0;
                          straight[index] = subset;
                      }
                  }
              }
          }
      }
  
      @Override
      public int getEntry(final int index) {
          final ColorSpaceSubset subset = subsets.get(index);
          return subset.rgb;
      }
  
      @Override
      public int getPaletteIndex(final int rgb) throws ImagingException {
          final int precisionMask = (1 << precision) - 1;
  
          final int index = rgb >> 24 - 3 * precision & precisionMask << (precision << 1) | rgb >> 16 - 2 * precision & precisionMask << precision
                  | rgb >> 8 - precision & precisionMask;
  
          return straight[index].getIndex();
      }
  
      @Override
      public int length() {
          return subsets.size();
      }
  }