/*
    * 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.myfaces.tobago.internal.layout;
  
  public class MathUtils {
  
    /**
     * Values smaller than this EPSILON should be treated as zero.
     */
    public static final double EPSILON = 0.0000001;
  
    /**
     * Adjusts the list of double values to rounded values with the same sum.
     * E. g. 2.3, 2.4, 2.5, 2.8 -> 2.0, 2.0, 3.0, 3.0
     *
     * @param list
     */
    public static void adjustRemainders(double[] list, double bias) {
      for (double v : list) {
        double lastBias;
        if (bias < 0.0) {
          lastBias = findAndAdjustMaxRemainder(list);
        } else {
          lastBias = findAndAdjustMinRemainder(list);
        }
        if (isZero(lastBias)) {
          break;
        }
        bias += lastBias;
      }
  
      assert isZero(bias);
    }
  
    public static double findAndAdjustMaxRemainder(double[] list) {
      double max = 0.0;
      Integer indexOfMax = null;
      for (int i = 0; i < list.length; i++) {
        double remainder = remainder(list[i]);
        if (remainder > max + EPSILON) {
          max = remainder;
          indexOfMax = i;
        }
      }
      if (indexOfMax != null) {
        list[indexOfMax] += 1.0 - max;
        return 1.0 - max;
      }
      return 0.0;
    }
  
    public static double findAndAdjustMinRemainder(double[] list) {
      double min = 1.0;
      Integer indexOfMin = null;
      for (int i = 0; i < list.length; i++) {
        double remainder = remainder(list[i]);
        if (remainder == 0) { // is zero
          continue;
        }
        if (remainder < min - EPSILON) {
          min = remainder;
          indexOfMin = i;
        }
      }
      if (indexOfMin != null) {
        list[indexOfMin] -= min;
        return -min;
      }
      return 0.0;
    }
  
    public static double remainder(double v) {
      return v - Math.floor(v);
    }
  
    public static boolean isZero(double factor) {
      return Math.abs(factor) < EPSILON;
    }
  
    public static boolean isNotZero(double factor) {
      return Math.abs(factor) >= EPSILON;
    }
 
   public static boolean isInteger(double value) {
     return isZero(value - Math.round(value));
   }
 
   public static boolean isNotInteger(double value) {
     return isNotZero(value - Math.round(value));
   }
 }