#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2017 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Linq;

namespace HeuristicLab.Algorithms.MemPR.Util {
  public static class Auxiliary {
    public static double[] PrepareProportional(IEnumerable<double> weights, bool windowing, bool inverseProportional) {
      double maxValue = double.MinValue, minValue = double.MaxValue;
      double[] valueArray = weights.ToArray();

      for (int i = 0; i < valueArray.Length; i++) {
        if (valueArray[i] > maxValue) maxValue = valueArray[i];
        if (valueArray[i] < minValue) minValue = valueArray[i];
      }
      if (minValue == maxValue) {  // all values are equal
        for (int i = 0; i < valueArray.Length; i++) {
          valueArray[i] = 1.0;
        }
      } else {
        if (windowing) {
          if (inverseProportional) InverseProportionalScale(valueArray, maxValue);
          else ProportionalScale(valueArray, minValue);
        } else {
          if (minValue < 0.0) throw new InvalidOperationException("Proportional selection without windowing does not work with values < 0.");
          if (inverseProportional) InverseProportionalScale(valueArray, 2 * maxValue);
        }
      }
      return valueArray;
    }
    private static void ProportionalScale(double[] values, double minValue) {
      for (int i = 0; i < values.Length; i++) {
        values[i] = values[i] - minValue;
      }
    }
    private static void InverseProportionalScale(double[] values, double maxValue) {
      for (int i = 0; i < values.Length; i++) {
        values[i] = maxValue - values[i];
      }
    }
  }
}