#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2013 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;
using HeuristicLab.Data;
using HeuristicLab.Encodings.PermutationEncoding;

namespace HeuristicLab.Analysis.AlgorithmBehavior {
  public static class AlgorithmBehaviorHelpers {
    public static bool IsSubtour(IntArray tour, Permutation permutation) {
      // determine starting position for subtour match
      int idx = permutation.Select((x, index) => new { Value = x, Index = index }).Single(x => x.Value == tour[0]).Index;
      bool isSubtour = true;
      for (int i = 1; i < tour.Length; i++) {
        if (tour[i] == permutation[(idx + 1) % permutation.Length]) { // check right side
          idx = (idx + 1) % permutation.Length;
        } else if (tour[i] == permutation[(idx - 1 + permutation.Length) % permutation.Length]) { // check left side
          idx = (idx - 1 + permutation.Length) % permutation.Length;
        } else {
          isSubtour = false;
          break;
        }
      }
      return isSubtour;
    }

    public static List<IntArray> ExtractSubtours(Permutation permutation) {
      var subtours = new List<IntArray>();
      for (int i = 2; i <= permutation.Count() / 2; i++) { // increase schema length from 2 to n/2
        for (int j = 0; j < permutation.Count(); j++) { // visit all positions in the permutation
          var schema = new IntArray(i);
          for (int k = 0; k < i; k++) schema[k] = permutation[(j + k) % permutation.Length]; // copy edge to schema
          subtours.Add(schema);
        }
      }
      return subtours;
    }

    public static List<IntArray> ExtractSubtours(Permutation permutation, int length) {
      var subtours = new List<IntArray>();
      int i = 2;
      for (int j = 0; j < permutation.Count(); j++) { // visit all positions in the permutation
        var schema = new IntArray(i);
        for (int k = 0; k < i; k++) schema[k] = permutation[(j + k) % permutation.Length]; // copy edge to schema
        subtours.Add(schema);
      }
      return subtours;
    }

    public static IList<IntArray> GenerateWildcardSchemata(IntArray schema) {
      string formatString = "{0:d" + schema.Length + "}";
      var combs = new List<bool[]>();
      string comb = string.Empty;

      // create all desired wildcard combinations
      long i = 0;
      int wildcardCount = 0; // first wildcard combination contains no wildcards
      while (wildcardCount < schema.Length) {
        wildcardCount = (comb = Convert.ToString(i++, 2)).PadLeft(schema.Length, '0').Count(x => x == '1');
        if (wildcardCount > (schema.Length / 8) && wildcardCount < (schema.Length / 2)) // only include wildcards within certain limits
          combs.Add(comb.Select(x => x == '1').ToArray()); // '1' becomes true which indicates a wildcard
      }

      // create all desired wildcard instances
      var wildcardSchemata = new List<IntArray>();
      foreach (var c in combs) {
        wildcardSchemata.Add(new IntArray(schema.Select((x, index) => c[index] ? -1 : x).ToArray())); // -1 is a wildcard in the schema
      }

      return wildcardSchemata;
    }

    // attention: brute force matching
    // should be replaced with KMP, BM or RK
    public static bool IsMatch(IntArray pattern, int[] tour) {
      bool match = false;
      for (int i = 0; i <= tour.Length - pattern.Length && !match; i++) {
        for (int j = 0; j < pattern.Length && (match = pattern[j] == tour[i + j] || pattern[j] == -1); j++) ;
      }
      return match;
    }
  }
}