#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2018 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.Linq;
using HEAL.Attic;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Encodings.IntegerVectorEncoding;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;

namespace HeuristicLab.Problems.Modifiers {
  [StorableType("28866F64-5BB4-41A0-95E9-7DF9A7C0B376")]
  [Item("ClusteringTranscodingProblemModifier", "A problem modifier that groups input parameters into clusters and sets them to equal values. Values assigned to cluster -1 will be fixed to their default values")]
  public class ClusteringTranscodingProblemModifier : TranscodingProblemModifier {
    #region ParameterNames
    private const string DefaultVectorParameterName = "DefaultVector";
    private const string ClusterAssignmentParameterName = "ClusterAssignment";
    #endregion

    #region Parameters
    public IValueParameter<IntegerVector> DefaultVectorParameter => (IValueParameter<IntegerVector>)Parameters[DefaultVectorParameterName];
    public IValueParameter<IntegerVector> ClusterAssignmentParameter => (IValueParameter<IntegerVector>)Parameters[ClusterAssignmentParameterName];
    #endregion

    #region ParameterNames
    public IntegerVector DefaultVector {
      get => DefaultVectorParameter.Value;
      set => DefaultVectorParameter.Value = value;
    }
    public IntegerVector ClusterAssignment {
      get => ClusterAssignmentParameter.Value;
      set => ClusterAssignmentParameter.Value = value;
    }
    #endregion

    #region Constructors & Cloning
    [StorableConstructor]
    protected ClusteringTranscodingProblemModifier(StorableConstructorFlag _) : base(_) { }
    protected ClusteringTranscodingProblemModifier(ClusteringTranscodingProblemModifier original, Cloner cloner) : base(original, cloner) {
      RegisterEvents();
    }
    public ClusteringTranscodingProblemModifier() {
      Parameters.Add(new ValueParameter<IntegerVector>(DefaultVectorParameterName, "The default values for every dimension of the original encoding", new IntegerVector(2)));
      Parameters.Add(new ValueParameter<IntegerVector>(ClusterAssignmentParameterName, "The cluster assignments for every dimension of the original encoding", new IntegerVector(2)));
      RegisterEvents();
    }
    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() { RegisterEvents(); }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new ClusteringTranscodingProblemModifier(this, cloner);
    }
    #endregion

    #region ParameterEvents
    private void RegisterEvents() {
      ClusterAssignmentParameter.ValueChanged -= ClusterAssignmentValueChanged;
      ClusterAssignmentParameter.ValueChanged += ClusterAssignmentValueChanged;
      ClusterAssignmentParameter.Value.ToStringChanged -= RedoEncoding;
      ClusterAssignmentParameter.Value.ToStringChanged += RedoEncoding;
      DefaultVectorParameter.ValueChanged -= DefaultVectorValueChanged;
      DefaultVectorParameter.ValueChanged += DefaultVectorValueChanged;
      DefaultVectorParameter.Value.ToStringChanged -= RedoEncoding;
      DefaultVectorParameter.Value.ToStringChanged += RedoEncoding;
    }
    private void ClusterAssignmentValueChanged(object sender, EventArgs e) {
      ClusterAssignmentParameter.Value.ToStringChanged -= RedoEncoding;
      ClusterAssignmentParameter.Value.ToStringChanged += RedoEncoding;
      RedoEncoding(sender, e);
    }
    private void DefaultVectorValueChanged(object sender, EventArgs e) {
      DefaultVectorParameter.Value.ToStringChanged -= RedoEncoding;
      DefaultVectorParameter.Value.ToStringChanged += RedoEncoding;
      RedoEncoding(sender, e);
    }
    private void RedoEncoding(object sender, EventArgs e) {
      InvokeEncodingChanged();
    }
    #endregion

    #region TranscodingProblemModifier

    protected override ISolutionCreator ChangeSolutionCreator(ISolutionCreator oldCreator) {
      if (oldCreator == null || encoding == null) return null;

      var nc = Encoding.Operators.SingleOrDefault(o => o.GetType() == oldCreator.GetType());
      return (ISolutionCreator)nc ?? throw new ArgumentException($"Could not transcode {oldCreator.GetType()}. Please extend {GetType()} to handle your specific solution creator.");

    }

    protected override IEncoding ChangeEncoding(IEncoding oldEncoding) {
      if (oldEncoding == null) {
        return null;
      }
      if (!(oldEncoding is IntegerVectorEncoding iEncoding)) throw new ArgumentException("This form of transcoding is only valid for IntegerVectorEncoding");
      if (iEncoding.Length != ClusterAssignment.Length) throw new ArgumentException("ClusterAssignment and original Encoding need to have equal length");
      if (iEncoding.Length != DefaultVector.Length) throw new ArgumentException("ClusterAssignment and default Vector need to have equal length");
      var clusters = ClusterAssignment.Max() + 1;
      var min = new int[clusters];
      var max = new int[clusters];
      var steps = new int[clusters];
      var b = new bool[clusters];
      for (var i = 0; i < iEncoding.Length; i++) {
        var t = ClusterAssignment[i];
        if (t < 0) continue;
        var i2 = i % iEncoding.Length;
        var iMin = iEncoding.Bounds[i2, 0];
        var iMax = iEncoding.Bounds[i2, 1];
        var iSteps = iEncoding.Bounds.Columns > 2 ? iEncoding.Bounds[i2, 2] : 1; //check
        if (!b[t] || min[t] < iMin) min[t] = iMin; //biggest possible minimum
        if (!b[t] || max[t] > iMax) max[t] = iMax; //smallest possible maximum 
        if (!b[t]) steps[t] = iSteps;
        if (steps[t] != iSteps && b[t]) throw new ArgumentException("step sizes for variables within clusters must not differ");
        b[t] = true;
      }
      if (!b.All(x => x)) throw new ArgumentException("At least one cluster is not mapped to any input variable");
      return new IntegerVectorEncoding(iEncoding.Name, clusters, min, max, steps);
    }
    protected override Individual ChangeIndividual(Individual newIndividual) {
      var intVec = newIndividual.IntegerVector();
      var enc = newIndividual.GetEncoding<IntegerVectorEncoding>();
      var individualScope = new Scope();
      foreach (var v in newIndividual.Values) //intentional shallow copy 
        individualScope.Variables.Add(new Variable(v.Key, v.Value));
      var oldIndividual = new SingleEncodingIndividual(enc, individualScope) { [enc.Name] = TransCode(intVec) };
      return oldIndividual;
    }
    #endregion

    #region Helpers
    private IntegerVector TransCode(IntegerVector newVector) {
      return new IntegerVector(ClusterAssignment.Select((v, i) => v >= 0 ? newVector[v] : DefaultVector[i]).ToArray());
    }
    #endregion
  }
}