using System;
using System.Linq;
using HEAL.Attic;
using HeuristicLab.Collections;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Encodings.IntegerVectorEncoding;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;

namespace HeuristicLab.Problems.Modifiers {
  [StorableType("903EE850-62D5-4F3E-8F0D-8D9D5415A5F1")]
  [Creatable(CreatableAttribute.Categories.Problems, Priority = 90)]
  [Item("MultiObjectiveModifiedProblem", "A wrapper problem for multi-objective problems that should be evaluated using Hive.")]
  public class MultiObjectiveModifiedProblem : MultiObjectiveBasicProblem<IEncoding>, IStatefulItem {
    private readonly MultiObjectiveEndPointProblemModifier<IEncoding> endPoint = new MultiObjectiveEndPointProblemModifier<IEncoding>();
    private ProblemModifier activeStart; //this is to avoid attaching to multiple modifiers
    public override bool[] Maximization => Parameters.ContainsKey("Maximization") ? MaximizationParameter.Value.CloneAsArray() : new[] { false, false };

    #region Parameter Names
    private const string ProblemParameterName = "Problem";
    private const string ModifierParameterName = "Modifiers";
    #endregion

    #region Parameters
    public IValueParameter<MultiObjectiveBasicProblem<IEncoding>> ProblemParameter => (IValueParameter<MultiObjectiveBasicProblem<IEncoding>>)Parameters[ProblemParameterName];

    public IFixedValueParameter<CheckedItemList<ProblemModifier>> ModifierParameter => (IFixedValueParameter<CheckedItemList<ProblemModifier>>)Parameters[ModifierParameterName];

    public IValueParameter<BoolArray> MaximizationParameter => ((IValueParameter<BoolArray>)Parameters["Maximization"]);
    #endregion

    #region Parameter Properties
    public MultiObjectiveBasicProblem<IEncoding> Problem {
      get => ProblemParameter.Value;
      set => ProblemParameter.Value = value;
    }

    public CheckedItemList<ProblemModifier> Modifiers => ModifierParameter.Value;
    #endregion

    #region Constructors & Cloning
    [StorableConstructor]
    protected MultiObjectiveModifiedProblem(StorableConstructorFlag _) : base(_) { }
    protected MultiObjectiveModifiedProblem(MultiObjectiveModifiedProblem original, Cloner cloner) : base(original, cloner) {
      Initialize();
    }
    public MultiObjectiveModifiedProblem() {
      var defaultModifiers = new CheckedItemList<ProblemModifier> {
        { new EvaluationCacheProblemModifier(), false },
        { new EvaluationRepetitionProblemModifier(), false },
        { new EvaluationLoggingProblemModifier(), false }
      };
      Parameters.Add(new ValueParameter<MultiObjectiveBasicProblem<IEncoding>>(ProblemParameterName, "The actual problem that should be used to evaluate individuals."));
      Parameters.Add(new FixedValueParameter<CheckedItemList<ProblemModifier>>(ModifierParameterName, "The modifiers applied to the problem (order can be important)", defaultModifiers));
      EncodingParameter.Hidden = true;
      MaximizationParameter.Hidden = true;
      SolutionCreatorParameter.Hidden = true;
      EvaluatorParameter.Hidden = true;
      Initialize();
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new MultiObjectiveModifiedProblem(this, cloner);
    }
    #endregion

    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
      if (Encoding == null) Encoding = new IntegerVectorEncoding("null-encoding");
      Initialize();
    }

    private void Initialize() {
      if (Problem != null) {
        Problem.OperatorsChanged -= Problem_OperatorsChanged;
        Problem.OperatorsChanged += Problem_OperatorsChanged;
      }
      ProblemParameter.ValueChanged -= ProblemParameter_ValueChanged;
      ProblemParameter.ValueChanged += ProblemParameter_ValueChanged;
      Modifiers.CheckedItemsChanged -= ActiveModifiersChanged;
      Modifiers.CheckedItemsChanged += ActiveModifiersChanged;
      Modifiers.ItemsMoved -= ActiveModifiersChanged; //This my fire unnecessarily but CheckedItemsChanged does not account for order ...
      Modifiers.ItemsMoved += ActiveModifiersChanged;
      Modifiers.ItemsAdded -= ActiveModifiersChanged;
      Modifiers.ItemsAdded += ActiveModifiersChanged;
      Modifiers.ItemsRemoved -= ActiveModifiersChanged;
      Modifiers.ItemsRemoved += ActiveModifiersChanged;
      Modifiers.ItemsReplaced -= ActiveModifiersChanged;
      Modifiers.ItemsReplaced += ActiveModifiersChanged;
      UpdateModifiers();
    }

    public override double[] Evaluate(Individual individual, IRandom random) {
      return activeStart.ModifiedEvaluate(individual, random);
    }

    public override void Analyze(Individual[] individuals, double[][] qualities, ResultCollection results, IRandom random) {
      activeStart.ModifiedAnalyze(individuals, qualities, results, random);
    }

    private bool updating;
    private void UpdateModifiers() {
      if (Problem == null || updating) return;
      updating = true;
      var am = Modifiers.CheckedItems.Select(x => x.Value).ToArray();

      //unwire modifiers to prevent cycles while setting and superfluous listeners
      foreach (var problemModifier in Modifiers) problemModifier.NextModifier = null;
      //wire modifiers
      for (var i = 0; i < am.Length - 1; i++) am[i].NextModifier = am[i + 1];
      if (am.Length != 0) am[am.Length - 1].NextModifier = endPoint;
      endPoint.Problem = Problem;

      //listen to activeStart changes
      if (activeStart != null) {
        activeStart.EncodingChanged -= StartEncodingChanged;
        activeStart.MaximizationChanged -= StartMaximizationChanged;
        activeStart.SolutionCreatorChanged -= StartSolutionCreatorChanged;
      }
      activeStart = am.Length == 0 ? endPoint : am[0];
      activeStart.EncodingChanged += StartEncodingChanged;
      activeStart.MaximizationChanged += StartMaximizationChanged;
      activeStart.SolutionCreatorChanged += StartSolutionCreatorChanged;

      foreach (var m in Modifiers) m.Initialize();

      updating = false;
      if (Encoding == activeStart.Encoding || activeStart.Encoding == null) return;
      Encoding = activeStart.Encoding;
    }

    private void StartMaximizationChanged(object sender, EventArgs e) {
      if (activeStart.Maximization == null) return;
      MaximizationParameter.Value = (BoolArray)activeStart.Maximization.AsReadOnly();
    }

    private void StartEncodingChanged(object sender, EventArgs e) {
      if (Encoding == activeStart.Encoding || activeStart.Encoding == null) return;
      Encoding = activeStart.Encoding;
    }

    private void StartSolutionCreatorChanged(object sender, EventArgs e) {
      if (SolutionCreator == activeStart.SolutionCreator || activeStart.SolutionCreator == null) return;
      SolutionCreator = activeStart.SolutionCreator;
    }

    private void ActiveModifiersChanged(object sender, CollectionItemsChangedEventArgs<IndexedItem<ProblemModifier>> e) {
      UpdateModifiers();
    }

    private void ProblemParameter_ValueChanged(object sender, EventArgs e) {
      if (Problem != null) {
        Problem.OperatorsChanged -= Problem_OperatorsChanged;
        Problem.OperatorsChanged += Problem_OperatorsChanged;
      }
      endPoint.Problem = Problem;
      UpdateModifiers();
    }

    private void Problem_OperatorsChanged(object sender, EventArgs e) {
      UpdateModifiers();
    }

    void IStatefulItem.InitializeState() {
      UpdateModifiers();
    }

    void IStatefulItem.ClearState() {
      UpdateModifiers();
    }
  }
}