using System;
using HeuristicLab.Collections;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Optimization;
using HeuristicLab.Parameters;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Operators {

  [Item("EngineAlgorithmOperator", "An operator the encapsulates a complete algorithm.")]
  [StorableClass]
  public class EngineAlgorithmOperator : AlgorithmOperator {

    [Storable]
    private OperatorGraph algorithmOperatorGraph;

    [Storable]
    protected EngineAlgorithm algorithm;
    public EngineAlgorithm Algorithm {
      get { return algorithm; }
      set {
        if (value == algorithm)
          return;
        if (algorithm != null) {
          DeregisterAlgorithmEvents();
          if (algorithmOperatorGraph != null)
            DeregisterOperatorGraphEvents();
          OperatorGraph.InitialOperator = null;
          OperatorGraph.Operators.Clear();
        }
        algorithm = value;
        OnAlgorithmChanged();
        if (algorithm != null) {
          foreach (IOperator op in algorithm.OperatorGraph.Operators)
            OperatorGraph.Operators.Add(op);
          OperatorGraph.InitialOperator = algorithm.OperatorGraph.InitialOperator;
          RegisterAlgorithmEvents();
          if (algorithm.OperatorGraph != null) {
            algorithmOperatorGraph = algorithm.OperatorGraph;
            RegisterOperatorGraphEvents();
          }
        }
      }
    }

    #region Events
    public event EventHandler AlgorithmChanged;

    protected virtual void OnAlgorithmChanged() {
      UpdateParameters();
      EventHandler handler = AlgorithmChanged;
      if (handler != null)
        handler(this, EventArgs.Empty);
    }

    private void RegisterAlgorithmEvents() {
      algorithm.OperatorGraphChanged += algorithm_OperatorGraphChanged;
      algorithm.ProblemChanged +=new EventHandler(algorithm_ProblemChanged);
    }

    void algorithm_ProblemChanged(object sender, EventArgs e) {
      UpdateParameters();
    }

    private void DeregisterAlgorithmEvents() {
      algorithm.OperatorGraphChanged -= algorithm_OperatorGraphChanged;
    }

    void algorithm_OperatorGraphChanged(object sender, EventArgs e) {
      if (algorithmOperatorGraph != null)
        DeregisterOperatorGraphEvents();
      algorithmOperatorGraph = null;
      if (algorithm.OperatorGraph != null) {
        algorithmOperatorGraph = algorithm.OperatorGraph;
        RegisterOperatorGraphEvents();
      }
    }

    private void RegisterOperatorGraphEvents() {
      algorithmOperatorGraph.InitialOperatorChanged += algorithmOperatorGraph_InitialOperatorChanged;
      algorithmOperatorGraph.Operators.CollectionReset += algorithmOperatorGraph_Operators_Changed;
      algorithmOperatorGraph.Operators.ItemsAdded += algorithmOperatorGraph_Operators_Changed;
      algorithmOperatorGraph.Operators.ItemsRemoved += algorithmOperatorGraph_Operators_Changed;
    }

    private void DeregisterOperatorGraphEvents() {
      algorithmOperatorGraph.InitialOperatorChanged -= algorithmOperatorGraph_InitialOperatorChanged;
      algorithmOperatorGraph.Operators.CollectionReset -= algorithmOperatorGraph_Operators_Changed;
      algorithmOperatorGraph.Operators.ItemsAdded -= algorithmOperatorGraph_Operators_Changed;
      algorithmOperatorGraph.Operators.ItemsRemoved -= algorithmOperatorGraph_Operators_Changed;
    }

    void algorithmOperatorGraph_Operators_Changed(object sender, CollectionItemsChangedEventArgs<IOperator> e) {
      OperatorGraph.Operators.Clear();
      foreach (IOperator op in algorithmOperatorGraph.Operators) {
        OperatorGraph.Operators.Add(op);
      }
    }

    void algorithmOperatorGraph_InitialOperatorChanged(object sender, EventArgs e) {
      OperatorGraph.InitialOperator = algorithmOperatorGraph.InitialOperator;
    }

    private void UpdateParameters() {
      // TODO: match previously set parameter values
      IOperator successor = Successor;
      Parameters.Clear();
      Parameters.Add(new OperatorParameter("Successor", successor));
      var alg = Algorithm as IParameterizedItem;
      foreach (var param in alg.Parameters) {
        Parameters.Add(WrapParameter(param));
      }
      if (Algorithm.Problem != null) {
        foreach (var param in Algorithm.Problem.Parameters) {
          Parameters.Add(WrapParameter(param));
        }
      }
      Parameters.Add(new ValueLookupParameter<NamedItemCollection<IResult>>("Results", "Results collection as passed through to the inner algorithn", "Results", false));
    }

    private static IValueLookupParameter WrapParameter(IParameter param) {
      IValueLookupParameter v = (IValueLookupParameter)Activator.CreateInstance(typeof(ValueLookupParameter<>).MakeGenericType(param.DataType), new object[] { param.Name, param.Description });
      v.ActualName = param.Name;
      IValueParameter valueParam = param as IValueParameter;
      if (valueParam != null)
        v.Value = valueParam.Value;
      return v;
    }
    #endregion

    #region Construction & Cloning
    [StorableConstructor]
    protected EngineAlgorithmOperator(bool deserializing) : base(deserializing) { }
    protected EngineAlgorithmOperator(EngineAlgorithmOperator original, Cloner cloner)
      : base(original, cloner) {
      this.algorithm = cloner.Clone(original.algorithm);
      this.algorithmOperatorGraph = cloner.Clone(original.algorithmOperatorGraph);
    }
    public EngineAlgorithmOperator() { }
    public override IDeepCloneable Clone(Cloner cloner) {
      return new EngineAlgorithmOperator(this, cloner);
    }
    #endregion

    public override IOperation Apply() {
      var alg = Algorithm as IParameterizedItem;
      foreach (var param in alg.Parameters) {
        param.ActualValue = Parameters[param.Name].ActualValue;
      }
      if (Algorithm.Problem != null) {
        foreach (var param in Algorithm.Problem.Parameters) {
          param.ActualValue = Parameters[param.Name].ActualValue;
        }
      }
      return base.Apply();
    }

  }
}