using System;
using System.Collections.Generic;
using System.Linq;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Data;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Problems.MetaOptimization {
  [StorableClass]
  public abstract class Range<T> : Item, IRange<T> where T : class, IItem, IStringConvertibleValue, IDeepCloneable {
    [Storable]
    private T lowerBound;
    public virtual T LowerBound {
      get { return lowerBound; }
      set {
        if (lowerBound != value) {
          if (lowerBound != null) {
            lowerBound.ValueChanged -= new EventHandler(lowerBound_ToStringChanged);
          }
          lowerBound = value;
          if (lowerBound != null) {
            lowerBound.ValueChanged += new EventHandler(lowerBound_ToStringChanged);
          }
          OnLowerBoundChanged();
        }
      }
    }

    [Storable]
    private T upperBound;
    public virtual T UpperBound {
      get { return upperBound; }
      set {
        if (upperBound != value) {
          if (upperBound != null) {
            upperBound.ValueChanged -= new EventHandler(upperBound_ToStringChanged);
          }
          upperBound = value;
          if (upperBound != null) {
            upperBound.ValueChanged += new EventHandler(upperBound_ToStringChanged);
          }
          OnUpperBoundChanged();
        }
      }
    }

    [Storable]
    private T stepSize;
    public virtual T StepSize {
      get { return stepSize; }
      set {
        if (stepSize != value) {
          if (stepSize != null) {
            stepSize.ValueChanged -= new EventHandler(stepSize_ToStringChanged);
          }
          stepSize = value;
          if (stepSize != null) {
            stepSize.ValueChanged += new EventHandler(stepSize_ToStringChanged);
          }
          OnStepSizeChanged();
        }
      }
    }

    #region IRange Members
    object IRange.LowerBound {
      get { return lowerBound; }
      set { lowerBound = (T)value; }
    }
    object IRange.UpperBound {
      get { return upperBound; }
      set { upperBound = (T)value; }
    }
    object IRange.StepSize {
      get { return stepSize; }
      set { stepSize = (T)value; }
    }
    #endregion

    #region Constructors and Cloning
    public Range(T lowerBound, T upperBound, T stepSize) {
      this.LowerBound = lowerBound;
      this.UpperBound = upperBound;
      this.StepSize = stepSize;
    }

    [StorableConstructor]
    protected Range(bool deserializing) : base(deserializing) { }
    protected Range(Range<T> original, Cloner cloner)
      : base(original, cloner) {
      this.LowerBound = cloner.Clone(original.LowerBound);
      this.UpperBound = cloner.Clone(original.UpperBound);
      this.StepSize = cloner.Clone(original.StepSize);
    }

    [StorableHook(HookType.AfterDeserialization)]
    private void AfterDeserialization() {
      if (lowerBound != null) {
        lowerBound.ValueChanged += new EventHandler(lowerBound_ToStringChanged);
      }
      if (upperBound != null) {
        upperBound.ValueChanged += new EventHandler(upperBound_ToStringChanged);
      }
      if (stepSize != null) {
        stepSize.ValueChanged += new EventHandler(stepSize_ToStringChanged);
      }
    }
    #endregion

    #region Events
    private void lowerBound_ToStringChanged(object sender, EventArgs e) {
      OnToStringChanged();
    }
    private void upperBound_ToStringChanged(object sender, EventArgs e) {
      OnToStringChanged();
    }
    private void stepSize_ToStringChanged(object sender, EventArgs e) {
      OnToStringChanged();
    }
    #endregion

    #region Eventhandler
    public event EventHandler LowerBoundChanged;
    private void OnLowerBoundChanged() {
      var handler = LowerBoundChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler UpperBoundChanged;
    private void OnUpperBoundChanged() {
      var handler = UpperBoundChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler StepSizeChanged;
    private void OnStepSizeChanged() {
      var handler = StepSizeChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler ValueChanged;
    private void OnValueChanged() {
      var handler = ValueChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    #endregion

    public override string ToString() {
      return string.Format("{0},{1}:{2}", LowerBound.ToString(), UpperBound.ToString(), StepSize.ToString());
    }

    #region IStringConvertibleValue Members

    public string GetValue() {
      return this.ToString();
    }
    public bool ReadOnly {
      get { return false; }
    }
    public bool SetValue(string value) {
      var parts1 = value.Split(':');
      if (parts1.Length != 2) return false;
      var parts2 = parts1[0].Split(',');
      if (parts2.Length != 2) return false;

      return
        lowerBound.SetValue(parts2[0]) &&
        upperBound.SetValue(parts2[1]) &&
        stepSize.SetValue(parts1[1]);
    }
    public bool Validate(string value, out string errorMessage) {
      // TODO: check that upper is larger than lower and that stepsize < upper-lower
      T lower = (T)lowerBound.Clone();
      T upper = (T)upperBound.Clone();
      T step = (T)stepSize.Clone();

      var parts1 = value.Split(':');
      if (parts1.Length != 2) {
        errorMessage = "Could not parse range."; return false;
      }
      var parts2 = parts1[0].Split(',');
      if (parts2.Length != 2) {
        errorMessage = "Could not parse range."; return false;
      }

      if (lowerBound.SetValue(parts2[0]) &&
          upperBound.SetValue(parts2[1]) &&
          stepSize.SetValue(parts1[1])) {
        errorMessage = string.Empty; return true;
      } else {
        errorMessage = "Could not parse range."; return false;
      }
    }

    #endregion

    public T GetRandomValue(IRandom random) {
      // by a chance return the extreme values of this range to intensify search in those regions
      if (random.NextDouble() < 0.1) {
        if (random.NextDouble() < 0.5) {
          return (T)LowerBound.Clone();
        } else {
          return (T)UpperBound.Clone();
        }
      }

      // otherwise sample a random value from the range
      return GetRandomSample(random);
    }

    protected abstract T GetRandomSample(IRandom random);

    IItem IRange.GetRandomValue(IRandom random) {
      return GetRandomValue(random);
    }

    public abstract IEnumerable<T> GetCombinations();
    IEnumerable<IItem> IRange.GetCombinations() {
      return GetCombinations().Cast<IItem>().ToArray();
    }

    public virtual double CalculateSimilarity(IItem a, IItem b) {
      return CalculateSimilarityValue((T)a, (T)b);
    }

    protected abstract double CalculateSimilarityValue(T a, T b);
  }
}