using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using HeuristicLab.Common;

namespace HeuristicLab.Algorithms.Bandits.Models {
  // mixture of two models with mixture weights
  public class MixtureModel : IModel {

    private readonly IModel u;
    private readonly IModel v;
    private readonly double w;

    // w is the weight for u (the weight for v is 1-w)
    public MixtureModel(IModel u, IModel v, double w) {
      Contract.Assert(w >= 0.0 && w <= 1.0);
      this.u = u;
      this.v = v;
      this.w = w;
    }

    public double Sample(Random random) {
      if (random.NextDouble() <= w) {
        return u.Sample(random);
      } else {
        return v.Sample(random);
      }
    }

    public void Update(double reward) {
      throw new NotSupportedException();
    }

    public void Reset() {
      throw new NotSupportedException();
    }

    public object Clone() {
      return new MixtureModel(u, v, w);
    }

    public override string ToString() {
      return string.Format("Mixture({0},{1},{2:F2})", u, v, w);
    }
  }
}