#ifndef LEMON_SIMANN_H

#define LEMON_SIMANN_H

namespace lemon {

  const double INFTY = 1e24;

  class SimAnnBase {

  public:

    class Controller;

  private:

    Controller *controller;

  protected:

    double curr_cost;

    double prev_cost;

    double best_cost;

    virtual void mutate() = 0;

    virtual void revert() = 0;

    virtual void saveAsBest() = 0;

  public:

    SimAnnBase() {

      curr_cost = prev_cost = best_cost = INFTY;

    }

    void setController(Controller &_controller) {

      controller = &_controller;

      controller->setBase(this);

    }

    double getCurrCost() { return curr_cost; }

    double getPrevCost() { return prev_cost; }

    double getBestCost() { return best_cost; }

    void run() {

      while (controller->next()) {

        mutate();

        if (controller->accept()) {

          controller->acceptEvent();

          if (curr_cost < best_cost) {

            saveAsBest();

            controller->improveEvent();

          }

        }

        else {

          revert();

          controller->rejectEvent();

        }

      }

    }

    class Controller {

    public:

      SimAnnBase *base;

      virtual void acceptEvent() {}

      virtual void improveEvent() {}

      virtual void rejectEvent() {}

      virtual void setBase(SimAnnBase *_base) { base = _base; }

      virtual bool next() = 0;

      virtual bool accept() = 0;

    };

  };

  template <typename E>

  class SimAnn : public SimAnnBase {

  private:

    E *curr_ent;

    E *best_ent;

  public:

    SimAnn() : SimAnnBase() {}

    void setEntity(E &ent) {

      curr_ent = new E(ent);

      best_ent = new E(ent);

    }

    E getBestEntity() { return *best_ent; }

    void mutate() {

      curr_ent->mutate();

    }

    void revert() {

      curr_ent->revert();

    }

    void saveAsBest() {

      *best_ent = *curr_ent;

      best_cost = curr_cost;

    }

  };

  class EntitySkeleton {

  public:

    // returns the new cost

    double mutate() { return 0.0; }

    // restores the entity to its previous state i.e. reverts the effects of

    // the last mutate()

    void revert() {}

  };

  class SimpleController : public SimAnnBase::Controller {

  public:

    long iter, last_impr, max_iter, max_no_impr;

    double temp, annealing_factor;

    SimpleController() {

      iter = last_impr = 0;

      max_iter = 500000;

      max_no_impr = 20000;

      annealing_factor = 0.9999;

      temp = 1000;

    }

    void acceptEvent() {

      iter++;

    }

    void improveEvent() {

      last_impr = iter;

    }

    void rejectEvent() {

      iter++;

    }

    bool next() {

      temp *= annealing_factor;

      bool quit = (iter > max_iter) || (iter - last_impr > max_no_impr);

      return !quit;

    }

    bool accept() {

      return (drand48() <= exp(base->getPrevCost() - base->getCurrCost() / temp));

    }

  };

}

#endif