/*
  Glaurung, a UCI chess playing engine.
  Copyright (C) 2004-2008 Tord Romstad

  Glaurung is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  Glaurung is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/


#if !defined(MATERIAL_H_INCLUDED)
#define MATERIAL_H_INCLUDED

////
//// Includes
////

#include "endgame.h"
#include "position.h"
#include "scale.h"


////
//// Types
////

/// MaterialInfo is a class which contains various information about a
/// material configuration.  It contains a material balance evaluation,
/// a function pointer to a special endgame evaluation function (which in
/// most cases is NULL, meaning that the standard evaluation function will
/// be used), and "scale factors" for black and white.
///
/// The scale factors are used to scale the evaluation score up or down.
/// For instance, in KRB vs KR endgames, the score is scaled down by a factor
/// of 4, which will result in scores of absolute value less than one pawn.

class MaterialInfo {

  friend class MaterialInfoTable;

public:
  Value mg_value() const;
  Value eg_value() const;
  ScaleFactor scale_factor(const Position &pos, Color c) const;
  int space_weight() const;
  bool specialized_eval_exists() const;
  Value evaluate(const Position &pos) const;

  static void init();

private:
  void clear();
  
  Key key;
  int16_t mgValue;
  int16_t egValue;
  uint8_t spaceWeight;
  uint8_t factor[2];
  EndgameEvaluationFunction *evaluationFunction;
  ScalingFunction *scalingFunction[2];
};


/// The MaterialInfoTable class represents a pawn hash table.  It is basically
/// just an array of MaterialInfo objects and a few methods for accessing these
/// objects.  The most important method is get_material_info, which looks up a
/// position in the table and returns a pointer to a MaterialInfo object.

class MaterialInfoTable {

public:
  MaterialInfoTable(unsigned numOfEntries);
  ~MaterialInfoTable();
  void clear();
  MaterialInfo *get_material_info(const Position &pos);

private:
  unsigned size;
  MaterialInfo *entries;
};


////
//// Inline functions
////

/// MaterialInfo::mg_value and MaterialInfo::eg_value simply returns the
/// material balance evaluation for the middle game and the endgame.

inline Value MaterialInfo::mg_value() const {
  return Value(mgValue);
}

inline Value MaterialInfo::eg_value() const {
  return Value(egValue);
}


/// MaterialInfo::clear() resets a MaterialInfo object to an empty state,
/// with all slots at their default values.

inline void MaterialInfo::clear() {
  mgValue = egValue = 0;
  factor[WHITE] = factor[BLACK] = uint8_t(SCALE_FACTOR_NORMAL);
  spaceWeight = 0;
  evaluationFunction = NULL;
  scalingFunction[WHITE] = scalingFunction[BLACK] = NULL;
}


/// MaterialInfo::scale_factor takes a position and a color as input, and
/// returns a scale factor for the given color.  We have to provide the
/// position in addition to the color, because the scale factor need not
/// be a constant:  It can also be a function which should be applied to
/// the position.  For instance, in KBP vs K endgames, a scaling function
/// which checks for draws with rook pawns and wrong-colored bishops.

inline ScaleFactor MaterialInfo::scale_factor(const Position &pos, Color c)
  const {
  if(scalingFunction[c] != NULL) {
    ScaleFactor sf = scalingFunction[c]->apply(pos);
    if(sf != SCALE_FACTOR_NONE)
      return sf;
  }
  return ScaleFactor(factor[c]);
}


/// MaterialInfo::space_weight() simply returns the weight for the space
/// evaluation for this material configuration.

inline int MaterialInfo::space_weight() const {
  return int(spaceWeight);
}


/// MaterialInfo::specialized_eval_exists decides whether there is a
/// specialized evaluation function for the current material configuration,
/// or if the normal evaluation function should be used.

inline bool MaterialInfo::specialized_eval_exists() const {
  return evaluationFunction != NULL;
}


/// MaterialInfo::evaluate applies a specialized evaluation function to a
/// given position object.  It should only be called when
/// this->specialized_eval_exists() returns 'true'.

inline Value MaterialInfo::evaluate(const Position &pos) const {
  return evaluationFunction->apply(pos);
}

#endif // !defined(MATERIAL_H_INCLUDED)