// -*- c++ -*-
//=============================================================================
// Copyright (C) 2011 by Denys Duchier
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by the
// Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.
// 
// This program 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 Lesser General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//=============================================================================

#ifndef GECODE_COMMON
#define GECODE_COMMON

#include "gecode/int.hh"
#include "gecode/set.hh"
#include "gecode/search.hh"
#include <vector>

namespace generic_gecode
{
  using namespace std;
  using namespace Gecode;

  // description of the optimization criterion
  struct Optimizing
  {
    enum What { OPT_NONE, OPT_INT, OPT_RATIO };
    enum How { OPT_MIN, OPT_MAX };
    int num;
    int den;
    What what;
    How how;
    Optimizing(): num(-1), den(-1), what(OPT_NONE), how(OPT_MAX) {}
    Optimizing(Optimizing& o)
      : num(o.num), den(o.den), what(o.what), how(o.how) {}
    void check_ok() const
    { if (what!=OPT_NONE)
	throw Exception("gecode-python","too many optimization criteria"); }
    void maximize(int i)
    { check_ok(); what = OPT_INT; how = OPT_MAX; num = i; };
    void maximize(int i,int j)
    { check_ok(); what = OPT_RATIO; how = OPT_MAX; num = i; den = j; };
    void minimize(int i)
    { check_ok(); what = OPT_INT; how = OPT_MIN; num = i; };
    void minimize(int i,int j)
    { check_ok(); what = OPT_RATIO; how = OPT_MIN; num = i; den = j; };
  };

  struct GenericSpace;

  struct GenericEngine
  {
    virtual GenericSpace* next(void)=0;
    virtual ~GenericEngine() {};
  };

  struct GenericDFS: GenericEngine
  {
    DFS<GenericSpace> engine;
    GenericDFS(GenericSpace* s,Search::Options& opt) : engine(s,opt) {}
    virtual GenericSpace* next(void) { return engine.next(); }
  };

  struct GenericBAB: GenericEngine
  {
    BAB<GenericSpace> engine;
    GenericBAB(GenericSpace* s,Search::Options& opt) : engine(s,opt) {}
    virtual GenericSpace* next(void) { return engine.next(); }
  };

  struct GenericRestart: GenericEngine
  {
    Restart<GenericSpace> engine;
    GenericRestart(GenericSpace* s,Search::Options& opt): engine(s,opt) {}
    virtual GenericSpace* next(void) { return engine.next(); }
  };

  struct LoadingDock
  {
    vector<IntVar>  ivars;
    vector<BoolVar> bvars;
    vector<SetVar>  svars;
    vector<int> ikeep;
    vector<int> bkeep;
    vector<int> skeep;

    bool keeping_some() const
    {
      return (ikeep.size() != 0)
	||   (bkeep.size() != 0)
	||   (skeep.size() != 0);
    }

    IntVar  get_ivar(int i) const { return ivars[i]; }
    BoolVar get_bvar(int i) const { return bvars[i]; }
    SetVar  get_svar(int i) const { return svars[i]; }

    int enter_ivar(const IntVar& v)
    { ivars.push_back(v); return static_cast<int>(ivars.size()-1); }

    int enter_bvar(const BoolVar& v)
    { bvars.push_back(v); return static_cast<int>(bvars.size()-1); }

    int enter_svar(const SetVar& v)
    { svars.push_back(v); return static_cast<int>(svars.size()-1); }

    int keep_ivar(int i) { ikeep.push_back(i); return static_cast<int>(ikeep.size()-1); }
    int keep_bvar(int i) { bkeep.push_back(i); return static_cast<int>(bkeep.size()-1); }
    int keep_svar(int i) { skeep.push_back(i); return static_cast<int>(skeep.size()-1); }

    void freeze(Space& home,
		IntVarArray& iarr, BoolVarArray& barr, SetVarArray& sarr,
		int& num, int& den)
    {
      if (keeping_some())
	{
	  // make sure that optimization vars (if any) are kept
	  if (num != -1)
	    {
	      const int _num(num);
	      const int _den(den);
	      int n = static_cast<int>(ikeep.size());
	      bool num_found(false);
	      bool den_found(false);
	      for (;n--;)
		{
		  const int idx(ikeep[n]);
		  if (idx==_num)
		    { num_found=true; if (den_found) break; }
		  if (idx==_den)
		    { den_found=true; if (num_found) break; }
		}
	      if (!num_found)
		{ ikeep.push_back(_num);
		  num=static_cast<int>(ikeep.size()-1); }
	      if (_den != -1 && !den_found)
		{ ikeep.push_back(_den);
		  den=static_cast<int>(ikeep.size()-1); }
	    }
	  { int n = static_cast<int>(ikeep.size());
	    iarr = IntVarArray(home, n);
	    for (;n--;) iarr[n]=ivars[ikeep[n]]; }
	  { int n = static_cast<int>(bkeep.size());
	    barr = BoolVarArray(home, n);
	    for (;n--;) barr[n]=bvars[bkeep[n]]; }
	  { int n = static_cast<int>(skeep.size());
	    sarr = SetVarArray(home, n);
	    for (;n--;) sarr[n]=svars[skeep[n]]; }
	}
      else
	{
	  { int n = static_cast<int>(ivars.size());
	    iarr = IntVarArray(home, n);
	    for (;n--;) iarr[n]=ivars[n]; }
	  { int n = static_cast<int>(bvars.size());
	    barr = BoolVarArray(home, n);
	    for (;n--;) barr[n]=bvars[n]; }
	  { int n = static_cast<int>(svars.size());
	    sarr = SetVarArray(home, n);
	    for (;n--;) sarr[n]=svars[n]; }
	}
    }
  };

  struct GenericSpace: Space
  {
    Optimizing optim;
    IntVarArray ivars;
    BoolVarArray bvars;
    SetVarArray svars;
    LoadingDock* dock;
    bool keeping_some;		// iff only SOME of the vars are kept

    Space* space() { return this; }

    GenericSpace(bool share, GenericSpace& s)
      : Space(share, s), optim(s.optim), dock(NULL), keeping_some(s.keeping_some)
    {
      ivars.update(*this, share, s.ivars);
      bvars.update(*this, share, s.bvars);
      svars.update(*this, share, s.svars);
    }

    Space* copy(bool share)
    { freeze(); return new GenericSpace(share, *this); }

    GenericSpace() : dock(new LoadingDock()), keeping_some(false) {}
    ~GenericSpace() { delete dock; }

    // throw some C++ exception on behalf of glue code
    void kaboom(const char* s)
    { throw Exception("gecode-python", s); }
    int ikaboom(const char* s)
    { kaboom(s); return 0; }

    // freeze the space before handing it off to a search engine
    void freeze()
    {
      if (dock)
	{
	  keeping_some = dock->keeping_some();
	  dock->freeze(*this, ivars, bvars, svars, optim.num, optim.den);
	  delete dock;
	  dock = NULL;
	}
    }

    IntVar  get_ivar(int i) const { return (dock)?dock->get_ivar(i):ivars[i]; }
    BoolVar get_bvar(int i) const { return (dock)?dock->get_bvar(i):bvars[i]; }
    SetVar  get_svar(int i) const { return (dock)?dock->get_svar(i):svars[i]; }

    int keep_ivar(int i)
    {
      if (dock) return dock->keep_ivar(i);
      else return ikaboom("too late to keep");
    }

    int keep_bvar(int i)
    {
      if (dock) return dock->keep_bvar(i);
      else return ikaboom("too late to keep");
    }

    int keep_svar(int i)
    {
      if (dock) return dock->keep_svar(i);
      else return ikaboom("too late to keep");
    }

    bool frozen() const { return dock==NULL; }
    bool has_keepers() const { return keeping_some; }
    // when frozen and has_keepers: which is just has_keepers actually
    bool use_keep_index() const { return has_keepers(); }

    GenericEngine* new_engine(bool restart, Search::Options& opt)
    {
      freeze();
      return (optim.what == Optimizing::OPT_NONE)
	? static_cast<GenericEngine*>(new GenericDFS(this,opt))
	: (restart
	   ? static_cast<GenericEngine*>(new GenericRestart(this,opt))
	   : static_cast<GenericEngine*>(new GenericBAB(this,opt)));
    }

    int _new_ivar(IntVar& v)
    {
      if (dock) return dock->enter_ivar(v);
      else return ikaboom("too late to create vars");
    }

    int new_ivar(int lo, int hi)
    {
      IntVar v(*this, lo, hi);
      return _new_ivar(v);
    }

    int new_ivar(IntSet& s)
    {
      IntVar v(*this, s);
      return _new_ivar(v);
    }

    int _new_bvar(BoolVar& v)
    {
      if (dock) return dock->enter_bvar(v);
      else return ikaboom("too late to create vars");
    }

    int new_bvar()
    {
      BoolVar v(*this, 0, 1);
      return _new_bvar(v);
    }

    int _new_svar(SetVar& v)
    {
      if (dock) return dock->enter_svar(v);
      else return ikaboom("too late to create vars");
    }

    int new_svar(int glbMin, int glbMax, int lubMin, int lubMax,
		 unsigned int cardMin=0,
		 unsigned int cardMax=Set::Limits::card)
    {
      SetVar v(*this, glbMin, glbMax, lubMin, lubMax, cardMin, cardMax);
      return _new_svar(v);
    }

    int new_svar(IntSet glb, int lubMin, int lubMax,
		 unsigned int cardMin=0,
		 unsigned int cardMax=Set::Limits::card)
    {
      SetVar v(*this, glb, lubMin, lubMax, cardMin, cardMax);
      return _new_svar(v);
    }

    int new_svar(int glbMin, int glbMax, IntSet lub,
		 unsigned int cardMin=0,
		 unsigned int cardMax=Set::Limits::card)
    {
      SetVar v(*this, glbMin, glbMax, lub, cardMin, cardMax);
      return _new_svar(v);
    }

    int new_svar(IntSet glb, IntSet lub,
		 unsigned int cardMin=0,
		 unsigned int cardMax=Set::Limits::card)
    {
      SetVar v(*this, glb, lub, cardMin, cardMax);
      return _new_svar(v);
    }

    void minimize(int i) { optim.minimize(i); }
    void minimize(int i, int j) { optim.minimize(i,j); }
    void maximize(int i) { optim.maximize(i); }
    void maximize(int i, int j) { optim.maximize(i,j); }

    virtual void constrain(const Space& s)
    {
      const GenericSpace& sol = static_cast<const GenericSpace&>(s);
      switch (optim.what)
	{
	case Optimizing::OPT_NONE:
	  break;
	case Optimizing::OPT_INT:
	  rel(*this, ivars[optim.num],
	      ((optim.how==Optimizing::OPT_MIN) ? IRT_LE : IRT_GR),
	      sol.ivars[optim.num].val());
	  break;
	case Optimizing::OPT_RATIO:
	  {
	    IntArgs c(2, sol.ivars[optim.den].val(),
		      -  sol.ivars[optim.num].val());
	    IntVarArgs v(2);
	    v[0] = ivars[optim.num];
	    v[1] = ivars[optim.den];
	    linear(*this, c, v,
		   ((optim.how==Optimizing::OPT_MIN) ? IRT_LE : IRT_GR), 0);
	    break;
	  }
	}
    }
  };
}

#ifdef DISJUNCTOR
#include "disjunctor.icc"
#endif

#endif
