/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *     Guido Tack <tack@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2004
 *     Guido Tack, 2006
 *
 *  Last modified:
 *     $Date: 2006-08-04 16:03:26 +0200 (Fri, 04 Aug 2006) $ by $Author: schulte $
 *     $Revision: 3512 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 *  See the file "LICENSE" for information on usage and
 *  redistribution of this file, and for a
 *     DISCLAIMER OF ALL WARRANTIES.
 *
 */

#include "gecode/iter.hh"
#include <algorithm>

namespace Gecode { namespace Int { namespace Arithmetic {

  template <class View, template <class View0,class View1> class Eq>
  ExecStatus
  prop_bnd(Space* home, View x0, View x1) {
    if (x0.assigned()) {
      GECODE_ME_CHECK(x1.eq(home,(x0.val() < 0) ? -x0.val() : x0.val()));
      return ES_SUBSUMED;
    }

    if (x1.assigned()) {
      if (x0.min() >= 0) {
	GECODE_ME_CHECK(x0.eq(home,x1.val()));
      } else if (x0.max() <= 0) {
	GECODE_ME_CHECK(x0.eq(home,-x1.val()));
      } else if (x1.val() == 0) {
	GECODE_ME_CHECK(x0.eq(home,0));
      } else {
	Iter::Ranges::Array::Range r[2]
	  = { {-x1.val(),-x1.val()}, {x1.val(),x1.val()} };
	Iter::Ranges::Array i(r,2);
	GECODE_ME_CHECK(x0.inter(home,i));
      }
      return ES_SUBSUMED;
    }

    if (x0.min() >= 0) {
      return (Eq<View,View>::post(home,x0,x1) == ES_FAILED)
	? ES_FAILED : ES_SUBSUMED;
    }

    if (x0.max() <= 0) {
      MinusView mx0(x0);
      return (Eq<MinusView,View>::post(home,mx0,x1) == ES_FAILED)
	? ES_FAILED : ES_SUBSUMED;
    }

    GECODE_ME_CHECK(x1.lq(home,std::max(x0.max(),-x0.min())));
    GECODE_ME_CHECK(x0.lq(home,x1.max()));
    GECODE_ME_CHECK(x0.gq(home,-x1.max()));
    return ES_NOFIX;
  }

  template <class View>
  forceinline
  AbsBnd<View>::AbsBnd(Space* home, View x0, View x1)
    : BinaryPropagator<View,PC_INT_BND>(home,x0,x1) {}

  template <class View>
  ExecStatus
  AbsBnd<View>::post(Space* home, View x0, View x1) {
    GECODE_ME_CHECK(x1.gq(home,0));
    if (!same(x0,x1)) {
      (void) new (home) AbsBnd<View>(home,x0,x1);
    }
    return ES_OK;
  }


  template <class View>
  forceinline
  AbsBnd<View>::AbsBnd(Space* home, bool share, AbsBnd<View>& p)
    : BinaryPropagator<View,PC_INT_BND>(home,share,p) {}

  template <class View>
  Actor*
  AbsBnd<View>::copy(Space* home,bool share) {
    return new (home) AbsBnd<View>(home,share,*this);
  }

  template <class View>
  PropCost
  AbsBnd<View>::cost(void) const {
    if (View::pme(this) == ME_INT_VAL)
      return PC_UNARY_LO;
    return PC_BINARY_LO;
  }

  template <class View>
  ExecStatus
  AbsBnd<View>::propagate(Space* home) {
    return prop_bnd<View,Rel::EqBnd>(home, x0, x1);
  }

  template <class View>
  forceinline
  AbsDom<View>::AbsDom(Space* home, View x0, View x1)
    : BinaryPropagator<View,PC_INT_DOM>(home,x0,x1) {}

  template <class View>
  ExecStatus
  AbsDom<View>::post(Space* home, View x0, View x1) {
    if (x0.min() >= 0) {
      return Rel::EqDom<View,View>::post(home,x0,x1);
    } else if (x0.max() <= 0) {
      MinusView mx0(x0);
      return Rel::EqDom<MinusView,View>::post(home,mx0,x1);
    }
    GECODE_ME_CHECK(x1.gq(home,0));
    if (!same(x0,x1)) {
      (void) new (home) AbsDom<View>(home,x0,x1);
    }
    return ES_OK;
  }

  template <class View>
  forceinline
  AbsDom<View>::AbsDom(Space* home, bool share, AbsDom<View>& p)
    : BinaryPropagator<View,PC_INT_DOM>(home,share,p) {}

  template <class View>
  Actor*
  AbsDom<View>::copy(Space* home,bool share) {
    return new (home) AbsDom<View>(home,share,*this);
  }

  template <class View>
  PropCost
  AbsDom<View>::cost(void) const {
    if (View::pme(this) == ME_INT_VAL)
      return PC_UNARY_LO;
    if (View::pme(this) == ME_INT_DOM)
      return PC_BINARY_HI;
    return PC_BINARY_LO;
  }

  template <class View>
  ExecStatus
  AbsDom<View>::propagate(Space* home) {

    if (View::pme(this) != ME_INT_DOM) {
      ExecStatus es = prop_bnd<View,Rel::EqDom>(home, x0, x1);
      if (es != ES_NOFIX)
	return es;
      return this->ES_NOFIX_PARTIAL(View::pme(ME_INT_DOM));
    }

    Iter::Ranges::Singleton positive(0, Limits::Int::int_max);
    Iter::Ranges::Singleton negative(Limits::Int::int_min, 0);

    IntVarRanges xr1(x0);
    IntVarRanges xr2(x0);

    Iter::Ranges::Inter<Iter::Ranges::Singleton,
      IntVarRanges> posInter(positive, xr1);
    Iter::Ranges::Inter<Iter::Ranges::Singleton,
      IntVarRanges> negInter(negative, xr2);
    Iter::Ranges::Minus<Iter::Ranges::Inter<Iter::Ranges::Singleton,
      IntVarRanges> > mneg(negInter);
    Iter::Ranges::Union<Iter::Ranges::Inter<Iter::Ranges::Singleton,
      IntVarRanges>,
      Iter::Ranges::Minus<Iter::Ranges::Inter<
      Iter::Ranges::Singleton,
      IntVarRanges> > >
      u(posInter, mneg);

    GECODE_ME_CHECK(x1.inter(home, u));

    IntVarRanges x1r1(x1);
    IntVarRanges x1r2(x1);

    Iter::Ranges::Minus<IntVarRanges> x1m(x1r2);
    Iter::Ranges::Union<IntVarRanges,
      Iter::Ranges::Minus<IntVarRanges> > u2(x1r1,x1m);
    GECODE_ME_CHECK(x0.inter(home, u2));

    if (x1.assigned())
      return ES_SUBSUMED;

    if (x0.min() >= 0) {
      return (Rel::EqDom<View,View>::post(home,x0,x1) == ES_FAILED)
	? ES_FAILED : ES_SUBSUMED;
    }

    if (x0.max() <= 0) {
      MinusView mx0(x0);
      return (Rel::EqDom<MinusView,View>::post(home,mx0,x1) == ES_FAILED)
	? ES_FAILED : ES_SUBSUMED;
    }

    return ES_FIX;
  }

}}}

// STATISTICS: int-prop