/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2004
 *
 *  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/int/rel.hh"

namespace Gecode { namespace Int { namespace Arithmetic {

  /*
   * Ternary bounds-consistent maximum
   *
   */

  template <class View>
  forceinline
  Max<View>::Max(Space* home, View x0, View x1, View x2)
    : TernaryPropagator<View,PC_INT_BND>(home,x0,x1,x2) {}

  template <class View>
  ExecStatus
  Max<View>::post(Space* home, View x0, View x1, View x2) {
    if (same(x0,x1))
      return Rel::EqBnd<View,View>::post(home,x0,x2);
    if (same(x0,x2))
      return Rel::Lq<View>::post(home,x1,x2);
    if (same(x1,x2))
      return Rel::Lq<View>::post(home,x0,x2);
    (void) new (home) Max<View>(home,x0,x1,x2);
    return ES_OK;
  }

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

  template <class View>
  forceinline
  Max<View>::Max(Space* home, bool share, Propagator& p,
		 View x0, View x1, View x2)
    : TernaryPropagator<View,PC_INT_BND>(home,share,p,x0,x1,x2) {}

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

  template <class View>
  ExecStatus
  Max<View>::propagate(Space* home) {
    bool mod = false;
    do {
      mod = false;
      {
	ModEvent me = x2.lq(home,std::max(x0.max(),x1.max()));
	if (me_failed(me)) return ES_FAILED;
	mod |= me_modified(me);
      }
      {
	ModEvent me = x2.gq(home,std::max(x0.min(),x1.min()));
	if (me_failed(me)) return ES_FAILED;
	mod |= me_modified(me);
      }
      {
	ModEvent me = x0.lq(home,x2.max());
	if (me_failed(me)) return ES_FAILED;
	mod |= me_modified(me);
      }
      {
	ModEvent me = x1.lq(home,x2.max());
	if (me_failed(me)) return ES_FAILED;
	mod |= me_modified(me);
      }
    } while (mod);
    if (x0.max() <= x1.min()) {
      GECODE_ES_CHECK((Rel::EqBnd<View,View>::post(home,x1,x2)));
      return ES_SUBSUMED;
    }
    if (x1.max() <= x0.min()) {
      GECODE_ES_CHECK((Rel::EqBnd<View,View>::post(home,x0,x2)));
      return ES_SUBSUMED;
    }
    return x0.assigned() && x1.assigned() && x2.assigned() ? ES_SUBSUMED : ES_FIX;
  }



  /*
   * Nary bounds-consistent maximum
   *
   */

  template <class View>
  forceinline
  NaryMax<View>::NaryMax(Space* home, ViewArray<View>& x, View y)
    : NaryOnePropagator<View,PC_INT_BND>(home,x,y) {}

  template <class View>
  ExecStatus
  NaryMax<View>::post(Space* home, ViewArray<View>& x, View y) {
    assert(x.size() > 0);
    x.unique();
    if (x.size() == 1)
      return Rel::EqBnd<View,View>::post(home,x[0],y);
    if (x.size() == 2)
      return Max<View>::post(home,x[0],x[1],y);
    if (x.same(y)) {
      // Check whether y occurs in x
      for (int i=x.size(); i--; )
	GECODE_ES_CHECK(Rel::Lq<View>::post(home,x[i],y));
    } else {
      (void) new (home) NaryMax<View>(home,x,y);
    }
    return ES_OK;
  }

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

  template <class View>
  Actor*
  NaryMax<View>::copy(Space* home, bool share) {
    if (x.size() == 1)
      return new (home) Rel::EqBnd<View,View>(home,share,*this,x[0],y);
    if (x.size() == 2)
      return new (home) Max<View>(home,share,*this,x[0],x[1],y);
    return new (home) NaryMax<View>(home,share,*this);
  }

  /// Status of propagation for nary max
  enum MaxPropStatus {
    MPS_ASSIGNED  = 1<<0, ///< All views are assigned
    MPS_REMOVED   = 1<<1, ///< A view is removed
    MPS_NEW_BOUND = 1<<2  ///< Telling has found a new upper bound
  };

  template <class View>
  ExecStatus
  NaryMax<View>::propagate(Space* home) {
  rerun:
    int maxmax = Limits::Int::int_min-1;
    int maxmin = Limits::Int::int_min-1;
    for (int i = x.size(); i--; ) {
      maxmax = std::max(x[i].max(),maxmax);
      maxmin = std::max(x[i].min(),maxmin);
    }
    GECODE_ME_CHECK(y.lq(home,maxmax));
    GECODE_ME_CHECK(y.gq(home,maxmin));
    maxmin = y.min();
    maxmax = y.max();
    int status = MPS_ASSIGNED;
    for (int i = x.size(); i--; ) {
      ModEvent me = x[i].lq(home,maxmax);
      if (me == ME_INT_FAILED)
	return ES_FAILED;
      if (me_modified(me) && (x[i].max() != maxmax))
	status |= MPS_NEW_BOUND;
      if (x[i].max() < maxmin) {
	x.move_lst(i,home,this,PC_INT_BND);
	status |= MPS_REMOVED;
      } else if (!x[i].assigned())
	status &= ~MPS_ASSIGNED;
    }
    if (x.size() == 0)
      return ES_FAILED;
    if ((status & MPS_REMOVED) != 0)
      goto rerun;
    if (((status & MPS_ASSIGNED) != 0) && y.assigned())
      return ES_SUBSUMED;
    return ((status & MPS_NEW_BOUND) != 0) ? ES_NOFIX : ES_FIX;
  }

}}}

// STATISTICS: int-prop