/*
 *  Main authors:
 *     Mikael Lagerkvist <lagerkvist@gecode.org>
 *
 *  Copyright:
 *     Mikael Lagerkvist, 2005
 *
 *  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.
 *
 */

/* This is the propagation algorithm of the cumulatives constraint as presented in
   @inproceedings{DBLP:conf/cp/BeldiceanuC02,
     author    = {Nicolas Beldiceanu and Mats Carlsson},
     title     = {A New Multi-resource cumulatives Constraint with Negative Heights.},
     booktitle = {CP},
     year      = {2002},
     pages     = {63-79},
     ee        = {http://link.springer.de/link/service/series/0558/bibs/2470/24700063.htm},
     crossref  = {DBLP:conf/cp/2002},
     bibsource = {DBLP, http://dblp.uni-trier.de}
   }
   @proceedings{DBLP:conf/cp/2002,
     editor    = {Pascal Van Hentenryck},
     title     = {Principles and Practice of Constraint Programming - CP 2002,
                  8th International Conference, CP 2002,
                  Ithaca, NY, USA, September 9-13, 2002, Proceedings},
     booktitle = {CP},
     publisher = {Springer},
     series    = {Lecture Notes in Computer Science},
     volume    = {2470},
     year      = {2002},
     isbn      = {3-540-44120-4},
     bibsource = {DBLP, http://dblp.uni-trier.de}
   }

 */

#include <vector>
#include <list>
#include <algorithm>


namespace Gecode { namespace Int { namespace Cumulatives {

  template <class ViewM, class ViewD, class ViewH, class View>
  forceinline
  Val<ViewM,ViewD,ViewH,View>::Val(Space* home, const ViewArray<ViewM>& _machine,
				   const ViewArray<View>& _start,
				   const ViewArray<ViewD>& _duration,
				   const ViewArray<View>& _end,
				   const ViewArray<ViewH>& _height,
				   const IntArgs& _limit,
				   bool _at_most) :
    Propagator(home,true),
    machine(_machine), start(_start), duration(_duration),
    end(_end), height(_height), limit(_limit.size()), at_most(_at_most) {
    for(int i = _limit.size(); i--; ) {
      limit[i] = _limit[i];
    }

    machine.subscribe(home,this,PC_INT_DOM);
    start.subscribe(home,this,PC_INT_BND);
    duration.subscribe(home,this,PC_INT_BND);
    end.subscribe(home,this,PC_INT_BND);
    height.subscribe(home,this,PC_INT_BND);
  }

  template <class ViewM, class ViewD, class ViewH, class View>
  ExecStatus
  Val<ViewM,ViewD,ViewH,View>
  ::post(Space* home, const ViewArray<ViewM>& machine,
	 const ViewArray<View>& start, const ViewArray<ViewD>& duration,
	 const ViewArray<View>& end, const ViewArray<ViewH>& height,
	 const IntArgs& limit, bool at_most) {
    (void) new (home) Val(home, machine, start, duration,
			  end, height, limit, at_most);

    return ES_OK;
  }

  template <class ViewM, class ViewD, class ViewH, class View>
  forceinline
  Val<ViewM,ViewD,ViewH,View>::Val(Space* home, bool share,
				   Val<ViewM,ViewD,ViewH,View>& p)
    : Propagator(home,share,p), at_most(p.at_most) {
    machine.update(home,share,p.machine);
    start.update(home, share, p.start);
    duration.update(home, share, p.duration);
    end.update(home, share, p.end);
    height.update(home, share, p.height);
    limit.update(share, p.limit);
  }

  template <class ViewM, class ViewD, class ViewH, class View>
  size_t
  Val<ViewM,ViewD,ViewH,View>::dispose(Space* home) {
    if (!home->failed()) {
      machine.cancel(home,this,PC_INT_DOM);
      start.cancel(home,this,PC_INT_BND);
      duration.cancel(home,this,PC_INT_BND);
      end.cancel(home,this,PC_INT_BND);
      height.cancel(home,this,PC_INT_BND);
    }
    limit.~SharedArray();
    (void) Propagator::dispose(home);
    return sizeof(*this);
  }

  template <class ViewM, class ViewD, class ViewH, class View>
  PropCost
  Val<ViewM,ViewD,ViewH,View>::cost(void) const {
    return cost_hi(start.size(), PC_QUADRATIC_LO);
  }

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

  /// Types of events for the sweep-line
  typedef enum {EVENT_CHCK, EVENT_PROF, EVENT_PRUN} ev_t;
  /// An event collects the information for one evnet for the sweep-line
  class Event
  {
  public:
    /// The type of the event
    ev_t e;
    /// The task this event refers to
    int task;
    /// The date of this event
    int date;
    /// The quantity changed by this event (if any)
    int inc;
    /** If the type is EVENT_PROF and it is the first of the pair,
     * this value is true. Added to handle contribution-values
     * correctly for both at_most and at_least.
     */
    bool first_prof;

    /// Simple constructor
    Event(ev_t _e, int _task, int _date, int _inc = 0, bool _first_prof = false)
      : e(_e), task(_task), date(_date), inc(_inc), first_prof(_first_prof)
    {}

    /// Order events based on date.
    bool operator<(const Event& e) {
      return date < e.date;
    }
  };


  template <class ViewM, class ViewD, class ViewH, class View>
  ExecStatus
  Val<ViewM,ViewD,ViewH,View>::prune(Space * home, int low, int up, int r,
		   int ntask, int sheight,
		   const std::vector<int>& contribution,
		   std::list<int>& prune_tasks) {

    if (ntask > 0 &&
	(at_most ? sheight > limit[r]
	 : sheight < limit[r])) {
      return ES_FAILED;
    }

    std::list<int>::iterator it = prune_tasks.begin();
    while (it != prune_tasks.end()) {
      int t = *it;
      // Algorithm 2.
      // Prune the machine, start, and end for required
      // tasks for machine r that have heights possibly greater than 0.
      if (ntask != 0 &&
	  (at_most ? height[t].min() < 0
	   : height[t].max() > 0) &&
	  (at_most ? sheight-contribution[t] > limit[r]
	   : sheight-contribution[t] < limit[r])) {
	if (me_failed(machine[t].eq(home, r))||
	    me_failed(start[t].gq(home, up-duration[t].max()+1))||
	    me_failed(start[t].lq(home, low))||
	    me_failed(end[t].lq(home,low+duration[t].max()))||
	    me_failed(end[t].gq(home, up+1))||
	    me_failed(duration[t].gq(home,std::min(up-start[t].max()+1,
						   end[t].min()-low)))
	    )
	  return ES_FAILED;
      }

      // Algorithm 3.
      // Remove values that prevent us from reaching the limit
      if (at_most ? height[t].min() < std::min(0, limit[r])
	  : height[t].max() < std::max(0, limit[r])) {
	if (at_most ? sheight-contribution[t]+height[t].min() > limit[r]
	    : sheight-contribution[t]+height[t].max() < limit[r]) {
	  if (end[t].min() > low  &&
	      start[t].max() <= up &&
	      duration[t].min() > 0) {
	    if (me_failed(machine[t].nq(home, r)))
	      return ES_FAILED;
	  } else if (machine[t].assigned()) {
	    int dtmin = duration[t].min();
	    if (dtmin > 0) {
	      Iter::Ranges::Singleton
		a(low-dtmin+1, up), b(low+1, up+dtmin);
  	      if (me_failed(start[t].minus(home,a)) ||
  		  me_failed(end[t].minus(home, b)))
  		return ES_FAILED;
	    }
	    if (me_failed(duration[t].lq(home,
					 std::max(std::max(low-start[t].min(),
							   end[t].max()-up-1),
						  0))))
	      return ES_FAILED;
	  }
	}
      }

      // Algorithm 4.
      // Remove bad negative values from for-sure heights.
      /* \note "It is not sufficient to only test for assignment of machine[t]
       *         since Algorithm 3 can remove the value." Check this against
       *         the conditions for Alg3.
       */
      if (machine[t].assigned() &&
	  machine[t].val() == r &&
	  end[t].min() > low    &&
	  start[t].max() <= up  &&
	  duration[t].min() > 0 ) {
	if (me_failed(at_most
		      ? height[t].lq(home, limit[r]-sheight+contribution[t])
		      : height[t].gq(home, limit[r]-sheight+contribution[t])))
	  return ES_FAILED;
      }

      // Remove tasks that are no longer relevant.
      /* @todo check condition more thouroughly - is
       *        \f$max(end_r)\geq up+1\f$  CORRECT?
       */
      if ((!machine[t].in(r)) ||
	  end[t].max() <= up+1) {
	// @todo more than one *it (probably not) ? ==> remove(*it)
	std::list<int>::iterator old = it++;
	prune_tasks.erase(old);
      } else {
	++it;
      }
    }

    return ES_OK;
  }

  template <class ViewM, class ViewD, class ViewH, class View>
  ExecStatus
  Val<ViewM,ViewD,ViewH,View>::propagate(Space* home) {
    ExecStatus res = ES_NOFIX;
    // Check for subsumption
    bool nnft = true; // no non-fixed tasks.
    for (int t = start.size(); t--; )
      if(!(duration[t].assigned() && end[t].assigned()   &&
	   machine[t].assigned()  && start[t].assigned() &&
	   height[t].assigned())) {
	nnft = false;
	break;
      }
    if(nnft) res = ES_SUBSUMED;


    // Propagate information for machine r
    for (int r = limit.size(); r--; ) {
      std::list<Event> events;

      // Find events for sweep-line
      for (int t = start.size(); t--; ) {
	if (machine[t].assigned() &&
	    machine[t].val() == r &&
	    start[t].max() < end[t].min()) {
	  if (at_most
	      ? height[t].min() > std::min(0, limit[r])
	      : height[t].max() < std::max(0, limit[r])) {
	    events.push_back(Event(EVENT_CHCK, t, start[t].max(), 1));
	    events.push_back(Event(EVENT_CHCK, t, end[t].min(), -1));
	  }
	  if (at_most
	      ? height[t].min() > 0
	      : height[t].max() < 0) {
	    events.push_back(Event(EVENT_PROF, t, start[t].max(),
				   at_most ? height[t].min()
				   : height[t].max(), true));
	    events.push_back(Event(EVENT_PROF, t, end[t].min(),
				   at_most ? -height[t].min()
				   : -height[t].max()));
	  }
	}
	
	if (machine[t].in(r)) {
	  if (at_most
	      ? height[t].min() < 0
	      : height[t].max() > 0) {
	    events.push_back(Event(EVENT_PROF, t, start[t].min(),
				   at_most ? height[t].min()
				   : height[t].max(), true));
	    events.push_back(Event(EVENT_PROF, t, end[t].max(),
				   at_most ? -height[t].min()
				   : -height[t].max()));
	  }
	  if (!(machine[t].assigned() &&
	         height[t].assigned() &&
	          start[t].assigned() &&
	            end[t].assigned())) {
	    events.push_back(Event(EVENT_PRUN, t, start[t].min()));
	  }
	}
      }

      // If there are no events, continue with next machine
      if (events.size() == 0)
	continue;

      // Sort the events according to date
      events.sort();

      // Sweep line along d, starting at 0
      int d        = 0;
      int ntask    = 0;
      int sheight  = 0;
      std::list<Event>::iterator it = events.begin();
      std::list<int> prune_tasks;
      std::vector<int> contribution(start.size(), at_most
				    ? Limits::Int::int_max
				    : Limits::Int::int_min);

      d = it->date;
      while (it != events.end()) {
	if (it->e != EVENT_PRUN) {
	  if (d != it->date) {
	    GECODE_ES_CHECK(prune(home, d, it->date-1, r,
				  ntask, sheight,
				  contribution, prune_tasks));
	    d = it->date;
	  }
	  if (it->e == EVENT_CHCK) {
	    ntask += it->inc;
	  } else /* if (it->e == EVENT_PROF) */ {
	    sheight += it->inc;
	    if(it->first_prof)
	      contribution[it->task] = at_most
		? std::min(contribution[it->task], it->inc)
		: std::max(contribution[it->task], it->inc);
	  }
	} else /* if (it->e == EVENT_PRUN) */ {
	  prune_tasks.push_back(it->task);
	}
	++it;
      }

      GECODE_ES_CHECK(prune(home, d, d, r,
			    ntask, sheight,
			    contribution, prune_tasks));
    }

    return res;
  }

}}}

// STATISTICS: int-prop