#include "PndOnlineSTTStdTSF.h"

#include "TGraph.h"
#include "TFitResult.h"

// return value here sucks
PndOnlineTrack *PndOnlineSTTStdTSF::FindTrackSegment(vector< list<PndOnlineTrackHit *> > &hit_channel_map) 
{
    vector<PndOnlineTrackHit *> segment_hits;
    PndOnlineTrack *new_track = NULL;

  
    bool layer1_hit = CheckHit(channel_list[0], hit_channel_map, segment_hits) 
	|| CheckHit(channel_list[3], hit_channel_map, segment_hits) 
	|| CheckHit(channel_list[7], hit_channel_map, segment_hits);
    bool layer2_hit = CheckHit(channel_list[1], hit_channel_map, segment_hits) 
	|| CheckHit(channel_list[5], hit_channel_map, segment_hits);
    bool layer3_hit = CheckHit(channel_list[4], hit_channel_map, segment_hits);
    bool layer4_hit = CheckHit(channel_list[2], hit_channel_map, segment_hits) 
	|| CheckHit(channel_list[6], hit_channel_map, segment_hits);

    int num_hit_layers = 0;
    if(layer1_hit) num_hit_layers++;
    if(layer2_hit) num_hit_layers++;
    if(layer3_hit) num_hit_layers++;
    if(layer4_hit) num_hit_layers++;

    //cout << " there are " << num_hit_layers << " layers with hits in them!" << endl;

    /*
    if(num_hit_layers == 4) {  // check for full track segment
	return true;
    } else if(num_hit_layers == 3) {  // check for partial track segment
	return true;
    } else {
	return false;
    }
    */


    if( (num_hit_layers == 4) || (num_hit_layers == 3) ) {  
	// build track segment
	//PndOnlineTrack *new_track = new PndOnlineTrack();
	new_track = new PndOnlineTrack();

	// hits are ordered by first layer -> last layer
	new_track->SetVertex( TVector3(segment_hits[0]->X(), segment_hits[0]->Y(), 
				       segment_hits[0]->Z() ) );

	// hack to get rough direction (for testing!)
	double n = segment_hits.size();
	double *x = new double[8];
	double *y = new double[8];
	for(int i=0; i<n; ++i) {
	    x[i] = segment_hits[i]->X();
	    y[i] = segment_hits[i]->Y();
	}

	TGraph gr(n, x, y);
	TFitResultPtr r = gr.Fit("1 ++ x","S");
	
	//cout << "RESULT = " << r->Value(0) << " " << r->Value(1) << endl;

	//  can only figure out transverse momentum here
	double sign = segment_hits[0]->X() > 0 ? 1. : -1.;
	new_track->SetMomentum( TVector3(sign, r->Value(1), 0.).Unit() );

	delete x,y;
	
	//new_track->Momentum().Print();
	//new_track->Vertex().Print();

	// guess t0 is the time of the oldest hit
	double best_t0 = segment_hits[0]->BaseHit()->GetTimeStamp();
	segment_hits[0]->SetStatus(PndOnlineTrackHit::kAssigned);

	for(int the_hit=1; the_hit<segment_hits.size(); the_hit++) {
	    segment_hits[the_hit]->SetStatus(PndOnlineTrackHit::kAssigned);
	    if(best_t0 > segment_hits[the_hit]->BaseHit()->GetTimeStamp()) 
		best_t0 = segment_hits[the_hit]->BaseHit()->GetTimeStamp();
	}
	new_track->SetT0(best_t0);

	new_track->Hits() = segment_hits;

	cout << " the new track has " << new_track->Hits().size() << " hits " << endl;

	
    }

    return new_track;
}