/* Copyright (c) 1997-2004
   Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Berlin, Germany)
   http://www.math.tu-berlin.de/polymake,  mailto:polymake@math.tu-berlin.de

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 2, or (at your option) any
   later version: http://www.gnu.org/licenses/gpl.txt.

   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.
*/

#ident "$Project: polymake $$Id: connected_sum.tcc 4861 2004-07-27 18:12:29Z gawrilow $"

#include <connected_sum.h>
#include <complex_tools.h>
#include <sstream>

namespace polymake { namespace topaz {
	
   typedef std_ext::hash_map<int,int> map;

   template <typename Complex_1, typename Complex_2>
   std::list< Set<int> > connected_sum(const Complex_1& C1,
				       const Complex_2& C2,
				       const int f1, const int f2,
				       Array<std::string>& L1,
				       const Array<std::string>& L2,
				       map& P)
   {
      typedef typename Complex_2::value_type Facet2;
      std::list< Set<int> > CS;
      
      // add facets of C1, omitting f1, and compute the vertex set of C1
      Set<int> V1, V2, facet1, facet2;
      int i=0;
      for (typename Entire<Complex_1>::const_iterator c_it=entire(C1); !c_it.at_end(); ++c_it, ++i) {
	 if (i==f1)
	    facet1=*c_it;
	 else
	    CS.push_back(*c_it);
	 V1 += *c_it;
      }
      
#ifdef POLY_DEBUG
      if (facet1.empty())
	 throw std::runtime_error("connected_sum: f1 is not a facet index.\ninvalid input");
#endif
      
      // find facet f2 and compute the vertex set of C2
      i=0;
      for (typename Entire<Complex_2>::const_iterator c_it=entire(C2); !c_it.at_end(); ++c_it, ++i) {
	 if (i==f2)
	    facet2=*c_it;
	 V2 += *c_it;
      }
#ifdef POLY_DEBUG
      if (facet2.empty())
	 throw std::runtime_error("connected_sum: f2 is not a facet index.\ninvalid input");
      
      if (facet1.size()!=facet2.size())
	 throw std::runtime_error("connected_sum: Dimensions of facets do not match.\ninvalid input"); 
#endif
      
      // compute new vertex indices for V2, identyfing facet1 and facet2
      int index_diff= V1.back()-V2.front()+1;
      map vertex_map(V2.size());
      typename Set<int>::iterator f1_it=facet1.begin();
      for (typename Entire< Set<int> >::iterator it=entire(V2); !it.at_end(); ++it) {
	 const int v=*it;
	 if (facet2.contains(v)) {
	    vertex_map[*it]= P.empty() ? *f1_it : P[*f1_it];
	    ++f1_it;
	    --index_diff;
	 } else
	    vertex_map[*it]=*it+index_diff;
      }
      
      // add facets of C2, omitting f2, and adjust the vertex indices
      i=0;
      for (typename Entire<Complex_2>::const_iterator c_it=entire(C2);
	   !c_it.at_end(); ++c_it, ++i)
	 if (i!=f2) {
	    Set<int> f;
	    for (typename Entire<Facet2>::const_iterator f_it=entire(*c_it);
		 !f_it.at_end(); ++f_it)
	       f+=vertex_map[*f_it];
	    CS.push_back(f);
	 }
      
      // adjust labels
      if (L1.size() != 0) {         // if L1.size()==0 => no L1 and L2 specified.
	 int count = L1.size();
	 L1.resize(count + L2.size() - facet1.size());
	 
	 for (int v=0; v<count; ++v)
	    if (!facet1.contains(v)) {
	       std::ostringstream label;
	       label << L1[v] << "_1";
	       L1[v] = label.str();
	    }
	 
	 for (int v=0; v<L2.size(); ++v)
	    if (!facet2.contains(v)) {
	       std::ostringstream label;
	       label << L2[v] << "_2";
	       std::string l = label.str();
	       L1[count] = label.str();;
	       ++count;
	    }
      }
      
      const Set<int> V = accumulate(CS, operations::add());
      if (adj_numbering(CS,V) && L1.size()!=0) {

	 // adjust labels
	 Array<std::string> L_tmp(V.size());
	 Array<std::string>::iterator l = L_tmp.begin();
	 for (Entire< Set<int> >::const_iterator v=entire(V);
	      !v.at_end(); ++v, ++l)
	    *l = L1[*v];
	 
	 L1 = L_tmp;
      }
      
      return CS;
   }
   
} };

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