/* linbox/blackbox/rational-reconstruction-base.h
 * Copyright (C) 2009 Anna Marszalek
 *
 * Written by Anna Marszalek <aniau@astronet.pl>
 *
 * ========LICENCE========
 * This file is part of the library LinBox.
 *
  * LinBox is free software: you can redistribute it and/or modify
 * it under the terms of the  GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 * ========LICENCE========
 */

#ifndef __LINBOX_charpoly_rational_H
#define __LINBOX_charpoly_rational_H

#include "linbox/util/commentator.h"
#include "linbox/util/timer.h"
#include "linbox/ring/modular.h"

//#include "linbox/field/gmp-rational.h"
#include "linbox/blackbox/rational-matrix-factory.h"
#include "linbox/algorithms/cra-early-multip.h"
#include "linbox/algorithms/cra-domain.h"
//#include "linbox/algorithms/rational-cra.h"
#include "linbox/algorithms/rational-reconstruction-base.h"
#include "linbox/algorithms/classic-rational-reconstruction.h"
#include "linbox/solutions/charpoly.h"
#include "linbox/blackbox/compose.h"
#include "linbox/blackbox/diagonal.h"

namespace LinBox
{
	//typedef GMPRationalField Rationals;
	//typedef Rationals::Element Quotient;

	/*
	 * Computes the characteristic polynomial of a rational dense matrix
	 */

	template<class T1, class T2>
	struct MyModularCharpoly{
		T1* t1;
		T2* t2;

		int switcher;

		MyModularCharpoly(T1* s1, T2* s2, int s = 1)  {t1=s1; t2=s2;switcher = s;}

		int setSwitcher(int s) {return switcher = s;}

		template<typename Polynomial, typename Field>
		Polynomial& operator()(Polynomial& P, const Field& F) const
		{
			if (switcher ==1) {
				t1->operator()(P,F);
			}
			else {
				t2->operator()(P,F);
			}
			return P;
		}
	};

	template <class Blackbox, class MyMethod>
	struct MyRationalModularCharpoly {
		const Blackbox &A;
		const MyMethod &M;
		const std::vector<Integer> &mul;//multiplicative prec;

		MyRationalModularCharpoly(const Blackbox& b, const MyMethod& n,
					  const std::vector<Integer >& p) :
			A(b), M(n), mul(p)
		{}
		MyRationalModularCharpoly(MyRationalModularCharpoly& C) :
			// MyRationalModularCharpoly(C.A,C.M,C.mul)
			A(C.A),M(C.M),mul(C.mul)
		{}

		template<typename Polynomial, typename Field>
		Polynomial& operator()(Polynomial& P, const Field& F) const
		{
			typedef typename Blackbox::template rebind<Field>::other FBlackbox;
			FBlackbox * Ap;
			MatrixHom::map(Ap, A, F);
			charpoly( P, *Ap, typename FieldTraits<Field>::categoryTag(), M);
			typename std::vector<Integer >::const_iterator it = mul.begin();
			typename Polynomial::iterator it_p = P.begin();
			for (;it_p !=P.end(); ++it, ++it_p) {
				typename Field::Element e;
				F.init(e, *it);
				F.mulin(*it_p,e);
			}

			delete Ap;
			return P;
		}
	};

	template <class Blackbox, class MyMethod>
	struct MyIntegerModularCharpoly {
		const Blackbox &A;
		const MyMethod &M;
		const std::vector<typename Blackbox::Field::Element> &vD;//diagonal div. prec;
		const std::vector<typename Blackbox::Field::Element > &mul;//multiplicative prec;

		MyIntegerModularCharpoly(const Blackbox& b, const MyMethod& n,
					 const std::vector<typename Blackbox::Field::Element>& ve,
					 const std::vector<typename Blackbox::Field::Element >& p) :
			A(b), M(n), vD(ve), mul(p) {}

		MyIntegerModularCharpoly(MyIntegerModularCharpoly& C) :
			// MyIntegerModularCharpoly(C.A,C.M,C.vD,C.mul)
			A(C.A),M(C.M),vD(C.vD),mul(C.mul)
		{}

		template<typename Polynomial, typename Field>
		Polynomial& operator()(Polynomial& P, const Field& F) const
		{
			typedef typename Blackbox::template rebind<Field>::other FBlackbox;
			FBlackbox * Ap;
			MatrixHom::map(Ap, A, F);

			typename std::vector<typename Blackbox::Field::Element>::const_iterator it;

			int i=0;
			for (it = vD.begin(); it != vD.end(); ++it,++i) {
				typename Field::Element t,tt;
				F.init(t,*it);
				F.invin(t);
				for (int j=0; j < A.coldim(); ++j) {
					F.mulin(Ap->refEntry(i,j),t);
				}
			}

			charpoly( P, *Ap, typename FieldTraits<Field>::categoryTag(), M);
			typename std::vector<typename Blackbox::Field::Element >::const_iterator it2 = mul.begin();
			typename Polynomial::iterator it_p = P.begin();
			for (;it_p !=P.end(); ++it2, ++it_p) {
				typename Field::Element e;
				F.init(e, *it2);
				F.mulin(*it_p,e);
			}

			delete Ap;
			return P;
		}
	};

	template <class Rationals, template <class> class Vector, class MyMethod >
	Vector<typename Rationals::Element>& rational_charpoly (Vector<typename Rationals::Element> &p,
								const BlasMatrix<Rationals > &A,
								const MyMethod &Met=  Method::Hybrid())
	{

		typedef typename Rationals::Element Quotient;

		commentator().start ("Rational Charpoly", "Rminpoly");

		RandomPrimeIterator genprime( 26-(int)ceil(log((double)A.rowdim())*0.7213475205));

		std::vector<Integer> F(A.rowdim()+1,1);
		std::vector<Integer> M(A.rowdim()+1,1);
		std::vector<Integer> Di(A.rowdim());

		RationalMatrixFactory<Givaro::ZRing<Integer>,Rationals,BlasMatrix<Rationals > > FA(&A);
		Integer da=1, di=1; Integer D=1;
		FA.denominator(da);

		for (int i=(int)M.size()-2; i >= 0 ; --i) {
			//c[m]=1, c[0]=det(A);
			FA.denominator(di,i);
			D *=di;
			Di[(size_t)i]=di;
			M[(size_t)i] = M[(size_t)i+1]*da;
		}
		for (int i=0; i < (int) M.size() ; ++i ) {
			gcd(M[(size_t)i],M[(size_t)i],D);
		}

		Givaro::ZRing<Integer> Z;
		BlasMatrix<Givaro::ZRing<Integer> > Atilde(Z,A.rowdim(), A.coldim());
		FA.makeAtilde(Atilde);

		ChineseRemainder< EarlyMultipCRA<Givaro::Modular<double> > > cra(4UL);
		MyRationalModularCharpoly<BlasMatrix<Rationals > , MyMethod> iteration1(A, Met, M);
		MyIntegerModularCharpoly<BlasMatrix<Givaro::ZRing<Integer> >, MyMethod> iteration2(Atilde, Met, Di, M);
		MyModularCharpoly<MyRationalModularCharpoly<BlasMatrix<Rationals > , MyMethod>,
		MyIntegerModularCharpoly<BlasMatrix<Givaro::ZRing<Integer> >, MyMethod> >  iteration(&iteration1,&iteration2);

		RReconstruction<Givaro::ZRing<Integer>, ClassicMaxQRationalReconstruction<Givaro::ZRing<Integer> > > RR;

		std::vector<Integer> PP; // use of integer due to non genericity of cra. PG 2005-08-04
		UserTimer t1,t2;
		t1.clear();
		t2.clear();
		t1.start();
		cra(2,PP,iteration1,genprime);
		t1.stop();
		t2.start();
		cra(2,PP,iteration2,genprime);
		t2.stop();



		if (t1.time() < t2.time()) {
			//cout << "ratim";
			iteration.setSwitcher(1);
		}
		else {
			//cout << "intim";
			iteration.setSwitcher(2);
		}

		int k=4;
		while (! cra(k,PP, iteration, genprime)) {
			k *=2;
			Integer m; //Integer r; Integer a,b;
			cra.getModulus(m);
			cra.result(PP);//need to divide
			for (int i=0; i < (int)PP.size(); ++i) {
				Integer D_1;
				inv(D_1,M[(size_t)i],m);
				PP[(size_t)i] = (PP[(size_t)i]*D_1) % m;
			}
			Integer den,den1;
			std::vector<Integer> num(A.rowdim()+1);
			std::vector<Integer> num1(A.rowdim()+1);
			if (RR.reconstructRational(num,den,PP,m,-1)) {//performs reconstruction strating form c[m], use c[(size_t)i] as prec for c[(size_t)i-1]
				cra(1,PP,iteration,genprime);
				cra.getModulus(m);
				for (int i=0; i < (int)PP.size(); ++i) {
					Integer D_1;
					inv(D_1,M[(size_t)i],m);
					PP[(size_t)i] = (PP[(size_t)i]*D_1) % m;
				}
				if (RR.reconstructRational(num1,den1,PP,m,-1)) {
					bool terminated = true;
					if (den==den1) {
						for (int i=0; i < (int)num.size(); ++i) {
							if (num[(size_t)i] != num1[(size_t)i]) {
								terminated =false;
								break;
							}
						}
					}
					else {
						terminated = false;
					}
					//set p
					if (terminated) {
						size_t i =0;
						integer t,tt,ttt;
						integer err;
						// size_t max_err = 0;
						Quotient qerr;
						p.resize(PP.size());
						typename Vector <typename Rationals::Element>::iterator it;
						Rationals Q;
						for (it= p.begin(); it != p.end(); ++it, ++i) {
							A.field().init(*it, num[(size_t)i],den);
							Q.get_den(t,*it);
							if (it != p.begin()) Q.get_den(tt,*(it-1));
							else tt = 1;
							Q.init(qerr,t,tt);

						}
						return p;
						// break;
					}
				}
			}
		}

		cra.result(PP);

		size_t i =0;
		integer t,tt;
		integer err;
		// size_t max_res=0;int max_i;
		// double rel;
		// size_t max_resu=0; int max_iu;
		// size_t max_err = 0;
		Quotient qerr;
		p.resize(PP.size());

		typename Vector <typename Rationals::Element>::iterator it;

		Rationals Q;
		for (it= p.begin(); it != p.end(); ++it, ++i) {
			A.field().init(*it, PP[(size_t)i],M[(size_t)i]);
			Q.get_den(t, *it);
			Q.get_num(tt,*it);
			err = M[(size_t)i]/t;
			// size_t resi = err.bitsize() + tt.bitsize() -1;
			// size_t resu = t.bitsize() + tt.bitsize() -1;
			// if (resi > max_res) {max_res = resi; max_i=i;}
			// if (resu > max_resu) {max_resu = resu; max_iu =i;}
			//size_t resu = t.bitsize() + tt.bitsize() -1;
			//if (err.bitsize() > max_err) max_err = err.bitsize();
		}

		// max_res=0;
		for (it= p.begin()+1; it != p.end(); ++it) {
			//A.field().init(*it, PP[(size_t)i],M[(size_t)i]);
			Q.get_den(t, *it);
			Q.get_den(tt, *(it-1));
			Q.init(qerr,t,tt);
			Q.get_num(tt, *it);
			// size_t resi = Q.bitsize(t,qerr) + tt.bitsize() -2;
			// if (resi > max_res) {max_res = resi; max_i=i;}
			//if (err.bitsize() > max_err) max_err = err.bitsize();
		}

		commentator().stop ("done", NULL, "Iminpoly");

		return p;

	}

}

#endif //__LINBOX_charpoly_rational_H

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