/* ************************************************************************
 * Copyright (c) 2018 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * ************************************************************************ */

#include "pairwise_amg.hpp"
#include "../../utils/def.hpp"
#include "../../utils/types.hpp"

#include "../../base/local_matrix.hpp"
#include "../../base/local_vector.hpp"

#include "../preconditioners/preconditioner.hpp"

#include "../../utils/allocate_free.hpp"
#include "../../utils/log.hpp"
#include "../../utils/math_functions.hpp"

#include <complex>
#include <list>

namespace rocalution
{

    template <class OperatorType, class VectorType, typename ValueType>
    PairwiseAMG<OperatorType, VectorType, ValueType>::PairwiseAMG()
    {
        log_debug(this, "PairwiseAMG::PairwiseAMG()", "default constructor");

        this->beta_        = static_cast<ValueType>(0.25);
        this->coarse_size_ = 300;

        // target coarsening factor
        this->coarsening_factor_ = 4.0;

        // number of pre- and post-smoothing steps
        this->iter_pre_smooth_  = 2;
        this->iter_post_smooth_ = 2;

        // set K-cycle to default
        this->cycle_ = 2;

        // disable scaling
        this->scaling_ = false;

        // disable ordering by default
        this->aggregation_ordering_ = NoOrdering;
    }

    template <class OperatorType, class VectorType, typename ValueType>
    PairwiseAMG<OperatorType, VectorType, ValueType>::~PairwiseAMG()
    {
        log_debug(this, "PairwiseAMG::PairwiseAMG()", "destructor");

        this->Clear();
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::Print(void) const
    {
        LOG_INFO("AMG solver");
        LOG_INFO("AMG number of levels " << this->levels_);
        LOG_INFO("AMG using pairwise aggregation");
        LOG_INFO("AMG coarsest operator size = " << this->op_level_[this->levels_ - 2]->GetM());
        LOG_INFO("AMG coarsest level nnz = " << this->op_level_[this->levels_ - 2]->GetNnz());
        LOG_INFO("AMG with smoother:");
        this->smoother_level_[0]->Print();
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::PrintStart_(void) const
    {
        assert(this->levels_ > 0);

        LOG_INFO("AMG solver starts");
        LOG_INFO("AMG number of levels " << this->levels_);
        LOG_INFO("AMG using pairwise aggregation");
        LOG_INFO("AMG coarsest operator size = " << this->op_level_[this->levels_ - 2]->GetM());
        LOG_INFO("AMG coarsest level nnz = " << this->op_level_[this->levels_ - 2]->GetNnz());
        LOG_INFO("AMG with smoother:");
        this->smoother_level_[0]->Print();
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::PrintEnd_(void) const
    {
        LOG_INFO("AMG ends");
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::SetBeta(ValueType beta)
    {
        log_debug(this, "PairwiseAMG::SetBeta()", beta);

        assert(beta > static_cast<ValueType>(0));
        assert(beta < static_cast<ValueType>(1));

        this->beta_ = beta;
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::SetCoarseningFactor(double factor)
    {
        log_debug(this, "PairwiseAMG::SetCoarseningFactor()", factor);

        assert(factor > 0.0);
        assert(factor < 20.0);

        this->coarsening_factor_ = factor;
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::SetOrdering(unsigned int ordering)
    {
        log_debug(this, "PairwiseAMG::SetOrdering()", ordering);

        assert(ordering >= 0 && ordering <= 5);

        this->aggregation_ordering_ = ordering;
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::BuildHierarchy(void)
    {
        log_debug(this, "PairwiseAMG::BuildHierarchy()", " #*# begin");

        if(this->hierarchy_ == false)
        {
            assert(this->build_ == false);
            this->hierarchy_ = true;

            // AMG will use operators for inter grid transfers
            assert(this->op_ != NULL);
            assert(this->coarse_size_ > 0);

            if(this->op_->GetM() <= (IndexType2)this->coarse_size_)
            {
                LOG_INFO("Problem size too small for AMG, use Krylov solver instead");
                FATAL_ERROR(__FILE__, __LINE__);
            }

            // Lists for the building procedure
            std::list<OperatorType*>     op_list_;
            std::list<OperatorType*>     restrict_list_;
            std::list<OperatorType*>     prolong_list_;
            std::list<LocalVector<int>*> trans_list_;

            this->levels_ = 1;

            // Build finest hierarchy
            op_list_.push_back(new OperatorType);
            restrict_list_.push_back(new OperatorType);
            prolong_list_.push_back(new OperatorType);
            trans_list_.push_back(new LocalVector<int>);

            op_list_.back()->CloneBackend(*this->op_);
            restrict_list_.back()->CloneBackend(*this->op_);
            prolong_list_.back()->CloneBackend(*this->op_);
            trans_list_.back()->CloneBackend(*this->op_);

            // Create prolongation and restriction operators
            this->Aggregate_(*this->op_,
                             prolong_list_.back(),
                             restrict_list_.back(),
                             op_list_.back(),
                             trans_list_.back());

            ++this->levels_;

            while(op_list_.back()->GetM() > (IndexType2)this->coarse_size_)
            {
                // Add new list elements
                restrict_list_.push_back(new OperatorType);
                prolong_list_.push_back(new OperatorType);
                OperatorType* prev_op_ = op_list_.back();
                op_list_.push_back(new OperatorType);
                trans_list_.push_back(new LocalVector<int>);

                op_list_.back()->CloneBackend(*this->op_);
                restrict_list_.back()->CloneBackend(*this->op_);
                prolong_list_.back()->CloneBackend(*this->op_);
                trans_list_.back()->CloneBackend(*this->op_);

                this->Aggregate_(*prev_op_,
                                 prolong_list_.back(),
                                 restrict_list_.back(),
                                 op_list_.back(),
                                 trans_list_.back());

                ++this->levels_;
            }

            // Allocate data structures
            this->op_level_          = new OperatorType*[this->levels_ - 1];
            this->restrict_op_level_ = new Operator<ValueType>*[this->levels_ - 1];
            this->prolong_op_level_  = new Operator<ValueType>*[this->levels_ - 1];
            this->trans_level_       = new LocalVector<int>*[this->levels_ - 1];

            typename std::list<OperatorType*>::iterator     op_it    = op_list_.begin();
            typename std::list<OperatorType*>::iterator     pro_it   = prolong_list_.begin();
            typename std::list<OperatorType*>::iterator     res_it   = restrict_list_.begin();
            typename std::list<LocalVector<int>*>::iterator trans_it = trans_list_.begin();

            for(int i = 0; i < this->levels_ - 1; ++i)
            {
                this->op_level_[i] = *op_it;
                this->op_level_[i]->Sort();
                ++op_it;

                this->restrict_op_level_[i] = *res_it;
                ++res_it;

                this->prolong_op_level_[i] = *pro_it;
                ++pro_it;

                this->trans_level_[i] = *trans_it;
                ++trans_it;
            }
        }

        log_debug(this, "PairwiseAMG::BuildHierarchy()", " #*# end");
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::BuildSmoothers(void)
    {
        log_debug(this, "PairwiseAMG::BuildSmoothers()", " #*# begin");

        // Smoother for each level
        this->smoother_level_
            = new IterativeLinearSolver<OperatorType, VectorType, ValueType>*[this->levels_ - 1];
        this->sm_default_ = new Solver<OperatorType, VectorType, ValueType>*[this->levels_ - 1];

        for(int i = 0; i < this->levels_ - 1; ++i)
        {
            FixedPoint<OperatorType, VectorType, ValueType>* sm
                = new FixedPoint<OperatorType, VectorType, ValueType>;
            Jacobi<OperatorType, VectorType, ValueType>* jac
                = new Jacobi<OperatorType, VectorType, ValueType>;

            sm->SetRelaxation(static_cast<ValueType>(0.67));
            sm->SetPreconditioner(*jac);
            sm->Verbose(0);
            this->smoother_level_[i] = sm;
            this->sm_default_[i]     = jac;
        }

        log_debug(this, "PairwiseAMG::BuildSmoothers()", " #*# end");
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::ReBuildNumeric(void)
    {
        log_debug(this, "PairwiseAMG::ReBuildNumeric()", " #*# begin");

        assert(this->levels_ > 1);
        assert(this->build_ == true);
        assert(this->op_ != NULL);

        this->op_level_[0]->Clear();
        this->op_level_[0]->CloneBackend(*this->op_);
        this->op_level_[0]->ConvertToCSR();

        this->trans_level_[0]->CloneBackend(*this->op_);

        this->op_->CoarsenOperator(this->op_level_[0],
                                   this->dim_level_[0],
                                   this->dim_level_[0],
                                   *this->trans_level_[0],
                                   this->Gsize_level_[0],
                                   this->rG_level_[0],
                                   this->rGsize_level_[0]);

        for(int i = 1; i < this->levels_ - 1; ++i)
        {
            this->op_level_[i]->Clear();
            this->op_level_[i]->ConvertToCSR();

            this->trans_level_[i]->CloneBackend(*this->op_level_[i]);

            if(i == this->levels_ - this->host_level_ - 1)
            {
                this->op_level_[i - 1]->MoveToHost();
            }

            this->op_level_[i - 1]->CoarsenOperator(this->op_level_[i],
                                                    this->dim_level_[i],
                                                    this->dim_level_[i],
                                                    *this->trans_level_[i],
                                                    this->Gsize_level_[i],
                                                    this->rG_level_[i],
                                                    this->rGsize_level_[i]);

            if(i == this->levels_ - this->host_level_ - 1)
            {
                this->op_level_[i - 1]->CloneBackend(*this->restrict_op_level_[i - 1]);
            }
        }

        this->smoother_level_[0]->ResetOperator(*this->op_);
        this->smoother_level_[0]->ReBuildNumeric();
        this->smoother_level_[0]->Verbose(0);

        for(int i = 1; i < this->levels_ - 1; ++i)
        {
            this->smoother_level_[i]->ResetOperator(*this->op_level_[i - 1]);
            this->smoother_level_[i]->ReBuildNumeric();
            this->smoother_level_[i]->Verbose(0);
        }

        this->solver_coarse_->ResetOperator(*this->op_level_[this->levels_ - 2]);
        this->solver_coarse_->ReBuildNumeric();
        this->solver_coarse_->Verbose(0);

        // Convert operator to op_format
        if(this->op_format_ != CSR)
        {
            for(int i = 0; i < this->levels_ - 1; ++i)
            {
                this->op_level_[i]->ConvertTo(this->op_format_);
            }
        }

        log_debug(this, "PairwiseAMG::ReBuildNumeric()", " #*# end");
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::ClearLocal(void)
    {
        log_debug(this, "PairwiseAMG::ClearLocal()", this->build_);

        if(this->build_ == true)
        {
            for(int i = 0; i < this->levels_ - 1; ++i)
            {
                delete this->trans_level_[i];

                free_host(&this->rG_level_[i]);
            }

            delete[] this->trans_level_;

            this->dim_level_.clear();
            this->Gsize_level_.clear();
            this->rGsize_level_.clear();
            this->rG_level_.clear();
        }
    }

    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::Aggregate_(const OperatorType&  op,
                                                                      Operator<ValueType>* pro,
                                                                      Operator<ValueType>* res,
                                                                      OperatorType*        coarse,
                                                                      LocalVector<int>*    trans)
    {
        log_debug(this, "PairwiseAMG::Aggregate_()", (const void*&)op, pro, res, coarse, trans);

        assert(pro != NULL);
        assert(res != NULL);
        assert(coarse != NULL);

        OperatorType* cast_res = dynamic_cast<OperatorType*>(res);
        OperatorType* cast_pro = dynamic_cast<OperatorType*>(pro);

        assert(cast_res != NULL);
        assert(cast_pro != NULL);

        int  nc;
        int* rG = NULL;
        int  Gsize;
        int  rGsize;

        // Allocate transfer mapping for current level
        trans->Allocate("transfer map", op.GetLocalM());

        op.InitialPairwiseAggregation(
            this->beta_, nc, trans, Gsize, &rG, rGsize, this->aggregation_ordering_);
        op.CoarsenOperator(coarse, nc, nc, *trans, Gsize, rG, rGsize);

        int cycle = 0;

        while(static_cast<double>(op.GetM()) / static_cast<double>(coarse->GetM())
              < this->coarsening_factor_)
        {
            coarse->FurtherPairwiseAggregation(
                this->beta_, nc, trans, Gsize, &rG, rGsize, this->aggregation_ordering_);
            op.CoarsenOperator(coarse, nc, nc, *trans, Gsize, rG, rGsize);

            ++cycle;

            if(cycle > 8)
            {
                LOG_VERBOSE_INFO(2,
                                 "*** warning: PairwiseAMG::Build() Coarsening cannot obtain "
                                 "satisfying coarsening factor");
            }
        }

        cast_res->CreateFromMap(*trans, op.GetLocalM(), nc, cast_pro);

        // Store data for possible coarse operator rebuild
        this->dim_level_.push_back(nc);
        this->Gsize_level_.push_back(Gsize);
        this->rGsize_level_.push_back(rGsize);
        this->rG_level_.push_back(rG);
    }

    // disabled function
    template <class OperatorType, class VectorType, typename ValueType>
    void PairwiseAMG<OperatorType, VectorType, ValueType>::Aggregate_(const OperatorType&  op,
                                                                      Operator<ValueType>* pro,
                                                                      Operator<ValueType>* res,
                                                                      OperatorType*        coarse)
    {
        FATAL_ERROR(__FILE__, __LINE__);
    }

    template class PairwiseAMG<LocalMatrix<double>, LocalVector<double>, double>;
    template class PairwiseAMG<LocalMatrix<float>, LocalVector<float>, float>;
#ifdef SUPPORT_COMPLEX
    template class PairwiseAMG<LocalMatrix<std::complex<double>>,
                               LocalVector<std::complex<double>>,
                               std::complex<double>>;
    template class PairwiseAMG<LocalMatrix<std::complex<float>>,
                               LocalVector<std::complex<float>>,
                               std::complex<float>>;
#endif

} // namespace rocalution