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#pragma once

#include "rocalution_bench_solver_results.hpp"
#include <chrono>

//
// @brief Simple struct to hold the definition of a linear system.
//
template <typename T>
struct rocalution_linear_system
{
    LocalMatrix<T> A{};
    LocalVector<T> B{};
    LocalVector<T> X{};
    LocalVector<T> S{};
};

//
// @brief Base struct for rocalution_bench.
// @details This structure is a base structure that contains the linear system to solve.
template <typename T>
struct rocalution_bench_itsolver
{
public:
    using results_t = rocalution_bench_solver_results;

private:
    rocalution_linear_system<T> m_linsys;

protected:
    static constexpr bool s_verbose = false;

    //
    // @brief Import the linear system Ax=b
    // @param[out]
    // A           matrix to import.
    // @param[out]
    // B           right-hand-side to import.
    // @param[out]
    // S           solution to import.
    // @return true if successful, false otherwise.
    //
    virtual bool ImportLinearSystem(LocalMatrix<T>& A, LocalVector<T>& B, LocalVector<T>& S) = 0;

    //
    // @brief Presolve the linear system.
    // @note This should only be call once.
    //
    virtual bool AnalyzeLinearSystem(LocalMatrix<T>& A, LocalVector<T>& B, LocalVector<T>& X) = 0;

    //
    // @brief Solve the linear system.
    //
    virtual bool SolveLinearSystem(LocalMatrix<T>& A,
                                   LocalVector<T>& B,
                                   LocalVector<T>& X,
                                   results_t&      results)
        = 0;

    //
    // @brief Log bench results.
    //
    virtual bool LogBenchResults(LocalMatrix<T>& A,
                                 LocalVector<T>& B,
                                 LocalVector<T>& X,
                                 LocalVector<T>& S,
                                 results_t&      results)
        = 0;

    //
    // Compute error approximation.
    //
    bool ComputeErrorApproximation(const LocalVector<T>& X,
                                   const LocalVector<T>& S,
                                   LocalVector<T>&       E,
                                   results_t&            results)
    {

        const auto N = X.GetSize();
        E.CopyFrom(X, 0, 0, N);
        E.ScaleAdd(-1.0, S);

        const T nrm2 = E.Norm();
        results.Set(results_t::norm_residual, nrm2);
        //
        // Compute some statistics about the error distribution.
        //
        {
            E.MoveToHost();
            T* v = new T[N];
            for(auto i = 0; i < N; ++i)
            {
                v[i] = T(std::abs(E[i]));
            }
            std::sort(v, v + N);
            results.Set(results_t::nrmmax_err, v[N - 1]);
            results.Set(results_t::nrmmax95_err, v[((N - 1) * 95) / 100]);
            results.Set(results_t::nrmmax75_err, v[((N - 1) * 75) / 100]);
            results.Set(results_t::nrmmax50_err, v[((N - 1) * 50) / 100]);
            delete[] v;
            E.MoveToAccelerator();
        }

        return true;
    };

public:
    virtual ~rocalution_bench_itsolver(){};

    bool Run(results_t& results)
    {

#define TIC(var_) double var_ = rocalution_time()
#define TAC(var_) var_ = ((rocalution_time() - var_) / 1e3)

        TIC(t_run);

        //
        // Import the linear system.
        //
        if(s_verbose)
        {
            std::cout << "Import linear system ..." << std::endl;
        }
        TIC(t_import_linear_system);
        {
            bool success
                = this->ImportLinearSystem(this->m_linsys.A, this->m_linsys.B, this->m_linsys.S);
            if(!success)
            {
                rocalution_bench_errmsg << "ImportLinearSystem failed." << std::endl;
                return false;
            }
        }
        TAC(t_import_linear_system);
        if(s_verbose)
        {
            std::cout << "Import linear system done." << std::endl;
        }

        //
        // Create unknown vector.
        //
        this->m_linsys.X.MoveToAccelerator();
        this->m_linsys.X.Allocate("x", this->m_linsys.A.GetN());
        this->m_linsys.X.Zeros();

        //
        // Analyze the linear system.
        //
        if(s_verbose)
        {
            std::cout << "Analyze linear system ..." << std::endl;
        }
        TIC(t_analyze_linear_system);
        {
            bool success
                = this->AnalyzeLinearSystem(this->m_linsys.A, this->m_linsys.B, this->m_linsys.X);
            if(!success)
            {
                rocalution_bench_errmsg << "AnalyzeLinearSystem  failed." << std::endl;
                return false;
            }
        }
        TAC(t_analyze_linear_system);

        if(s_verbose)
        {
            std::cout << "Analyze linear system done." << std::endl;
        }
        //
        // Solve the linear system.
        //
        if(s_verbose)
        {
            std::cout << "Solve linear system ..." << std::endl;
        }
        TIC(t_solve_linear_system);
        {
            bool success = this->SolveLinearSystem(
                this->m_linsys.A, this->m_linsys.B, this->m_linsys.X, results);
            if(!success)
            {
                rocalution_bench_errmsg << "SolveLinearSystem  failed." << std::endl;
                return false;
            }
        }
        TAC(t_solve_linear_system);
        if(s_verbose)
        {
            std::cout << "Solve linear system done." << std::endl;
        }

        //
        // Compute Error Approximation.
        //
        if(s_verbose)
        {
            std::cout << "Compute error approximation ..." << std::endl;
        }

        {
            LocalVector<T> E;
            E.MoveToAccelerator();
            E.Allocate("e", this->m_linsys.X.GetSize());

            bool success
                = this->ComputeErrorApproximation(this->m_linsys.X, this->m_linsys.S, E, results);
            if(!success)
            {
                rocalution_bench_errmsg << "ComputeErrorApproximation failed." << std::endl;
                return false;
            }
        }

        if(s_verbose)
        {
            std::cout << "Compute error approximation done." << std::endl;
        }
        TAC(t_run);

        //
        // LOG RESULTS.
        //
        results.Set(results_t::time_import, t_import_linear_system);
        results.Set(results_t::time_analyze, t_analyze_linear_system);
        results.Set(results_t::time_solve, t_solve_linear_system);
        results.Set(results_t::time_global, t_run);

        {
            bool success = this->LogBenchResults(
                this->m_linsys.A, this->m_linsys.B, this->m_linsys.X, this->m_linsys.S, results);
            if(!success)
            {
                rocalution_bench_errmsg << "LogBenchResults failed." << std::endl;
                return false;
            }
        }

        return true;
    }
};