#ifndef STORM_SOLVER_NATIVELINEAREQUATIONSOLVER_H_
#define STORM_SOLVER_NATIVELINEAREQUATIONSOLVER_H_

#include <ostream>

#include "storm/solver/LinearEquationSolver.h"

#include "storm/solver/SolverSelectionOptions.h"
#include "storm/solver/NativeMultiplier.h"
#include "storm/solver/SolverStatus.h"
#include "storm/solver/helper/SoundValueIterationHelper.h"

#include "storm/utility/NumberTraits.h"

namespace storm {
    
    class Environment;
    
    namespace solver {
        
        /*!
         * A class that uses storm's native matrix operations to implement the LinearEquationSolver interface.
         */
        template<typename ValueType>
        class NativeLinearEquationSolver : public LinearEquationSolver<ValueType> {
        public:
            NativeLinearEquationSolver();
            NativeLinearEquationSolver(storm::storage::SparseMatrix<ValueType> const& A);
            NativeLinearEquationSolver(storm::storage::SparseMatrix<ValueType>&& A);
            
            virtual void setMatrix(storm::storage::SparseMatrix<ValueType> const& A) override;
            virtual void setMatrix(storm::storage::SparseMatrix<ValueType>&& A) override;
            
            virtual LinearEquationSolverProblemFormat getEquationProblemFormat(storm::Environment const& env) const override;
            virtual LinearEquationSolverRequirements getRequirements(Environment const& env) const override;

            virtual void clearCache() const override;

        protected:
            virtual bool internalSolveEquations(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const override;
            
        private:
            struct PowerIterationResult {
                PowerIterationResult(uint64_t iterations, SolverStatus status) : iterations(iterations), status(status) {
                    // Intentionally left empty.
                }
                
                uint64_t iterations;
                SolverStatus status;
            };
            
            template <typename ValueTypePrime>
            friend class NativeLinearEquationSolver;
            
            PowerIterationResult performPowerIteration(Environment const& env, std::vector<ValueType>*& currentX, std::vector<ValueType>*& newX, std::vector<ValueType> const& b, ValueType const& precision, bool relative, SolverGuarantee const& guarantee, uint64_t currentIterations, uint64_t maxIterations, storm::solver::MultiplicationStyle const& multiplicationStyle) const;
            
            void logIterations(bool converged, bool terminate, uint64_t iterations) const;
            
            virtual uint64_t getMatrixRowCount() const override;
            virtual uint64_t getMatrixColumnCount() const override;

            NativeLinearEquationSolverMethod getMethod(Environment const& env, bool isExactMode) const;

            virtual bool solveEquationsSOR(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b, ValueType const& omega) const;
            virtual bool solveEquationsJacobi(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            virtual bool solveEquationsWalkerChae(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            virtual bool solveEquationsPower(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            virtual bool solveEquationsSoundValueIteration(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            virtual bool solveEquationsOptimisticValueIteration(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            virtual bool solveEquationsIntervalIteration(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            virtual bool solveEquationsRationalSearch(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;

            template<typename RationalType, typename ImpreciseType>
            bool solveEquationsRationalSearchHelper(storm::Environment const& env, NativeLinearEquationSolver<ImpreciseType> const& impreciseSolver, storm::storage::SparseMatrix<RationalType> const& rationalA, std::vector<RationalType>& rationalX, std::vector<RationalType> const& rationalB, storm::storage::SparseMatrix<ImpreciseType> const& A, std::vector<ImpreciseType>& x, std::vector<ImpreciseType> const& b, std::vector<ImpreciseType>& tmpX) const;
            template<typename ImpreciseType>
            typename std::enable_if<std::is_same<ValueType, ImpreciseType>::value && !NumberTraits<ValueType>::IsExact, bool>::type solveEquationsRationalSearchHelper(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            template<typename ImpreciseType>
            typename std::enable_if<std::is_same<ValueType, ImpreciseType>::value && NumberTraits<ValueType>::IsExact, bool>::type solveEquationsRationalSearchHelper(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            template<typename ImpreciseType>
            typename std::enable_if<!std::is_same<ValueType, ImpreciseType>::value, bool>::type solveEquationsRationalSearchHelper(storm::Environment const& env, std::vector<ValueType>& x, std::vector<ValueType> const& b) const;
            template<typename RationalType, typename ImpreciseType>
            static bool sharpen(uint64_t precision, storm::storage::SparseMatrix<RationalType> const& A, std::vector<ImpreciseType> const& x, std::vector<RationalType> const& b, std::vector<RationalType>& tmp);
            static bool isSolution(storm::storage::SparseMatrix<ValueType> const& matrix, std::vector<ValueType> const& values, std::vector<ValueType> const& b);
            
            // If the solver takes posession of the matrix, we store the moved matrix in this member, so it gets deleted
            // when the solver is destructed.
            std::unique_ptr<storm::storage::SparseMatrix<ValueType>> localA;
            
            // A pointer to the original sparse matrix given to this solver. If the solver takes posession of the matrix
            // the pointer refers to localA.
            storm::storage::SparseMatrix<ValueType> const* A;
            
            // An object to dispatch all multiplication operations.
            mutable std::unique_ptr<Multiplier<ValueType>> multiplier;

            // cached auxiliary data
            mutable std::unique_ptr<std::vector<ValueType>> cachedRowVector2; // A.getRowCount() rows
            mutable std::unique_ptr<storm::solver::helper::SoundValueIterationHelper<ValueType>> soundValueIterationHelper;
            
            struct JacobiDecomposition {
                JacobiDecomposition(Environment const& env, storm::storage::SparseMatrix<ValueType> const& A);
                
                storm::storage::SparseMatrix<ValueType> LUMatrix;
                std::vector<ValueType> DVector;
                std::unique_ptr<storm::solver::Multiplier<ValueType>> multiplier;
            };
            mutable std::unique_ptr<JacobiDecomposition> jacobiDecomposition;
            
            struct WalkerChaeData {
                WalkerChaeData(Environment const& env, storm::storage::SparseMatrix<ValueType> const& originalMatrix, std::vector<ValueType> const& originalB);
                
                void computeWalkerChaeMatrix(storm::storage::SparseMatrix<ValueType> const& originalMatrix);
                void computeNewB(std::vector<ValueType> const& originalB);
                void precomputeAuxiliaryData();
                
                storm::storage::SparseMatrix<ValueType> matrix;
                std::vector<ValueType> b;
                ValueType t;
                std::unique_ptr<storm::solver::Multiplier<ValueType>> multiplier;

                // Auxiliary data.
                std::vector<ValueType> columnSums;
                std::vector<ValueType> newX;
            };
            mutable std::unique_ptr<WalkerChaeData> walkerChaeData;
        };
        
        template<typename ValueType>
        class NativeLinearEquationSolverFactory : public LinearEquationSolverFactory<ValueType> {
        public:
            using LinearEquationSolverFactory<ValueType>::create;
            
            virtual std::unique_ptr<storm::solver::LinearEquationSolver<ValueType>> create(Environment const& env) const override;
            
            virtual std::unique_ptr<LinearEquationSolverFactory<ValueType>> clone() const override;

        };
    }
}

#endif /* STORM_SOLVER_NATIVELINEAREQUATIONSOLVER_H_ */