#ifndef STORM_STORAGE_DD_SYLVAN_SYLVANADDITERATOR_H_
#define STORM_STORAGE_DD_SYLVAN_SYLVANADDITERATOR_H_

#include <unordered_map>

#include "storm/storage/dd/AddIterator.h"
#include "storm/storage/expressions/SimpleValuation.h"

#include "storm/adapters/sylvan.h"

namespace storm {
    namespace dd {
        // Forward-declare the DdManager class.
        template<DdType Type>
        class DdManager;
        
        template<DdType Type, typename ValueType>
        class InternalAdd;
        
        template<typename ValueType>
        class AddIterator<DdType::Sylvan, ValueType> {
        public:
            friend class InternalAdd<DdType::Sylvan, ValueType>;
            
            // Default-instantiate the constructor.
            AddIterator();
            
            // Forbid copy-construction and copy assignment, because ownership of the internal pointer is unclear then.
            AddIterator(AddIterator<DdType::Sylvan, ValueType> const& other) = delete;
            AddIterator& operator=(AddIterator<DdType::Sylvan, ValueType> const& other) = delete;
            
            // Provide move-construction and move-assignment, though.
            AddIterator(AddIterator<DdType::Sylvan, ValueType>&& other) = default;
            AddIterator& operator=(AddIterator<DdType::Sylvan, ValueType>&& other) = default;
            
            /*!
             * Moves the iterator one position forward.
             */
            AddIterator<DdType::Sylvan, ValueType>& operator++();
            
            /*!
             * Returns a pair consisting of a valuation of meta variables and the value to which this valuation is
             * mapped. Note that the result is returned by value.
             *
             * @return A pair of a valuation and the function value.
             */
            std::pair<storm::expressions::SimpleValuation, ValueType> operator*() const;
            
            /*!
             * Compares the iterator with the given one. Two iterators are considered equal when all their underlying
             * data members are the same or they both are at their end.
             *
             * @param other The iterator with which to compare.
             * @return True if the two iterators are considered equal.
             */
            bool operator==(AddIterator<DdType::Sylvan, ValueType> const& other) const;
            
            /*!
             * Compares the iterator with the given one. Two iterators are considered unequal iff they are not
             * considered equal.
             *
             * @param other The iterator with which to compare.
             * @return True if the two iterators are considered unequal.
             */
            bool operator!=(AddIterator<DdType::Sylvan, ValueType> const& other) const;
            
        private:
            /*!
             * Constructs a forward iterator using the given generator with the given set of relevant meta variables.
             *
             * @param ddManager The manager responsible for the DD over which to iterate.
             * @param mtbdd The MTBDD over which to iterate.
             * @param variables The variables contained in the MTBDD, represented as a cube.
             * @param numberOfDdVariables The number of DD variables contained in this MTBDD.
             * @param isAtEnd A flag that indicates whether the iterator is at its end and may not be moved forward any
             * more.
             * @param metaVariables The meta variables that appear in the DD.
             * @param enumerateDontCareMetaVariables If set to true, all meta variable assignments are enumerated, even
             * if a meta variable does not at all influence the the function value.
             */
            AddIterator(DdManager<DdType::Sylvan> const& ddManager, sylvan::Mtbdd mtbdd, sylvan::Bdd variables, uint_fast64_t numberOfDdVariables, bool isAtEnd, std::set<storm::expressions::Variable> const* metaVariables, bool enumerateDontCareMetaVariables);
            
            /*!
             * Creates an iterator to the function argument-value-pairs of the given MTBDD.
             *
             * @param ddManager The manager responsible for the DD over which to iterate.
             * @param mtbdd The MTBDD over which to iterate.
             * @param variables The variables contained in the MTBDD, represented as a cube.
             * @param numberOfDdVariables The number of DD variables contained in this MTBDD.
             * @param metaVariables The meta variables that appear in the DD.
             * @param enumerateDontCareMetaVariables If set to true, all meta variable assignments are enumerated, even
             * if a meta variable does not at all influence the the function value.
             */
            static AddIterator createBeginIterator(DdManager<DdType::Sylvan> const& ddManager, sylvan::Mtbdd mtbdd, sylvan::Bdd variables, uint_fast64_t numberOfDdVariables, std::set<storm::expressions::Variable> const* metaVariables, bool enumerateDontCareMetaVariables = true);
            
            /*!
             * Creates an iterator that can be used to determine the end of the iteration process.
             *
             * @param ddManager The manager responsible for the DD over which to iterate.
             */
            static AddIterator createEndIterator(DdManager<DdType::Sylvan> const& ddManager);
            
            /*!
             * Recreates the internal information when a new cube needs to be treated.
             */
            void treatNewCube();
            
            /*!
             * Updates the internal information when the next solution of the current cube needs to be treated.
             */
            void treatNextInCube();
            
            /*!
             * Creates the mapping of global variable indices to local ones.
             */
            void createGlobalToLocalIndexMapping();
            
            // The manager responsible for the meta variables (and therefore the underlying DD).
            DdManager<DdType::Sylvan> const* ddManager;

            // The MTBDD over which to iterate.
            sylvan::Mtbdd mtbdd;
            
            // The cube of variables in the MTBDD.
            sylvan::Bdd variables;
            
            // The currently considered cube of the DD.
            std::vector<uint8_t> cube;
            
            // The function value of the current cube, represented by the corresponding leaf.
            MTBDD leaf;
            
            // A flag that indicates whether the iterator is at its end and may not be moved further. This is also used
            // for the check against the end iterator.
            bool isAtEnd;
            
            // The set of meta variables appearing in the DD.
            std::set<storm::expressions::Variable> const* metaVariables;
            
            // A mapping from global variable indices to local (i.e. appearing the MTBDD) ones.
            std::unordered_map<uint_fast64_t, uint_fast64_t> globalToLocalIndexMap;
            
            // A flag that indicates whether the iterator is supposed to enumerate meta variable valuations even if
            // they don't influence the function value.
            bool enumerateDontCareMetaVariables;
            
            // A number that represents how many assignments of the current cube have already been returned previously.
            // This is needed, because cubes may represent many assignments (if they have don't care variables).
            uint_fast64_t cubeCounter;
            
            // A vector of tuples of the form <metaVariable, bitIndex>.
            std::vector<std::tuple<storm::expressions::Variable, uint_fast64_t>> relevantDontCareDdVariables;
            
            // The current valuation of meta variables.
            storm::expressions::SimpleValuation currentValuation;
            
        };
    }
}

#endif /* STORM_STORAGE_DD_SYLVAN_SYLVANADDITERATOR_H_ */