std::string generateCodeForModel(CellmlApiObjects* capi,
                                 std::map<std::string, unsigned char>& variableTypes,
                                 std::map<std::string, std::map<unsigned char, int> >& variableIndices,
                                 int numberOfInputs, int numberOfStates)
{
    std::stringstream code;
    std::string codeString;
    if (! (capi && capi->codeInformation))
    {
        std::cerr << "CellML Model Definition::generateCodeForModel: missing model implementation?" << std::endl;
        return "";
    }
    // We need to regenerate the code information to make use of the flagged variables.
    ObjRef<iface::cellml_services::CodeGeneratorBootstrap> cgb = CreateCodeGeneratorBootstrap();
    ObjRef<iface::cellml_services::CodeGenerator> cg = cgb->createCodeGenerator();
    // catch any exceptions from the CellML API
    try
    {
        // annotate the source variables in the model with the code-names based on existing annotations
        for (unsigned int i=0; i < capi->cevas->length(); i++)
        {
            ObjRef<iface::cellml_services::ConnectedVariableSet> cvs = capi->cevas->getVariableSet(i);
            ObjRef<iface::cellml_api::CellMLVariable> sv = cvs->sourceVariable();
            std::string currentId = getVariableUniqueId(sv);
            std::map<std::string, unsigned char>::iterator typeit(variableTypes.find(currentId));
            if (typeit != variableTypes.end())
            {
                std::wstringstream ename;
                // here we assign an array and index based on the "primary" purpose of the variable. Later
                // we will add in secondary purposes.
                unsigned char vType = typeit->second;
                if (vType & csim::StateType)
                {
                    ename << L"CSIM_STATE[" << variableIndices[currentId][csim::StateType] << L"]";
                }
                else if (vType & csim::IndependentType)
                {
                    // do nothing, but stop input and output annotations
                }
                else if (vType & csim::InputType)
                {
                    ename << L"CSIM_INPUT[" << variableIndices[currentId][csim::InputType] << L"]";
                }
                else if (vType & csim::OutputType)
                {
                    ename << L"CSIM_OUTPUT[" << variableIndices[currentId][csim::OutputType] << L"]";
                }
                capi->annotations->setStringAnnotation(sv, L"expression", ename.str());

                if (vType & csim::StateType)
                {
                    ename.str(L"");
                    ename.clear();
                    ename << L"CSIM_RATE[" << variableIndices[currentId][csim::StateType] << L"]";
                    capi->annotations->setStringAnnotation(sv, L"expression_d1", ename.str());
                }
            }
        }
        cg->useCeVAS(capi->cevas);
        cg->useAnnoSet(capi->annotations);
        ObjRef<iface::cellml_services::CodeInformation> cci = cg->generateCode(capi->model);
        std::wstring m = cci->errorMessage();
        if (m != L"")
        {
            std::cerr << "CellML Model Definition::generateCodeForModel: error generating code?" << std::endl;
            return "";
        }
        iface::cellml_services::ModelConstraintLevel mcl = cci->constraintLevel();
        if (mcl == iface::cellml_services::UNDERCONSTRAINED)
        {
            std::cerr << "Model is underconstrained" << std::endl;
            return "";
        }
        else if (mcl == iface::cellml_services::OVERCONSTRAINED)
        {
            std::cerr << "Model is overconstrained" << std::endl;
            return "";
        }
        else if (mcl == iface::cellml_services::UNSUITABLY_CONSTRAINED)
        {
            std::cerr << "Model is unsuitably constrained" << std::endl;
            return "";
        }
        std::cout << "Model is correctly constrained" << std::endl;
        // create the code in the format we know how to handle
        code << "//#include <math.h>\n"
        /* required functions */
             << "double fabs(double x);\n"
             << "double acos(double x);\n"
             << "double acosh(double x);\n"
             << "double atan(double x);\n"
             << "double atanh(double x);\n"
             << "double asin(double x);\n"
             << "double asinh(double x);\n"
             << "double acos(double x);\n"
             << "double acosh(double x);\n"
             << "double asin(double x);\n"
             << "double asinh(double x);\n"
             << "double atan(double x);\n"
             << "double atanh(double x);\n"
             << "double ceil(double x);\n"
             << "double cos(double x);\n"
             << "double cosh(double x);\n"
             << "double tan(double x);\n"
             << "double tanh(double x);\n"
             << "double sin(double x);\n"
             << "double sinh(double x);\n"
             << "double exp(double x);\n"
             << "double floor(double x);\n"
             << "double pow(double x, double y);\n"
             << "double factorial(double x);\n"
             << "double log(double x);\n"
             << "double arbitrary_log(double x, double base);\n"
             << "double gcd_pair(double a, double b);\n"
             << "double lcm_pair(double a, double b);\n"
             << "double gcd_multi(unsigned int size, ...);\n"
             << "double lcm_multi(unsigned int size, ...);\n"
             << "double multi_min(unsigned int size, ...);\n"
             << "double multi_max(unsigned int size, ...);\n"
             << "void NR_MINIMISE(double(*func)"
                "(double VOI, double *C, double *R, double *S, double *A),"
                "double VOI, double *C, double *R, double *S, double *A, "
                "double *V);\n";
        std::wstring frag = cci->functionsString();
        code << ws2s(frag);

        int nAlgebraic = cci->algebraicIndexCount();
        int nConstants = cci->constantIndexCount();

        code << "\n\nvoid csim_rhs_routine(double VOI, double* CSIM_STATE, double* CSIM_RATE, double* CSIM_OUTPUT, "
             << "double* CSIM_INPUT)\n{\n\n"
             << "double DUMMY_ASSIGNMENT;\n"
             << "double CONSTANTS["
             << nConstants
             << "], ALGEBRAIC["
             << nAlgebraic
             << "];\n\n";

        /* initConsts - all variables which aren't state variables but have
         *              an initial_value attribute, and any variables & rates
         *              which follow.
         */
        code << ws2s(cci->initConstsString());

        /* rates      - All rates which are not static.
         */
        code << ws2s(cci->ratesString());

        /* variables  - All variables not computed by initConsts or rates
         *  (i.e., these are not required for the integration of the model and
         *   thus only need to be called for output or presentation or similar
         *   purposes)
         */
        code << ws2s(cci->variablesString());

        // add in the setting of any outputs that are not already defined
        for (unsigned int i=0; i < capi->cevas->length(); i++)
        {
            ObjRef<iface::cellml_services::ConnectedVariableSet> cvs = capi->cevas->getVariableSet(i);
            ObjRef<iface::cellml_api::CellMLVariable> sv = cvs->sourceVariable();
            std::string currentId = getVariableUniqueId(sv);
            std::map<std::string, unsigned char>::iterator typeit(variableTypes.find(currentId));
            if (typeit != variableTypes.end())
            {
                unsigned char vType = typeit->second;
                if (vType & csim::OutputType)
                {
                    if (vType & csim::StateType)
                        code << "CSIM_OUTPUT[" << variableIndices[currentId][csim::OutputType]
                                << "] = CSIM_STATE[" << variableIndices[currentId][csim::StateType]
                                   << "];\n";
                    else if (vType & csim::InputType)
                        code << "CSIM_OUTPUT[" << variableIndices[currentId][csim::OutputType]
                                << "] = CSIM_INPUT[" << variableIndices[currentId][csim::InputType]
                                   << "];\n";
                    else if (vType & csim::IndependentType)
                        code << "CSIM_OUTPUT[" << variableIndices[currentId][csim::OutputType]
                                << "] = VOI;\n";
                }
            }
        }

        // close the subroutine
        code << "\n\n}//csim_rhs_routine()\n\n";

        // and now clear out initialisation of state variables and known variables from
        // the RHS routine.
        codeString = clearCodeAssignments(code.str(), "CSIM_STATE", numberOfStates);
        codeString = clearCodeAssignments(codeString, "CSIM_INPUT", numberOfInputs);

        // and finally create the initialisation routine
        std::stringstream initRoutine;
        initRoutine << "\nvoid csim_initialise_routine(double* CSIM_STATE, double* CSIM_OUTPUT, double* CSIM_INPUT)\n{\n";
        // FIXME: this doesn't need to be in the interface?
        initRoutine << "double CSIM_RATES[" << numberOfStates << "];\n";
        initRoutine << "double CONSTANTS[" << nConstants << "];\n";
        initRoutine << ws2s(cci->initConstsString());
        initRoutine << "\n}\n";

        codeString += initRoutine.str();
    }
    catch (...)
    {
        std::cerr << "CellML Model Definition::generateCodeForModel: something went wrong generating code?" << std::endl;
        return "";
    }
    return codeString;
}
int CellmlModelDefinition::instantiateCellmlApiObjects()
{
    try
    {
        // create an annotation set to manage our variable usages
        ObjRef<iface::cellml_services::AnnotationToolService> ats = CreateAnnotationToolService();
        ObjRef<iface::cellml_services::AnnotationSet> as = ats->createAnnotationSet();
        mCapi->annotations = as;
        // mapping the connections between variables is a very expensive operation, so we want to
        // only do it once and keep hold of the mapping (tracker item 3294)
        ObjRef<iface::cellml_services::CeVASBootstrap> cvbs = CreateCeVASBootstrap();
        ObjRef<iface::cellml_services::CeVAS> cevas = cvbs->createCeVASForModel(mCapi->model);
        std::wstring msg = cevas->modelError();
        if (msg != L"")
        {
            std::cerr << "loadModel: Error creating CellML Variable Association Service: "
                      << ws2s(msg) << std::endl;
            return -2;
        }
        mCapi->cevas = cevas;
        // now check we can generate code and grab hold of the initial code information
        ObjRef<iface::cellml_services::CodeGeneratorBootstrap> cgb = CreateCodeGeneratorBootstrap();
        ObjRef<iface::cellml_services::CodeGenerator> cg = cgb->createCodeGenerator();
        try
        {
            cg->useCeVAS(cevas);
            ObjRef<iface::cellml_services::CodeInformation> cci = cg->generateCode(mCapi->model);
            msg = cci->errorMessage();
            if (msg != L"")
            {
                std::cerr << "CellmlModelDefintion::loadModel: Error generating code: "
                          << ws2s(msg) << std::endl;
                return -4;
            }
            // TODO: we are only interested in models we can work with?
            if (cci->constraintLevel() != iface::cellml_services::CORRECTLY_CONSTRAINED)
            {
                std::cerr << "CellmlModelDefintion::loadModel: Model is not correctly constrained: "
                          << std::endl;
                return -5;
            }
            mCapi->codeInformation = cci;
            // always flag all state variables and the variable of integration
            ObjRef<iface::cellml_services::ComputationTargetIterator> cti = cci->iterateTargets();
            while (true)
            {
                ObjRef<iface::cellml_services::ComputationTarget> ct = cti->nextComputationTarget();
                if (ct == NULL) break;
                if (ct->degree() > 0) break; // only want to initialise the base variables not the differential
                ObjRef<iface::cellml_api::CellMLVariable> v(ct->variable());
                if (ct->type() == iface::cellml_services::STATE_VARIABLE)
                {
                    mVariableTypes[getVariableUniqueId(v)] = csim::StateType;
                    mVariableIndices[getVariableUniqueId(v)][csim::StateType] = mStateCounter;
                    mStateCounter++;
                }
                else if (ct->type() == iface::cellml_services::VARIABLE_OF_INTEGRATION)
                {
                    mVariableTypes[getVariableUniqueId(v)] = csim::IndependentType;
                    mNumberOfIndependentVariables++;
                }
                else
                {
                    // need to initialise the variable type
                    mVariableTypes[getVariableUniqueId(v)] = csim::UndefinedType;
                }
            }
        }
        catch (...)
        {
            std::cerr << "loadModel: Error generating the code information for the model" << std::endl;
            return -3;
        }
        // if we get to here, everything worked.
        mModelLoaded = true;
    }
    catch (...)
    {
      std::wcerr << L"Error instantiating CellML API objects." << std::endl;
      return -1;
    }
    return csim::CSIM_OK;
}