///////////////////////////////////////////////////////////////////////////////
//
// File: Module.cpp
//
// For more information, please see: http://www.nektar.info
//
// The MIT License
//
// Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
// Department of Aeronautics, Imperial College London (UK), and Scientific
// Computing and Imaging Institute, University of Utah (USA).
//
// 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.
//
// Description: Python wrapper for Module.
//
///////////////////////////////////////////////////////////////////////////////

#include <FieldUtils/Module.h>
#include <LibUtilities/Python/NekPyConfig.hpp>
#include <boost/python/raw_function.hpp>
#include <boost/program_options.hpp>

using namespace Nektar;
using namespace Nektar::FieldUtils;

/**
 * @brief Module wrapper to handle virtual function calls in @c Module and its
 * subclasses as defined by the template parameter @tparam MODTYPE.
 */
template <class MODTYPE>
struct ModuleWrap : public MODTYPE, public py::wrapper<MODTYPE>
{
    /**
     * @brief Constructor, which is identical to FieldUtils::Module.
     *
     * @param field  Input field.
     */
    ModuleWrap(FieldSharedPtr field) : MODTYPE(field), py::wrapper<MODTYPE>()
    {
    }

    /**
     * @brief Concrete implementation of the Module::Process function.
     */
    void Process(po::variables_map &vm) override
    {
        this->get_override("Process")();
    }

    std::string GetModuleName() override
    {
        py::override f = this->get_override("GetModuleName");
        return py::call<std::string>(f.ptr());
    }

    ModulePriority GetModulePriority() override
    {
        py::override f = this->get_override("GetModulePriority");
        return py::call<ModulePriority>(f.ptr());
    }

    /**
     * @brief Defines a configuration option for this module.
     *
     * @param key     The name of the configuration option.
     * @param def     The option's default value.
     * @param desc    A text description of the option.
     * @param isBool  If true, this option is a boolean-type (true/false).
     */
    void AddConfigOption(std::string key, std::string def, std::string desc,
                         bool isBool)
    {
        ConfigOption conf(isBool, def, desc);
        this->m_config[key] = conf;
    }

    // We expose Module::m_f as a public member variable so that we can
    // adjust this using Python attributes.
    using MODTYPE::m_f;
};

// Wrapper around Module::Process(&vm).
// Performs switching of m_comm if nparts > 1.
void Module_Process(ModuleSharedPtr m)
{
    if (m->m_f->m_nParts > 1)
    {
        if (m->GetModulePriority() == eOutput)
        {
            m->m_f->m_comm = m->m_f->m_partComm;
            if (m->GetModuleName() != "OutputInfo")
            {
                m->RegisterConfig("writemultiplefiles");
            }
        }
        else if (m->GetModulePriority() == eCreateGraph)
        {
            m->m_f->m_comm = m->m_f->m_partComm;
        }
        else
        {
            m->m_f->m_comm = m->m_f->m_defComm;
        }
    }
    m->SetDefaults();
    m->Process(m->m_f->m_vm);
}

template <typename T>
T Module_GetConfig(std::shared_ptr<Module> mod, const std::string &key)
{
    return mod->GetConfigOption(key).as<T>();
}

template <typename MODTYPE> struct ModuleTypeProxy
{
};

template <> struct ModuleTypeProxy<InputModule>
{
    static const ModuleType value = eInputModule;
};

template <> struct ModuleTypeProxy<ProcessModule>
{
    static const ModuleType value = eProcessModule;
};

template <> struct ModuleTypeProxy<OutputModule>
{
    static const ModuleType value = eOutputModule;
};

const ModuleType ModuleTypeProxy<InputModule>::value;
const ModuleType ModuleTypeProxy<ProcessModule>::value;
const ModuleType ModuleTypeProxy<OutputModule>::value;

/**
 * @brief Lightweight wrapper for Module factory creation function.
 *
 * @param  modType  Module type (input/process/output).
 * @param  modName  Module name (typically filename extension).
 * @param  field    Field that will be passed between modules.
 * @tparam MODTYPE  Subclass of Module (e.g #InputModule, #OutputModule)
 */
template <typename MODTYPE>
ModuleSharedPtr Module_Create(py::tuple args, py::dict kwargs)
{
    ModuleType modType = ModuleTypeProxy<MODTYPE>::value;

    using NekError = ErrorUtil::NekError;

    if (modType == eProcessModule && py::len(args) != 2)
    {
        throw NekError("ProcessModule.Create() requires two arguments: "
                       "module name and a Field object.");
    }
    else if (modType != eProcessModule && py::len(args) < 2)
    {
        throw NekError(ModuleTypeMap[modType] + "Module.Create() requires "
                       "two arguments: module name and a Field object; "
                       "optionally a filename.");
    }

    std::string modName = py::extract<std::string>(args[0]);
    ModuleKey modKey = std::make_pair(modType, modName);

    if (!py::extract<FieldSharedPtr>(args[1]).check())
    {
        throw NekError("Second argument to Create() should be a Field object.");
    }

    FieldSharedPtr field = py::extract<FieldSharedPtr>(args[1]);
    ModuleSharedPtr mod  = GetModuleFactory().CreateInstance(modKey, field);

    if (modType == eInputModule)
    {
        // For input modules we can try to interpret the remaining arguments as
        // input files. Assume that the file's type is identical to the module
        // name.
        for (int i = 2; i < py::len(args); ++i)
        {
            std::string in_fname = py::extract<std::string>(args[i]);
            mod->RegisterConfig("infile", in_fname);
            mod->AddFile(modName, in_fname);
        }
    }
    else if (modType == eOutputModule && py::len(args) >= 3)
    {
        // For output modules we can try to interpret the remaining argument as
        // an output file.
        mod->RegisterConfig("outfile", py::extract<std::string>(args[2]));
    }

    // Process keyword arguments.
    py::list items = kwargs.items();

    for (int i = 0; i < py::len(items); ++i)
    {
        std::string arg = py::extract<std::string>(items[i][0]);

        if (arg == "infile" && modKey.first == eInputModule)
        {
            py::extract<py::dict> dict_check(items[i][1]);

            if (!dict_check.check())
            {
                throw NekError("infile should be a dictionary.");
            }

            py::dict ftype_fname_dict = py::extract<py::dict>(items[i][1]);
            py::list ft_fn_items      = ftype_fname_dict.items();
            for (int i = 0; i < py::len(ft_fn_items); ++i)
            {
                std::string f_type =
                    py::extract<std::string>(ft_fn_items[i][0]);
                std::string f_name = py::extract<std::string>(
                    ft_fn_items[i][1].attr("__str__")());
                mod->RegisterConfig(arg, f_name);
                mod->AddFile(f_type, f_name);
            }
        }
        else
        {
            std::string val =
                py::extract<std::string>(items[i][1].attr("__str__")());
            mod->RegisterConfig(arg, val);
        }
    }

    mod->SetDefaults();

    return mod;
}

/**
 * @brief Lightweight wrapper for FieldUtils::Module::RegisterConfig.
 *
 * @param mod    Module to call
 * @param key    Configuration key.
 * @param value  Optional value (some configuration options are boolean).
 */
void Module_RegisterConfig(std::shared_ptr<Module> mod, std::string const &key,
                           std::string const &value)
{
    mod->RegisterConfig(key, value);
}

template <typename MODTYPE>
void ModuleWrap_AddConfigOption(std::shared_ptr<ModuleWrap<MODTYPE>> mod,
                                std::string const &key,
                                std::string const &defValue,
                                std::string const &desc, bool isBool)
{
    mod->AddConfigOption(key, defValue, desc, isBool);
}

class ModuleRegisterHelper
{
public:
    ModuleRegisterHelper(py::object obj) : m_obj(obj)
    {
        py::incref(obj.ptr());
    }

    ~ModuleRegisterHelper()
    {
        py::decref(m_obj.ptr());
    }

    ModuleSharedPtr create(FieldSharedPtr field)
    {
        py::object inst = m_obj(field);
        return py::extract<ModuleSharedPtr>(inst);
    }

protected:
    py::object m_obj;
};

#if PY_MAJOR_VERSION == 2
void ModuleCapsuleDestructor(void *ptr)
{
    ModuleRegisterHelper *tmp = (ModuleRegisterHelper *)ptr;
    delete tmp;
}
#else
void ModuleCapsuleDestructor(PyObject *ptr)
{
    ModuleRegisterHelper *tmp =
        (ModuleRegisterHelper *)PyCapsule_GetPointer(ptr, 0);
    delete tmp;
}
#endif

/**
 * @brief Lightweight wrapper for the Module factory RegisterCreatorFunction, to
 * support the ability for Python subclasses of Module to register themselves
 * with the Nektar++ Module factory.
 *
 * This function wraps the NekFactory RegisterCreatorFunction. This function
 * expects a function pointer to a C++ object that will construct a Module. In
 * this case we therefore need to construct a function call that will construct
 * our Python object (which is a subclass of Module), and then pass this back to
 * Boost.Python to give the Python object back.
 *
 * We have to do some indirection here to get this to work, but we can
 * achieve this with the following strategy:
 *
 * - Create a @c ModuleRegisterHelper object, which as an argument will store
 *   the Python class instance that will be instantiated from the Python side.
 * - Using std::bind, construct a function pointer to the helper's creation
 *   function, ModuleRegisterHelper::create.
 * - Create a Python capsule that will contain the @c ModuleRegisterHelper
 *   instance, and register this in the global namespace of the current
 *   module. This then ties the capsule to the lifetime of the module.
 */
void Module_Register(ModuleType const &modType, std::string const &modName,
                     py::object &obj)
{
    // Create a module register helper, which will call the C++ function to
    // create the module.
    ModuleRegisterHelper *helper = new ModuleRegisterHelper(obj);

    // Register this with the module factory using std::bind to grab a function
    // pointer to that particular object's function.
    GetModuleFactory().RegisterCreatorFunction(
        ModuleKey(modType, modName), std::bind(&ModuleRegisterHelper::create,
                                               helper, std::placeholders::_1));

    // Create a capsule that will be embedded in the __main__ namespace. So
    // deallocation will occur, but only once Python ends or the Python module
    // is deallocated.
    std::string modkey =
        "_" + std::string(ModuleTypeMap[modType]) + "_" + modName;

#if PY_MAJOR_VERSION == 2
    py::object capsule(
        py::handle<>(PyCObject_FromVoidPtr(helper, ModuleCapsuleDestructor)));
#else
    py::object capsule(
        py::handle<>(PyCapsule_New(helper, 0, ModuleCapsuleDestructor)));
#endif

    // Embed this in __main__.
    py::import("__main__").attr(modkey.c_str()) = capsule;
}

template <typename MODTYPE> struct ModuleWrapConverter
{
    ModuleWrapConverter()
    {
        // An important bit of code which will register allow
        // shared_ptr<MODTYPE> as something that boost::python recognises,
        // otherwise modules constructed from the factory will not work from
        // Python.
        py::objects::class_value_wrapper<
            std::shared_ptr<MODTYPE>,
            py::objects::make_ptr_instance<
                MODTYPE, py::objects::pointer_holder<std::shared_ptr<MODTYPE>,
                                                     MODTYPE>>>();
    }
};

template <typename MODTYPE> struct PythonModuleClass
{
    PythonModuleClass(std::string modName)
    {
        py::class_<ModuleWrap<MODTYPE>, std::shared_ptr<ModuleWrap<MODTYPE>>,
                   py::bases<Module>, boost::noncopyable>(
            modName.c_str(), py::init<FieldSharedPtr>())

            .def("AddConfigOption", ModuleWrap_AddConfigOption<MODTYPE>,
                 (py::arg("key"), py::arg("defValue"), py::arg("desc"),
                  py::arg("isBool") = false))

            // Allow direct access to field object through a property.
            .def_readwrite("field", &ModuleWrap<MODTYPE>::m_f)

            // Process function for this module.
            .def("Process", py::pure_virtual(&Module_Process))
            .def("Run", py::pure_virtual(&Module_Process))
            .def("Create", py::raw_function(Module_Create<MODTYPE>))
            .staticmethod("Create");

        ModuleWrapConverter<MODTYPE>();
    }
};

void export_Module()
{
    // Export ModuleType enum.
    NEKPY_WRAP_ENUM_STRING(ModuleType, ModuleTypeMap);

    // Define ModuleWrap to be implicitly convertible to a Module, since it
    // seems that doesn't sometimes get picked up.
    py::implicitly_convertible<std::shared_ptr<ModuleWrap<Module>>,
                               std::shared_ptr<Module>>();
    py::implicitly_convertible<std::shared_ptr<ModuleWrap<InputModule>>,
                               std::shared_ptr<Module>>();
    py::implicitly_convertible<std::shared_ptr<ModuleWrap<OutputModule>>,
                               std::shared_ptr<Module>>();
    py::implicitly_convertible<std::shared_ptr<ModuleWrap<ProcessModule>>,
                               std::shared_ptr<Module>>();

    // Wrapper for the Module class. Note that since Module contains a pure
    // virtual function, we need the ModuleWrap helper class to handle this for
    // us. In the lightweight wrappers above, we therefore need to ensure we're
    // passing std::shared_ptr<Module> as the first argument, otherwise they
    // won't accept objects constructed from Python.
    py::class_<ModuleWrap<Module>, std::shared_ptr<ModuleWrap<Module>>,
               boost::noncopyable>("Module", py::init<FieldSharedPtr>())

        // Process function for this module.
        .def("Process", py::pure_virtual(&Module_Process))
        .def("Run", py::pure_virtual(&Module_Process))

        // Configuration options.
        .def("RegisterConfig", Module_RegisterConfig,
             (py::arg("key"), py::arg("value") = ""))
        .def("PrintConfig", &Module::PrintConfig)
        .def("SetDefaults", &Module::SetDefaults)
        .def("GetStringConfig", Module_GetConfig<std::string>)
        .def("GetFloatConfig", Module_GetConfig<double>)
        .def("GetIntConfig", Module_GetConfig<int>)
        .def("GetBoolConfig", Module_GetConfig<bool>)
        .def("AddConfigOption", ModuleWrap_AddConfigOption<Module>,
             (py::arg("key"), py::arg("defValue"), py::arg("desc"),
              py::arg("isBool") = false))

        // Allow direct access to field object through a property.
        .def_readwrite("field", &ModuleWrap<Module>::m_f)

        // Factory functions.
        .def("Register", &Module_Register)
        .staticmethod("Register");

    ModuleWrapConverter<Module>();

    PythonModuleClass<InputModule>("InputModule");
    PythonModuleClass<ProcessModule>("ProcessModule");
    PythonModuleClass<OutputModule>("OutputModule");
}
