/*************************************************************************************//*!
\file           SHDotNetRuntime.h
\author         Tng Kah Wei, kahwei.tng, 390009620
\par            email: kahwei.tng\@digipen.edu
\date           Oct 2, 2021
\brief          Contains the interface of a wrapper class for interfacing with the
                .NET 5 Runtime.
 
Copyright (C) 2021 DigiPen Institute of Technology.
Reproduction or disclosure of this file or its contents without the prior written consent 
of DigiPen Institute of Technology is prohibited.
*//**************************************************************************************/
#pragma once

// Standard Libraries
#include <iomanip>          // std::setfill, std::setw
#include <stdexcept>        // std::runtime_error
#include <string>           // std::string
#include <sstream>          // std::ostringstream
// External Dependencies
#include <Windows.h>        // HMODULE
#include <coreclrhost.h>    // coreclr_*

namespace SHADE
{
  /********************************************************************************//*!
  @brief    Class that encapsulates the state of the .NET Core Runtime lifecycle.
  *//*********************************************************************************/
  class SHDotNetRuntime
  {
    public:
    /*----------------------------------------------------------------------------------*/
    /* Constructors/Destructor                                                          */
    /*----------------------------------------------------------------------------------*/
    /****************************************************************************//*!
    @brief    Default constructor that immediately initializes the CoreCLR.

    @param[in]      autoInit
        If true, loads the CoreCLR by calling Init().
    *//*****************************************************************************/
    SHDotNetRuntime(bool autoInit = true);
    /****************************************************************************//*!
    @brief    Destructor that unloads the CoreCLR if it has not been unloaded
              yet.
    *//*****************************************************************************/
    ~SHDotNetRuntime();

    // Disallow copy and moving
    SHDotNetRuntime(const SHDotNetRuntime&) = delete;
    SHDotNetRuntime(SHDotNetRuntime&&) = delete;

    /*----------------------------------------------------------------------------------*/
    /* Lifecycle Functions                                                              */
    /*----------------------------------------------------------------------------------*/
    /****************************************************************************//*!
    @brief    Loads the CoreCLR and grabs pointers to bootstrapping functions and 
              kickstarts the CoreCLR.
              
    @throws   SystemExitException
        Thrown if there is a failure in loading the CLR and related functions.
    *//*****************************************************************************/
    void Init();
    /****************************************************************************//*!
    @brief    Unloads the CoreCLR.

    @throws   SystemExitException
        Thrown if there is a failure in unloading the CLR.
    *//*****************************************************************************/
    void Exit();

    /*----------------------------------------------------------------------------------*/
    /* Usage Functions                                                                  */
    /*----------------------------------------------------------------------------------*/
    /****************************************************************************//*!
    @brief    Checks if the DotNetRuntime has successfully been initialised.

    @return   True if this DotNetRuntime has been initialised.  
    *//*****************************************************************************/
    inline bool IsLoaded() { return coreClr != nullptr; }
    /****************************************************************************//*!
    @brief    Retrieves a function pointer from the a CLR assembly based on the 
              specified assembly, type and function names.

    @tparam        FunctionType
            Type of the function pointer that the specified function name will 
            provide.
            
    @params[in]    assemblyName
            Name of the CoreCLR assembly that contains the function.
    @params[in]    typeName
            Name of the CoreCLR type in the assembly that contains the function.
            Nested types are separated by a period(.).
    @params[in]    functionName
            Name of the CoreCLR function to get a pointer to.

    @returns  Pointer to the function in the assembly that was specified.
    *//*****************************************************************************/
    template<typename FunctionType>
    FunctionType GetFunctionPtr(const std::string_view& assemblyName, 
                                const std::string_view& typeName, 
                                const std::string_view& functionName);

    private:
    /*-----------------------------------------------------------------------------*/
    /* Data Members                                                                */
    /*-----------------------------------------------------------------------------*/
    bool initialised = false;
    // References to CoreCLR key components
    HMODULE coreClr = nullptr;
    void* hostHandle = nullptr;
    unsigned int domainId = 0;
    // Function Pointers to CoreCLR functions
    coreclr_initialize_ptr      initializeCoreClr     = nullptr;
    coreclr_create_delegate_ptr createManagedDelegate = nullptr;
    coreclr_shutdown_ptr        shutdownCoreClr       = nullptr;

    /*-----------------------------------------------------------------------------*/
    /* Helper Functions                                                            */
    /*-----------------------------------------------------------------------------*/
    /****************************************************************************//*!
    @brief    Retrieves a function pointer from the CoreCLR based on the specified
              function name.

    @tparam        FunctionType
            Type of the function pointer that the specified function name will 
            provide.

    @params[in]    functionName
            Name of the CoreCLR function to get a pointer to.

    @returns  Pointer to the function in the CoreCLR that was specified.
    *//*****************************************************************************/
    template<typename FunctionType>
    FunctionType getCoreClrFunctionPtr(const std::string& functionName);
    /****************************************************************************//*!
    @brief    Compiles a semicolon separated string of trusted platform assemblies by
              searching the specified directory.

    @params[in]    directory
            Path to the directory where the trusted platform assemblies reside.

    @returns  Semicolon separated string of trusted platform assemblies.
    *//*****************************************************************************/
    static std::string buildTpaList(const std::string& directory);
    static void throwIfFailed(const std::string& errMsg, int resultCode);
  };
} 

#include "SHDotNetRuntime.hpp"