/*************************************************************************************//*!
\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
{
  /*************************************************************************************/
  /*!
  
   class SHDotNetRuntime

   \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 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 std::runtime_error
       Thrown if there is a failure in loading the CLR and related functions.

    */ 
    /***********************************************************************************/
    void Init();
    /***********************************************************************************/
    /*!

     \brief
       Unloads the CoreCLR.

     \throws std::runtime_error
       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() const noexcept { return initialised; }

    /***********************************************************************************/
    /*!

     \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.
     \param assemblyName
       Name of the CoreCLR assembly that contains the function.
     \param typeName
       Name of the CoreCLR type in the assembly that contains the function. Nested types
       are separated by a period(.).
     \param functionName
       Name of the CoreCLR function to get a pointer to.
     \return
       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) const;

    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.
     \param functionName
       Name of the CoreCLR function to get a pointer to.
     \return 
       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.
      
     \param directory
       Path to the directory where the trusted platform assemblies reside.
     \return 
       Semicolon separated string of trusted platform assemblies.

    */ 
    /***********************************************************************************/
    static std::string buildTpaList(const std::string& directory);
    /***********************************************************************************/
    /*! 
     
     \brief
       Takes in a Win32 result code and throws an exception it if there is an error.
      
     \param errMsg
       Error message to display if the resultCode is a failure code.
     \param resultCode
       Result code of the function to check.

    */ 
    /***********************************************************************************/
    static void throwIfFailed(const std::string& errMsg, int resultCode);
  };
} 

#include "SHDotNetRuntime.hpp"