/******************************************************************************
*	File		-	core.cpp
*	Author		-	Joey Pollack
*	Date		-	2021/08/30 (y/m/d)
*	Mod Date	-	2021/08/30 (y/m/d)
*	Description	-	The Core Engine Class. Manages the engine components.
******************************************************************************/

#include "core.h"
#include "version.h"

// Sub Systems
#include <graphics/window.h>
#include <graphics/glGraphics.h>

namespace lunarium
{
    Core* Core::mpInstance = nullptr;
    Core::Core()
        : mbIsInit(false), mpArgs(nullptr), mpWindow(nullptr), mpGraphics(nullptr)
    {
    
    }

    Core& Core::GetInstance()
    {
        if (!mpInstance)
        {
            mpInstance = new Core;
        }

        return *mpInstance;
    }

    void Core::Shutdown()
    {
        if (!mpInstance)
            return;
        
        Logger::Log(LogCategory::CORE, LogLevel::INFO, "Lunarium is shutting down!");

        // Shutdown subsystems
        delete mpInstance->mpGraphics;
        mpInstance->mpGraphics = nullptr;

        delete mpInstance->mpWindow;
        mpInstance->mpWindow = nullptr;

        delete mpInstance->mpArgs;
        mpInstance->mpArgs = nullptr;

        mpInstance->mbIsInit = false;
        delete mpInstance;
        mpInstance = nullptr;

    }

    void Core::Initialize(int argc, char** argv)
    {
        // Setup the log system
		mMasterLogFile.open("Lunarium_Master.log", std::ios_base::app);
		mMasterLogFile << "\n\n";


		mErrorLogFile.open("Lunarium_Errors.log", std::ios_base::app);
		mErrorLogFile << "\n\n";

		if (mMasterLogFile.is_open())
			Logger::GetInstance()->AddListener(new FileListener(mMasterLogFile));


		if (mErrorLogFile.is_open())
			Logger::GetInstance()->AddListener(new FileListener(mErrorLogFile, LogLevel::ERROR | LogLevel::FATAL_ERROR));
        
        Logger::Log(LogCategory::CORE, LogLevel::INFO, "Running Lunarium version %s", Version::GetVersion().ToString().c_str());

        // Attempt to load the engine state file. This file should be placed in the same directory as the lunarium program.
        if (Failed(State::CreateFromFile("lunarium_state.xml", mState)))
        {
            Logger::Log(LogCategory::CORE, LogLevel::WARNING, "Unable to load state file: lunarium_state.xml. Loading default state.");
            mState = State::CreateDefault();
        }
        else
        {
            Logger::Log(LogCategory::CORE, LogLevel::INFO, "Loaded state file: lunarium_state.xml");
        }

        // Parse command line args -- None right now
        std::vector<Args::SwitchDesc> sd;
        mpArgs = new Args(argc, argv, '-', sd);

        OpRes result;

        // Init Graphics/Window system
        mpWindow = new Window;
        result = mpWindow->Initialize(mState);
        if (Failed(result))
        {
            Logger::Log(LogCategory::CORE, LogLevel::FATAL_ERROR, 
                        "Could not initialize the Window system: %s", result.Description);
            return;
        }

        if (Renderer::OPENGL == mState.Display.RenderFramework)
        {
            mpGraphics = new OglGraphics;
        }
        else if (Renderer::VULKAN == mState.Display.RenderFramework)
        {
            Logger::Log(LogCategory::CORE, LogLevel::FATAL_ERROR, 
                        "Can not create Vulkan graphics system because it is not yet implemented. Must use OpenGL instead.");
            return;
        }
        else
        {
            Logger::Log(LogCategory::CORE, LogLevel::FATAL_ERROR, 
                        "Could not create graphics system: Unknown render framework specified.");
            return;
        }

        // TODO: This should probably be based on a state setting instead
#ifdef _DEBUG
        result = mpGraphics->Initialize(mpWindow);
#else   
        result = mpGraphics->Initialize(mpWindow, false);
#endif

        if (Failed(result))
        {
            Logger::Log(LogCategory::CORE, LogLevel::FATAL_ERROR,
                    "Could not initialized the graphics system: %s", result.Description);
            return;
        }

        // DEBUG
        mpGraphics->SetClearColor(Color(0.0f, 0.0f, 0.0f, 1.0f));

        mbIsInit = true;
    }

    bool Core::IsInit() const
    {
        return mbIsInit;
    }

    const State& Core::GetState() const
    {
        return mState;
    }

    void Core::RunGameLoop()
    {
        mFrameCounter.Reset();

        // TODO: Init frame counter
        while (!mpWindow->ShouldWindowClose())
        {
            mFrameCounter.NewFrame();

            // Display FPS in window title for now
            std::string title = "Lunarium - FPS: ";
            title += std::to_string(mFrameCounter.GetFrameData().CurrentFPS);
            glfwSetWindowTitle(mpWindow->GetWindow(), title.c_str());

            // Poll input
            Window::PollEvents();

            // HACK: Temporary solution to close the program
            if (glfwGetKey(mpWindow->GetWindow(), GLFW_KEY_ESCAPE) == GLFW_PRESS)
            {
                mpWindow->SetShouldCloseFlag(true);
            }

            // Update game state

            // Render
            mpGraphics->BeginDraw();

            mpGraphics->EndDraw();
        }
    }
}