#include "externals.hh"

#include "imgui_impl_sdl.h"
#include "utilities.hh"
#include "texture.hh"
#include "rendertarget.hh"


/*= T_Main ===================================================================*/

struct T_Main
{
	T_Main( );
	~T_Main( );

	void mainLoop( );

    private:
	const std::string projectFile;
	SDL_Window * window;
	SDL_GLContext gl;

	bool done = false;
	bool capture = false;
	ImVec2 mouseInitial;
	ImVec2 mouseMove;

	T_Camera camera;

	T_FilesWatcher watcher;
	std::unique_ptr< T_ShaderProgram > spRaymarch;
	std::unique_ptr< T_ShaderProgram > spCopy;

	std::unique_ptr< T_Texture > txRaymarchOutput;
	std::unique_ptr< T_Rendertarget > rtRaymarchOutput;

	void startIteration( );
	void handleCapture( );
	void makeUI( );
	void render( );

	void initProgram( );
};

/*----------------------------------------------------------------------------*/

T_Main::T_Main( )
{
	SDL_Init( SDL_INIT_VIDEO | SDL_INIT_TIMER );

	// Setup window
	SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER , 1 );
	SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE , 24 );
	SDL_GL_SetAttribute( SDL_GL_STENCIL_SIZE , 8 );
	SDL_GL_SetAttribute( SDL_GL_CONTEXT_MAJOR_VERSION , 2 );
	SDL_GL_SetAttribute( SDL_GL_CONTEXT_MINOR_VERSION , 2 );
	SDL_DisplayMode current;
	SDL_GetCurrentDisplayMode( 0 , &current );
	window = SDL_CreateWindow( "DEMO",
			SDL_WINDOWPOS_CENTERED , SDL_WINDOWPOS_CENTERED ,
			1280 , 720 ,
			SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE );
	gl = SDL_GL_CreateContext( window );
	glewInit();
	ImGui_ImplSdl_Init( window );

	initProgram( );
	txRaymarchOutput = std::make_unique< T_Texture >(
			1280 , 720 , E_TexType::RGBA8 );
	rtRaymarchOutput = std::make_unique < T_Rendertarget >(
			T_RendertargetSetup( ).add( *txRaymarchOutput ).create( ) );
}

void T_Main::mainLoop( )
{
	while ( !done ) {
		startIteration( );
		if ( !done ) {
			handleCapture( );
			makeUI( );
			watcher.check( );
			render( );
		}
	}
}

T_Main::~T_Main( )
{
	ImGui_ImplSdl_Shutdown( );
	SDL_GL_DeleteContext( gl );
	SDL_DestroyWindow( window );
	SDL_Quit( );
}

/*----------------------------------------------------------------------------*/

void T_Main::startIteration( )
{
	SDL_Event event;
	mouseMove = ImVec2( );
	while ( SDL_PollEvent( &event ) ) {
		ImGui_ImplSdl_ProcessEvent( &event );
		if ( event.type == SDL_QUIT ) {
			done = true;
			return;
		}

		if ( capture && event.type == SDL_MOUSEMOTION ) {
			mouseMove.x += event.motion.xrel;
			mouseMove.y += event.motion.yrel;
		}
	}

	ImGui_ImplSdl_NewFrame( window , capture , mouseInitial );
	ImGui::GetIO( ).MouseDrawCursor = true;
}

void T_Main::handleCapture( )
{
	auto const& io( ImGui::GetIO( ) );
	const bool lmb( ImGui::IsMouseDown( 0 ) );
	const bool mb( lmb || ImGui::IsMouseDown( 1 ) );
	const bool appCanGrab( !( ImGui::IsMouseHoveringAnyWindow( )
				|| io.WantCaptureMouse
				|| io.WantCaptureKeyboard ) );
	const bool shift( io.KeyShift );
	const bool ctrl( io.KeyCtrl );

	if ( capture && !mb ) {
		capture = false;
		ImGui::CaptureMouseFromApp( false );
		SDL_SetRelativeMouseMode( SDL_FALSE );
		SDL_WarpMouseInWindow( window ,
				int( mouseInitial.x ) ,
				int( mouseInitial.y ) );
		ImGui::SetMouseCursor( ImGuiMouseCursor_Arrow );
	} else if ( capture ) {
		ImGui::SetMouseCursor( ImGuiMouseCursor_Move );
		camera.handleDND( mouseMove , ctrl , shift , lmb );
	} else if ( appCanGrab && mb ) {
		capture = true;
		mouseInitial = ImGui::GetMousePos( );
		ImGui::CaptureMouseFromApp( true );
		SDL_SetRelativeMouseMode( SDL_TRUE );
		ImGui::SetMouseCursor( ImGuiMouseCursor_Move );
	}

	if ( ( appCanGrab || capture ) && io.MouseWheel ) {
		camera.handleWheel( io.MouseWheel , ctrl , shift );
	}
}

void T_Main::makeUI( )
{
	auto const& dspSize( ImGui::GetIO( ).DisplaySize );
	ImGui::SetNextWindowSize( ImVec2( 300 , dspSize.y ) ,
			ImGuiSetCond_Once );
	ImGui::SetNextWindowPos( ImVec2( ) , ImGuiSetCond_Once );
	ImGui::Begin( "Yay! Demo!" );

	camera.makeUI( );

	ImGui::End( );
}

void T_Main::render( )
{
	if ( spRaymarch->activate( ) && rtRaymarchOutput->activate( ) ) {
		glClearColor( 0 , 1 , 1 , 1 );
		glClear( GL_COLOR_BUFFER_BIT );
		enum {
			U_TIME			= 0 ,
			U_RESOLUTION		= 1 ,
			U_CAM_POS		= 2 ,
			U_LOOK_AT		= 3 ,
			U_CAM_UP		= 4 ,
			U_NEAR_PLANE		= 5 ,
			U_LIGHT_DIR		= 6 ,
			U_RENDER		= 7 ,
		};

		auto const& dspSize( ImGui::GetIO( ).DisplaySize );
		glUniform1f( U_TIME , 0 );
		glUniform2f( U_RESOLUTION , dspSize.x , dspSize.y );

		glUniform3fv( U_CAM_POS , 1 , &camera.pos.x );
		glUniform3fv( U_LOOK_AT , 1 , &camera.lookAt.x );
		glUniform3fv( U_CAM_UP , 1 , &camera.up.x );
		glUniform1f( U_NEAR_PLANE , camera.np );

		glUniform3f( U_LIGHT_DIR , 0 , 1 , 1 );
		glUniform4f( U_RENDER , 128 , 0.9 , 0.001 , 100 );

		glRectf( -1, -1 , 1 , 1 );
	}

	T_Rendertarget::MainOutput( );
	glClearColor( 1 , 0 , 1 , 1 );
	glClear( GL_COLOR_BUFFER_BIT );
	if ( spCopy->activate( ) ) {
		T_TextureBinding tb( 0 );
		tb.set( 0 , *txRaymarchOutput );
		tb.bind( );
		glRectf( -1, -1 , 1 , 1 );
		glBindTexture( GL_TEXTURE_2D , 0 );
	}

	glUseProgram( 0 );
	ImGui::Render( );
	SDL_GL_SwapWindow( window );
}


void T_Main::initProgram( )
{
	spRaymarch = std::make_unique< T_ShaderProgram >(
			GL_FRAGMENT_SHADER , watcher );
	spRaymarch->addFile( "raymarch-header.glsl" );
	spRaymarch->addFile( "map.glsl" );
	spRaymarch->addFile( "raymarcher.glsl" );
	spRaymarch->load( );

	spCopy = std::make_unique< T_ShaderProgram >( GL_FRAGMENT_SHADER ,
			watcher );
	spCopy->addFile( "copy.glsl" );
	spCopy->load( );
}


/*============================================================================*/

int main( int , char** )
{
	T_Main m;
	m.mainLoop( );

#if 0
	// Frame time history
	const int nFrameTimes = 200;
	float frameTimes[ nFrameTimes ];
	memset( frameTimes , 0 , sizeof( float ) * nFrameTimes );
#endif
#if 0
		// Update frame time history
		memmove( frameTimes , &frameTimes[ 1 ] ,
				( nFrameTimes - 1 ) * sizeof( float ) );
		frameTimes[ nFrameTimes - 1 ] = 1000.0f / ImGui::GetIO( ).Framerate;
#endif

	return 0;
}