#include "externals.hh"
#include "ui.hh"
#include "ui-app.hh"
#include "ui-imgui-sdl.hh"
#include "ui-texture.hh"

#include <imgui_internal.h>


/*= T_UIApp =================================================================*/

namespace {
#include "font-awesome.inl"

static const ImWchar IconsRanges_[] = {
	ICON_MIN_FA ,
	ICON_MAX_FA ,
	0
};
} // namespace <anon>

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

	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( );
	if ( !GLEW_VERSION_4_5 ) {
		fprintf( stderr , "OpenGL 4.5 required\n" );
		exit( 1 );
	}

	ImGui_ImplSdl_Init( window_ );

	using namespace ImGui;
	StyleColorsDark( );
	ImGuiIO& io{ GetIO( ) };
	io.IniFilename = nullptr;
	{
		ImFontConfig cfg;
		cfg.SizePixels = 13.0f;
		defaultFont_ = io.Fonts->AddFontDefault( &cfg );

		ImFontConfig icons;
		icons.MergeMode = true;
		icons.PixelSnapH = true;
		io.Fonts->AddFontFromMemoryCompressedBase85TTF(
				FontAwesome__compressed_data_base85 , 13.f ,
				&icons , IconsRanges_ );
	}
	{
		ImFontConfig cfg;
		cfg.SizePixels = 9.0f;
		smallFont_ = io.Fonts->AddFontDefault( &cfg );

		ImFontConfig icons;
		icons.MergeMode = true;
		icons.PixelSnapH = true;
		icons.DstFont = smallFont_;
		io.Fonts->AddFontFromMemoryCompressedBase85TTF(
				FontAwesome__compressed_data_base85 , 9.f ,
				&icons , IconsRanges_ );
	}
}

T_UIApp::~T_UIApp( )
{
	ImGui_ImplSdl_Shutdown( );
	SDL_GL_DeleteContext( gl_ );
	SDL_DestroyWindow( window_ );
	SDL_Quit( );
}

void T_UIApp::addAction(
		T_UIAction action ) noexcept
{
	actions_.set( std::move( action ) );
}

void T_UIApp::actionMenu(
		T_String const& id ) const noexcept
{
	auto const* const a{ actions_.get( id ) };
	if ( a ) {
		a->menuItem( );
	}
}

void T_UIApp::actionButton(
		T_String const& id ) const noexcept
{
	auto const* const a{ actions_.get( id ) };
	if ( a ) {
		a->tbButton( );
	}
}

void T_UIApp::handleEvents( ) noexcept
{
	SDL_Event event;
	mMove_ = ImVec2( );
	while ( SDL_PollEvent( &event ) ) {
		ImGui_ImplSdl_ProcessEvent( &event );
		if ( event.type == SDL_QUIT ) {
#warning FIXME request confirmation
			exiting_ = true;
			return;
		}

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

	ImGui_ImplSdl_NewFrame( window_ , mCapture_ , mInitial_ );
	ImGui::GetIO( ).MouseDrawCursor = true;
	handleMouseCapture( );
}

void T_UIApp::handleMouseCapture( ) noexcept
{
	using namespace ImGui;
	auto const& io( GetIO( ) );
	const T_MouseButtons mb( ([]() {;
			T_MouseButtons mb;
			if ( IsMouseDown( 0 ) ) {
				mb |= E_MouseButton::LEFT;
			}
			if ( IsMouseDown( 1 ) ) {
				mb |= E_MouseButton::RIGHT;
			}
			if ( IsMouseDown( 2 ) ) {
				mb |= E_MouseButton::MIDDLE;
			}
			return mb;
		})() );
	const T_KeyboardModifiers kb( ([&io]() {
			T_KeyboardModifiers kb;
			if ( io.KeyCtrl ) {
				kb |= E_KeyboardModifier::CTRL;
			}
			if ( io.KeyShift ) {
				kb |= E_KeyboardModifier::SHIFT;
			}
			if ( io.KeyAlt ) {
				kb |= E_KeyboardModifier::ALT;
			}
			return kb;
		})() );
	const bool appCanGrab( !( ImGui::IsMouseHoveringAnyWindow( )
				|| io.WantCaptureMouse
				|| io.WantCaptureKeyboard ) );

	if ( mCapture_ && !( mb && mDelegate_ ) ) {
		mCapture_ = false;
		CaptureMouseFromApp( false );
		SDL_SetRelativeMouseMode( SDL_FALSE );
		SDL_WarpMouseInWindow( window_ , mInitial_.x , mInitial_.y );
		SetMouseCursor( ImGuiMouseCursor_Arrow );

	} else if ( mCapture_ && mDelegate_ ) {
		SetMouseCursor( ImGuiMouseCursor_Move );
		mDelegate_->handleDragAndDrop( mMove_ , kb , mb );

	} else if ( appCanGrab && mb && mDelegate_ ) {
		mCapture_ = true;
		mInitial_ = GetMousePos( );
		CaptureMouseFromApp( true );
		SDL_SetRelativeMouseMode( SDL_TRUE );
		SetMouseCursor( ImGuiMouseCursor_Move );
	}

	if ( ( appCanGrab || mCapture_ ) && io.MouseWheel && mDelegate_ ) {
		mDelegate_->handleWheel( io.MouseWheel , kb , mb );
	}
}

void T_UIApp::render( ) noexcept
{
	handleDialogs( );
	glUseProgram( 0 );
	glBindProgramPipeline( 0 );
	UI::Textures( ).reset( );
	glClearColor( 0 , 0 , 0 , 1 );
	ImGui::Render( );
}

void T_UIApp::swap( ) const noexcept
{
	SDL_GL_SwapWindow( window_ );
}

void T_UIApp::handleDialogs( ) noexcept
{
	const auto nDialogs{ modals_.size( ) };
	for ( auto i = 0u ; i < nDialogs ; i ++ ) {
		const bool keep{ modals_[ i ]->draw( ) };
		assert( keep || i + 1 == nDialogs );
		if ( !keep ) {
			modals_.removeLast( );
		}
	}
}