#define IMGUI_DEFINE_MATH_OPERATORS

#include <SDL.h>

#include "sys_imgui.h"

#ifdef D3_SDL_X11
#include <dlfcn.h>
#include <SDL_syswm.h>
//char *XGetDefault(Display* display, const char*	program, const char* option)
typedef char* (*MY_XGETDEFAULTFUN)(Display*, const char*, const char*);
#endif

#include "../libs/imgui/backends/imgui_impl_opengl2.h"
#include "../libs/imgui/backends/imgui_impl_sdl2.h"

#include "framework/Common.h"
#include "framework/KeyInput.h"
#include "renderer/qgl.h"
#include "renderer/tr_local.h" // glconfig

extern void Com_DrawDhewm3SettingsMenu(); // in framework/dhewm3SettingsMenu.cpp

static idCVar imgui_scale( "imgui_scale", "-1.0", CVAR_SYSTEM|CVAR_FLOAT|CVAR_ARCHIVE, "factor to scale ImGUI menus by (-1: auto)" ); // TODO: limit values?

idCVar imgui_style( "imgui_style", "0", CVAR_SYSTEM|CVAR_INTEGER|CVAR_ARCHIVE, "Which ImGui style to use. 0: Dhewm3 theme, 1: Default ImGui theme, 2: User theme", 0.0f, 2.0f );

// implemented in imgui_savestyle.cpp
namespace DG {
	// writes the given ImGuiStyle to the given filename (opened with fopen())
	// returns true on success, false if opening the file failed
	extern bool WriteImGuiStyle( const ImGuiStyle& style, const char* filename );

	// reads the the given filename (opened with fopen())
	// and sets the given ImGuiStyle accordingly.
	// if any attributes/colors/behaviors are missing the the file,
	// they are not modified in style, so it probably makes sense to initialize
	// style to a sane default before calling that function.
	// returns true on success, false if opening the file failed
	extern bool ReadImGuiStyle( ImGuiStyle& style, const char* filename );
} //namespace DG

namespace D3 {
namespace ImGuiHooks {

#include "proggyvector_font.h"

static SDL_Window* sdlWindow = NULL;
ImGuiContext* imguiCtx = NULL;
static bool haveNewFrame = false;
static int openImguiWindows = 0; // or-ed enum D3ImGuiWindow values

static ImGuiStyle userStyle;

// was there a key down or button (mouse/gamepad) down event this frame?
// used to make the warning overlay disappear
static bool hadKeyDownEvent = false;

static idStr warningOverlayText;
static double warningOverlayStartTime = -100.0;
static ImVec2 warningOverlayStartPos;

idStr GetUserStyleFilename()
{
	// TODO: put this into the config dir
	return idStr( "user.imstyle" );
}

static void UpdateWarningOverlay()
{
	double timeNow = ImGui::GetTime();
	if ( timeNow - warningOverlayStartTime > 4.0f ) {
		warningOverlayStartTime = -100.0f;
		return;
	}

	// also hide if a key was pressed or maybe even if the mouse was moved (too much)
	ImVec2 mdv = ImGui::GetMousePos() - warningOverlayStartPos; // Mouse Delta Vector
	float mouseDelta = sqrtf( mdv.x * mdv.x + mdv.y * mdv.y );
	const float fontSize = ImGui::GetFontSize();
	if ( mouseDelta > fontSize * 4.0f || hadKeyDownEvent ) {
		warningOverlayStartTime = -100.0f;
		return;
	}

	ImGui::SetNextWindowPos(ImGui::GetMainViewport()->GetCenter(), ImGuiCond_Always, ImVec2(0.5f, 0.5f));
	ImGui::PushStyleColor( ImGuiCol_WindowBg, ImVec4(1.0f, 0.4f, 0.4f, 0.4f) );
	float padSize = fontSize * 2.0f;
	ImGui::PushStyleVar( ImGuiStyleVar_WindowPadding, ImVec2(padSize, padSize) );

	int winFlags = ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoMove
			| ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_AlwaysAutoResize;
	ImGui::Begin("WarningOverlay", NULL, winFlags);

	ImDrawList* drawList = ImGui::GetWindowDrawList();
	ImVec2 points[] = {
		{0, 40}, {40, 40}, {20, 0}, // triangle
		{20, 12}, {20, 28}, // line
		{20, 33} // dot
	};

	float iconScale = 1.0f; // TODO: global scale also used for fontsize

	ImVec2 offset = ImGui::GetWindowPos() + ImVec2(fontSize, fontSize);
	for ( ImVec2& v : points ) {
		v.x = roundf( v.x * iconScale );
		v.y = roundf( v.y * iconScale );
		v += offset;
	}

	ImU32 color = ImGui::GetColorU32( ImVec4(0.1f, 0.1f, 0.1f, 1.0f) );

	drawList->AddTriangle( points[0], points[1], points[2], color, roundf( iconScale * 4.0f ) );

	drawList->AddPolyline( points+3, 2, color, 0, roundf( iconScale * 3.0f ) );

	float dotRadius = 2.0f * iconScale;
	drawList->AddEllipseFilled( points[5], ImVec2(dotRadius, dotRadius), color, 0, 6 );

	ImGui::Indent( 40.0f * iconScale );
	ImGui::TextUnformatted( warningOverlayText.c_str() );

	ImGui::End();

	ImGui::PopStyleVar(); // WindowPadding
	ImGui::PopStyleColor(); // WindowBg
}

void ShowWarningOverlay( const char* text )
{
	warningOverlayText = text;
	warningOverlayStartTime = ImGui::GetTime();
	warningOverlayStartPos = ImGui::GetMousePos();
}


static float GetDefaultDPI()
{
	SDL_Window* win = sdlWindow;
	float dpi = -1.0f;
#ifdef D3_SDL_X11
	SDL_SysWMinfo wmInfo = {};
	SDL_VERSION(&wmInfo.version)
	if(SDL_GetWindowWMInfo(win, &wmInfo) && wmInfo.subsystem == SDL_SYSWM_X11) {
		Display* display = wmInfo.info.x11.display;

		static void* libX11 = NULL;
		if(libX11 == NULL) {
			libX11 = dlopen("libX11.so.6", RTLD_LAZY);
		}
		if(libX11 == NULL) {
			libX11 = dlopen("libX11.so", RTLD_LAZY);
		}
		if(libX11 != NULL) {
			MY_XGETDEFAULTFUN my_xgetdefault = (MY_XGETDEFAULTFUN)dlsym(libX11, "XGetDefault");
			if(my_xgetdefault != NULL) {
				//char *XGetDefault(Display* display, const char*	program, const char* option)
				const char* dpiStr = my_xgetdefault(display, "Xft", "dpi");
				printf("XX dpistr = '%s'\n", dpiStr);
				if(dpiStr != NULL) {
					dpi = atof(dpiStr);
				}
			}
		}
	}
	if (dpi == -1.0f)
#endif
	{
		int winIdx = SDL_GetWindowDisplayIndex( win );
		if (winIdx >= 0) {
			SDL_GetDisplayDPI(winIdx, NULL, &dpi, NULL);
		}
	}
	return dpi;
}

static float GetDefaultScale()
{
	float ret = GetDefaultDPI() / 96.0f;
	ret = round(ret*2.0)*0.5; // round to .0 or .5
	return ret;
}

float GetScale()
{
	float ret = imgui_scale.GetFloat();
	if (ret < 0.0f) {
		ret = GetDefaultScale();
	}
	return ret;
}

void SetScale( float scale )
{
	ImGuiIO& io = ImGui::GetIO();
	float realScale = (scale < 0.0f) ? GetDefaultScale() : scale;
	io.FontGlobalScale = realScale;
	// TODO: could instead set fontsize to 18.0f * scale
	//  (io.Fonts->ClearFonts() and then add again with new size - but must be done before NewFrame() / after EndFrame())
	imgui_scale.SetFloat( scale );
}

static bool imgui_initialized = false;

// using void* instead of SDL_Window and SDL_GLContext to avoid dragging SDL headers into sys_imgui.h
bool Init(void* _sdlWindow, void* sdlGlContext)
{
	common->Printf( "Initializing ImGui\n" );

	sdlWindow = (SDL_Window*)_sdlWindow;

	// Setup Dear ImGui context
	IMGUI_CHECKVERSION();
	imguiCtx = ImGui::CreateContext();
	if ( imguiCtx == NULL ) {
		common->Warning( "Failed to create ImGui Context!\n" );
		return false;
	}
	ImGuiIO& io = ImGui::GetIO(); (void)io;
	io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
	io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls

	SetImGuiStyle( Style::Dhewm3 );
	userStyle = ImGui::GetStyle(); // set dhewm3 style as default, in case the user style is missing values
	if ( DG::ReadImGuiStyle( userStyle, GetUserStyleFilename() ) && imgui_style.GetInteger() == 2 ) {
		ImGui::GetStyle() = userStyle;
	} else if ( imgui_style.GetInteger() == 1 ) {
		ImGui::GetStyle() = ImGuiStyle();
		ImGui::StyleColorsDark();
	}

	ImFontConfig fontCfg;
	strcpy(fontCfg.Name, "ProggyVector");
	ImFont* font = io.Fonts->AddFontFromMemoryCompressedTTF(ProggyVector_compressed_data, ProggyVector_compressed_size, 18.0f, nullptr);

	SetScale( GetScale() );

	// Setup Platform/Renderer backends
	if ( ! ImGui_ImplSDL2_InitForOpenGL( sdlWindow, sdlGlContext ) ) {
		ImGui::DestroyContext( imguiCtx );
		imguiCtx = NULL;
		common->Warning( "Failed to initialize ImGui SDL platform backend!\n" );
		return false;
	}

	if ( ! ImGui_ImplOpenGL2_Init() ) {
		ImGui_ImplSDL2_Shutdown();
		ImGui::DestroyContext( imguiCtx );
		imguiCtx = NULL;
		common->Warning( "Failed to initialize ImGui OpenGL renderer backend!\n" );
		return false;
	}

	// Load Fonts
	// - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
	// - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
	// - If the file cannot be loaded, the function will return a nullptr. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
	// - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
	// - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
	// - Read 'docs/FONTS.md' for more instructions and details.
	// - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
	//io.Fonts->AddFontDefault();
	//io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
	//ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, nullptr, io.Fonts->GetGlyphRangesJapanese());
	//IM_ASSERT(font != nullptr);

	const char* f10bind = idKeyInput::GetBinding( K_F10 );
	if ( f10bind && f10bind[0] != '\0' ) {
		if ( idStr::Icmp( f10bind, "dhewm3Settings" ) != 0 ) {
			// if F10 is already bound, but not to dhewm3Settings, show a message
			common->Printf( "... the F10 key is already bound to '%s', otherwise it could be used to open the dhewm3 Settings Menu\n" , f10bind );
		}
	} else {
		idKeyInput::SetBinding( K_F10, "dhewm3Settings" );
	}

	imgui_initialized = true;
	return true;
}

void Shutdown()
{
	if ( imgui_initialized ) {
		common->Printf( "Shutting down ImGui\n" );

		// TODO: only if init was successful!
		ImGui_ImplOpenGL2_Shutdown();
		ImGui_ImplSDL2_Shutdown();
		ImGui::DestroyContext( imguiCtx );
		imgui_initialized = false;
	}
}

// NewFrame() is called once per D3 frame, after all events have been gotten
// => ProcessEvent() has already been called (probably multiple times)
void NewFrame()
{
	if (openImguiWindows == 0)
		return;

	// Start the Dear ImGui frame
	ImGui_ImplOpenGL2_NewFrame();
	ImGui_ImplSDL2_NewFrame();
	ImGui::NewFrame();
	haveNewFrame = true;

	UpdateWarningOverlay();

	if (openImguiWindows & D3_ImGuiWin_Settings) {
		Com_DrawDhewm3SettingsMenu();
	}

	if (openImguiWindows & D3_ImGuiWin_Demo) {
		bool show_demo_window = true;
		ImGui::ShowDemoWindow(&show_demo_window);
		if(!show_demo_window)
			CloseWindow(D3_ImGuiWin_Demo);
	}
}

bool keybindModeEnabled = false;

// called with every SDL event by Sys_GetEvent()
// returns true if ImGui has handled the event (so it shouldn't be handled by D3)
bool ProcessEvent(const void* sdlEvent)
{
	if (openImguiWindows == 0)
		return false;

	const SDL_Event* ev = (const SDL_Event*)sdlEvent;
	// ImGui_ImplSDL2_ProcessEvent() doc says:
	//   You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
	//   - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
	//   - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
	//   Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.

	bool imguiUsedEvent = ImGui_ImplSDL2_ProcessEvent( ev );
	if ( keybindModeEnabled ) {
		// in keybind mode, all input events are passed to Doom3 so it can translate them
		// to internal events and we can access and use them to create a new binding
		return false;
	}

	if ( ImGui::IsWindowFocused( ImGuiFocusedFlags_AnyWindow )
	    && (ev->type == SDL_CONTROLLERAXISMOTION || ev->type == SDL_CONTROLLERBUTTONDOWN) ) {
		// don't pass on controller axis events to avoid moving the mouse cursor
		// and controller button events to avoid emulating mouse clicks
		return true;
	}

	switch( ev->type ) {
		// Hack: detect if any key was pressed to close the warning overlay
		case SDL_CONTROLLERBUTTONDOWN:
		case SDL_MOUSEWHEEL:
		case SDL_MOUSEBUTTONDOWN:
		case SDL_KEYDOWN:
			// TODO: controller trigger?
			hadKeyDownEvent = true;
	}
	if( imguiUsedEvent ) {
		ImGuiIO& io = ImGui::GetIO();

		if ( io.WantCaptureMouse ) {
			switch( ev->type ) {
				case SDL_MOUSEMOTION:
				case SDL_MOUSEWHEEL:
				case SDL_MOUSEBUTTONDOWN:

				// Note: still pass button up events to the engine, so if they were pressed down
				//   before an imgui window got focus they don't remain pressed indefinitely
				//case SDL_MOUSEBUTTONUP:
					return true;
			}
		}

		if ( io.WantCaptureKeyboard ) {
			switch( ev->type ) {
				case SDL_TEXTINPUT:
					return true;
				case SDL_KEYDOWN:
				//case SDL_KEYUP: NOTE: see above why key up events are passed to the engine
					if ( ev->key.keysym.sym < SDLK_F1 || ev->key.keysym.sym > SDLK_F12) {
						// F1 - F12 are passed to the engine so its shortcuts
						// (like quickload or screenshot) still work
						// Doom3's menu does the same
						return true;
					}
			}
		}

	}

	return false;
}

void SetKeyBindMode( bool enable )
{
	keybindModeEnabled = enable;
	// make sure no keys are registered as down, neither when entering nor when exiting keybind mode
	idKeyInput::ClearStates();
}

void EndFrame()
{
	if (openImguiWindows == 0 && !haveNewFrame)
		return;

	// I think this can happen if we're not coming from idCommon::Frame() but screenshot or sth
	if ( !haveNewFrame ) {
		NewFrame();
	}
	haveNewFrame = false;
	ImGui::Render();

	// Doom3 uses the OpenGL ARB shader extensions, for most things it renders.
	// disable those shaders, the OpenGL classic integration of ImGui doesn't use shaders
	qglDisable( GL_VERTEX_PROGRAM_ARB );
	qglDisable( GL_FRAGMENT_PROGRAM_ARB );

	// Doom3 uses OpenGL's ARB_vertex_buffer_object extension to use VBOs on the GPU
	// as buffers for glDrawElements() (instead of passing userspace buffers to that function)
	// ImGui however uses userspace buffers, so remember the currently bound VBO
	// and unbind it (after drawing, bind it again)
	GLint curArrayBuffer = 0;
	if ( glConfig.ARBVertexBufferObjectAvailable ) {
		qglGetIntegerv( GL_ARRAY_BUFFER_BINDING_ARB, &curArrayBuffer );
		qglBindBufferARB( GL_ARRAY_BUFFER_ARB, 0 );
	}

	// disable all texture units, ImGui_ImplOpenGL2_RenderDrawData() will enable texture 0
	// and bind its own textures to it as needed
	for ( int i = glConfig.maxTextureUnits - 1 ; i >= 0 ; i-- ) {
		GL_SelectTexture( i );
		qglDisable( GL_TEXTURE_2D );
		if ( glConfig.texture3DAvailable ) {
			qglDisable( GL_TEXTURE_3D );
		}
		if ( glConfig.cubeMapAvailable ) {
			qglDisable( GL_TEXTURE_CUBE_MAP_EXT );
		}
	}

	ImGui_ImplOpenGL2_RenderDrawData( ImGui::GetDrawData() );

	if ( curArrayBuffer != 0 ) {
		qglBindBufferARB( GL_ARRAY_BUFFER_ARB, curArrayBuffer );
	}

	// reset this at the end of each frame, will be set again by ProcessEvent()
	if ( hadKeyDownEvent ) {
		hadKeyDownEvent = false;
	}
}


void OpenWindow( D3ImGuiWindow win )
{
	openImguiWindows |= win;
}

void CloseWindow( D3ImGuiWindow win )
{
	openImguiWindows &= ~win;
}

int GetOpenWindowsMask()
{
	return openImguiWindows;
}

void SetImGuiStyle( Style d3style )
{
	ImGuiStyle& style = ImGui::GetStyle();
	if ( d3style == Style::Dhewm3 ) {
		style = ImGuiStyle(); // start with default style
		// make it look a bit nicer with rounded edges
		style.WindowRounding = 2.0f;
		style.FrameRounding = 3.0f;
		//style.ChildRounding = 6.0f;
		style.ScrollbarRounding = 8.0f;
		style.GrabRounding = 1.0f;
		style.PopupRounding = 2.0f;
		SetDhewm3StyleColors();
	} else if ( d3style == Style::User ) {
		style = userStyle;
	} else {
		assert( d3style == Style::ImGui_Default && "invalid/unknown style" );
		style = ImGuiStyle();
		ImGui::StyleColorsDark();
	}
}

void SetDhewm3StyleColors()
{
	ImGui::StyleColorsDark();
	ImGuiStyle& style = ImGui::GetStyle();
	ImVec4* colors = style.Colors;
	colors[ImGuiCol_TitleBg]    = ImVec4(0.28f, 0.36f, 0.48f, 0.88f);
	colors[ImGuiCol_TabHovered] = ImVec4(0.42f, 0.69f, 1.00f, 0.80f);
	colors[ImGuiCol_TabActive]  = ImVec4(0.24f, 0.51f, 0.83f, 1.00f);
}

void SetUserStyleColors()
{
	ImGuiStyle& style = ImGui::GetStyle();
	for ( int i=0; i < ImGuiCol_COUNT; ++i ) {
		style.Colors[i] = userStyle.Colors[i];
	}
}

bool WriteUserStyle()
{
	userStyle = ImGui::GetStyle();
	if( !DG::WriteImGuiStyle( ImGui::GetStyle(), GetUserStyleFilename() ) ) {
		common->Warning( "Couldn't write ImGui userstyle!\n" );
		return false;
	}
	return true;
}

}} //namespace D3::ImGuiHooks