//---
//	SDL interface: for rendering tests on computer
//---

#ifdef TEX_PLATFORM_SDL

#include <SDL2/SDL.h>
#include <stdlib.h>
#include <TeX/TeX.h>
#include <TeX/parser.h>

/* Rendering window and renderer */
static SDL_Window *w = NULL;
static SDL_Renderer *r = NULL;

/* Font surface */
static SDL_Texture *font = NULL;

/* Font configuration */

#ifndef LARGE_FONT /* Small font */

#define FONT_FILE    "font5x7.bmp"
#define FONT_WIDTH   5
#define FONT_HEIGHT  7
#define FONT_OUTER   1
#define FONT_INNER   2
#define FONT_OFFSET  0

#else /* Large font */

#define FONT_FILE    "font10x12.bmp"
#define FONT_WIDTH   10
#define FONT_HEIGHT  12
#define FONT_OUTER   3
#define FONT_INNER   3
#define FONT_OFFSET  32

#endif /* Font size */

//---
//	Interface functions
//---

/* intf_pixel() - Set a single pixel */
void intf_pixel(int x, int y, int color)
{
	int R = color >> 16;
	int G = (color >> 8) & 0xff;
	int B = color & 0xff;

	SDL_SetRenderDrawColor(r, R, G, B, 255);
	SDL_RenderDrawPoint(r, x, y);
}

/* intf_line() - Draw a line */
void intf_line(int x1, int y1, int x2, int y2, int color)
{
	int R = color >> 16;
	int G = (color >> 8) & 0xff;
	int B = color & 0xff;

	SDL_SetRenderDrawColor(r, R, G, B, 255);
	SDL_RenderDrawLine(r, x1, y1, x2, y2);
}

/* intf_size() - Get the dimensions of a string */
void intf_size(char const *str, int *width, int *height)
{
	*width = (FONT_WIDTH + 1) * strlen(str) - 1;
	*height = FONT_HEIGHT;
}

/* intf_text() - Draw variable-width text */
void intf_text(char const *str, int x, int y, int color)
{
	int R = color >> 16;
	int G = (color >> 8) & 0xff;
	int B = color & 0xff;
	SDL_SetRenderDrawColor(r, R, G, B, 255);

	int c;
	while((c = *str++))
	{
		int row = (c - FONT_OFFSET) >> 4;
		int col = (c - FONT_OFFSET) & 15;

		SDL_Rect src = {
			.x = FONT_OUTER + (FONT_WIDTH + FONT_INNER) * col,
			.y = FONT_OUTER + (FONT_HEIGHT + FONT_INNER) * row,
			.w = FONT_WIDTH,
			.h = FONT_HEIGHT,
		};
		SDL_Rect dst = { .x = x, .y = y, .w = src.w, .h = src.h };

		SDL_RenderCopy(r, font, &src, &dst);
		x += FONT_WIDTH + 1;
	}

//	SDL_Rect rect = { .x = x, .y = y };
//	intf_size(str, &rect.w, &rect.h);
//	SDL_RenderDrawRect(r, &rect);
}

//---
//	Initialization and finalization
//---

__attribute__((constructor))
static void init(void)
{
	#define fail(msg) { \
		fprintf(stderr, "error: " msg ": %s\n", SDL_GetError()); \
		exit(1); \
	}

	if(SDL_Init(SDL_INIT_VIDEO) < 0) fail("failed to initialize SDL");

	int c = SDL_WINDOWPOS_CENTERED;
	w = SDL_CreateWindow("2D rendering", c, c, 256, 128, 0);
	if(!w) fail("cannot create SDL window");

	r = SDL_CreateRenderer(w, -1, SDL_RENDERER_ACCELERATED);
	if(!r) fail("cannot create SDL renderer");

	SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "0");

	/* Load the font */
	SDL_Surface *font_surf = SDL_LoadBMP(FONT_FILE);
	if(!font_surf) fail("cannot load font");

	font = SDL_CreateTextureFromSurface(r, font_surf);
	SDL_FreeSurface(font_surf);
	if(!font) fail("cannot convert font to texture");

	/* Make the window visible */
	SDL_RenderPresent(r);

	/* Set interface functions */
	TeX_intf_pixel(intf_pixel);
	TeX_intf_line(intf_line);
	TeX_intf_size(intf_size);
	TeX_intf_text(intf_text);

	#undef fail
}

__attribute__((destructor))
static void fini(void)
{
	if(font) SDL_DestroyTexture(font);
	if(r) SDL_DestroyRenderer(r);
	if(w) SDL_DestroyWindow(w);
	SDL_Quit();
}

//---
//	Backend example
//---

int main(void)
{
	char const * formula =
	"\\frac{x_7\\left<X,Y\\right>+3\\left<\\frac{A}{B}\\right>}{"
		"\\left\\{\\frac{\\frac{2}{3}}{27}\\right\\}^2"
	"}";

	struct TeX_Flow *flow = TeX_parse(formula);
	if(!flow) { puts("parsing error!"); return 1; }
	TeX_debug_flow(flow, 0);

	SDL_SetRenderDrawColor(r, 0xff, 0xff, 0xff, 0xff);
	SDL_RenderClear(r);
	TeX_draw(flow, 10, 10, 0x000000);
	SDL_RenderPresent(r);

	SDL_Event e;
	while(1)
	{
		SDL_WaitEvent(&e);
		if(e.type == SDL_QUIT) break;
	}

	TeX_free(flow);
	return 0;
}

#endif /* TEX_PLATFORM_SDL */