#include <SDL2/SDL.h>
#include <stdio.h>
#include <math.h>

/* 
Copyright (c) 2020 Devine Lu Linvega

Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE.
*/

#define HOR 32
#define VER 16
#define PAD 2
#define SZ (HOR * VER * 16)

typedef unsigned char Uint8;

typedef struct {
	int unsaved;
	char name[256];
	Uint8 data[SZ];
} Document;

typedef struct {
	int x, y;
} Point2d;

typedef struct {
	int size, color, selection;
	Point2d *touch, origin;
} Brush;

typedef enum {
	POINT,
	LINE,
	ARC,
	BEZIER,
	RECTANGLE,
	ELLIPSE,
	TRANSLATE,
	TRIANGLE
} LineType;

typedef enum {
	SQUARE,
	ROUND,
	DIAGONAL
} LineCap;

typedef struct {
	int size, color, len;
	Point2d points[256];
	LineType type;
	LineCap cap;
} Path2d;

typedef struct {
	int len;
	Path2d paths[256];
} Shape2d;

Document doc;
Path2d stack;
Shape2d shape;
Brush brush;

int WIDTH = 8 * HOR + 8 * PAD * 2;
int HEIGHT = 8 * (VER + 2) + 8 * PAD * 2;
int FPS = 30, GUIDES = 1, ZOOM = 2;

Uint32 theme[] = {
	0x000000,
	0xFFFFFF,
	0x72DEC2,
	0x666666,
	0x222222};

Uint8 icons[][8] = {
	{0x38, 0x7c, 0xfe, 0xfe, 0xfe, 0x7c, 0x38, 0x00},
	{0x38, 0x44, 0x82, 0x82, 0x82, 0x44, 0x38, 0x00},
	{0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x00},
	{0x06, 0x18, 0x20, 0x40, 0x40, 0x80, 0x80, 0x00},
	{0x02, 0x02, 0x04, 0x38, 0x40, 0x80, 0x80, 0x00},
	{0xfe, 0x82, 0x82, 0x82, 0x82, 0x82, 0xfe, 0x00},
	{0x1e, 0x06, 0x0a, 0x12, 0x20, 0x40, 0x80, 0x00},
	{0x06, 0x18, 0x22, 0x40, 0x42, 0x80, 0xaa, 0x00},
	{0x02, 0x06, 0x0e, 0x1e, 0x3e, 0x7e, 0xfe, 0x00}, /* triangle */
	{0x00, 0x00, 0x00, 0x82, 0x44, 0x38, 0x00, 0x00}, /* eye open */
	{0x00, 0x38, 0x44, 0x92, 0x28, 0x10, 0x00, 0x00}, /* eye closed */
	{0x10, 0x54, 0x28, 0xc6, 0x28, 0x54, 0x10, 0x00}, /* unsaved */
	{0x04, 0x0a, 0x7a, 0x82, 0xbc, 0xa0, 0x40, 0x00}, /* cap:round */
	{0x0e, 0x0a, 0xfa, 0x82, 0xbe, 0xa0, 0xe0, 0x00}, /* cap:square */
	{0x0a, 0x14, 0x14, 0x28, 0x50, 0x50, 0xa0, 0x00}, /* cap:diagonal */
	{0x0e, 0x06, 0x0a, 0x10, 0x22, 0x40, 0xaa, 0x00}, /* transform:translate */
	{0x02, 0x7c, 0x52, 0x70, 0x42, 0x40, 0xaa, 0x00}, /* transform:scale */
	{0x0e, 0x30, 0x42, 0x40, 0x82, 0x80, 0xaa, 0x00}  /* transform:rotate */
};

SDL_Window *gWindow = NULL;
SDL_Renderer *gRenderer = NULL;
SDL_Texture *gTexture = NULL;
Uint32 *pixels;

#pragma mark - Helpers

Point2d *
setpt2d(Point2d *p, int x, int y)
{
	p->x = x;
	p->y = y;
	return p;
}

Point2d
Pt2d(int x, int y)
{
	Point2d p;
	setpt2d(&p, x, y);
	return p;
}

Point2d
mid2d(Point2d a, Point2d b, int seg, int segs)
{
	return Pt2d(
		a.x + ((b.x - a.x) / (double)segs) * seg,
		a.y + ((b.y - a.y) / (double)segs) * seg);
}

Point2d *
mag2d(Point2d *a, int step)
{
	return setpt2d(a,
		abs((a->x + step / 2) / step) * step,
		abs((a->y + step / 2) / step) * step);
}

Point2d
add2d(Point2d *a, Point2d *b)
{
	return Pt2d(a->x + b->x, a->y + b->y);
}

int
equ2d(Point2d *a, Point2d *b)
{
	return a->x == b->x && a->y == b->y;
}

int
dis2d(Point2d *a, Point2d *b)
{
	return (b->x - a->x) * (b->x - a->x) + (b->y - a->y) * (b->y - a->y);
}

int
cpos(char *s, char c)
{
	int i = 0;
	while(s[i] && s[i])
		if(s[i++] == c)
			return i - 1;
	return -1;
}

int
slen(char *s)
{
	int i = 0;
	while(s[i] && s[++i])
		;
	return i;
}

int
scmp(char *a, char *b)
{
	int i = 0;
	while(a[i] == b[i])
		if(!a[i++])
			return 1;
	return 0;
}

char *
scpy(char *src, char *dst, int len)
{
	int i = 0;
	while((dst[i] = src[i]) && i < len - 2)
		i++;
	dst[i + 1] = '\0';
	return dst;
}

int
sint(char *s, int len)
{
	int num = 0, i = 0;
	while(s[i] && i < len && (s[i] >= '0' && s[i] <= '9'))
		num = num * 10 + (s[i++] - '0');
	return num;
}

int
cancast(LineType type)
{
	if(type == POINT && stack.len >= 1)
		return 1;
	else if(type == LINE && stack.len >= 2)
		return 1;
	else if(type == RECTANGLE && stack.len >= 2)
		return 1;
	else if(type == ELLIPSE && stack.len >= 2)
		return 1;
	else if(type == ARC && stack.len >= 3)
		return 1;
	else if(type == BEZIER && stack.len >= 3 && stack.len % 2 == 1)
		return 1;
	else if(type == TRANSLATE && stack.len >= 2)
		return 1;
	else if(type == TRIANGLE && stack.len >= 2)
		return 1;
	return 0;
}

int
inbounds(int x, int y)
{
	return !(x < 0 || x > HOR * 8 || y < 0 || y > VER * 8);
}

int
colortheme(Uint32 hex)
{
	int i = 0;
	for(i = 0; i < 5; ++i)
		if(theme[i] == hex)
			return i;
	return 0;
}

Path2d *
getselection(void)
{
	if(shape.len < 1)
		return NULL;
	return &shape.paths[brush.selection];
}

#pragma mark - Draw

void
clear(Uint32 *dst)
{
	int i, j;
	for(i = 0; i < HEIGHT; i++)
		for(j = 0; j < WIDTH; j++)
			dst[i * WIDTH + j] = theme[0];
}

int
keypixel(int x, int y)
{
	return (y + PAD * 8) * WIDTH + (x + PAD * 8);
}

int
getpixel(Uint32 *dst, int x, int y)
{
	return dst[keypixel(x, y)];
}

void
putpixel(Uint32 *dst, int x, int y, int color)
{
	if(x >= 0 && x < WIDTH - 8 && y >= 0 && y < HEIGHT - 8)
		dst[(y + PAD * 8) * WIDTH + (x + PAD * 8)] = theme[color];
}

void
putcap(Uint32 *dst, int x, int y, LineCap cap, int size, int color)
{
	int w, h;
	Point2d a = Pt2d(x, y);
	for(h = 0; h < size; ++h)
		for(w = 0; w < size; ++w) {
			Point2d b = Pt2d(x - size / 2 + w, y - size / 2 + h);
			if(cap == ROUND && dis2d(&a, &b) < size)
				putpixel(dst, b.x, b.y, color);
			else if(cap == DIAGONAL && (h == w || h == w + 1))
				putpixel(dst, b.x, b.y, color);
			else if(cap == SQUARE)
				putpixel(dst, b.x, b.y, color);
		}
}

void
line(Uint32 *dst, int ax, int ay, int bx, int by, LineCap cap, int size, int color)
{
	int dx = abs(bx - ax), sx = ax < bx ? 1 : -1;
	int dy = -abs(by - ay), sy = ay < by ? 1 : -1;
	int err = dx + dy, e2;
	for(;;) {
		putcap(dst, ax, ay, cap, size, color);
		if(ax == bx && ay == by)
			break;
		e2 = 2 * err;
		if(e2 >= dy) {
			err += dy;
			ax += sx;
		}
		if(e2 <= dx) {
			err += dx;
			ay += sy;
		}
	}
}

void
ellipse(Uint32 *dst, int x0, int y0, int x1, int y1, int cadran, LineCap cap, int size, int color)
{
	int a = abs(x1 - x0), b = abs(y1 - y0), b1 = b & 1;
	int dx = 4 * (1.0 - a) * b * b, dy = 4 * (b1 + 1) * a * a;
	int err = dx + dy + b1 * a * a, e2;
	if(x0 > x1) {
		x0 = x1;
		x1 += a;
	}
	if(y0 > y1)
		y0 = y1;
	y0 += (b + 1) >> 1;
	y1 = y0 - b1;
	a = 8 * a * a;
	b1 = 8 * b * b;
	do {
		if(cadran == -1 || cadran == 1)
			putcap(dst, x1, y0, cap, size, color);
		if(cadran == -1 || cadran == 2)
			putcap(dst, x0, y0, cap, size, color);
		if(cadran == -1 || cadran == 3)
			putcap(dst, x0, y1, cap, size, color);
		if(cadran == -1 || cadran == 0)
			putcap(dst, x1, y1, cap, size, color);
		e2 = 2 * err;
		if(e2 <= dy) {
			y0++;
			y1--;
			err += dy += a;
		}
		if(e2 >= dx || 2 * err > dy) {
			x0++;
			x1--;
			err += dx += b1;
		}
	} while(x0 <= x1);
}

void
arc(Uint32 *dst, int x0, int y0, int x1, int y1, int x2, int y2, LineCap cap, int size, int color)
{
	int cadran, col = (y1 - y0) * (x2 - x1) - (y2 - y1) * (x1 - x0);
	x1 = x2;
	y1 = y2;
	if(x2 > x0 && y2 > y0) {
		if(col < 0) {
			x0 = x0 - (x2 - x0);
			y1 = y2 + (y2 - y0);
			cadran = 0;
		} else {
			y0 = y0 - (y2 - y0);
			x1 = x2 + (x2 - x0);
			cadran = 2;
		}
	} else if(x2 < x0 && y2 > y0) {
		if(col < 0) {
			y0 = y0 - (y2 - y0);
			x1 = x2 + (x2 - x0);
			cadran = 1;
		} else {
			x0 = x0 - (x2 - x0);
			y1 = y2 + (y2 - y0);
			cadran = 3;
		}
	} else if(x2 < x0 && y2 < y0) {
		if(col < 0) {
			x0 = x0 - (x2 - x0);
			y1 = y2 + (y2 - y0);
			cadran = 2;
		} else {
			y0 = y0 - (y2 - y0);
			x1 = x2 + (x2 - x0);
			cadran = 0;
		}
	} else {
		if(col < 0) {
			y0 = y0 - (y2 - y0);
			x1 = x2 + (x2 - x0);
			cadran = 3;
		} else {
			x0 = x0 - (x2 - x0);
			y1 = y2 + (y2 - y0);
			cadran = 1;
		}
	}
	ellipse(dst, x0, y0, x1, y1, cadran, cap, size, color);
}

void
rectangle(Uint32 *dst, int x0, int y0, int x1, int y1, LineCap cap, int size, int color)
{
	line(dst, x0, y0, x0, y1, cap, size, color);
	line(dst, x0, y1, x1, y1, cap, size, color);
	line(dst, x1, y1, x1, y0, cap, size, color);
	line(dst, x1, y0, x0, y0, cap, size, color);
}

void
handle(Uint32 *dst, int x0, int y0, int r, int color)
{
	line(dst, x0, y0 - r, x0 + r, y0, SQUARE, 1, color);
	line(dst, x0 + r, y0, x0, y0 + r, SQUARE, 1, color);
	line(dst, x0, y0 + r, x0 - r, y0, SQUARE, 1, color);
	line(dst, x0 - r, y0, x0, y0 - r, SQUARE, 1, color);
}

int
intri2d(Point2d p, Point2d p0, Point2d p1, Point2d p2)
{
	int a;
	int s = p0.y * p2.x - p0.x * p2.y + (p2.y - p0.y) * p.x + (p0.x - p2.x) * p.y;
	int t = p0.x * p1.y - p0.y * p1.x + (p0.y - p1.y) * p.x + (p1.x - p0.x) * p.y;
	if((s < 0) != (t < 0))
		return 0;
	a = -p1.y * p2.x + p0.y * (p2.x - p1.x) + p0.x * (p1.y - p2.y) + p1.x * p2.y;
	return a < 0 ? (s <= 0 && s + t >= a) : (s >= 0 && s + t <= a);
}

void
triangle(Uint32 *dst, int x0, int y0, int x1, int y1, int x2, int y2, LineCap cap, int size, int color)
{
	int minx = (x0 <= x1 && x0 <= x2) ? x0 : (x1 <= x0 && x1 <= x2) ? x1
																	: x2;
	int miny = (y0 <= y1 && y0 <= y2) ? y0 : (y1 <= y0 && y1 <= y2) ? y1
																	: y2;
	int maxx = (x0 >= x1 && x0 >= x2) ? x0 : (x1 >= x0 && x1 >= x2) ? x1
																	: x2;
	int maxy = (y0 >= y1 && y0 >= y2) ? y0 : (y1 >= y0 && y1 >= y2) ? y1
																	: y2;
	int x, y;
	for(y = miny; y < maxy; ++y)
		for(x = minx; x < maxx; ++x)
			if(intri2d(Pt2d(x, y), Pt2d(x0, y0), Pt2d(x1, y1), Pt2d(x2, y2)))
				putcap(dst, x, y, cap, size, color);
}

void
arrow(Uint32 *dst, int x0, int y0, int x1, int y1, int color)
{
	int Par = 8;
	double slopy = atan2((y1 - y0), (x1 - x0)), cosy = cos(slopy), siny = sin(slopy);
	line(dst, x1, y1, x0, y0, SQUARE, 1, color);
	line(dst, x1, y1, x1 + (int)(-Par * cosy - (Par / 2.0 * siny)), y1 + (int)(-Par * siny + (Par / 2.0 * cosy)), SQUARE, 1, color);
	line(dst, x1, y1, x1 + (int)(-Par * cosy + (Par / 2.0 * siny)), y1 - (int)(Par / 2.0 * cosy + Par * siny), SQUARE, 1, color);
}

void
bezier(Uint32 *dst, int x0, int y0, int x1, int y1, int x2, int y2, LineCap cap, int size, int color)
{
	int i, segs = 8;
	Point2d prev = Pt2d(x0, y0);
	for(i = 0; i <= segs; i++) {
		Point2d a = mid2d(Pt2d(x0, y0), Pt2d(x1, y1), i, segs);
		Point2d b = mid2d(Pt2d(x1, y1), Pt2d(x2, y2), i, segs);
		Point2d c = mid2d(a, b, i, segs);
		line(dst, prev.x, prev.y, c.x, c.y, cap, size, color);
		prev = c;
	}
}

void
drawpath(Uint32 *dst, Path2d *path, int guides)
{
	int j;
	/* Draw translation */
	if(path->len > 0 && GUIDES && (brush.origin.x != 0 || brush.origin.y != 0)) {
		Point2d offset = add2d(&path->points[0], &brush.origin);
		arrow(dst, path->points[0].x, path->points[0].y, offset.x, offset.y, 3);
		handle(dst, path->points[0].x, path->points[0].y, 4, 3);
	}
	/* Draw paths */
	for(j = 0; j < path->len; ++j) {
		Point2d a = add2d(&path->points[j], &brush.origin);
		if(j < path->len - 1) {
			Point2d b = add2d(&path->points[j + 1], &brush.origin);
			if(path->type == LINE)
				line(dst, a.x, a.y, b.x, b.y, path->cap, path->size, path->color);
			else if(path->type == RECTANGLE)
				rectangle(dst, a.x, a.y, b.x, b.y, path->cap, path->size, path->color);
			else if(path->type == ELLIPSE)
				ellipse(dst, a.x, a.y, b.x, b.y, -1, path->cap, path->size, path->color);
			else if(path->type == TRANSLATE) {
				setpt2d(&brush.origin, brush.origin.x + b.x - a.x, brush.origin.y + b.y - a.y);
				if(GUIDES)
					arrow(dst, a.x, a.y, b.x, b.y, 4);
			}
		}
		if(j < path->len - 2) {
			Point2d b = add2d(&path->points[j + 1], &brush.origin);
			Point2d c = add2d(&path->points[j + 2], &brush.origin);
			if(path->type == ARC)
				arc(dst, a.x, a.y, b.x, b.y, c.x, c.y, path->cap, path->size, path->color);
			else if(path->type == BEZIER)
				bezier(dst, a.x, a.y, b.x, b.y, c.x, c.y, path->cap, path->size, path->color);
			else if(path->type == TRIANGLE)
				triangle(dst, a.x, a.y, b.x, b.y, c.x, c.y, path->cap, path->size, path->color);
			if(path->type == ARC || path->type == BEZIER)
				j++;
		}
		if(path->type == POINT)
			putcap(dst, a.x, a.y, path->cap, path->size, path->color);
	}
	for(j = 0; j < path->len; ++j)
		if(guides)
			handle(dst, path->points[j].x, path->points[j].y, 2, path->color + 1);
}

void
drawguides(Uint32 *dst, int step)
{
	int x, y;
	for(x = 2; x < HOR * 8; x++)
		for(y = 2; y < VER * 8; y++)
			if(x % (step * 2) == y % (step * 2) && x % (step * 2) == 0)
				putpixel(dst, x, y, 3);
			else if(x % step == 0 && y % 2 == 0)
				putpixel(dst, x, y, 4);
			else if(y % step == 0 && x % 2 == 0)
				putpixel(dst, x, y, 4);
}

void
drawicn(Uint32 *dst, int x, int y, Uint8 *sprite, int fg, int bg)
{
	int v, h;
	for(v = 0; v < 8; v++)
		for(h = 0; h < 8; h++) {
			int ch1 = (sprite[v] >> (7 - h)) & 0x1;
			putpixel(dst, x + h, y + v, ch1 ? fg : bg);
		}
}

void
drawui(Uint32 *dst)
{
	int clr = brush.selection >= 0 ? shape.paths[brush.selection].color : 1;
	int bottom = VER * 8 + 8;
	Path2d *selection = getselection();
	drawicn(dst, 0, bottom, icons[clr == 1 ? 1 : 0], 1, 0);
	drawicn(dst, 1 * 8, bottom, icons[clr == 2 ? 1 : 0], 2, 0);
	drawicn(dst, 2 * 8, bottom, icons[clr == 3 ? 1 : 0], 3, 0);
	drawicn(dst, 4 * 8, bottom, icons[2], cancast(LINE) ? 2 : 3, 0);
	drawicn(dst, 5 * 8, bottom, icons[3], cancast(ARC) ? 2 : 3, 0);
	drawicn(dst, 6 * 8, bottom, icons[4], cancast(BEZIER) ? 2 : 3, 0);
	drawicn(dst, 7 * 8, bottom, icons[5], cancast(RECTANGLE) ? 2 : 3, 0);
	drawicn(dst, 8 * 8, bottom, icons[1], cancast(ELLIPSE) ? 2 : 3, 0);
	drawicn(dst, 9 * 8, bottom, icons[8], cancast(TRIANGLE) ? 2 : 3, 0);
	if(selection && selection->size > 1) {
		drawicn(dst, 11 * 8, bottom, icons[12], selection->cap == ROUND ? 1 : 2, 0);
		drawicn(dst, 12 * 8, bottom, icons[13], selection->cap == SQUARE ? 1 : 2, 0);
		drawicn(dst, 13 * 8, bottom, icons[14], selection->cap == DIAGONAL ? 1 : 2, 0);
	} else {
		drawicn(dst, 11 * 8, bottom, icons[12], 3, 0);
		drawicn(dst, 12 * 8, bottom, icons[13], 3, 0);
		drawicn(dst, 13 * 8, bottom, icons[14], 3, 0);
	}
	drawicn(dst, 15 * 8, bottom, icons[15], 3, 0);
	drawicn(dst, 16 * 8, bottom, icons[16], 3, 0);
	drawicn(dst, 17 * 8, bottom, icons[17], 3, 0);
	drawicn(dst, 19 * 8, bottom, icons[GUIDES ? 10 : 9], GUIDES ? 1 : 2, 0);
	drawicn(dst, (HOR - 1) * 8, bottom, icons[11], doc.unsaved ? 2 : 3, 0); /* save state */
}

void
redraw(Uint32 *dst)
{
	int i;
	clear(dst);
	setpt2d(&brush.origin, 0, 0);
	if(GUIDES)
		drawguides(dst, 16);
	/* draw shape */
	for(i = 0; i < shape.len; i++)
		drawpath(dst, &shape.paths[i], GUIDES && brush.selection == i);
	/* draw stack */
	for(i = 0; i < stack.len; ++i) {
		Point2d *a = &stack.points[i];
		if(i < stack.len - 1) {
			Point2d *b = &stack.points[i + 1];
			line(dst, a->x, a->y, b->x, b->y, SQUARE, 1, 4);
		}
	}
	for(i = 0; i < stack.len; ++i) {
		Point2d *a = &stack.points[i];
		handle(dst, a->x, a->y, 2, brush.color + 1);
	}
	drawui(dst);
	SDL_UpdateTexture(gTexture, NULL, dst, WIDTH * sizeof(Uint32));
	SDL_RenderClear(gRenderer);
	SDL_RenderCopy(gRenderer, gTexture, NULL, NULL);
	SDL_RenderPresent(gRenderer);
}

#pragma mark - Options

int
error(char *msg, const char *err)
{
	printf("Error %s: %s\n", msg, err);
	return 0;
}

void
savemode(int *i, int v)
{
	*i = v;
	redraw(pixels);
}

void
makedoc(Document *d, char *name)
{
	int i;
	for(i = 0; i < SZ; ++i)
		d->data[i] = 0x00;
	d->unsaved = 0;
	scpy(name, d->name, 256);
	printf("Made: %s\n", d->name);
	redraw(pixels);
}

int
savedoc(Document *d, char *name)
{
	int i, j, c = -1;
	FILE *f = fopen(name, "w");
	char *names[] = {
		"point",
		"line",
		"arc",
		"bezier",
		"rectangle",
		"ellipse",
		"translate"};
	for(i = 0; i < shape.len; ++i) {
		Path2d *p = &shape.paths[i];
		if(c != p->color) {
			fprintf(f, "%d setcolor\n", p->color);
			c = p->color;
		}
		for(j = 0; j < p->len; ++j)
			fprintf(f, "%d,%d ", p->points[j].x, p->points[j].y);
		fprintf(f, "%s\n", names[(int)p->type]);
	}
	fclose(f);
	d->unsaved = 0;
	scpy(name, d->name, 256);
	fclose(f);
	printf("Saved: %s\n", d->name);
	redraw(pixels);
	return 1;
}

int
opendoc(Document *d, char *name)
{
	FILE *f = fopen(name, "r");
	if(!f)
		return error("Load", "Invalid input file");
	fread(doc.data, sizeof(doc.data), 1, f);
	d->unsaved = 0;
	scpy(name, doc.name, 256);
	fclose(f);
	printf("Loaded: %s\n", doc.name);
	redraw(pixels);
	return 1;
}

void
putchr(Uint8 *chrbuf, int row, int col, int color)
{
	if(row < 0 || row > SZ - 8)
		return;
	if(color == 0 || color == 2)
		chrbuf[row] &= ~(1UL << (7 - col));
	else
		chrbuf[row] |= 1UL << (7 - col);
	if(color == 0 || color == 1)
		chrbuf[row + 8] &= ~(1UL << (7 - col));
	else
		chrbuf[row + 8] |= 1UL << (7 - col);
}

int
savechr(void)
{
	int h, v, x, y;
	Uint8 chrbuf[SZ];
	FILE *f = fopen("dotgrid-export.chr", "wb");
	for(v = 0; v < VER; ++v)
		for(h = 0; h < HOR; ++h)
			for(y = 0; y < 8; ++y)
				for(x = 0; x < 8; ++x)
					putchr(chrbuf,
						y + (h + v * HOR) * 16,
						x,
						colortheme(getpixel(pixels, h * 8 + x, v * 8 + y)));
	if(!fwrite(chrbuf, sizeof(chrbuf), 1, f))
		error("Save", "Invalid output file");
	fclose(f);
	puts("Exported dotgrid-export.chr");
	return 1;
}

void
modzoom(int mod)
{
	if((mod > 0 && ZOOM < 4) || (mod < 0 && ZOOM > 1)) {
		ZOOM += mod;
		SDL_SetWindowSize(gWindow, WIDTH * ZOOM, HEIGHT * ZOOM);
	}
}

void
addpoint(Point2d p)
{
	if(stack.len > 0 && equ2d(&p, &stack.points[stack.len - 1]))
		return;
	if(!inbounds(p.x, p.y))
		return;
	stack.points[stack.len++] = p;
	redraw(pixels);
}

void
selectpoint(Point2d *touch)
{
	int i, j;
	brush.touch = NULL;
	if(!inbounds(touch->x, touch->y))
		return;
	for(i = 0; i < shape.len; ++i) {
		Path2d *p = &shape.paths[i];
		for(j = 0; j < p->len; ++j)
			if(equ2d(touch, &p->points[j])) {
				brush.touch = &p->points[j];
				brush.selection = i;
				redraw(pixels);
				break;
			}
	}
}

void
dragpoint(Point2d *touch)
{
	if(equ2d(touch, brush.touch))
		return;
	if(!inbounds(touch->x, touch->y))
		return;
	setpt2d(brush.touch, touch->x, touch->y);
	stack.len = 0;
	redraw(pixels);
}

void
cancel(void)
{
	brush.selection = shape.len - 1;
	stack.len = 0;
	redraw(pixels);
}

void
cast(LineType type)
{
	int i;
	if(!cancast(type))
		return;
	shape.paths[shape.len].len = stack.len;
	for(i = 0; i < shape.paths[shape.len].len; ++i)
		setpt2d(&shape.paths[shape.len].points[i], stack.points[i].x, stack.points[i].y);
	shape.paths[shape.len].size = brush.size;
	shape.paths[shape.len].color = brush.color;
	shape.paths[shape.len].type = type;
	shape.paths[shape.len++].cap = SQUARE;
	cancel();
}

void
erase(void)
{
	if(stack.len > 0)
		stack.len = 0;
	else if(shape.len > 0)
		shape.len--;
	cancel();
}

void
destroy(void)
{
	shape.len = 0;
	cancel();
}

void
setcolor(int c)
{
	if(brush.selection >= 0)
		shape.paths[brush.selection].color = c;
	brush.color = c;
	redraw(pixels);
}

void
setbrushsize(int c)
{
	if(brush.selection >= 0)
		shape.paths[brush.selection].size = c;
	brush.size = c;
	redraw(pixels);
}

void
setcap(LineCap cap)
{
	Path2d *sel = getselection();
	if(sel) {
		sel->cap = cap;
		redraw(pixels);
	}
}

void
loadtxt(FILE *f)
{
	char line[256], query[256];
	int i = 0, querylen = 0, setting = 0;
	if(!f)
		return;
	while(fgets(line, 256, f)) {
		if(line[0] == ';')
			continue;
		i = 0;
		while(line[i]) {
			if(line[i] == ' ' || line[i] == '\n' || !line[i]) {
				int c = cpos(query, ',');
				if(c >= 0)
					addpoint(Pt2d(
						sint(query, c),
						sint(query + c + 1, slen(query) - c - 1)));
				else if(i > 0 && scmp(query, "setcolor"))
					brush.color = setting;
				else if(scmp(query, "line"))
					cast(LINE);
				else if(scmp(query, "arc"))
					cast(ARC);
				else if(scmp(query, "bezier"))
					cast(BEZIER);
				else if(scmp(query, "point"))
					cast(POINT);
				else if(scmp(query, "rectangle"))
					cast(RECTANGLE);
				else if(scmp(query, "ellipse"))
					cast(ELLIPSE);
				else if(scmp(query, "translate"))
					cast(TRANSLATE);
				else if(slen(query) == 1)
					setting = query[0] - '0';
				querylen = 0;
				query[0] = '\0';
			} else {
				query[querylen++] = line[i];
				query[querylen] = '\0';
			}
			i++;
		}
	}
	fclose(f);
}

void
selectoption(int option)
{
	switch(option) {
	case 0: setcolor(1); break;
	case 1: setcolor(2); break;
	case 2: setcolor(3); break;
	case 4: cast(LINE); break;
	case 5: cast(ARC); break;
	case 6: cast(BEZIER); break;
	case 7: cast(RECTANGLE); break;
	case 8: cast(ELLIPSE); break;
	case 9: cast(TRIANGLE); break;
	case 11: setcap(ROUND); break;
	case 12: setcap(SQUARE); break;
	case 13: setcap(DIAGONAL); break;
	case 19: savemode(&GUIDES, !GUIDES); break;
	}
}

void
quit(void)
{
	free(pixels);
	SDL_DestroyTexture(gTexture);
	gTexture = NULL;
	SDL_DestroyRenderer(gRenderer);
	gRenderer = NULL;
	SDL_DestroyWindow(gWindow);
	gWindow = NULL;
	SDL_Quit();
	exit(0);
}

#pragma mark - Triggers

void
domouse(SDL_Event *event)
{
	Point2d magnet;
	Point2d touch = Pt2d(
		(event->motion.x - (PAD * 8 * ZOOM)) / ZOOM,
		(event->motion.y - (PAD * 8 * ZOOM)) / ZOOM);
	mag2d(setpt2d(&magnet, touch.x, touch.y), 8);
	switch(event->type) {
	case SDL_MOUSEBUTTONUP:
		if(magnet.y >= VER * 8 + 8)
			; /* interface */
		else if(brush.touch && !equ2d(&magnet, brush.touch))
			dragpoint(&magnet);
		else if(brush.selection == shape.len - 1)
			addpoint(magnet);
		brush.touch = NULL;
		break;
	case SDL_MOUSEBUTTONDOWN:
		if(event->motion.y / ZOOM / 8 - PAD == VER + 1)
			selectoption(event->motion.x / ZOOM / 8 - PAD);
		else
			selectpoint(&magnet);
		break;
	case SDL_MOUSEMOTION:
		if(brush.touch && !equ2d(&magnet, brush.touch))
			dragpoint(&touch);
		break;
	}
}

void
dokey(SDL_Event *event)
{
	int shift = SDL_GetModState() & KMOD_LSHIFT || SDL_GetModState() & KMOD_RSHIFT;
	int ctrl = SDL_GetModState() & KMOD_LCTRL || SDL_GetModState() & KMOD_RCTRL;
	if(ctrl) {
		switch(event->key.keysym.sym) {
		/* Generic */
		case SDLK_n: makedoc(&doc, "untitled.chr"); break;
		case SDLK_r: opendoc(&doc, doc.name); break;
		case SDLK_s: shift ? savechr() : savedoc(&doc, doc.name); break;
		case SDLK_h: savemode(&GUIDES, !GUIDES); break;
		}
	} else {
		switch(event->key.keysym.sym) {
		case SDLK_EQUALS:
		case SDLK_PLUS: modzoom(1); break;
		case SDLK_UNDERSCORE:
		case SDLK_MINUS: modzoom(-1); break;
		case SDLK_ESCAPE: cancel(); break;
		case SDLK_BACKSPACE: erase(); break;
		case SDLK_1: setcolor(1); break;
		case SDLK_2: setcolor(2); break;
		case SDLK_3: setcolor(3); break;
		case SDLK_a: cast(LINE); break;
		case SDLK_s: cast(ARC); break;
		case SDLK_d: cast(BEZIER); break;
		case SDLK_z: setbrushsize(brush.size + (brush.size > 1 ? -1 : 0)); break;
		case SDLK_x: setbrushsize(brush.size + (brush.size < 32 ? 1 : 0)); break;
		/*
		case SDLK_z: cast(POINT); break;
		case SDLK_x: cast(RECTANGLE); break;
		*/
		case SDLK_c: cast(ELLIPSE); break;
		case SDLK_v: cast(TRANSLATE); break;
		case SDLK_t: cast(TRIANGLE); break;
		}
	}
}

int
init(void)
{
	if(SDL_Init(SDL_INIT_VIDEO) < 0)
		return error("Init", SDL_GetError());
	gWindow = SDL_CreateWindow("Dotgrid",
		SDL_WINDOWPOS_UNDEFINED,
		SDL_WINDOWPOS_UNDEFINED,
		WIDTH * ZOOM,
		HEIGHT * ZOOM,
		SDL_WINDOW_SHOWN);
	if(gWindow == NULL)
		return error("Window", SDL_GetError());
	gRenderer = SDL_CreateRenderer(gWindow, -1, 0);
	if(gRenderer == NULL)
		return error("Renderer", SDL_GetError());
	gTexture = SDL_CreateTexture(gRenderer,
		SDL_PIXELFORMAT_ARGB8888,
		SDL_TEXTUREACCESS_STATIC,
		WIDTH,
		HEIGHT);
	if(gTexture == NULL)
		return error("Texture", SDL_GetError());
	pixels = (Uint32 *)malloc(WIDTH * HEIGHT * sizeof(Uint32));
	if(pixels == NULL)
		return error("Pixels", "Failed to allocate memory");
	clear(pixels);
	return 1;
}

int
main(int argc, char *argv[])
{
	int ticknext = 0;
	if(!init())
		return error("Init", "Failure");
	if(argc > 1)
		loadtxt(fopen(argv[1], "r"));
	brush.size = 1;
	cancel();
	setcolor(1);
	while(1) {
		int tick = SDL_GetTicks();
		SDL_Event event;
		if(tick < ticknext)
			SDL_Delay(ticknext - tick);
		ticknext = tick + (1000 / FPS);
		while(SDL_PollEvent(&event) != 0) {
			switch(event.type) {
			case SDL_QUIT: quit(); break;
			case SDL_MOUSEBUTTONUP:
			case SDL_MOUSEBUTTONDOWN:
			case SDL_MOUSEMOTION: domouse(&event); break;
			case SDL_KEYDOWN: dokey(&event); break;
			case SDL_WINDOWEVENT:
				if(event.window.event == SDL_WINDOWEVENT_EXPOSED)
					redraw(pixels);
				break;
			}
		}
	}
	quit();
	return 0;
}