/* See LICENSE for licence details. */
#include <errno.h>
#include <math.h>
#include <png.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <X11/keysym.h>
#include <X11/XKBlib.h>
#include <X11/Xatom.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xft/Xft.h>

#include "arg.h"
#include "drw.h"

char *argv0;

/* macros */
#define LEN(a)         (sizeof(a) / sizeof(a)[0])
#define LIMIT(x, a, b) (x) = (x) < (a) ? (a) : (x) > (b) ? (b) : (x)
#define MAXFONTSTRLEN  128

typedef enum {
	NONE = 0,
	LOADED = 1,
	SCALED = 2,
	DRAWN = 4
} imgstate;

typedef struct {
	unsigned char *buf;
	unsigned int bufwidth, bufheight;
	imgstate state;
	XImage *ximg;
	FILE *f;
	png_structp png_ptr;
	png_infop info_ptr;
	int numpasses;
} Image;

typedef struct {
	char *text;
	Image *img;
} Slide;

/* Purely graphic info */
typedef struct {
	Display *dpy;
	Window win;
	Atom wmdeletewin, netwmname;
	Visual *vis;
	XSetWindowAttributes attrs;
	int scr;
	int w, h;
	int uw, uh; /* usable dimensions for drawing text and images */
} XWindow;

typedef union {
	int i;
	unsigned int ui;
	float f;
	const void *v;
} Arg;

typedef struct {
	unsigned int b;
	void (*func)(const Arg *);
	const Arg arg;
} Mousekey;

typedef struct {
	KeySym keysym;
	void (*func)(const Arg *);
	const Arg arg;
} Shortcut;

static Image *pngopen(char *filename);
static int pngread(Image *img);
static int pngprepare(Image *img);
static void pngscale(Image *img);
static void pngdraw(Image *img);

static void getfontsize(char *str, unsigned int *width, unsigned int *height);
static void cleanup();
static void eprintf(const char *, ...);
static void die(const char *, ...);
static void load(FILE *fp);
static void advance(const Arg *arg);
static void quit(const Arg *arg);
static void resize(int width, int height);
static void run();
static void usage();
static void xdraw();
static void xhints();
static void xinit();
static void xloadfonts();

static void bpress(XEvent *);
static void cmessage(XEvent *);
static void expose(XEvent *);
static void kpress(XEvent *);
static void configure(XEvent *);

/* config.h for applying patches and the configuration. */
#include "config.h"

/* Globals */
static Slide *slides = NULL;
static int idx = 0;
static int slidecount = 0;
static XWindow xw;
static Drw *d = NULL;
static Scm *sc;
static Fnt *fonts[NUMFONTSCALES];
static int running = 1;

static void (*handler[LASTEvent])(XEvent *) = {
	[ButtonPress] = bpress,
	[ClientMessage] = cmessage,
	[ConfigureNotify] = configure,
	[Expose] = expose,
	[KeyPress] = kpress,
};

Image *pngopen(char *filename)
{
	FILE *f;
	unsigned char buf[8];
	Image *img;

	if (!(f = fopen(filename, "rb"))) {
		eprintf("could not open file %s:", filename);
		return NULL;
	}

	if (fread(buf, 1, 8, f) != 8 || png_sig_cmp(buf, 1, 8))
		return NULL;

	img = malloc(sizeof(Image));
	if (!(img->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
					NULL, NULL))) {
		free(img);
		return NULL;
	}
	if (!(img->info_ptr = png_create_info_struct(img->png_ptr))) {
		png_destroy_read_struct(&img->png_ptr, NULL, NULL);
		free(img);
		return NULL;
	}
	if (setjmp(png_jmpbuf(img->png_ptr))) {
		png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
		free(img);
		return NULL;
	}

	img->f = f;
	rewind(f);
	png_init_io(img->png_ptr, f);
	png_read_info(img->png_ptr, img->info_ptr);
	img->bufwidth = png_get_image_width(img->png_ptr, img->info_ptr);
	img->bufheight = png_get_image_height(img->png_ptr, img->info_ptr);

	return img;
}

int pngread(Image *img)
{
	unsigned int y;
	png_bytepp row_pointers;

	if (!img)
		return 0;

	if (img->state & LOADED)
		return 2;

	if (img->buf)
		free(img->buf);
	if (!(img->buf = malloc(3 * img->bufwidth * img->bufheight)))
		return 0;

	if (setjmp(png_jmpbuf(img->png_ptr))) {
		png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
		return 0;
	}

	{
		int color_type = png_get_color_type(img->png_ptr, img->info_ptr);
		int bit_depth = png_get_bit_depth(img->png_ptr, img->info_ptr);
		if (color_type == PNG_COLOR_TYPE_PALETTE)
			png_set_expand(img->png_ptr);
		if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
			png_set_expand(img->png_ptr);
		if (png_get_valid(img->png_ptr, img->info_ptr, PNG_INFO_tRNS))
			png_set_expand(img->png_ptr);
		if (bit_depth == 16)
			png_set_strip_16(img->png_ptr);
		if (color_type == PNG_COLOR_TYPE_GRAY
				|| color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
			png_set_gray_to_rgb(img->png_ptr);

		png_color_16 my_background = {.red = 0xff, .green = 0xff, .blue = 0xff};
		png_color_16p image_background;

		if (png_get_bKGD(img->png_ptr, img->info_ptr, &image_background))
			png_set_background(img->png_ptr, image_background, PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
		else
			png_set_background(img->png_ptr, &my_background, PNG_BACKGROUND_GAMMA_SCREEN, 2, 1.0);

		if (png_get_interlace_type(img->png_ptr, img->info_ptr) == PNG_INTERLACE_ADAM7)
			img->numpasses = png_set_interlace_handling(img->png_ptr);
		else
			img->numpasses = 1;
		png_read_update_info(img->png_ptr, img->info_ptr);
	}

	row_pointers = (png_bytepp)malloc(img->bufheight * sizeof(png_bytep));
	for (y = 0; y < img->bufheight; y++)
		row_pointers[y] = img->buf + y * img->bufwidth * 3;

	png_read_image(img->png_ptr, row_pointers);
	free(row_pointers);

	png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
	fclose(img->f);
	img->state |= LOADED;

	return 1;
}

int pngprepare(Image *img)
{
	int depth = DefaultDepth(xw.dpy, xw.scr);
	int width = xw.uw;
	int height = xw.uh;

	if (xw.uw * img->bufheight > xw.uh * img->bufwidth)
		width = img->bufwidth * xw.uh / img->bufheight;
	else
		height = img->bufheight * xw.uw / img->bufwidth;

	if (depth < 24) {
		eprintf("display depths <24 not supported.");
		return 0;
	}

	if (!(img->ximg = XCreateImage(xw.dpy, CopyFromParent, depth, ZPixmap, 0,
				NULL, width, height, 32, 0))) {
		eprintf("could not create XImage");
		return 0;
	}

	if (!(img->ximg->data = malloc(img->ximg->bytes_per_line * height))) {
		eprintf("could not alloc data section for XImage");
		XDestroyImage(img->ximg);
		img->ximg = NULL;
		return 0;
	}

	if (!XInitImage(img->ximg)) {
		eprintf("could not init XImage");
		free(img->ximg->data);
		XDestroyImage(img->ximg);
		img->ximg = NULL;
		return 0;
	}

	pngscale(img);
	img->state |= SCALED;
	return 1;
}

void pngscale(Image *img)
{
	unsigned int x, y;
	unsigned int width = img->ximg->width;
	unsigned int height = img->ximg->height;
	char* newBuf = img->ximg->data;
	unsigned char* ibuf;
	unsigned int jdy = img->ximg->bytes_per_line / 4 - width;
	unsigned int dx = (img->bufwidth << 10) / width;

	for (y = 0; y < height; y++) {
		unsigned int bufx = img->bufwidth / width;
		ibuf = &img->buf[y * img->bufheight / height * img->bufwidth * 3];

		for (x = 0; x < width; x++) {
			*newBuf++ = (ibuf[(bufx >> 10)*3+2]);
			*newBuf++ = (ibuf[(bufx >> 10)*3+1]);
			*newBuf++ = (ibuf[(bufx >> 10)*3+0]);
			newBuf++;
			bufx += dx;
		}
		newBuf += jdy;
	}
}

void pngdraw(Image *img)
{
	int xoffset = (xw.w - img->ximg->width) / 2;
	int yoffset = (xw.h - img->ximg->height) / 2;
	XPutImage(xw.dpy, xw.win, d->gc, img->ximg, 0, 0,
			xoffset, yoffset, img->ximg->width, img->ximg->height);
	XFlush(xw.dpy);
	img->state |= DRAWN;
}

void getfontsize(char *str, unsigned int *width, unsigned int *height)
{
	size_t i;

	for (i = 0; i < NUMFONTSCALES; i++) {
		drw_setfontset(d, fonts[i]);
		*height = fonts[i]->h;
		*width = drw_fontset_getwidth(d, str);
		if (*width  > xw.uw || *height > xw.uh)
			break;
	}
	if (i > 0) {
		drw_setfontset(d, fonts[i-1]);
		*height = fonts[i-1]->h;
		*width = drw_fontset_getwidth(d, str);
	}
	*width += d->fonts->h;
}

void cleanup()
{
	drw_scm_free(sc);
	drw_free(d);

	XDestroyWindow(xw.dpy, xw.win);
	XSync(xw.dpy, False);
	XCloseDisplay(xw.dpy);
	if (slides) {
		free(slides);
		slides = NULL;
	}
}

void die(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);

	if (fmt[0] != '\0' && fmt[strlen(fmt)-1] == ':') {
		fputc(' ', stderr);
		perror(NULL);
	} else {
		fputc('\n', stderr);
	}
	exit(1);
}

void eprintf(const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);

	if (fmt[0] != '\0' && fmt[strlen(fmt)-1] == ':') {
		fputc(' ', stderr);
		perror(NULL);
	} else {
		fputc('\n', stderr);
	}
}

void load(FILE *fp)
{
	static size_t size = 0;
	char buf[BUFSIZ], *p;
	size_t i = slidecount;

	/* read each line from fp and add it to the item list */
	while (fgets(buf, sizeof(buf), fp)) {
		if ((i+1) * sizeof(*slides) >= size)
			if (!(slides = realloc(slides, (size += BUFSIZ))))
				die("cannot realloc %u bytes:", size);
		if (*buf == '#')
			continue;
		if ((p = strchr(buf, '\n')))
			*p = '\0';
		if (!(slides[i].text = strdup(buf)))
			die("cannot strdup %u bytes:", strlen(buf)+1);
		if (slides[i].text[0] == '@')
			slides[i].img = pngopen(slides[i].text + 1);
		i++;
	}
	if (slides)
		slides[i].text = NULL;
	slidecount = i;
}

void advance(const Arg *arg)
{
	int new_idx = idx + arg->i;
	LIMIT(new_idx, 0, slidecount-1);
	if (new_idx != idx) {
		if (slides[idx].img)
			slides[idx].img->state &= ~(DRAWN | SCALED);
		idx = new_idx;
		xdraw();
		if (slidecount > idx + 1 && slides[idx + 1].img && !pngread(slides[idx + 1].img))
			die("could not read image %s", slides[idx + 1].text + 1);
		if (0 < idx && slides[idx - 1].img && !pngread(slides[idx - 1].img))
			die("could not read image %s", slides[idx - 1].text + 1);
	}
}

void quit(const Arg *arg)
{
	running = 0;
}

void resize(int width, int height)
{
	xw.w = width;
	xw.h = height;
	xw.uw = usablewidth * width;
	xw.uh = usableheight * height;
	drw_resize(d, width, height);
}

void run()
{
	XEvent ev;

	/* Waiting for window mapping */
	while (1) {
		XNextEvent(xw.dpy, &ev);
		if (ev.type == ConfigureNotify) {
			resize(ev.xconfigure.width, ev.xconfigure.height);
		} else if (ev.type == MapNotify) {
			break;
		}
	}

	while (running) {
		XNextEvent(xw.dpy, &ev);
		if (handler[ev.type])
			(handler[ev.type])(&ev);
	}
}

void usage()
{
	die("sent " VERSION " (c) 2014-2015 markus.teich@stusta.mhn.de\n" \
	"usage: sent FILE1 [FILE2 ...]", argv0);
}

void xdraw()
{
	unsigned int height, width;
	Image *im = slides[idx].img;

	getfontsize(slides[idx].text, &width, &height);
	XClearWindow(xw.dpy, xw.win);

	if (!im) {
		drw_rect(d, 0, 0, xw.w, xw.h, 1, 1);
		drw_text(d, (xw.w - width) / 2, (xw.h - height) / 2, width, height, slides[idx].text, 0);
		drw_map(d, xw.win, 0, 0, xw.w, xw.h);
	} else if (!(im->state & LOADED) && !pngread(im)) {
		eprintf("could not read image %s", slides[idx].text + 1);
	} else if (!(im->state & SCALED) && !pngprepare(im)) {
		eprintf("could not prepare image %s for drawing", slides[idx].text + 1);
	} else if (!(im->state & DRAWN)) {
		pngdraw(im);
	}
}

void xhints()
{
	XClassHint class = {.res_name = "sent", .res_class = "presenter"};
	XWMHints wm = {.flags = InputHint, .input = True};
	XSizeHints *sizeh = NULL;

	if (!(sizeh = XAllocSizeHints()))
		die("sent: Could not alloc size hints");

	sizeh->flags = PSize;
	sizeh->height = xw.h;
	sizeh->width = xw.w;

	XSetWMProperties(xw.dpy, xw.win, NULL, NULL, NULL, 0, sizeh, &wm, &class);
	XFree(sizeh);
}

void xinit()
{
	XTextProperty prop;

	if (!(xw.dpy = XOpenDisplay(NULL)))
		die("Can't open display.");
	xw.scr = XDefaultScreen(xw.dpy);
	xw.vis = XDefaultVisual(xw.dpy, xw.scr);
	xw.w = DisplayWidth(xw.dpy, xw.scr);
	xw.h = DisplayHeight(xw.dpy, xw.scr);

	xw.attrs.background_pixel = WhitePixel(xw.dpy, xw.scr);
	xw.attrs.bit_gravity = CenterGravity;
	xw.attrs.event_mask = KeyPressMask | ExposureMask | StructureNotifyMask
		| ButtonMotionMask | ButtonPressMask;

	xw.win = XCreateWindow(xw.dpy, XRootWindow(xw.dpy, xw.scr), 0, 0,
			xw.w, xw.h, 0, XDefaultDepth(xw.dpy, xw.scr), InputOutput, xw.vis,
			CWBackPixel | CWBitGravity | CWEventMask, &xw.attrs);

	xw.wmdeletewin = XInternAtom(xw.dpy, "WM_DELETE_WINDOW", False);
	xw.netwmname = XInternAtom(xw.dpy, "_NET_WM_NAME", False);
	XSetWMProtocols(xw.dpy, xw.win, &xw.wmdeletewin, 1);

	if (!(d = drw_create(xw.dpy, xw.scr, xw.win, xw.w, xw.h)))
		die("Can't create drawing context.");
	sc = drw_scm_create(d, fgcol, bgcol);
	drw_setscheme(d, sc);

	xloadfonts();

	XStringListToTextProperty(&argv0, 1, &prop);
	XSetWMName(xw.dpy, xw.win, &prop);
	XSetTextProperty(xw.dpy, xw.win, &prop, xw.netwmname);
	XFree(prop.value);
	XMapWindow(xw.dpy, xw.win);
	xhints();
	XSync(xw.dpy, False);
}

void xloadfonts()
{
	int i, j;
	char *fstrs[LEN(fontfallbacks)];

	for (j = 0; j < LEN(fontfallbacks); j++) {
		if (!(fstrs[j] = malloc(MAXFONTSTRLEN)))
			die("could not malloc fstrs");
	}

	for (i = 0; i < NUMFONTSCALES; i++) {
		for (j = 0; j < LEN(fontfallbacks); j++) {
			if (MAXFONTSTRLEN < snprintf(fstrs[j], MAXFONTSTRLEN, "%s:size=%d", fontfallbacks[j], FONTSZ(i)))
				die("font string too long");
		}
		fonts[i] = drw_fontset_create(d, (const char**)fstrs, LEN(fstrs));
	}
}

void bpress(XEvent *e)
{
	unsigned int i;

	for (i = 0; i < LEN(mshortcuts); i++)
		if (e->xbutton.button == mshortcuts[i].b && mshortcuts[i].func)
			mshortcuts[i].func(&(mshortcuts[i].arg));
}

void cmessage(XEvent *e)
{
	if (e->xclient.data.l[0] == xw.wmdeletewin)
		running = 0;
}

void expose(XEvent *e)
{
	if (0 == e->xexpose.count)
		xdraw();
}

void kpress(XEvent *e)
{
	unsigned int i;
	KeySym sym;

	sym = XkbKeycodeToKeysym(xw.dpy, (KeyCode)e->xkey.keycode, 0, 0);
	for (i = 0; i < LEN(shortcuts); i++)
		if (sym == shortcuts[i].keysym && shortcuts[i].func)
			shortcuts[i].func(&(shortcuts[i].arg));
}

void configure(XEvent *e)
{
	resize(e->xconfigure.width, e->xconfigure.height);
	if (slides[idx].img)
		slides[idx].img->state &= ~(DRAWN | SCALED);
	xdraw();
}

int main(int argc, char *argv[])
{
	int i;
	FILE *fp = NULL;

	ARGBEGIN {
	case 'v':
	default:
		usage();
	} ARGEND;

	for (i = 0; i < argc; i++) {
		if ((fp = strcmp(argv[i], "-") ? fopen(argv[i], "r") : stdin)) {
			load(fp);
			fclose(fp);
		} else {
			eprintf("could not open %s for reading:", argv[i]);
		}
	}

	if (!slides || !slides[0].text)
		usage();

	xinit();
	run();

	cleanup();
	return EXIT_SUCCESS;
}