#define _XOPEN_SOURCE 700
#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <ctype.h>
#include <grp.h>
#include <pwd.h>
#if HAVE_SHADOW_H
#include <shadow.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <crypt.h>
#include "../accent.h"

#define WIDTH 400
#define HEIGHT 100

static int
auth(const char *user, const char *pass)
{
	struct passwd *pw = getpwnam(user);
	const char *hash;
	if (!pw)
		return 0;
#if HAVE_SHADOW_H
	struct spwd *sp = getspnam(user);
	hash = sp ? sp->sp_pwdp : pw->pw_passwd;
#else
	hash = pw->pw_passwd;
#endif
	if (!hash || hash[0] == '!' || hash[0] == '*')
		return 0;
	return strcmp(crypt(pass, hash), hash) == 0;
}

static void
draw(Display *dpy, Window win, GC gc, const char *prompt,
     const char *input, int hidden)
{
	XClearWindow(dpy, win);
	XDrawString(dpy, win, gc, 10, 25, prompt, strlen(prompt));
	if (input && *input) {
		char buf[128];
		const char *show = input;
		if (hidden) {
			size_t n = strlen(input);
			if (n >= sizeof buf)
				n = sizeof buf - 1;
			memset(buf, '*', n);
			buf[n] = '\0';
			show = buf;
		}
		XDrawString(dpy, win, gc, 10, 50, show, strlen(show));
	}
	XFlush(dpy);
}

int
main(void)
{
	Display *dpy;
	Window win;
	XEvent ev;
	GC gc;
	XFontStruct *font;
	int screen;
	Colormap cmap;
	XColor xcol;
	ColorShm *blk = NULL;
	char accent[8] = "#005577";

	if (!(dpy = XOpenDisplay(NULL))) {
		fprintf(stderr, "slogin: cannot open display\n");
		return 1;
	}
	readaccent(&blk, accent);
	screen = DefaultScreen(dpy);
	cmap = DefaultColormap(dpy, screen);
	XParseColor(dpy, cmap, accent, &xcol);
	XAllocColor(dpy, cmap, &xcol);
	win = XCreateSimpleWindow(dpy, RootWindow(dpy, screen),
		DisplayWidth(dpy, screen)/2 - WIDTH/2,
		DisplayHeight(dpy, screen)/2 - HEIGHT/2,
		WIDTH, HEIGHT, 2, xcol.pixel, BlackPixel(dpy, screen));
	XStoreName(dpy, win, "slogin");
	XSelectInput(dpy, win, ExposureMask | KeyPressMask);
	XMapRaised(dpy, win);
	gc = XCreateGC(dpy, win, 0, NULL);
	XSetForeground(dpy, gc, xcol.pixel);
	font = XLoadQueryFont(dpy, "fixed");
	if (font)
		XSetFont(dpy, gc, font->fid);

	char user[64] = "";
	char pass[64] = "";
	int stage = 0;
	draw(dpy, win, gc, "user:", user, 0);

	for (;;) {
		if (XPending(dpy)) {
			XNextEvent(dpy, &ev);
			if (ev.type == Expose) {
				draw(dpy, win, gc, stage ? "pass:" : "user:",
					stage ? pass : user, stage);
			} else if (ev.type == KeyPress) {
				char buf[32];
				KeySym ksym;
				int len = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, NULL);
				if (ksym == XK_Return) {
					if (stage == 0) {
						stage = 1;
						draw(dpy, win, gc, "pass:", pass, 1);
					} else {
						if (auth(user, pass)) {
							struct passwd *pw = getpwnam(user);
							if (!pw)
								exit(1);
							chdir(pw->pw_dir);
							setenv("HOME", pw->pw_dir, 1);
							setenv("SHELL", pw->pw_shell, 1);
							setenv("USER", pw->pw_name, 1);
							setenv("LOGNAME", pw->pw_name, 1);
							initgroups(pw->pw_name, pw->pw_gid);
							setgid(pw->pw_gid);
							setuid(pw->pw_uid);
							execlp(pw->pw_shell, pw->pw_shell, "-l", NULL);
							perror("execlp");
							exit(1);
						} else {
							user[0] = pass[0] = '\0';
							stage = 0;
							draw(dpy, win, gc, "user:", user, 0);
						}
					}
				} else if (ksym == XK_BackSpace) {
					if (stage == 0) {
						size_t n = strlen(user);
						if (n) user[n-1] = '\0';
						draw(dpy, win, gc, "user:", user, 0);
					} else {
						size_t n = strlen(pass);
						if (n) pass[n-1] = '\0';
						draw(dpy, win, gc, "pass:", pass, 1);
					}
				} else if (len && !iscntrl((unsigned char)buf[0])) {
					if (stage == 0 && strlen(user) + len < sizeof user - 1) {
						strncat(user, buf, len);
						draw(dpy, win, gc, "user:", user, 0);
					} else if (stage == 1 && strlen(pass) + len < sizeof pass - 1) {
						strncat(pass, buf, len);
						draw(dpy, win, gc, "pass:", pass, 1);
					}
				}
			}
		}
		if (readaccent(&blk, accent)) {
			XParseColor(dpy, cmap, accent, &xcol);
			XAllocColor(dpy, cmap, &xcol);
			XSetForeground(dpy, gc, xcol.pixel);
			XSetWindowBorder(dpy, win, xcol.pixel);
		}
		usleep(20000);
	}
}