/* See LICENSE file for license details. */
#define _XOPEN_SOURCE 700
#include <X11/Xlib.h>
#include <X11/Xft/Xft.h>
#include <X11/keysym.h>
#include <unistd.h>
#include <pwd.h>
#include <grp.h>
#include <shadow.h>
#include <crypt.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>

#include "../accent.h"
#include "config.h"

static ColorShm *accentshm;
static char accentcol[8] = "#005577";

static void
die(const char *fmt, ...)
{
    va_list ap;
    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);
    exit(1);
}

static void
updateaccent(void)
{
    if (!readaccent(&accentshm, accentcol))
        memcpy(accentcol, "#005577", 8);
}

static const char *
gethash(const char *user)
{
    struct passwd *pw;
    const char *hash;
    if (!(pw = getpwnam(user)))
        return NULL;
    hash = pw->pw_passwd;
#if HAVE_SHADOW_H
    if (!strcmp(hash, "x")) {
        struct spwd *sp;
        if (!(sp = getspnam(user)))
            return NULL;
        hash = sp->sp_pwdp;
    }
#endif
    return hash;
}

static int
auth(const char *user, const char *pass)
{
    const char *hash = gethash(user);
    char *cryptpw;
    if (!hash)
        return 0;
    if (!(cryptpw = crypt(pass, hash)))
        return 0;
    return !strcmp(cryptpw, hash);
}

static void
runsession(const char *user, const char *pass)
{
    struct passwd *pw;
    if (!auth(user, pass))
        return;
    if (!(pw = getpwnam(user)))
        return;
    if (initgroups(user, pw->pw_gid) < 0)
        die("slogin: initgroups failed\n");
    if (setgid(pw->pw_gid) < 0)
        die("slogin: setgid failed\n");
    if (setuid(pw->pw_uid) < 0)
        die("slogin: setuid failed\n");
    setenv("HOME", pw->pw_dir, 1);
    chdir(pw->pw_dir);
    setsid();
    execvp(logincmd[0], (char *const *)logincmd);
    die("slogin: exec failed\n");
}

static void
drawscreen(Display *dpy, Window win, XftDraw *draw, XftFont *font,
           XftColor *fg, XftColor *accent,
           const char *user, const char *pass, int stage)
{
    char buf[256];
    int width = DisplayWidth(dpy, DefaultScreen(dpy));
    int height = DisplayHeight(dpy, DefaultScreen(dpy));
    int w = 400, h = 100;
    int x = (width - w)/2;
    int y = (height - h)/2;
    GC gc = DefaultGC(dpy, DefaultScreen(dpy));

    XClearWindow(dpy, win);
    XSetForeground(dpy, gc, accent->pixel);
    XDrawRectangle(dpy, win, gc, x, y, w, h);

    if (stage == 0)
        snprintf(buf, sizeof buf, "login: %s", user);
    else {
        char stars[sizeof buf];
        size_t i, len = strlen(pass);
        for (i = 0; i < len && i < sizeof stars - 1; i++)
            stars[i] = '*';
        stars[i] = '\0';
        snprintf(buf, sizeof buf, "password: %s", stars);
    }
    XftDrawStringUtf8(draw, fg, font, x + 20, y + h/2 + font->ascent/2,
                      (XftChar8 *)buf, strlen(buf));
    XFlush(dpy);
}

int
main(void)
{
    Display *dpy;
    int scr;
    Window root, win;
    XEvent ev;
    XftDraw *xdraw;
    XftFont *font;
    XftColor xfg, xbg, xaccent;
    char user[64] = "", pass[64] = "";
    int stage = 0;
    KeySym ksym;
    char buf[32];
    int len;

    updateaccent();
    if (!(dpy = XOpenDisplay(NULL)))
        die("slogin: cannot open display\n");
    scr = DefaultScreen(dpy);
    root = RootWindow(dpy, scr);
    win = XCreateSimpleWindow(dpy, root, 0, 0,
        DisplayWidth(dpy, scr), DisplayHeight(dpy, scr),
        0, BlackPixel(dpy, scr), BlackPixel(dpy, scr));
    XSelectInput(dpy, win, KeyPressMask | ExposureMask);
    XMapRaised(dpy, win);

    font = XftFontOpenName(dpy, scr, fontname);
    if (!font)
        die("slogin: cannot load font\n");
    xdraw = XftDrawCreate(dpy, win, DefaultVisual(dpy, scr), DefaultColormap(dpy, scr));
    XftColorAllocName(dpy, DefaultVisual(dpy, scr), DefaultColormap(dpy, scr), fgcolor, &xfg);
    XftColorAllocName(dpy, DefaultVisual(dpy, scr), DefaultColormap(dpy, scr), bgcolor, &xbg);
    XftColorAllocName(dpy, DefaultVisual(dpy, scr), DefaultColormap(dpy, scr), accentcol, &xaccent);
    XSetWindowBackground(dpy, win, xbg.pixel);
    XClearWindow(dpy, win);

    for (;;) {
        XNextEvent(dpy, &ev);
        if (ev.type == Expose) {
            drawscreen(dpy, win, xdraw, font, &xfg, &xaccent,
                       user, pass, stage);
        } else if (ev.type == KeyPress) {
            len = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, NULL);
            if (ksym == XK_Return) {
                if (stage == 0)
                    stage = 1;
                else {
                    runsession(user, pass);
                    stage = 0;
                    user[0] = pass[0] = '\0';
                }
            } else if (ksym == XK_BackSpace) {
                if (stage == 0 && strlen(user) > 0)
                    user[strlen(user)-1] = '\0';
                else if (stage == 1 && strlen(pass) > 0)
                    pass[strlen(pass)-1] = '\0';
            } else if (len && buf[0] >= ' ' && buf[0] <= '~') {
                if (stage == 0 && strlen(user) + len < sizeof user) {
                    strncat(user, buf, len);
                    user[strlen(user)] = '\0';
                } else if (stage == 1 && strlen(pass) + len < sizeof pass) {
                    strncat(pass, buf, len);
                    pass[strlen(pass)] = '\0';
                }
            }
            drawscreen(dpy, win, xdraw, font, &xfg, &xaccent,
                       user, pass, stage);
        }
    }
}