/*
 * vim:ts=8:expandtab
 *
 * i3lock - an improved version of slock
 *
 * i3lock © 2009 Michael Stapelberg and contributors
 * slock  © 2006-2008 Anselm R Garbe
 *
 * See file LICENSE for license information.
 *
 * Note that on any error (calloc is out of memory for example)
 * we do not do anything so that the user can fix the error by
 * himself (kill X to get more free memory or stop some other
 * program using SSH/console).
 *
 */
#define _XOPEN_SOURCE 500

#include <ctype.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <X11/keysym.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/dpms.h>
#include <stdbool.h>
#include <getopt.h>

#include <security/pam_appl.h>

static char passwd[256];

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

        va_start(ap, errstr);
        vfprintf(stderr, errstr, ap);
        va_end(ap);
        exit(EXIT_FAILURE);
}

/*
 * Callback function for PAM. We only react on password request callbacks.
 *
 */
static int conv_callback(int num_msg, const struct pam_message **msg,
                         struct pam_response **resp, void *appdata_ptr) {
        if (num_msg == 0)
                return 1;

        /* PAM expects an arry of responses, one for each message */
        if ((*resp = calloc(num_msg, sizeof(struct pam_message))) == NULL) {
                perror("calloc");
                return 1;
        }

        for (int c = 0; c < num_msg; c++) {
                if (msg[c]->msg_style != PAM_PROMPT_ECHO_OFF &&
                    msg[c]->msg_style != PAM_PROMPT_ECHO_ON)
                        continue;

                /* return code is currently not used but should be set to zero */
                resp[c]->resp_retcode = 0;
                if ((resp[c]->resp = strdup(passwd)) == NULL) {
                        perror("strdup");
                        return 1;
                }
        }

        return 0;
}

int main(int argc, char *argv[]) {
        char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
        char buf[32];
        char *username;
        int num, screen;

        unsigned int len;
        bool running = true;

        /* By default, fork, don’t beep and don’t turn off monitor */
        bool dont_fork = false;
        bool beep = false;
        bool dpms = false;
        Cursor invisible;
        Display *dpy;
        KeySym ksym;
        Pixmap pmap;
        Window root, w;
        XColor black, dummy;
        XEvent ev;
        XSetWindowAttributes wa;

        pam_handle_t *handle;
        struct pam_conv conv = {conv_callback, NULL};

        char opt;
        int optind = 0;
        static struct option long_options[] = {
                {"version", no_argument, NULL, 'v'},
                {"nofork", no_argument, NULL, 'n'},
                {"beep", no_argument, NULL, 'b'},
                {"dpms", no_argument, NULL, 'd'},
                {NULL, no_argument, NULL, 0}
        };

        while ((opt = getopt_long(argc, argv, "vnbd", long_options, &optind)) != -1) {
                switch (opt) {
                        case 'v':
                                die("i3lock-"VERSION", © 2009 Michael Stapelberg\n"
                                    "based on slock, which is © 2006-2008 Anselm R Garbe\n");
                        case 'n':
                                dont_fork = true;
                                break;
                        case 'b':
                                beep = true;
                                break;
                        case 'd':
                                dpms = true;
                                break;
                        default:
                                die("i3lock: Unknown option. Syntax: i3lock [-v] [-n] [-b] [-d]\n");
                }
        }

        if ((username = getenv("USER")) == NULL)
                die("USER environment variable not set, please set it.\n");

        int ret = pam_start("i3lock", username, &conv, &handle);
        if (ret != PAM_SUCCESS)
                die("PAM: %s\n", pam_strerror(handle, ret));

        if(!(dpy = XOpenDisplay(0)))
                die("i3lock: cannot open display\n");
        screen = DefaultScreen(dpy);
        root = RootWindow(dpy, screen);

        if (!dont_fork) {
                if (fork() != 0)
                        return 0;
        }

        /* init */
        wa.override_redirect = 1;
        wa.background_pixel = WhitePixel(dpy, screen);
        w = XCreateWindow(dpy, root, 0, 0, DisplayWidth(dpy, screen), DisplayHeight(dpy, screen),
                        0, DefaultDepth(dpy, screen), CopyFromParent,
                        DefaultVisual(dpy, screen), CWOverrideRedirect | CWBackPixel, &wa);
        XAllocNamedColor(dpy, DefaultColormap(dpy, screen), "black", &black, &dummy);
        pmap = XCreateBitmapFromData(dpy, w, curs, 8, 8);
        invisible = XCreatePixmapCursor(dpy, pmap, pmap, &black, &black, 0, 0);
        XDefineCursor(dpy, w, invisible);
        XMapRaised(dpy, w);
        for(len = 1000; len; len--) {
                if(XGrabPointer(dpy, root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
                        GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
                        break;
                usleep(1000);
        }
        if((running = running && (len > 0))) {
                for(len = 1000; len; len--) {
                        if(XGrabKeyboard(dpy, root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
                                == GrabSuccess)
                                break;
                        usleep(1000);
                }
                running = (len > 0);
        }
        len = 0;
        XSync(dpy, False);

        /* main event loop */
        while(running && !XNextEvent(dpy, &ev)) {
                if (len == 0 && dpms && DPMSCapable(dpy)) {
                        DPMSEnable(dpy);
                        DPMSForceLevel(dpy, DPMSModeOff);
                }

                if(ev.type != KeyPress)
                        continue;

                buf[0] = 0;
                num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
                if(IsKeypadKey(ksym)) {
                        if(ksym == XK_KP_Enter)
                                ksym = XK_Return;
                        else if(ksym >= XK_KP_0 && ksym <= XK_KP_9)
                                ksym = (ksym - XK_KP_0) + XK_0;
                }
                if(IsFunctionKey(ksym) ||
                   IsKeypadKey(ksym) ||
                   IsMiscFunctionKey(ksym) ||
                   IsPFKey(ksym) ||
                   IsPrivateKeypadKey(ksym))
                        continue;
                switch(ksym) {
                case XK_Return:
                        passwd[len] = 0;
                        if ((ret = pam_authenticate(handle, 0)) == PAM_SUCCESS)
                                running = false;
                        else {
                                fprintf(stderr, "PAM: %s\n", pam_strerror(handle, ret));
                                if (beep)
                                        XBell(dpy, 100);
                        }
                        len = 0;
                        break;
                case XK_Escape:
                        len = 0;
                        break;
                case XK_BackSpace:
                        if (len > 0)
                                len--;
                        break;
                default:
                        if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
                                memcpy(passwd + len, buf, num);
                                len += num;
                        }
                        break;
                }
        }
        XUngrabPointer(dpy, CurrentTime);
        XFreePixmap(dpy, pmap);
        XDestroyWindow(dpy, w);
        XCloseDisplay(dpy);
        return 0;
}