/**
 * Xtimer is a program that executes a given command or program after a given
 * time if no X11 keybord or mouse input happend in the given time.
 *
 * Author: Johannes Findeisen <you@hanez.org> - 2025
 * License: Apache-2.0 (see LICENSE)
 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h> // For INT_MAX and INT_MIN
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/extensions/XInput2.h>

int main(int argc, char *argv[])
{
    if (argc < 3) {
        fprintf(stderr, "Usage: %s <seconds> <program> [arguments...]\n",
                argv[0]);
        return EXIT_FAILURE;
    }

    // Validate the first parameter (wait time)
    char *endptr;
    long wait_time = strtol(argv[1], &endptr, 10);

    // Check for valid integer input
    if (*endptr != '\0' || wait_time <= 0 || wait_time > INT_MAX) {
        fprintf(stderr,
"Error: First argument must be a positive integer within the range 1 to %d.\n",
INT_MAX);
        return EXIT_FAILURE;
    }

    // Safely cast the wait_time to an int (it's safe after the above check)
    int wait_time_seconds = (int)wait_time;

    // Initialize X11 display
    Display *display = XOpenDisplay(NULL);
    if (!display) {
        fprintf(stderr, "Error: Unable to open X display.\n");
        return EXIT_FAILURE;
    }

    // Check for XInput2 support
    int opcode, event, error;
    if (!XQueryExtension(display, "XInputExtension", &opcode, &event, &error)) {
        fprintf(stderr,
                "Error: X Input Extension is not supported on this display.\n");
        XCloseDisplay(display);
        return EXIT_FAILURE;
    }

    // Select events to monitor (keyboard, mouse clicks, and motion)
    Window root = DefaultRootWindow(display);
    XIEventMask evmask;
    unsigned char mask[(XI_LASTEVENT + 7) / 8] = {0};
    evmask.deviceid = XIAllDevices;
    evmask.mask_len = sizeof(mask);
    evmask.mask = mask;

    XISetMask(mask, XI_KeyPress);
    XISetMask(mask, XI_KeyRelease);
    XISetMask(mask, XI_ButtonPress);
    XISetMask(mask, XI_ButtonRelease);
    XISetMask(mask, XI_Motion); // Listen for mouse motion events

    if (XISelectEvents(display, root, &evmask, 1) != Success) {
        fprintf(stderr, "Error: Unable to select input events.\n");
        XCloseDisplay(display);
        return EXIT_FAILURE;
    }

    // Timer logic with input monitoring
    time_t start_time, current_time;
    start_time = time(NULL);

    while (1) {
        current_time = time(NULL);

        // Check if the timer has expired
        if (current_time - start_time >= wait_time_seconds) {
            break;
        }

        // Check for input events
        while (XPending(display) > 0) {
            XEvent event;
            XNextEvent(display, &event);

            if (event.xcookie.type == GenericEvent &&
                event.xcookie.extension == opcode && // Use the opcode obtained earlier
                XGetEventData(display, &event.xcookie)) {
                XIDeviceEvent *xi_event = (XIDeviceEvent *)event.xcookie.data;
                if (xi_event->evtype == XI_KeyPress ||
                    xi_event->evtype == XI_ButtonPress ||
                    xi_event->evtype == XI_Motion) {
                    // Reset the timer on input or mouse movement
                    start_time = time(NULL);
                }
                XFreeEventData(display, &event.xcookie);
            }
        }

        // Sleep briefly to reduce CPU usage
        usleep(10000); // 10 milliseconds
    }

    // Close the X display
    XCloseDisplay(display);

    // Execute the program with optional arguments
    execvp(argv[2], &argv[2]);

    // If execvp returns, an error occurred
    perror("Error executing program");
    return EXIT_FAILURE;
}