// Taken from https://github.com/mackstann/tinywm

#include <X11/Xlib.h>
#include <X11/keysym.h>
#include <X11/XKBlib.h>

#define MODMASK Mod1Mask
#define MAX(a, b) ((a) > (b) ? (a) : (b))

static Window root;

static Display* dpy;
static XWindowAttributes attr;
static XButtonEvent start;

void grab_input(Window* root) {
    XGrabKey(dpy, XKeysymToKeycode(dpy, XStringToKeysym("1")), MODMASK, *root, True, GrabModeAsync, GrabModeAsync);
    XGrabKey(dpy, XKeysymToKeycode(dpy, XStringToKeysym("Q")), MODMASK, *root, True, GrabModeAsync, GrabModeAsync);
    XGrabButton(dpy, 1, MODMASK, *root, True, ButtonPressMask|ButtonReleaseMask|PointerMotionMask, GrabModeAsync, GrabModeAsync, None, None);
    XGrabButton(dpy, 3, MODMASK, *root, True, ButtonPressMask|ButtonReleaseMask|PointerMotionMask, GrabModeAsync, GrabModeAsync, None, None);
}

void handle_event_keypress(XEvent *e) {
    if (e->xkey.subwindow != None) {
        KeySym keysym = XkbKeycodeToKeysym(dpy, e->xkey.keycode, 0, 0);
        if (keysym == XK_q) {
            XKillClient(dpy, e->xkey.subwindow);
        } else if (keysym == XK_1) {
            XRaiseWindow(dpy, e->xkey.subwindow);
        }
    }
}

void handle_event_buttonpress(XEvent *e) {
    if (e->xkey.subwindow != None) {
        XGetWindowAttributes(dpy, e->xbutton.subwindow, &attr);
        start = e->xbutton;
    }
}

void handle_event_motionnotify(XEvent *e) {
    if (start.subwindow != None) {
        int xdiff = e->xbutton.x_root - start.x_root;
        int ydiff = e->xbutton.y_root - start.y_root;
        XMoveResizeWindow(dpy, start.subwindow,
            attr.x + (start.button==1 ? xdiff : 0),
            attr.y + (start.button==1 ? ydiff : 0),
            MAX(1, attr.width + (start.button==3 ? xdiff : 0)),
            MAX(1, attr.height + (start.button==3 ? ydiff : 0)));
    }
}

void handle_event_buttonrelease(XEvent *e) {
    start.subwindow = None;
}

void handle_event_mappingnotify(XEvent *e) {
    XMappingEvent *ev = &e->xmapping;

    if (ev->request == MappingKeyboard || ev->request == MappingModifier) {
        XRefreshKeyboardMapping(ev);
        grab_input(&root);
    }
}

static void (*event_handlers[LASTEvent])(XEvent *e) = {
    [KeyPress] = handle_event_keypress,
    [ButtonPress] = handle_event_buttonpress,
    [ButtonRelease] = handle_event_buttonrelease,
    [MotionNotify] = handle_event_motionnotify,

    // Below are events that are not 100% needed but without them some programs may break!
    // TODO: MapRequest, ConfigureRequest
    [MappingNotify] = handle_event_mappingnotify
};

int main() {
    if(!(dpy = XOpenDisplay(0x0))) return 1;

    XEvent ev;
    root = DefaultRootWindow(dpy);
    grab_input(&root);
    start.subwindow = None;

    for (;;) {
        XNextEvent(dpy, &ev);
        if (event_handlers[ev.type]) event_handlers[ev.type](&ev);
    }
    return 0;
}