/* gcc -o pager pager.c -lX11 -lXmu -ldockapp */
#if 0
#include <X11/extensions/Xrender.h>
#endif
#include <X11/Xatom.h>
#include <dockapp.h>

#define DOCKAPP_SIZE 56
#define SPEED 100
#define ACTIVE_DESKTOP 1
#define ACTIVE_WINDOW 2

static GC lightGrayGC, darkGrayGC, active_desktopGC, inactive_desktopGC, active_windowGC, inactive_windowGC;
static Atom num_desktops_atom, current_desktop_atom, client_list_atom, client_desktop_atom, client_state_atom, active_window_atom;
static Atom shaded_state, skip_pager_state, hidden_state;
static long desktop = -1;

int error_handler(Display *display, XErrorEvent *event) {
  char buffer[512];
  int length;

  switch (event->error_code) {
    case BadWindow:
      /* The window may have gone away since we queried the window manager. */
    break;

    default:
      if (XGetErrorText(display, event->error_code, buffer, sizeof(buffer))) {
        fprintf(stderr, "%s\n", buffer);
        exit(100);
      }
    break;
  }

  return 0;
}

void setup_atom(Atom *atom, const char *prop) {
  *atom = XInternAtom(DADisplay, prop, True);
  if (*atom == None) exit(111);
}

void get_atom_longs(Atom atom, Atom type, Window window, long **data, unsigned long *num_items) {
  Atom actual;
  int format;
  unsigned long num_bytes;

  XGetWindowProperty(DADisplay, window, atom, 0, 8192, False, type, &actual, &format, num_items, &num_bytes, (unsigned char **) data);
}

long get_atom_long(Atom atom, Atom type, Window window) {
  long *data;
  long ret = 0;
  unsigned long num_items;

  get_atom_longs(atom, type, window, &data, &num_items);
  if (num_items) ret = data[0];
  XFree(data);

  return ret;
}

void setup_GCs() {
  XGCValues gcv;

  /* GC's */
  gcv.foreground = DAGetColor("darkGray");
  XChangeGC(DADisplay, DAClearGC, GCForeground, &gcv);

  gcv.foreground = DAGetColor("lightGray");
  gcv.graphics_exposures = False;

  lightGrayGC	= XCreateGC(DADisplay, DAWindow, GCForeground|GCGraphicsExposures, &gcv);

  gcv.foreground = DAGetColor("#222222");
  darkGrayGC	=  XCreateGC(DADisplay, DAWindow, GCForeground|GCGraphicsExposures, &gcv);

  gcv.foreground = DAGetColor("#bbbbbb");
  active_desktopGC = XCreateGC(DADisplay, DAWindow, GCForeground|GCGraphicsExposures, &gcv);

  gcv.foreground = DAGetColor("#777777");
  inactive_desktopGC = XCreateGC(DADisplay, DAWindow, GCForeground|GCGraphicsExposures, &gcv);

  gcv.foreground = DAGetColor("#20b2ae");
  active_windowGC = XCreateGC(DADisplay, DAWindow, GCForeground|GCGraphicsExposures, &gcv);

  gcv.foreground = DAGetColor("#999999");
  inactive_windowGC = XCreateGC(DADisplay, DAWindow, GCForeground|GCGraphicsExposures, &gcv);
}

void draw_relief(Pixmap pixmap, unsigned int width, unsigned int height, GC desktopGC) {
  /* Drawing */
  XFillRectangle(DADisplay, pixmap, desktopGC, 0, 0, width, height);

  XDrawLine(DADisplay, pixmap, darkGrayGC, 0, 0, 0, height - 2);
  XDrawLine(DADisplay, pixmap, darkGrayGC, 1, 0, width - 1, 0);

  XDrawLine(DADisplay, pixmap, lightGrayGC, 0, height - 1, width - 1, height - 1);
  XDrawLine(DADisplay, pixmap, lightGrayGC, width - 1, 1, width - 1, height - 2);
}

void change() {
  XEvent event;
  Window root = DefaultRootWindow(DADisplay);

  event.type = ClientMessage;
  event.xclient.type = ClientMessage;
  event.xclient.window = root;
  event.xclient.message_type = current_desktop_atom;
  event.xclient.format = 32;
  event.xclient.data.l[0] = desktop;

  XSendEvent(DADisplay, root, False, SubstructureNotifyMask, &event);
}

void page() {
  Window root, dockapp_root, child, active_window;
  XWindowAttributes attr;
  Pixmap pixmap;
  DARect rect;
  long i, j;
  unsigned long num_clients, num_states;
  unsigned int root_width, root_height;
  unsigned int dockapp_x, dockapp_y, dockapp_width, dockapp_height, dockapp_border, dockapp_depth;
  unsigned int x, y, width, height, border, depth;
  double scale;
  long *clients, *states;
  long client_desktop, active_desktop;
  int active;
  GC gc;

  /* XXX: Use _NET_DESKTOP_GEOMETRY. */
  root_width = DisplayWidth(DADisplay, DefaultScreen(DADisplay));
  root_height = DisplayWidth(DADisplay, DefaultScreen(DADisplay));

  pixmap = DAMakePixmap();
  XGetGeometry(DADisplay, pixmap, &dockapp_root, &dockapp_x, &dockapp_y, &dockapp_width, &dockapp_height, &dockapp_border, &dockapp_depth);
  scale = (double) root_width / (double) dockapp_width;

  active_window = get_atom_long(active_window_atom, XA_WINDOW, dockapp_root);
  active_desktop = get_atom_long(current_desktop_atom, XA_CARDINAL, DefaultRootWindow(DADisplay));

  if (active_desktop == desktop) gc = active_desktopGC;
  else gc = inactive_desktopGC;
  draw_relief(pixmap, dockapp_width, dockapp_height, gc);

  get_atom_longs(client_list_atom, XA_WINDOW, dockapp_root, &clients, &num_clients);
  for (i = 0; i < num_clients; i++) {
    int draw = 1;
    client_desktop = get_atom_long(client_desktop_atom, XA_CARDINAL, clients[i]);
    if (client_desktop != desktop && client_desktop != -1) continue;
    if (! XGetGeometry(DADisplay, clients[i], &root, &x, &y, &width, &height, &border, &depth)) continue;
    if (! XTranslateCoordinates(DADisplay, clients[i], root, x, y, &x, &y, &child)) continue;
    get_atom_longs(client_state_atom, XA_ATOM, clients[i], &states, &num_states);
    for (j = 0; j < num_states; j++) {
      if (states[j] == shaded_state) draw = 0;
      if (states[j] == skip_pager_state) draw = 0;
      if (states[j] == hidden_state) draw = 0;
    }
    if (! draw) continue;

    rect.x = (double) x / scale;
    rect.y = (double) y / scale;
    rect.width = (double) width / scale;
    rect.height = (double) height / scale;

    if (clients[i] == active_window) gc = active_windowGC;
    else gc = inactive_windowGC;
    XFillRectangle(DADisplay, pixmap, gc, rect.x, rect.y, rect.width, rect.height);

    /* Thumbnail. */
#if 0
      XRenderPictureAttributes pa;
      Pixmap client_pixmap = XCreatePixmap(DADisplay, wins[i], width, height, DefaultDepth(DADisplay, DefaultScreen(DADisplay)));
      //XCopyArea(DADisplay, wins[i], client_pixmap, DefaultGC(DADisplay, DefaultScreen(DADisplay)), 0, 0, width, height, 0, 0);
      Picture client_picture = XRenderCreatePicture(DADisplay, client_pixmap, XRenderFindVisualFormat(DADisplay, attr.visual), CPSubwindowMode, &pa);

      XTransform xform = {{
        { XDoubleToFixed(1.0), 0, 0 },
        { 0, XDoubleToFixed(1.0), 0 },
        { 0, 0, XDoubleToFixed(scale) },
      }};

      XRenderSetPictureFilter(DADisplay, client_picture, FilterBilinear, 0, 0);
      XRenderSetPictureTransform(DADisplay, client_picture, &xform);
      XRenderComposite(DADisplay, PictOpSrc, client_picture, None, picture, 0, 0, 0, 0, rect.x, rect.y, rect.width, rect.height);
      XFreePixmap(DADisplay, client_pixmap);
      XSync(DADisplay, False);
#endif

    XDrawLine(DADisplay, pixmap, darkGrayGC, rect.x, rect.y, rect.x, rect.y + rect.height - 2);
    XDrawLine(DADisplay, pixmap, darkGrayGC, rect.x + 1, rect.y, rect.x + rect.width - 1, rect.y);
    XDrawLine(DADisplay, pixmap, lightGrayGC, rect.x, rect.y + rect.height - 1, rect.x + rect.width - 1, rect.y + rect.height - 1);
    XDrawLine(DADisplay, pixmap, lightGrayGC, rect.x + rect.width - 1, rect.y + 1, rect.x + rect.width - 1, rect.y + rect.height - 2);
  }

  DASetPixmap(pixmap);
  XFreePixmap(DADisplay, pixmap);
}

int main(int argc, char **argv) {
  Display *display;
  unsigned int root_width, root_height;
  unsigned int dockapp_width, dockapp_height;
  long num_desktops;
  double aspect;
  DACallbacks callbacks = { 0, change, 0, 0, 0, 0, page };
  DAProgramOption options = { "-d", "--desktop", "Desktop to page", DOInteger, 0, { (int *) &desktop } };

  DASetExpectedVersion(20020126);

  display = XOpenDisplay(0);

  root_width = DisplayWidth(display, DefaultScreen(display));
  root_height = DisplayHeight(display, DefaultScreen(display));
  aspect = (double) root_width / (double) root_height;

  if (root_width > root_height) {
    dockapp_width = DOCKAPP_SIZE;
    dockapp_height = (double) DOCKAPP_SIZE / aspect;
  }
  else {
    dockapp_height = DOCKAPP_SIZE;
    dockapp_width = (double) DOCKAPP_SIZE / aspect;
  }

  DAParseArguments(argc, argv, &options, 1, "BLURB", "BLORB");
  DAOpenDisplay(0, argc, argv);
  DACreateIcon("pager", dockapp_width, dockapp_height, argc, argv);

  DASetCallbacks(&callbacks);
  DASetTimeout(SPEED);

  setup_atom(&num_desktops_atom, "_NET_NUMBER_OF_DESKTOPS");
  setup_atom(&current_desktop_atom, "_NET_CURRENT_DESKTOP");
  setup_atom(&client_list_atom, "_NET_CLIENT_LIST_STACKING");
  setup_atom(&client_desktop_atom, "_NET_WM_DESKTOP");
  setup_atom(&client_state_atom, "_NET_WM_STATE");
  setup_atom(&active_window_atom, "_NET_ACTIVE_WINDOW");

  setup_atom(&shaded_state, "_NET_WM_STATE_SHADED");
  setup_atom(&skip_pager_state, "_NET_WM_STATE_SKIP_PAGER");
  setup_atom(&hidden_state, "_NET_WM_STATE_HIDDEN");

  num_desktops = get_atom_long(num_desktops_atom, XA_CARDINAL, DefaultRootWindow(DADisplay));
  if (desktop < 1) {
    desktop = get_atom_long(current_desktop_atom, XA_CARDINAL, DefaultRootWindow(DADisplay));
  }
  else if (desktop-- > num_desktops) {
    fprintf(stderr, "There are only %d desktops!\n", num_desktops);
    exit(111);
  }

  XSetErrorHandler(error_handler);
  setup_GCs();
  DAShow();
  DAEventLoop();
}