#include "Python.h"

#include <SystemConfiguration/SystemConfiguration.h>

#define SCNR_REACHABLE "SCNetworkIsReachable"
static CFStringRef SCNR_Reachable = CFSTR(SCNR_REACHABLE);
static SCNetworkReachabilityContext SCNR_Context = {0, NULL, NULL, NULL, NULL};

static void
SCNR_callback(SCNetworkReachabilityRef target,
	      SCNetworkConnectionFlags flags, void *tagString);

static Boolean
SCNR_reachable(SCNetworkConnectionFlags flags) {
  /* not reachable if it requires a non-automatic connection */
  return ((flags & kSCNetworkFlagsReachable) &&
	  (!(flags & kSCNetworkFlagsConnectionRequired) ||
	   (flags & kSCNetworkFlagsConnectionAutomatic)));
}

/* XXX should have a way to cancel (e.g. on location detach) */

static void
SCNR_schedule(CFStringRef tagString,
	      SCNetworkReachabilityRef target) {
  SCNR_Context.info = (void *)tagString;
  SCNetworkReachabilitySetCallback(target, SCNR_callback, &SCNR_Context);
  SCNetworkReachabilityScheduleWithRunLoop(target,
					   CFRunLoopGetCurrent(),
					   kCFRunLoopDefaultMode);
}

static void
SCNR_callback(SCNetworkReachabilityRef target,
	      SCNetworkConnectionFlags flags, void *tagString) {
  if (SCNR_reachable(flags)) {
    CFNotificationCenterPostNotification(CFNotificationCenterGetLocalCenter(),
					 SCNR_Reachable, tagString, NULL, false);
    CFRelease((CFStringRef)tagString);
  } else {
    SCNR_schedule(tagString, target);
  }
}

static PyObject *
SCNR_notify_when_reachable(PyObject *self, PyObject *args) {
  const char *hostname;
  const char *tag;
  if (!PyArg_ParseTuple(args, "ss", &hostname, &tag))
    return NULL;

  SCNetworkConnectionFlags flags;
  if (SCNetworkCheckReachabilityByName(hostname, &flags) &&
      SCNR_reachable(flags))
    return PyBool_FromLong(0);

  SCNetworkReachabilityRef target =
    SCNetworkReachabilityCreateWithName(NULL, hostname);
  CFStringRef tagString =
    CFStringCreateWithCString(NULL, tag, kCFStringEncodingUTF8);

  SCNR_schedule(tagString, target);

  return PyBool_FromLong(1);
}


static PyMethodDef SCNetworkReachabilitymodule_methods[] = {
  {"notify_when_reachable", SCNR_notify_when_reachable, METH_VARARGS,
   "notify_when_reachable(hostname, tag) -> bool\n\n"
   "Deliver the SCNetworkIsReachable runloop notification with object tag\n"
   "when the host becomes reachable, or return false if it's currently\n"
   "reachable."},
  {NULL, NULL, 0, NULL}
};

PyMODINIT_FUNC
initSCNetworkReachability(void) {
  PyObject *module = Py_InitModule("SCNetworkReachability",
				   SCNetworkReachabilitymodule_methods);
  PyObject *dict = PyModule_GetDict(module);
  PyObject *reachable = PyString_FromString(SCNR_REACHABLE);
  PyDict_SetItemString(dict, SCNR_REACHABLE, reachable);
  Py_DECREF(reachable);
}