/*
 * Nicer signal handling, integrated into the runloop.
 */

#include <mach/mach.h>
#include <mach/mach_error.h>
#include <CoreFoundation/CoreFoundation.h>
#include "pyobjc-api.h"

PyDoc_STRVAR(machsignals_doc,
	"_machsignals - signal handling integrated into the runloop\n"
	"\n"
	"This module exports a dictionary that contains the functions that \n"
	"should be called when a signal is caught.\n"
	"\n"
	"The function 'handleSignal' installs a C signal handler that will \n"
	"make sure our signal handler is called."
);

static mach_port_t exit_m_port       = MACH_PORT_NULL;
static PyObject *signalmapping;


static void
SIGCallback(CFMachPortRef port __attribute__((__unused__)), void *msg, CFIndex size __attribute__((__unused__)), void *info __attribute__((__unused__)))
{
	PyObject *tmp;
	PyObject *callable;
	int signum;
	// this is abuse of msgh_id
	signum = ((mach_msg_header_t*)msg)->msgh_id;
	if (!signalmapping) {
		return;
	}
	PyObjC_BEGIN_WITH_GIL
	do {
		tmp = PyInt_FromLong((long)signum);
		if (!tmp) break;

		callable = PyDict_GetItem(signalmapping, tmp);
		Py_DECREF(tmp);
		if (!callable) {
            tmp = NULL;
            break;
        }

		tmp = PyObject_CallFunction(callable, "i", signum);
		Py_XDECREF(tmp);
	} while (0);
	if (!tmp)
		PyObjC_GIL_FORWARD_EXC();
	PyObjC_END_WITH_GIL
}

static void
HandleSIG(int signum)
{
	/*
	 * Send a mach_msg to ourselves (since that is signal safe) telling us 
	 * to handle a signal.
	 */
	mach_msg_return_t msg_result;
	mach_msg_header_t header;

	header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND, 0);
	header.msgh_remote_port = exit_m_port;
	header.msgh_local_port = MACH_PORT_NULL;
	header.msgh_size = sizeof(header);
	// this is abuse of msgh_id
	header.msgh_id = signum;

	msg_result = mach_msg_send(&header);
}

PyDoc_STRVAR(machsignals_handleSignal_doc, 
	"handleSignal(signum) -> None\n"
	"\n"
	"Handle a signal using the registered mach callback\n"
	"Raises an ObjC exception if the callback fails"
);
static PyObject*
machsignals_handleSignal(PyObject *self __attribute__((__unused__)), PyObject *args, PyObject *kwds)
{
	static char* keywords[] = { "signum", 0 };
	int signum;
	
	if (!PyArg_ParseTupleAndKeywords(args, kwds,
		"i:handleSignal", keywords,
		&signum)) {
		return NULL;
	}

	signal(signum, HandleSIG);

	Py_INCREF(Py_None);
	return Py_None;
}

static PyMethodDef machsignals_methods[] = {
	{
		"handleSignal",
		(PyCFunction)machsignals_handleSignal,
		METH_VARARGS|METH_KEYWORDS,
		machsignals_handleSignal_doc
	},
	{ 0, 0, 0, 0}
};

void init_machsignals(void);
void
init_machsignals(void)
{
	PyObject *m;
	PyObject *d;
	CFMachPortRef e_port;
	CFRunLoopSourceRef e_rls;

	m = Py_InitModule4("_machsignals", machsignals_methods,
		machsignals_doc, NULL, PYTHON_API_VERSION);
	if (!m) return;

	d = PyModule_GetDict(m);
	if (!d) return;

	if (PyObjC_ImportAPI(m) < 0) {
		printf("Importing objc failed\n");
		return;
	}

	signalmapping = PyDict_New();
	if (!signalmapping) return;

	PyObject_SetAttrString(m, "_signalmapping", signalmapping);

	e_port = CFMachPortCreate(NULL, SIGCallback, NULL, NULL);
	exit_m_port = CFMachPortGetPort(e_port);
	e_rls = CFMachPortCreateRunLoopSource(NULL, e_port, 0);
	CFRunLoopAddSource(CFRunLoopGetCurrent(), e_rls, kCFRunLoopDefaultMode);
	CFRelease(e_rls);
}