#include "Python.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int fac(int n)
{
	if(n < 0)
	{
		return 0;
	}
	if(n < 2)
	{
		return 1;
	}
	return n * fac(n - 1);
}
	

char * reverse(char * src)
{
	char tmp = 0;
	char * head = NULL;
	char * tail = NULL;
	if(src == NULL)
	{
		return NULL;
	}
	if(src[0] == '\0')
	{
		return src;
	}
	head = src;
	tail = src + strlen(src) - 1;
	while(head < tail)
	{
		tmp = *head;
		*head = *tail;
		*tail = tmp;
		head ++;
		tail --;
	}
	return src;
}

int main()
{
	printf("4! == %d\n",fac(4));
	printf("8! == %d\n",fac(8));
	printf("12! == %d\n",fac(12));
	
	char src[BUFSIZ];
	
	memset(src,0x00,sizeof(src));
	strcpy(src,"abcdef");
	printf("reversing '%s' ",src);
	printf("we get '%s'\n",reverse(src));

	memset(src,0x00,sizeof(src));
	strcpy(src,"madam");
	printf("reversing '%s' ",src);
	printf("we get '%s'\n",reverse(src));
	return 0;
}

PyObject * Extest_fac(PyObject * self,PyObject * args)
{
	int res = 0;
	int num = 0;
	PyObject * retval = NULL;
	
	res = PyArg_ParseTuple(args,"i",&num);
	if(!res)
	{
		return NULL;
	}
	res = fac(num);
	
	retval = (PyObject *)Py_BuildValue("i",res);
	return retval;
}

PyObject * Extest_doppel(PyObject * self,PyObject * args)
{
	PyObject * retval = NULL;
	char * orig_str = NULL;
	char * dupe_str = NULL;
	int res = 0;

	res = PyArg_ParseTuple(args,"s",&orig_str);
	if(!res)
	{
		return NULL;
	}
	if(orig_str == NULL)
	{
		return NULL;
	}
	dupe_str = strdup(orig_str);
	dupe_str = reverse(dupe_str);
	retval = (PyObject *)Py_BuildValue("ss",orig_str,dupe_str);
	free(dupe_str);
	return retval;
}


static PyMethodDef ExtestMethods[] =
{
	{"fac",Extest_fac,METH_VARARGS},
	{"doppel",Extest_doppel,METH_VARARGS},
	{NULL,NULL},
};

void initExtest()
{
	Py_InitModule("Extest",ExtestMethods);
}