#include <string.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <Python.h>
//
static PyObject *py_push_data(PyObject *self, PyObject *args);
static char push_data_docstring[] =
    "Send data as quickly as possible into a socket.";
//
static PyObject *py_pull_data(PyObject *self, PyObject *args);
static char pull_data_docstring[] =
    "Receive data as quickly as possible from a socket.";
//
static char module_docstring[] =
    "This module provides accelerated functions which would perform slower in pure Python.";
//
static PyMethodDef module_methods[] = {
	{"push_data", py_push_data, METH_VARARGS, push_data_docstring},
	{"pull_data", py_pull_data, METH_VARARGS, pull_data_docstring},
	{NULL, NULL, 0, NULL}
};
//
static struct PyModuleDef _coremodule = {
	PyModuleDef_HEAD_INIT,
	"accelerated_functions", // name of module
	module_docstring, // module documentation, may be NULL
	-1, /* size of per-interpreter state of the module,
	       or -1 if the module keeps state in global variables. */
	module_methods,
};
//
PyMODINIT_FUNC PyInit_accelerated_functions(void){
	return PyModule_Create(&_coremodule);
}
//
long min(long num1, long num2){
	return (num1 > num2) ? num2 : num1;
}
//
int push_data(int socket, long bytes_total, char* buffer, int buffer_len){
	long bytes_written = 0;
	//
	struct pollfd poll_fds[1];
	int num_poll_fds = 0;
	//
	memset(poll_fds, 0, sizeof(poll_fds));
	poll_fds[0].fd = socket;
	poll_fds[0].events = POLLOUT;
	num_poll_fds++;
	//
	while(bytes_written < bytes_total){
		int rc = poll(poll_fds, num_poll_fds, 1*60*1000);
		//
		if(rc < 0){
			return -1;
		}else if(rc == 0){
			return -1;
		}
		//
		if(poll_fds[0].revents == 0){
			continue;
		}else if(poll_fds[0].revents != POLLOUT){
			return -1;
		}
		//
		long bytes_to_send = min(buffer_len, bytes_total-bytes_written);
		int n = send(poll_fds[0].fd, buffer, bytes_to_send, 0);
		//
		if(n < 0){
			return -1;
		}
		//
		bytes_written += n;
	}
	//
	return 0;
}
//
int pull_data(int socket, long bytes_total, int buffer_len, double* time_ptr){
	long bytes_read = 0;
	char* buffer = malloc(buffer_len);
	struct timeval time_of_first_byte, time_of_last_byte;
	//
	struct pollfd poll_fds[1];
	int num_poll_fds = 0;
	//
	if(buffer == NULL){
		return -1;
	}
	//
	memset(poll_fds, 0, sizeof(poll_fds));
	poll_fds[0].fd = socket;
	poll_fds[0].events = POLLIN;
	num_poll_fds++;
	//
	while(bytes_read < bytes_total){
		int rc = poll(poll_fds, num_poll_fds, 1*60*1000);
		//
		if(rc < 0){
			printf("Here1\n");
			free(buffer);
			return -1;
		}else if(rc == 0){
			printf("Here2\n");
			free(buffer);
			return -1;
		}
		//
		if(poll_fds[0].revents == 0){
			continue;
		}else if(poll_fds[0].revents != POLLIN){
			printf("Here3\n");
			free(buffer);
			return -1;
		}
		//
		long bytes_to_recv = min(buffer_len, bytes_total-bytes_read);
		int n = recv(poll_fds[0].fd, buffer, bytes_to_recv, 0);
		//
		if(n < 0){
			printf("Here4\n");
			free(buffer);
			return -1;
		}
		//
		if(n > 0 && bytes_read == 0){
			gettimeofday(&time_of_first_byte, NULL);
		}
		//
		bytes_read += n;
	}
	//
	gettimeofday(&time_of_last_byte, NULL);
	*time_ptr = (time_of_last_byte.tv_sec-time_of_first_byte.tv_sec) + (time_of_last_byte.tv_usec-time_of_first_byte.tv_usec)/(1000.0*1000.0);
	//
	free(buffer);
	return 0;
}
//
static PyObject *py_push_data(PyObject *self, PyObject *args){
	PyObject *yerr_obj;
	int socket;
	long bytes_total;
	char* buffer = NULL;
	int buffer_len;
	//
	if(!PyArg_ParseTuple(args, "ily#", &socket, &bytes_total, &buffer, &buffer_len, &yerr_obj)){
		return NULL;
	}
	//
	int ret_val;
	Py_BEGIN_ALLOW_THREADS
	// GIL is unlocked, but don't do expensive operations in
	// other threads or it might slow this one down
	ret_val = push_data(socket, bytes_total, buffer, buffer_len);
	Py_END_ALLOW_THREADS
	//
	PyObject* py_ret_val = PyLong_FromLong(ret_val);
	//
	return py_ret_val;
}
//
static PyObject *py_pull_data(PyObject *self, PyObject *args){
	PyObject *yerr_obj;
	int socket;
	long bytes_total;
	int buffer_len;
	//
	if(!PyArg_ParseTuple(args, "ili", &socket, &bytes_total, &buffer_len, &yerr_obj)){
		return NULL;
	}
	//
	double elapsed_time = 0;
	int ret_val;
	Py_BEGIN_ALLOW_THREADS
	// GIL is unlocked, but don't do expensive operations in
	// other threads or it might slow this one down
	ret_val = pull_data(socket, bytes_total, buffer_len, &elapsed_time);
	Py_END_ALLOW_THREADS
	//
	PyObject* py_ret_val = Py_BuildValue("(id)", ret_val, elapsed_time);
	//
	return py_ret_val;
}