#include <string.h>
#include <sys/time.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <Python.h>
//
#define USE_NEW_HISTORY
//
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, 15*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;
}
//
#ifdef USE_NEW_HISTORY
typedef struct {
	unsigned long bytes;
	double timestamp;
} byte_delta;

int pull_data(int socket, long bytes_total, int buffer_len, double* time_first_ptr,
              double* time_last_ptr, byte_delta* deltas, size_t deltas_len,
              size_t* deltas_elements_needed){
#else
int pull_data(int socket, long bytes_total, int buffer_len, double* time_first_ptr,
              double* time_last_ptr, unsigned long* byte_counter,
              size_t byte_counter_len, size_t* byte_counter_elements_needed,
              unsigned long* byte_counter_start){
#endif
	long bytes_read = 0;
	char* buffer = malloc(buffer_len);
	struct timeval time_of_first_byte, time_of_last_byte, time_current, time_elapsed;
#ifdef USE_NEW_HISTORY
#else
	struct timeval rounded_time_of_first_byte;
#endif
	//
	struct pollfd poll_fds[1];
	int num_poll_fds = 0;
	//
	if(buffer == NULL){
		return -1;
	}
	//
#ifdef USE_NEW_HISTORY
	*deltas_elements_needed = 0;
#endif
	//
	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, 15*60*1000);
		//
		if(rc < 0){
			printf("Here1\n");
			free(buffer);
			return -1;
		}else if(rc == 0){
			printf("Call to poll() timed out (bytes_read=%ld)\n", bytes_read);
			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;
		}else if(n == 0){
			// the socket was closed gracefully, but before we finished reading all the data
			free(buffer);
			return -1;
		}
		//
		if(n > 0 && bytes_read == 0){
			gettimeofday(&time_of_first_byte, NULL);
#ifdef USE_NEW_HISTORY
#else
			rounded_time_of_first_byte.tv_sec = time_of_first_byte.tv_sec;
			rounded_time_of_first_byte.tv_usec = 0;
#endif
		}
		//
		if(n > 0){
			gettimeofday(&time_current, NULL);
#ifdef USE_NEW_HISTORY
			if(*deltas_elements_needed < deltas_len){
				deltas[*deltas_elements_needed].bytes = n;
				deltas[*deltas_elements_needed].timestamp = time_current.tv_sec + time_current.tv_usec/(1000.0*1000.0);
				*deltas_elements_needed += 1;
			}
#else
			timersub(&time_current, &rounded_time_of_first_byte, &time_elapsed);
			*byte_counter_elements_needed = time_elapsed.tv_sec+1;
			if(time_elapsed.tv_sec < byte_counter_len){
				byte_counter[time_elapsed.tv_sec] += n;
			}
#endif
		}
		//
		bytes_read += n;
	}
	//
	gettimeofday(&time_of_last_byte, NULL);
	*time_first_ptr = time_of_first_byte.tv_sec + time_of_first_byte.tv_usec/(1000.0*1000.0);
	*time_last_ptr = time_of_last_byte.tv_sec + time_of_last_byte.tv_usec/(1000.0*1000.0);
#ifdef USE_NEW_HISTORY
#else
	*byte_counter_start = rounded_time_of_first_byte.tv_sec;
#endif
	//
	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 time_of_first_byte = 0;
	double time_of_last_byte = 0;
#ifdef USE_NEW_HISTORY
	byte_delta deltas[100000] = {0}; // 100000*16 B = ~1.5 MiB
	size_t deltas_elements_needed = 0;
#else
	unsigned long byte_counter[60*10] = {0}; // record 10 minutes of data
	size_t byte_counter_elements_needed = 0;
	unsigned long byte_counter_start = 0;
#endif
	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
#ifdef USE_NEW_HISTORY
	ret_val = pull_data(socket, bytes_total, buffer_len, &time_of_first_byte, &time_of_last_byte,
	                    deltas, sizeof(deltas)/sizeof(deltas[0]), &deltas_elements_needed);
#else
	ret_val = pull_data(socket, bytes_total, buffer_len, &time_of_first_byte, &time_of_last_byte,
	                    byte_counter, sizeof(byte_counter)/sizeof(byte_counter[0]),
	                    &byte_counter_elements_needed, &byte_counter_start);
#endif
	Py_END_ALLOW_THREADS
	//
#ifdef USE_NEW_HISTORY
	size_t deltas_elements_used = deltas_elements_needed;
	if(deltas_elements_used > sizeof(deltas)/sizeof(deltas[0])){
		deltas_elements_used = sizeof(deltas)/sizeof(deltas[0]);
	}
	//
	PyObject* py_delta_bytes = PyList_New(deltas_elements_used);
	PyObject* py_delta_timestamps = PyList_New(deltas_elements_used);
	for(size_t i=0; i<deltas_elements_used; i++){
		PyList_SetItem(py_delta_bytes, i, PyLong_FromLong(deltas[i].bytes));
		PyList_SetItem(py_delta_timestamps, i, PyFloat_FromDouble(deltas[i].timestamp));
	}
#else
	size_t byte_counter_elements_used = byte_counter_elements_needed;
	if(byte_counter_elements_used > sizeof(byte_counter)/sizeof(byte_counter[0])){
		byte_counter_elements_used = sizeof(byte_counter)/sizeof(byte_counter[0]);
	}
	//
	PyObject* py_byte_counter = PyList_New(byte_counter_elements_used);
	for(size_t i=0; i<byte_counter_elements_used; i++){
		PyList_SetItem(py_byte_counter, i, PyLong_FromLong(byte_counter[i]));
	}
#endif
	//
#ifdef USE_NEW_HISTORY
	PyObject* py_ret_val = Py_BuildValue("(idd{sNsN})", ret_val, time_of_first_byte, time_of_last_byte, "bytes", py_delta_bytes, "timestamps", py_delta_timestamps);
#else
	PyObject* py_ret_val = Py_BuildValue("(iddNi)", ret_val, time_of_first_byte, time_of_last_byte, py_byte_counter, byte_counter_start);
#endif
	//
	return py_ret_val;
}