/*
 * Copyright (C) 2019 Weber Yann
 * 
 * This file is part of PyFCGI.
 * 
 * PyFCGI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * PyFCGI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with PyFCGI.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "pyworker.h"


static short _wtimeout;
/**@brief 1 if worker idle else 0 */
static short _worker_idle;
/**@brief Indicate that a worker is idle */
static inline void worker_set_idle();
/**@brief Indicate that a worker is busy */
static inline void worker_set_busy();

/**@brief Process results from a pep333 worker
 * @param out out stream from libFCGI
 * @param ret application function returned value
 */
static inline int work333_send_result(FCGX_Stream* out, PyObject* ret);


static int worker_piper_sigrcv = 0;

int work333(int wrk_id)
{
	PyObject *entry_fun, *py_osmod, *entry_ret, *environ,
		*start_response, *args;
	FCGX_Stream *in_stream, *out_stream, *err_stream;
	char **envp;
	int count;
	int max_reqs;
	struct timeval start, stop;
	FCGX_Request *request;

	max_reqs = PyFCGI_conf.max_reqs;

	pyfcgi_log(LOG_INFO, "Worker started with PEP333 App");

	pyinit();
	pyfcgi_log(LOG_DEBUG, "Python started");
	//importing os
	py_osmod = python_osmod();
	//importing libpyfcgi
	if(!pyinit_libpyfcgi())
	{
		exit(PYFCGI_FATAL);
	}
	pyfcgi_log(LOG_DEBUG, "libpyfcgi imported");


	// loading module
	entry_fun = import_entrypoint();

	pyfcgi_log(LOG_INFO, "Waiting request with %s.%s()",
		PyFCGI_conf.py_entrymod, PyFCGI_conf.py_entryfun);

	if(!entry_fun) //but exit if import failed
	{
		pyfcgi_log(LOG_ALERT, "Unable to import entrypoint");
		exit(PYFCGI_FATAL);
	}

	start_response = get_start_response();

	// Initialise FCGI request
	request = &(PyFCGI_conf.context.fcgi_request);
	if(FCGX_InitRequest(request, PyFCGI_conf.context.fcgi_socket,
		FCGI_FAIL_ACCEPT_ON_INTR) == -1)
	{
		pyfcgi_log(LOG_ALERT, "Unable to init FCGI request");
		exit(PYFCGI_FATAL);
	}

	_worker_idle = 0;
	worker_set_idle();
	// requests accepting loop
	count = 0;
	while ((!count || count != max_reqs) &&
		FCGX_Accept_r(request) == 0)
	{
		
		in_stream = request->in;
		out_stream = request->out;
		err_stream = request->err;
		envp = request->envp;

		pyfcgi_wd_arm();
		sem_post(PyFCGI_SEM(SEM_WREQS).sem); // increment request counter discarding OF
		gettimeofday(&start, NULL);
		worker_set_busy();
		count++;
		environ = update_pyenv(py_osmod, envp);
		_wtimeout = 0;

		libpyfcgi_clean_response();
		libpyfcgi.out = out_stream;
		libpyfcgi.in = in_stream;
		args = Py_BuildValue("OO", environ, start_response);
		// Call application function
		entry_ret = PyObject_CallObject(entry_fun, args);
		if(entry_ret && entry_ret != Py_None )
		{
			Py_INCREF(entry_ret);
		}
		
		if(_wtimeout)
		{
			PyObject *type, *exc, *tb, *tmp;
			// Changing exception to a TimeoutError, but keeping
			// the traceback to display
			PyErr_Fetch(&type, &exc, &tb);
			PyErr_SetString(PyExc_TimeoutError, "Request timeout");
			PyErr_Fetch(&type, &exc, &tmp);
			PyErr_Restore(type, exc, tb);
			log_expt(LOG_ERR);
			libpyfcgi_timeout(); // Sending headers if possible
		}
		if(PyErr_Occurred())
		{
			pyfcgi_log(LOG_ERR, "PEP333 entrypoint function triggered an exception");
			log_expt(LOG_ERR);
		}
		// able to process returned value
		// Simulate python call of libpyfcgi.write_body()
		if(entry_ret && entry_ret != Py_None)
		{
			_pyfcgi_write_body(entry_ret);
			if(PyErr_Occurred())
			{
				log_expt(LOG_ERR);
			}
			Py_DECREF(entry_ret);
		}

		// clean stuffs
		Py_DECREF(args);
		Py_DECREF(environ);

		FCGX_FClose(out_stream);
		FCGX_FClose(in_stream);
		FCGX_FClose(err_stream);
		FCGX_Finish_r(request);

		gettimeofday(&stop, NULL);
		stop.tv_sec = stop.tv_sec - start.tv_sec;
		stop.tv_usec = stop.tv_usec - start.tv_usec;
		if(stop.tv_usec < 0)
		{
			stop.tv_usec += 1000000;
			stop.tv_sec -= 1;
		}
		pyfcgi_wd_pause();
		if(_wtimeout)
		{
			exit(PYFCGI_TIMEOUT);
		}
		pyfcgi_log(LOG_DEBUG, "Worker[%d] request %d END [OK] %lu bytes in %ld.%06lds",
			wrk_id, count, libpyfcgi.rep_sz, stop.tv_sec, stop.tv_usec);
		worker_set_idle();
	}
	worker_set_busy();
	return 0;
}

static inline int work333_send_result(FCGX_Stream *out, PyObject* ret)
{
	return 0;
}

int work(int wrk_id)
{
	PyObject *entry_fun, *pystdout_flush, *pystderr_flush, *py_osmod,
		*environ;
	FCGX_Stream *in_stream, *out_stream, *err_stream;
	char **envp;
	int count, pipe_out[2], pipe_err[2], pipe_ctl[2], err, piper_status;
	int max_reqs;
	struct sigaction act;
	struct timeval start, stop;
	sigset_t emptyset;
	char buf[PIPE_BUF];
	size_t rep_sz;
	piper_args_t piper_args;
	char *piper_stack;

	max_reqs = PyFCGI_conf.max_reqs;
	piper_args.wrk_id = wrk_id;
	piper_args.act = &act;

	// preparing sigaction for piper
	if(sigemptyset(&emptyset))
	{
		err = errno;
		pyfcgi_log(	LOG_ALERT, "sigemptyset fails in piper : %s",
			strerror(err));
		exit(err);
	}
	act.sa_handler = worker_piper_sighandler;
	act.sa_mask = emptyset;
	//act.sa_flags = SA_RESTART;
	act.sa_flags = 0;
	act.sa_restorer = NULL;


	if( !(piper_stack = malloc(PIPER_STACK_SZ)) )
	{
		err = errno;
		pyfcgi_log(LOG_ALERT, "Error while allocating piper stack : %s",
		       strerror(err));
		exit(err);
	}

	pyfcgi_log(LOG_INFO, "Worker %d started", wrk_id);

	update_python_path(); // add cwd to python path
	Py_Initialize(); // "start" python
	update_python_fd(pipe_out, pipe_err);
	piper_args.pystdout = pipe_out[0];
	piper_args.pystderr = pipe_err[0];

	fetch_pyflush(&pystdout_flush, &pystderr_flush);
	pyfcgi_log(	LOG_INFO,
		"Worker[%d] Python started", wrk_id);
	
	//importing os
	py_osmod = python_osmod();
	// loading module
	entry_fun = import_entrypoint();

	pyfcgi_log(	LOG_INFO,
		"Worker[%d] Waiting request with %s.%s()", wrk_id,
		PyFCGI_conf.py_entrymod, PyFCGI_conf.py_entryfun);



	if(!entry_fun) //but exit if import failed
	{
		pyfcgi_log(LOG_ALERT, "Unable to import entrypoint");
		exit(PYFCGI_FATAL);

	}

	if(pipe(pipe_ctl) == -1)
	{
		err = errno;
		pyfcgi_log(LOG_ALERT,
		       "Worker[%d] Pipe fails for piper ctl : %s",
		       wrk_id, strerror(err));
		exit(err);
	}
	piper_args.ctl_pipe = pipe_ctl[1];

	_worker_idle = 0;
	worker_set_idle();

	count = 0;
	while ((!count || count != max_reqs) && FCGX_Accept(&in_stream, &out_stream, &err_stream, &envp) >= 0)
	{
		pyfcgi_wd_arm();
		sem_post(PyFCGI_SEM(SEM_WREQS).sem); // increment request counter discarding OF
		gettimeofday(&start, NULL);
		worker_set_busy();

		count++;
		piper_args.out = out_stream;
		//piper_args.req_id = count;
		worker_piper_sigrcv = 0;
//		if(!PyFCGI_conf.pep333)
		/**@todo avoid clone on each request... (using named pipes ?) */
		pid_t pid = clone(worker_piper, piper_stack + PIPER_STACK_SZ - 1,
		                  CLONE_CHILD_CLEARTID | CLONE_CHILD_SETTID | \
				  SIGCHLD | \
				  CLONE_FILES | CLONE_FS | CLONE_IO | CLONE_VM,
				  &piper_args);
		if(pid < 0)
		{
			err = errno;
			pyfcgi_log(LOG_ALERT,
			       "Worker[%d] req #%d Fork failed for piper : %s",
			       wrk_id, count, strerror(err));
			exit(err);
		}
		environ = update_pyenv(py_osmod, envp);
		Py_DECREF(environ);
		//close(pipe_ctl[1]);
		PyObject_CallObject(entry_fun, NULL);
		if(PyErr_Occurred())
		{
			log_expt(LOG_ERR);
		}
		else
		{
			/*
			pyfcgi_log(LOG_DEBUG, "Worker[%d] request %d funcall [OK]",
				wrk_id, count);
			*/
		}
		PyObject_CallObject(pystdout_flush, NULL);
		PyObject_CallObject(pystderr_flush, NULL);
		read(pipe_ctl[0], &buf, 1); // unblock when child ready
		FCGX_FClose(in_stream);
		FCGX_FClose(err_stream);
		//close(pipe_ctl[0]);

		kill(pid, WPIPER_SIG); //indicate child python call ended
		waitpid(pid, &piper_status, 0);
		if(WIFSIGNALED(piper_status))
		{
			pyfcgi_log(LOG_ERR,
			       "Woker[%d] req #%d piper terminated by sig %d",
			       wrk_id, count, WTERMSIG(piper_status));
			exit(40);
		}
		else if(WEXITSTATUS(piper_status))
		{
			pyfcgi_log(LOG_ERR,
			       "Woker[%d] req #%d piper exited with error status %d",
			       wrk_id, count, WEXITSTATUS(piper_status));
			exit(41);
		}

		FCGI_Finish();
		if(ctl_get_rep_sz(pipe_ctl[0], &rep_sz))
		{
			rep_sz = 0;
		}
		//Increase sem showing the worker is idle
		worker_set_idle();
		gettimeofday(&stop, NULL);
		stop.tv_sec = stop.tv_sec - start.tv_sec;
		stop.tv_usec = stop.tv_usec - start.tv_usec;
		if(stop.tv_usec < 0)
		{
			stop.tv_usec += 1000000;
			stop.tv_sec -= 1;
		}
		pyfcgi_wd_pause();
		pyfcgi_log(LOG_DEBUG, "Worker[%d] request %d END [OK] %lu bytes in %ld.%06lds",
			wrk_id, count, rep_sz, stop.tv_sec, stop.tv_usec);
	}
	worker_set_busy();
	free(piper_stack);
	Py_Exit(count == max_reqs ?0:EXIT_PYERR);
}

/*
void worker_piper(int wrk_id, int req_id, int pystdout, int pystderr,
	int ctl_pipe, FCGX_Stream* out)
*/
int worker_piper(void *ptr)
{
	piper_args_t *args;
	struct pollfd fds[2];
	int err, ret, cont, poll_ret;
	short revents, closed, nfds;
	char buf[PIPE_BUF];
	size_t out_sz;

	args = ptr;
	int wrk_id, pystdout, pystderr, ctl_pipe;
	//int req_id;
	FCGX_Stream *out;
	struct sigaction *act;
	wrk_id = args->wrk_id;
	//req_id = args->req_id;
	pystdout = args->pystdout;
	pystderr = args->pystderr;
	ctl_pipe = args->ctl_pipe;
	out = args->out;
	act = args->act;

	if(sigaction(WPIPER_SIG, act, NULL))
	{
		err = errno;
		pyfcgi_log(	LOG_ALERT, "Unable to sigaction in piper : %s",
			strerror(err));
		exit(err);
	}
	write(ctl_pipe, " ", 1);


	//pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d piper", wrk_id, req_id);

	fds[0].fd = pystderr;
	fds[1].fd = pystdout;
	fds[0].events = fds[1].events = POLLIN;
	fds[0].revents = fds[1].revents = 0;
	nfds = 2;


	closed = out_sz = 0;
	cont = 2;
	while(cont)
	{
		poll_ret = poll(fds, nfds, 0);
//pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d poll_ret = %d", wrk_id, req_id, poll_ret);
		if(poll_ret < 0)
		{
			err = errno;
			if(err == EINTR)
			{
				continue;
			}
			pyfcgi_log( LOG_WARNING, "Poll error : %s",
			        strerror(err));
			fds[0].revents = fds[1].revents = 0;
			continue;
		}
		if(!poll_ret && worker_piper_sigrcv)
		{
			cont--;
			continue;
		}
		if(poll_ret && (revents = fds[1].revents))
		{
			/*
			pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d STDOUT evt !",
			       wrk_id, req_id);
			*/
			poll_ret--;
			if(revents & POLLIN)
			{
				/*
				pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d POLLIN STDOUT !",
				       wrk_id, req_id);
				*/
				ret = read(pystdout, buf, PIPE_BUF);
				/*
				pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d read(stdout) ret %d",
				       wrk_id, req_id, ret);
				*/
				if(ret < 0)
				{
					err = errno;
					if(err == EINTR)
					{
						continue;
					}
					pyfcgi_log( LOG_ERR,
						"Error reading python stdout : %s",
						strerror(err));
					exit(err);
				}
				//buf[ret] = '\0';
				ret = FCGX_PutStr(buf, ret, out);
				out_sz += ret;
				if(ret < PIPE_BUF && worker_piper_sigrcv)
				{
					FCGX_FClose(out);
					FCGI_Finish();
					write(ctl_pipe, &out_sz, sizeof(size_t));
					closed = 1;
					nfds = 1;
				}
			}
			//TODO handle other poll events
		}
		if(poll_ret && (revents = fds[0].revents))
		{
			/*
			pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d STDERR evt !",
			       wrk_id, req_id);
			*/
			if(revents & POLLIN)
			{
				/*
				pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d POLLIN STDERR !",
				       wrk_id, req_id);
				*/
				while(1)
				{
					ret = read(pystderr, buf, PIPE_BUF);
					if(ret < 0)
					{
						err = errno;
						if(err == EINTR)
						{
							continue;
						}
						pyfcgi_log( LOG_ERR,
						        "Error reading python stdout : %s",
							strerror(err));
						exit(err);
					}
					buf[ret] = '\0';
					pyfcgi_log(LOG_ERR,
					       "Worker[%d] Python error : %s",
					       wrk_id, buf);
					break;
				}
			}
			//TODO handle other poll events
		}
		fds[0].revents = fds[1].revents = 0;
	}
	/*
	pyfcgi_log(LOG_DEBUG, "Worker[%d] req #%d piper exiting...",
	       wrk_id, req_id);
	*/
	if(!closed)
	{
		FCGX_FClose(out);
		FCGI_Finish();
		write(ctl_pipe, &out_sz, sizeof(size_t));
	}
	return 0;
}

void worker_log_pipes(int pipe_std, int pipe_err, PyObject *flush[2])
{
	size_t ret;
	char buff[4096];
	int i, poll_ret;
	int loglevels[2] = {LOG_INFO, LOG_WARNING};
	struct pollfd fds[2];
	short isflush[2] = {0,0};
	char *outnames[2] = {"sys.stdout", "sys.stderr"};

	fds[0].fd = pipe_std;
	fds[1].fd = pipe_err;
	fds[0].events = fds[1].events = POLLIN;
	fds[0].revents = fds[1].revents = 0;

	for(i=0; i<2; i++)
	{
		do
		{
			poll_ret = poll(&(fds[i]), 1, 0);
			if(poll_ret)
			{
				ret = read(pipe_std, buff, 4096);
				if(ret == -1)
				{
					pyfcgi_log(LOG_ERR, "Error reading python %s pipe : %s",
						outnames[i], strerror(errno));
					exit(PYFCGI_WORKER_FAIL);
				}
				pyfcgi_log(loglevels[i], "Pyton %s  : '%s'",
					outnames[i], buff);
			}
			if(!isflush[i] && (!poll_ret || ret < 4096))
			{
				isflush[i] = 1;
				PyObject_CallObject(flush[i], NULL);
				if(PyErr_Occurred())
				{
					pyfcgi_log(LOG_ERR, "Exception while flushing %s",
						outnames[i]);
					log_expt(LOG_ERR);
					exit(PYFCGI_WORKER_FAIL);
				}
			}
		}while(poll_ret && !isflush[i]);
	}
}

void worker_piper_sighandler(int signum)
{
	worker_piper_sigrcv = 1;
	//pyfcgi_log(LOG_DEBUG, "SIG");
}

int ctl_get_rep_sz(int ctl_pipe, size_t* rep_sz)
{
	struct pollfd fds;
	int ret, err;

	fds.fd = ctl_pipe;
	fds.events = POLLIN;
	fds.revents = 0;

	if( (ret = poll(&fds, 1, 0)) < 0)
	{
		err = errno;
		pyfcgi_log(LOG_ERR, "Failed to poll ctl pipe : %s",
		       strerror(err));
		return -1;
	}
	if(!ret)
	{
		pyfcgi_log(LOG_ERR, "No data in ctl pipe for rep_sz...");
		return -1;
	}
	ret = read(ctl_pipe, rep_sz, sizeof(size_t));
	if(ret < 0)
	{
		pyfcgi_log(LOG_ERR, "Error reading ctl pipe : %s",
		       strerror(errno));
		return -1;
	}
	if(ret < sizeof(size_t))
	{
		pyfcgi_log(LOG_ERR, "Incomplete read from ctl pipe, no rep_sz...");
		return -1;
	}
	return 0;
}

static void worker_set_idle()
{
	int err;
	if(_worker_idle) { return; }
	if(sem_post(PyFCGI_SEM(SEM_WSTATE).sem) < 0)
	{
		err = errno;
		pyfcgi_log(LOG_ERR, "error incrementing the WSTATE semaphore : %s",
			strerror(err));
		return;
	}
	_worker_idle = 1;
}

static void worker_set_busy()
{
	int err;
	short retry;
	struct timespec timeout;
	timeout.tv_sec = 0;
	timeout.tv_nsec = 100000; //0.0001s

	if(!_worker_idle) { return; }
	/**@todo The pool handler WILL decrement the sem to figure if the pool
	 * is busy -__- Using sem_wait make sure that the worker will be able
	 * to set busy, but it can also freeze if not able to set busy....
	 * sem_timedwait require to get abstime -_- The better way is
	 * maybe to nanosleep 0.01s and retry a sem_trywait... SysV sem are
	 * better T_T
	 */
	err = 0;
	retry = 10;
	do
	{
		err = 0;
		if(sem_trywait(PyFCGI_SEM(SEM_WSTATE).sem) < 0)
		{
			err = errno;
			if(err == EAGAIN)
			{
				nanosleep(&timeout, NULL);
				err = 1;
			}
			else
			{
				pyfcgi_log(LOG_ERR,
					"error decrementing the WSTATE semaphore : %s",
					strerror(err));
				kill(PyFCGI_conf.context.ppid, SIGTERM);
				return;
			}
		}
		retry--;
	}while(err & retry);
	if(err)
	{
		pyfcgi_log(LOG_ALERT,
			"Unable to set busy ! WSTATE sem is allready 0 !!!");
		_worker_idle = 0;
		kill(PyFCGI_conf.context.ppid, SIGTERM);
		kill(PyFCGI_conf.context.pid, SIGTERM);
		return;
	}
	_worker_idle = 0;
}

void worker_sighandler(int signum)
{
	pyfcgi_log(LOG_INFO, "%s signal received, exiting...", strsignal(signum));
	worker_set_busy();
	pyfcgi_IPC_close(IPC_WSTATE | IPC_WREQS);
	exit(0);
}

void worker_sigalrmhandler(int signum)
{
	_wtimeout = 1;
	if(!_worker_idle)
	{
		// Call PyErr_Interrupt() in order to stop python
		PyErr_SetInterrupt();
	}
	worker_set_busy();
	pyfcgi_IPC_close(IPC_WSTATE | IPC_WREQS);
	return;
}