/*
 * Usurpation – null (stdio) im proto
 *
 * Copyright (C) 2019 Gediminas Jakutis
 * Copyright (C) 2019 Paulius Ratkevičius
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; version 2.1
 * of the License.
 *
 * This program 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */

#include <errno.h>
#include "proto_stdio.h"
#include "proto_stdio_private.h"


void message_receive(char *arg)
{
	int cancelstate;

	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancelstate);
	pthread_mutex_lock(&state.out_m);
	state.writebuf = strdup(arg);
	pthread_mutex_unlock(&state.out_m);
	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &cancelstate);
	pthread_testcancel();
	nanosleep(&respite, NULL);
}

char *message_send(void)
{
	char *ret = NULL;
	int cancelstate;

	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancelstate);
	pthread_mutex_lock(&state.out_m);

	if (state.readbuf) {
		ret = strdup(state.readbuf);
		free(state.readbuf);
		state.readbuf = NULL;
		state.readbufsize = 0;
	}

	pthread_mutex_unlock(&state.out_m);
	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &cancelstate);
	pthread_testcancel();

	return ret;
}

static void *read_stdin(void *arg)
{
	int cancelstate;

	(void) arg;

	while(1) {
		pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancelstate);
		pthread_mutex_lock(&state.in_m);

		if (!state.readbuf) {
			state.readbufsize = getline(&state.readbuf, NULL, stdin);
		}

		pthread_mutex_unlock(&state.in_m);
		pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &cancelstate);
		pthread_testcancel();
		nanosleep(&respite, NULL);
	}

	return NULL;
}


static void *write_stdout(void *arg)
{
	int cancelstate;

	(void) arg;

	while(1) {
		pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cancelstate);
		pthread_mutex_lock(&state.out_m);

		if (state.writebuf) {
			if (state.writebuf[strlen(state.writebuf) - 1] == '\n') {
				printf("%s", state.writebuf);
			} else {
				printf("%s\n", state.writebuf);
			}

			free(state.writebuf);
			state.writebuf = NULL;
			state.writebufsize = 0;
		}

		pthread_mutex_unlock(&state.out_m);
		pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &cancelstate);
		pthread_testcancel();
		nanosleep(&respite, NULL);
	}

	return NULL;
}


int proto_stdio_init(void)
{

	int ret = 0;

	/* aquire the """singleton""" mutex */
	if (pthread_mutex_trylock(&state.mutex)) {
		/* TODO: use proper error numbers */
		ret = 1;
	} else {
		if ((ret = pthread_create(&state.stdio_in, NULL, read_stdin, NULL))) {
			proto_stdio_close();
		}

		if ((ret = pthread_create(&state.stdio_out, NULL, write_stdout, NULL))) {
			proto_stdio_close();
		}
	}

	return ret;
}

void proto_stdio_close(void)
{
	int status;

	status = pthread_mutex_trylock(&state.mutex);

	if (status == EBUSY) {
		pthread_cancel(state.stdio_in);
		pthread_cancel(state.stdio_out);
		pthread_join(state.stdio_in, NULL);
		pthread_join(state.stdio_out, NULL);
	} else if (!status) {
		pthread_mutex_unlock(&state.mutex);
	}
}