/** LWS-releated functions.
 *
 * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
 * @copyright 2017, Institute for Automation of Complex Power Systems, EONERC
 * @license GNU General Public License (version 3)
 *
 * VILLASnode
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************************/

#include <libwebsockets.h>
#include <string.h>

#include <villas/config.h>
#include <villas/utils.h>
#include <villas/log.h>
#include <villas/web.h>
#include <villas/api/session.h>

#include <villas/nodes/websocket.h>

/* Forward declarations */
lws_callback_function api_ws_protocol_cb;
lws_callback_function api_http_protocol_cb;
lws_callback_function websocket_protocol_cb;

/** List of libwebsockets protocols. */
 struct lws_protocols protocols[] = {
 	{
 		.name = "http",
 		.callback = lws_callback_http_dummy,
 		.per_session_data_size = 0,
 		.rx_buffer_size = 1024
 	},
#ifdef WITH_API
	{
		.name = "http-api",
		.callback = api_http_protocol_cb,
		.per_session_data_size = sizeof(struct api_session),
		.rx_buffer_size = 1024
	},
	{
		.name = "api",
		.callback = api_ws_protocol_cb,
		.per_session_data_size = sizeof(struct api_session),
		.rx_buffer_size = 0
	},
#endif /* WITH_API */
#ifdef LIBWEBSOCKETS_FOUND
	{
		.name = "live",
		.callback = websocket_protocol_cb,
		.per_session_data_size = sizeof(struct websocket_connection),
		.rx_buffer_size = 0
	},
#endif /* LIBWEBSOCKETS_FOUND */
#if 0 /* not supported yet */
	{
		.name = "log",
		.callback = log_ws_protocol_cb,
		.per_session_data_size = 0,
		.rx_buffer_size = 0
	},
	{
		.name = "stats",
		.callback = stats_ws_protocol_cb,
		.per_session_data_size = sizeof(struct api_session),
		.rx_buffer_size = 0
	},
#endif
	{ NULL /* terminator */ }
};

/** List of libwebsockets mounts. */
static struct lws_http_mount mounts[] = {
	{
		.mountpoint = "/",
		.origin = NULL,
		.def = "/index.html",
		.cgienv = NULL,
		.cgi_timeout = 0,
		.cache_max_age = 0,
		.cache_reusable = 0,
		.cache_revalidate = 0,
		.cache_intermediaries = 0,
		.origin_protocol = LWSMPRO_FILE,
		.mountpoint_len = 1,
#ifdef WITH_API
		.mount_next = &mounts[1]
	},
	{
		.mountpoint = "/api/v1",
		.origin = "http-api",
		.def = NULL,
		.cgienv = NULL,
		.cgi_timeout = 0,
		.cache_max_age = 0,
		.cache_reusable = 0,
		.cache_revalidate = 0,
		.cache_intermediaries = 0,
		.origin_protocol = LWSMPRO_CALLBACK,
		.mountpoint_len = 7,
#endif /* WITH_API */
		.mount_next = NULL
	}
};

/** List of libwebsockets extensions. */
static const struct lws_extension extensions[] = {
	{
		"permessage-deflate",
		lws_extension_callback_pm_deflate,
		"permessage-deflate"
	},
	{
		"deflate-frame",
		lws_extension_callback_pm_deflate,
		"deflate_frame"
	},
	{ NULL /* terminator */ }
};

extern struct log *global_log;

static void logger(int level, const char *msg) {
	int len = strlen(msg);
	if (strchr(msg, '\n'))
		len -= 1;

	/* Decrease severity for some errors. */
	if (strstr(msg, "Unable to open") == msg)
		level = LLL_WARN;

	switch (level) {
		case LLL_ERR:		log_print(global_log, CLR_RED("Web  "), "%.*s", len, msg); break;
		case LLL_WARN:		log_print(global_log, CLR_YEL("Web  "), "%.*s", len, msg); break;
		case LLL_NOTICE:	log_print(global_log, CLR_WHT("Web  "), "%.*s", len, msg); break;
		case LLL_INFO:		log_print(global_log,         "Web  ",  "%.*s", len, msg); break;
		default: /* Everything else is debug */
					log_print(global_log, CLR_GRY("Web  "), "%.*s", len, msg); break;
	}
}

static void * web_worker(void *ctx)
{
	struct web *w = ctx;

	for (;;)
		lws_service(w->context, 100);

	return NULL;
}

int web_init(struct web *w, struct api *a)
{
	int lvl = LLL_ERR | LLL_WARN | LLL_NOTICE;

	if (global_log->level >=10 && global_log->facilities & LOG_WEB)
		lvl |= (1 << LLL_COUNT) - 1;

	lws_set_log_level(lvl, logger);

	w->api = a;

	/* Default values */
	w->port = getuid() > 0 ? 8080 : 80; /**< @todo Use libcap to check if user can bind to ports < 1024 */
	w->htdocs = strdup(WEB_PATH);

	w->state = STATE_INITIALIZED;

	return 0;
}

int web_parse(struct web *w, json_t *cfg)
{
	int ret, enabled = 1;
	const char *ssl_cert = NULL;
	const char *ssl_private_key = NULL;
	const char *htdocs = NULL;
	json_error_t err;

	ret = json_unpack_ex(cfg, &err, 0, "{ s?: s, s?: s, s?: s, s?: i, s?: b }",
		"ssl_cert", &ssl_cert,
		"ssl_private_key", &ssl_private_key,
		"htdocs", &htdocs,
		"port", &w->port,
		"enabled", &enabled
	);
	if (ret)
		jerror(&err, "Failed to http section of configuration file");

	if (ssl_cert)
		w->ssl_cert = strdup(ssl_cert);

	if (ssl_private_key)
		w->ssl_private_key = strdup(ssl_private_key);

	if (htdocs) {
		if (w->htdocs)
			free(w->htdocs);

		w->htdocs = strdup(htdocs);
	}

	if (!enabled)
		w->port = CONTEXT_PORT_NO_LISTEN;

	w->state = STATE_PARSED;

	return 0;
}

int web_start(struct web *w)
{
	int ret;

	/* Start server */
	struct lws_context_creation_info ctx_info = {
		.options = LWS_SERVER_OPTION_EXPLICIT_VHOSTS | LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT,
		.gid = -1,
		.uid = -1,
		.user = (void *) w,
		.protocols = protocols,
		.mounts = mounts,
		.extensions = extensions,
		.port = w->port,
		.ssl_cert_filepath = w->ssl_cert,
		.ssl_private_key_filepath = w->ssl_private_key
	};

	info("Starting Web sub-system: webroot=%s", w->htdocs);

	{
		/* update web root of mount point */
		mounts[0].origin = w->htdocs;

		w->context = lws_create_context(&ctx_info);
		if (w->context == NULL)
			error("WebSocket: failed to initialize server context");

		w->vhost = lws_create_vhost(w->context, &ctx_info);
		if (w->vhost == NULL)
			error("WebSocket: failed to initialize virtual host");
	}

	ret = pthread_create(&w->thread, NULL, web_worker, w);
	if (ret)
		error("Failed to start Web worker thread");

	w->state = STATE_STARTED;

	return ret;
}

int web_stop(struct web *w)
{
	int ret;

	if (w->state != STATE_STARTED)
		return 0;

	info("Stopping Web sub-system");

	{
		lws_cancel_service(w->context);

		/** @todo Wait for all connections to be closed */

		ret = pthread_cancel(w->thread);
		if (ret)
			serror("Failed to cancel Web worker thread");

		ret = pthread_join(w->thread, NULL);
		if (ret)
			serror("Failed to join Web worker thread");
	}

	w->state = STATE_STOPPED;

	return 0;
}

int web_destroy(struct web *w)
{
	if (w->state == STATE_DESTROYED)
		return 0;

	if (w->context) {
		lws_context_destroy(w->context);
	}

	if (w->ssl_cert)
		free(w->ssl_cert);

	if (w->ssl_private_key)
		free(w->ssl_private_key);

	if (w->htdocs)
		free(w->htdocs);

	w->state = STATE_DESTROYED;

	return 0;
}