/*
 * Copyright (C) 2015, 2016 "IoT.bzh"
 * Author "Romain Forlot" <romain.forlot@iot.bzh>
 * Author "Loic Collignon" <loic.collignon@iot.bzh>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	 http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "low-can-binding.hpp"

#include <queue>
#include <mutex>
#include <vector>
#include <thread>
#include <fcntl.h>
#include <linux/can.h>
#include <json-c/json.h>
#include <systemd/sd-event.h>

#include "timer.hpp"
#include "signals.hpp"
#include "can-bus.hpp"
#include "openxc.pb.h"
#include "can-signals.hpp"
#include "can-message.hpp"
#include "openxc-utils.hpp"

extern "C"
{
	#include <afb/afb-service-itf.h>
};

/*
 *	Interface between the daemon and the binding
 */
const struct afb_binding_interface *binder_interface;

can_bus_t *can_bus_handler;

/********************************************************************************
*
*		Subscription and unsubscription
*
*********************************************************************************/

static int make_subscription_unsubscription(struct afb_req request, const std::string& sig_name, std::map<std::string, struct afb_event>& s, bool subscribe)
{
	/* Make the subscription or unsubscription to the event */
	if (((subscribe ? afb_req_subscribe : afb_req_unsubscribe)(request, s[sig_name.c_str()])) < 0)
	{
		ERROR(binder_interface, "Operation goes wrong for signal: %s", sig_name);
		return 0;
	}
	return 1;

}

static int create_event_handle(const std::string& sig_name, std::map<std::string, struct afb_event>& s)
{
	s[sig_name] = afb_daemon_make_event(binder_interface->daemon, sig_name.c_str());
	if (!afb_event_is_valid(s[sig_name]))
	{
		ERROR(binder_interface, "Can't create an event, something goes wrong.");
		return 0;
	}
	return 1;
}

static int subscribe_unsubscribe_signal(struct afb_req request, bool subscribe, const std::string& sig)
{
	int ret;

	std::lock_guard<std::mutex> subscribed_signals_lock(get_subscribed_signals_mutex());
	std::map<std::string, struct afb_event>& s = get_subscribed_signals();
	if (s.find(sig) != s.end() && !afb_event_is_valid(s[std::string(sig)]))
	{
		if(!subscribe)
		{
			NOTICE(binder_interface, "Event isn't valid, it can't be unsubscribed.");
			ret = -1;
		}
		else
			/* Event it isn't valid annymore, recreate it */
			ret = create_event_handle(sig, s);
	}
	else
	{
		/* Event don't exist , so let's create it */
		struct afb_event empty_event = {nullptr, nullptr};
		subscribed_signals[sig] = empty_event;
		ret = create_event_handle(sig, s);
	}

	/* Check whether or not the event handler has been correctly created and
	 * make the subscription/unsubscription operation is so.
	 */
	if (ret <= 0)
		return ret;
	return make_subscription_unsubscription(request, sig, s, subscribe);
}

/**
 * @fn static int subscribe_unsubscribe_signals(struct afb_req request, bool subscribe, const std::vector<CanSignal>& signals)
 * @brief subscribe to all signals in the vector signals
 *
 * @param[in] afb_req request : contain original request use to subscribe or unsubscribe
 * @param[in] subscribe boolean value used to chose between a subscription operation or an unsubscription
 * @param[in] CanSignal  vector with CanSignal to subscribe
 *
 * @return Number of correctly subscribed signal
 */
static int subscribe_unsubscribe_signals(struct afb_req request, bool subscribe, std::vector<std::string>& signals)
{
	int rets = 0;

	for(auto& signal_i : signals)
	{
		int ret = subscribe_unsubscribe_signal(request, subscribe, signal_i);
		if(ret <= 0)
			return ret;
		rets++;
		DEBUG(binder_interface, "Signal: %s subscribed", signal_i.c_str());
	}
	return rets;
}

static int subscribe_unsubscribe_name(struct afb_req request, bool subscribe, const char *name)
{
	std::vector<std::string> sig;
	int ret = 0;

	openxc_DynamicField search_key = build_DynamicField(std::string(name));
	sig = find_signals(search_key);
	if (sig.empty())
		ret = 0;

	ret = subscribe_unsubscribe_signals(request, subscribe, sig);
	NOTICE(binder_interface, "Subscribed correctly to %d/%d signal(s).", ret, (int)sig.size());

	return ret;
}

static void subscribe_unsubscribe(struct afb_req request, bool subscribe)
{
	int ok, i, n;
	struct json_object *args, *a, *x;

	/* makes the subscription/unsubscription */
	args = afb_req_json(request);
	if (args == NULL || !json_object_object_get_ex(args, "event", &a)) {
		ok = subscribe_unsubscribe_name(request, subscribe, "*");
	} else if (json_object_get_type(a) != json_type_array) {
		ok = subscribe_unsubscribe_name(request, subscribe, json_object_get_string(a));
	} else {
		n = json_object_array_length(a);
		ok = 0;
		for (i = 0 ; i < n ; i++) {
			x = json_object_array_get_idx(a, i);
			if (subscribe_unsubscribe_name(request, subscribe, json_object_get_string(x)))
				ok++;
		}
		ok = (ok == n);
	}

	/* send the report */
	if (ok)
		afb_req_success(request, NULL, NULL);
	else
		afb_req_fail(request, "error", NULL);
}

extern "C"
{
	static void subscribe(struct afb_req request)
	{
		subscribe_unsubscribe(request, true);
	}

	static void unsubscribe(struct afb_req request)
	{
		subscribe_unsubscribe(request, false);
	}

	static const struct afb_verb_desc_v1 verbs[]=
	{
		{ .name= "subscribe",	.session= AFB_SESSION_NONE, .callback= subscribe,	.info= "subscribe to notification of CAN bus messages." },
		{ .name= "unsubscribe",	.session= AFB_SESSION_NONE, .callback= unsubscribe,	.info= "unsubscribe a previous subscription." }
	};

	static const struct afb_binding binding_desc {
		AFB_BINDING_VERSION_1,
		{
			"Low level CAN bus service",
			"low-can",
			verbs
		}
	};

	const struct afb_binding *afbBindingV1Register (const struct afb_binding_interface *itf)
	{
		binder_interface = itf;

		return &binding_desc;
	}

	/**
	* @brief Initialize the binding.
	* 
	* @param[in] service Structure which represent the Application Framework Binder.
	* 
	* @return Exit code, zero if success.
	*/
	int afbBindingV1ServiceInit(struct afb_service service)
	{
		int fd_conf;
		fd_conf = afb_daemon_rootdir_open_locale(binder_interface->daemon, "can_buses.json", O_RDONLY, NULL);

		/* Initialize the CAN bus handler */
		can_bus_handler = new can_bus_t(fd_conf);

		/* Open CAN socket */
		if(can_bus_handler->init_can_dev() == 0)
		{
			can_bus_handler->start_threads();
			return 0;
		}
		ERROR(binder_interface, "There was something wrong with CAN device Initialization. Check your config file maybe");
		return 1;
	}
};