/*
 * 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 <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/can.h>
#include <linux/can/raw.h>
#include <fcntl.h>
#include <systemd/sd-event.h>
#include <errno.h>
#include <vector>
#include <map>
#include <queue>
#include <string>
#include <functional>
#include <memory>
#include <thread>

#include <json-c/json.h>
#include <openxc.pb.h>

#include <afb/afb-binding.h>
#include <afb/afb-service-itf.h>

#include "ll-can-binding.h"
#include "obd2.h"

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


/********************************************************************************
*
*		Event management
*
*********************************************************************************/

/*
 * TBF TBF TBF
 * called on an event on the CAN bus
 */
static int on_event(sd_event_source *s, int fd, uint32_t revents, void *userdata)
{
	openxc_CanMessage can_message;

	can_message = openxc_CanMessage_init_default;

	/* read available data */
	if ((revents & EPOLLIN) != 0)
	{
		read_can(&can_message);
		send_event();
	}

	/* check if error or hangup */
	if ((revents & (EPOLLERR|EPOLLRDHUP|EPOLLHUP)) != 0)
	{
		sd_event_source_unref(s);
		close(fd);
		connect_to_event_loop();
	}

	return 0;
}

/*
 * Get the event loop running.
 * Will trigger on_event function on EPOLLIN event on socket
 *
 * Return 0 or positive value on success. Else negative value for failure.
 */
static int connect_to_event_loop(CanBus &CanBus_handler)
{
	sd_event *event_loop;
	sd_event_source *source;
	int rc;

	if (CanBus_handler.socket < 0)
	{
		return CanBus_handler.socket;
	}

	event_loop = afb_daemon_get_event_loop(interface->daemon);
	rc = sd_event_add_io(event_loop, &source, CanBus_handler.socket, EPOLLIN, on_event, NULL);
	if (rc < 0)
	{
		CanBus_handler.close();
		ERROR(interface, "Can't connect CAN bus %s to the event loop", CanBus_handler.device);
	} else
	{
		NOTICE(interface, "Connected CAN bus %s to the event loop", CanBus_handler.device);
	}

	return rc;
}

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

static int subscribe_unsubscribe_sig(struct afb_req request, int subscribe, struct signal *sig)
{
	if (!afb_event_is_valid(sig->event)) {
		if (!subscribe)
			return 1;
		sig->event = afb_daemon_make_event(afbitf->daemon, sig->name);
		if (!afb_event_is_valid(sig->event)) {
			return 0;
		}
	}

	if (((subscribe ? afb_req_subscribe : afb_req_unsubscribe)(request, sig->event)) < 0) {
		return 0;
	}

	return 1;
}

static int subscribe_unsubscribe_all(struct afb_req request, int subscribe)
{
	int i, n, e;

	n = sizeof OBD2_PIDS / sizeof * OBD2_PIDS;
	e = 0;
	for (i = 0 ; i < n ; i++)
		e += !subscribe_unsubscribe_sig(request, subscribe, &OBD2_PIDS[i]);
	return e == 0;
}

static int subscribe_unsubscribe_name(struct afb_req request, int subscribe, const char *name)
{
	struct signal *sig;

	if (0 == strcmp(name, "*"))
		return subscribe_unsubscribe_all(request, subscribe);

	sig = getsig(name);
	if (sig == NULL) {
		return 0;
	}

	return subscribe_unsubscribe_sig(request, subscribe, sig);
}

static void subscribe_unsubscribe(struct afb_req request, int 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_all(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);
}

static void subscribe(struct afb_req request)
{
	subscribe_unsubscribe(request, 1);
}

static void unsubscribe(struct afb_req request)
{
	subscribe_unsubscribe(request, 0);
}
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." },
	{NULL}
};

static const struct afb_binding binding_desc = {
	.type = AFB_BINDING_VERSION_1,
	.v1 = {
		.info = "CAN bus service",
		.prefix = "can",
		.verbs = verbs
	}
};

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

	return &binding_desc;
}

int afbBindingV1ServiceInit(struct afb_service service)
{
	/* Open JSON conf file */

	/* Open CAN socket */
	CanBus_t CanBus_handler;
	CanBus_handler.open();
    CanBus_handler.start_threads();

	return connect_to_event_loop(CanBus_handler);
}