/*
 * Copyright (c) 2021 Ampere Computing LLC
 *
 * 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.
 *
 * This is a daemon that forwards requests and receive responses from SSIF over
 * the D-Bus IPMI Interface.
 */

#include <getopt.h>
#include <linux/ipmi_bmc.h>

#include <CLI/CLI.hpp>
#include <boost/algorithm/string/replace.hpp>
#include <boost/asio.hpp>
#include <phosphor-logging/log.hpp>
#include <sdbusplus/asio/connection.hpp>
#include <sdbusplus/asio/object_server.hpp>
#include <sdbusplus/timer.hpp>
#include <sdbusplus/asio/sd_event.hpp>

#include <iostream>

/* Max length of ipmi ssif message included netfn and cmd field */
#define IPMI_SSIF_PAYLOAD_MAX 254

using namespace phosphor::logging;

struct ipmi_cmd {
	uint8_t netfn;
	uint8_t lun;
	uint8_t cmd;
} prev_req_cmd;

static constexpr const char devBase[] = "/dev/ipmi-ssif-host";
/* SSIF use IPMI SSIF channel */
static constexpr const char *ssifBus =
	"xyz.openbmc_project.Ipmi.Channel.ipmi_ssif";
static constexpr const char *ssifObj =
	"/xyz/openbmc_project/Ipmi/Channel/ipmi_ssif";
/* The timer of driver is set to 15 seconds, need to send
 * response before timeout occurs
 */
static constexpr const unsigned int hostReqTimeout = 14000000;

class SsifChannel {
    public:
	static constexpr size_t ssifMessageSize =
		IPMI_SSIF_PAYLOAD_MAX + sizeof(unsigned int);
	size_t sizeofLenField = sizeof(unsigned int);
	static constexpr uint8_t netFnShift = 2;
	static constexpr uint8_t lunMask = (1 << netFnShift) - 1;

	SsifChannel(std::shared_ptr<boost::asio::io_context> &io,
		    std::shared_ptr<sdbusplus::asio::connection> &bus,
		    const std::string &channel, bool verbose,
		    int numberOfReqNotRsp);
	bool initOK() const
	{
		return !!dev;
	}
	void channelAbort(const char *msg, const boost::system::error_code &ec);
	void async_read();
	void processMessage(const boost::system::error_code &ecRd, size_t rlen);
	int showNumOfReqNotRsp();
	std::unique_ptr<boost::asio::posix::stream_descriptor> dev = nullptr;

    protected:
	std::array<uint8_t, ssifMessageSize> xferBuffer;
	std::shared_ptr<boost::asio::io_context> io;
	std::shared_ptr<sdbusplus::asio::connection> bus;
	std::shared_ptr<sdbusplus::asio::object_server> server;
	bool verbose;
	/* This variable is always 0 when a request is responsed properly,
	 * any value larger than 0 meaning there is/are request(s) which
	 * not processed properly
	 * */
	int numberOfReqNotRsp;
};

std::unique_ptr<phosphor::Timer> rspTimer __attribute__((init_priority(101)));
std::unique_ptr<SsifChannel> ssifchannel = nullptr;

SsifChannel::SsifChannel(std::shared_ptr<boost::asio::io_context> &io,
			 std::shared_ptr<sdbusplus::asio::connection> &bus,
			 const std::string &device, bool verbose,
			 int numberOfReqNotRsp)
	: io(io), bus(bus), verbose(verbose),
	  numberOfReqNotRsp(numberOfReqNotRsp)
{
	std::string devName = devBase;
	if (!device.empty()) {
		devName = device;
	}

	// open device
	int fd = open(devName.c_str(), O_RDWR | O_NONBLOCK);
	if (fd < 0) {
		std::string msgToLog =
			"Couldn't open SSIF driver with flags O_RDWR."
			" FILENAME=" +
			devName + " ERROR=" + strerror(errno);
		log<level::ERR>(msgToLog.c_str());
		return;
	} else {
		dev = std::make_unique<boost::asio::posix::stream_descriptor>(
			*io, fd);
	}

	async_read();
	// register interfaces...
	server = std::make_shared<sdbusplus::asio::object_server>(bus);
	std::shared_ptr<sdbusplus::asio::dbus_interface> iface =
		server->add_interface(ssifObj, ssifBus);
	iface->initialize();
}

void SsifChannel::channelAbort(const char *msg,
			       const boost::system::error_code &ec)
{
	std::string msgToLog = std::string(msg) + " ERROR=" + ec.message();
	log<level::ERR>(msgToLog.c_str());
	// bail; maybe a restart from systemd can clear the error
	io->stop();
}

void SsifChannel::async_read()
{
	boost::asio::async_read(
		*dev, boost::asio::buffer(xferBuffer, xferBuffer.size()),
		boost::asio::transfer_at_least(2),
		[this](const boost::system::error_code &ec, size_t rlen) {
			processMessage(ec, rlen);
		});
}

int SsifChannel::showNumOfReqNotRsp()
{
	return numberOfReqNotRsp;
}

void rspTimerHandler()
{
	std::vector<uint8_t> rsp;
	constexpr uint8_t ccResponseNotAvailable = 0xce;

	rsp.resize(ssifchannel->sizeofLenField + sizeof(prev_req_cmd.cmd) +
		   sizeof(prev_req_cmd.netfn) + sizeof(ccResponseNotAvailable));
	std::string msgToLog =
		"timeout, send response to keep host alive"
		" netfn=" +
		std::to_string(prev_req_cmd.netfn) +
		" lun=" + std::to_string(prev_req_cmd.lun) +
		" cmd=" + std::to_string(prev_req_cmd.cmd) +
		" cc=" + std::to_string(ccResponseNotAvailable) +
		" numberOfReqNotRsp=" +
		std::to_string(ssifchannel->showNumOfReqNotRsp());
	log<level::INFO>(msgToLog.c_str());

	unsigned int *t = (unsigned int *)&rsp[0];
	*t = 3;
	rsp[ssifchannel->sizeofLenField] =
		((prev_req_cmd.netfn + 1) << ssifchannel->netFnShift) |
		(prev_req_cmd.lun & ssifchannel->lunMask);
	rsp[ssifchannel->sizeofLenField + 1] = prev_req_cmd.cmd;
	rsp[ssifchannel->sizeofLenField + 2] = ccResponseNotAvailable;

	boost::system::error_code ecWr;

	size_t wlen = boost::asio::write(*(ssifchannel->dev),
					 boost::asio::buffer(rsp), ecWr);
	if (ecWr || wlen != rsp.size()) {
		msgToLog =
			"Failed to send ssif respond message:"
			" size=" +
			std::to_string(wlen) +
			" expect=" + std::to_string(rsp.size()) +
			" error=" + ecWr.message() +
			" netfn=" + std::to_string(prev_req_cmd.netfn + 1) +
			" lun=" + std::to_string(prev_req_cmd.lun) + " cmd=" +
			std::to_string(rsp[ssifchannel->sizeofLenField + 1]) +
			" cc=" + std::to_string(ccResponseNotAvailable);
		log<level::ERR>(msgToLog.c_str());
	}
}

void initTimer()
{
	if (!rspTimer) {
		rspTimer = std::make_unique<phosphor::Timer>(rspTimerHandler);
	}
}

void SsifChannel::processMessage(const boost::system::error_code &ecRd,
				 size_t rlen)
{
	if (ecRd || rlen < 2) {
		channelAbort("Failed to read req msg", ecRd);
		return;
	}
	async_read();

	auto rawIter = xferBuffer.cbegin();
	auto rawEnd = rawIter + rlen;
	uint8_t netfn = rawIter[sizeofLenField] >> netFnShift;
	uint8_t lun = rawIter[sizeofLenField] & lunMask;
	uint8_t cmd = rawIter[sizeofLenField + 1];

	/* keep track of previous request */
	prev_req_cmd.netfn = netfn;
	prev_req_cmd.lun = lun;
	prev_req_cmd.cmd = cmd;

	/* there is a request coming */
	numberOfReqNotRsp++;
	/* start response timer */
	rspTimer->start(std::chrono::microseconds(hostReqTimeout), false);

	if (verbose) {
		unsigned int lenRecv;
		unsigned int *p = (unsigned int *)rawIter;
		lenRecv = p[0];
		std::string msgToLog = "Read ssif request message with"
				       " len=" +
				       std::to_string(lenRecv) +
				       " netfn=" + std::to_string(netfn) +
				       " lun=" + std::to_string(lun) +
				       " cmd=" + std::to_string(cmd) +
				       " numberOfReqNotRsp=" +
				       std::to_string(numberOfReqNotRsp);
		log<level::INFO>(msgToLog.c_str());
	}
	// copy out payload
	std::vector<uint8_t> data(rawIter + sizeofLenField + 2, rawEnd);
	// non-session bridges still need to pass an empty options map
	std::map<std::string, std::variant<int> > options;
	// the response is a tuple because dbus can only return a single value
	using IpmiDbusRspType = std::tuple<uint8_t, uint8_t, uint8_t, uint8_t,
					   std::vector<uint8_t> >;
	static constexpr const char ipmiQueueService[] =
		"xyz.openbmc_project.Ipmi.Host";
	static constexpr const char ipmiQueuePath[] =
		"/xyz/openbmc_project/Ipmi";
	static constexpr const char ipmiQueueIntf[] =
		"xyz.openbmc_project.Ipmi.Server";
	static constexpr const char ipmiQueueMethod[] = "execute";
	/* now, we do not care dbus timeout, since we already have actions
	 * before dbus timeout occurs
	 */
	static constexpr unsigned int dbusTimeout = 60000000;
	bus->async_method_call_timed(
		[this, netfnCap{ netfn }, lunCap{ lun },
		 cmdCap{ cmd }](const boost::system::error_code &ec,
				const IpmiDbusRspType &response) {
			std::vector<uint8_t> rsp;
			const auto &[netfn, lun, cmd, cc, payload] = response;
			numberOfReqNotRsp--;
			if (ec) {
				std::string msgToLog =
					"ssif<->ipmid bus error:"
					" netfn=" +
					std::to_string(netfn) +
					" lun=" + std::to_string(lun) +
					" cmd=" + std::to_string(cmd) +
					" error=" + ec.message();
				log<level::ERR>(msgToLog.c_str());
				rsp.resize(sizeofLenField + sizeof(netfn) +
					   sizeof(cmd) + sizeof(cc));
				/* if dbusTimeout, just return and do not send any response
				 * to let host continue with other commands, response here
				 * is potentially make the response duplicated
				 * */
				return;
			} else {
				if ((prev_req_cmd.netfn != (netfn - 1) ||
				     prev_req_cmd.lun != lun ||
				     prev_req_cmd.cmd != cmd) ||
				    ((prev_req_cmd.netfn == (netfn - 1) &&
				      prev_req_cmd.lun == lun &&
				      prev_req_cmd.cmd == cmd) &&
				     numberOfReqNotRsp != 0)) {
					/* Only send response to the last request command to void
					 * duplicated response which makes host driver confused and
					 * failed to create interface
					 *
					 * Drop responses which are (1) different from the request
					 * (2) parameters are the same as request but handshake flow
					 * are in dupplicate request state
					 * */
					if (verbose) {
						std::string msgToLog =
							"Drop ssif respond message with"
							" len=" +
							std::to_string(
								payload.size() +
								3) +
							" netfn=" +
							std::to_string(netfn) +
							" lun=" +
							std::to_string(lun) +
							" cmd=" +
							std::to_string(cmd) +
							" cc=" +
							std::to_string(cc) +
							" numberOfReqNotRsp=" +
							std::to_string(
								numberOfReqNotRsp);
						log<level::INFO>(
							msgToLog.c_str());
					}
					return;
				}
				rsp.resize(sizeofLenField + sizeof(netfn) +
					   sizeof(cmd) + sizeof(cc) +
					   payload.size());

				// write the response
				auto rspIter = rsp.begin();
				unsigned int *p = (unsigned int *)&rspIter[0];
				*p = payload.size() + 3;
				rspIter[sizeofLenField] =
					(netfn << netFnShift) | (lun & lunMask);
				rspIter[sizeofLenField + 1] = cmd;
				rspIter[sizeofLenField + 2] = cc;
				if (payload.size()) {
					std::copy(payload.cbegin(),
						  payload.cend(),
						  rspIter + sizeofLenField + 3);
				}
			}
			if (verbose) {
				std::string msgToLog =
					"Send ssif respond message with"
					" len=" +
					std::to_string(payload.size() + 3) +
					" netfn=" + std::to_string(netfn) +
					" lun=" + std::to_string(lun) +
					" cmd=" + std::to_string(cmd) +
					" cc=" + std::to_string(cc) +
					" numberOfReqNotRsp=" +
					std::to_string(numberOfReqNotRsp);
				log<level::INFO>(msgToLog.c_str());
			}
			boost::system::error_code ecWr;
			size_t wlen = boost::asio::write(
				*dev, boost::asio::buffer(rsp), ecWr);
			if (ecWr || wlen != rsp.size()) {
				std::string msgToLog =
					"Failed to send ssif respond message:"
					" size=" +
					std::to_string(wlen) + " expect=" +
					std::to_string(rsp.size()) +
					" error=" + ecWr.message() +
					" netfn=" + std::to_string(netfn) +
					" lun=" + std::to_string(lun) +
					" cmd=" + std::to_string(cmd) +
					" cc=" + std::to_string(cc);
				log<level::ERR>(msgToLog.c_str());
			}
			rspTimer->stop();
		},
		ipmiQueueService, ipmiQueuePath, ipmiQueueIntf, ipmiQueueMethod,
		dbusTimeout, netfn, lun, cmd, data, options);
}

int main(int argc, char *argv[])
{
	CLI::App app("SSIF IPMI bridge");
	std::string device;
	app.add_option("-d,--device", device,
		       "use <DEVICE> file. Default is /dev/ipmi-ssif-host");
	bool verbose = false;
	int numberOfReqNotRsp = 0;
	app.add_option("-v,--verbose", verbose, "print more verbose output");
	CLI11_PARSE(app, argc, argv);

	// Connect to system bus
	auto io = std::make_shared<boost::asio::io_context>();
	sd_bus *dbus;
	sd_bus_default_system(&dbus);

	/* This might be a phosphor::Timer bug, without timer t2, rspTimer
	 * will not work
	 */
	phosphor::Timer t2([]() { ; });
	t2.start(std::chrono::microseconds(500000), true);
	auto bus = std::make_shared<sdbusplus::asio::connection>(*io, dbus);
	bus->request_name(ssifBus);
	// Create the SSIF channel, listening on D-Bus and on the SSIF device
	ssifchannel = make_unique<SsifChannel>(io, bus, device, verbose,
					       numberOfReqNotRsp);
	if (!ssifchannel->initOK()) {
		return EXIT_FAILURE;
	}
	initTimer();
	sdbusplus::asio::sd_event_wrapper sdEvents(*io);
	io->run();

	return 0;
}