//---------------------------------------------------------------------------
//
// SCSI Target Emulator RaSCSI Reloaded
// for Raspberry Pi
//
// Powered by XM6 TypeG Technology.
// Copyright (C) 2016-2020 GIMONS
// Copyright (C) 2022 Uwe Seimet
//
//---------------------------------------------------------------------------

// TODO Evaluate CHECK CONDITION after sending a command
// TODO Send IDENTIFY message in order to support LUNS > 7

#include "shared/log.h"
#include "shared/rasutil.h"
#include "shared/rascsi_exceptions.h"
#include "shared/rascsi_version.h"
#include "hal/gpiobus_factory.h"
#include "hal/gpiobus.h"
#include "hal/systimer.h"
#include "rasdump/rasdump_core.h"
#include <sys/stat.h>
#include <csignal>
#include <cstddef>
#include <unistd.h>
#include <cstring>
#include <iostream>
#include <fstream>

using namespace std;
using namespace spdlog;
using namespace scsi_defs;
using namespace ras_util;

void RasDump::CleanUp()
{
	if (bus != nullptr) {
		bus->Cleanup();
	}
}

void RasDump::KillHandler(int)
{
	CleanUp();

	exit(EXIT_SUCCESS);
}

bool RasDump::Banner(const vector<char *>& args) const
{
	cout << ras_util::Banner("RaSCSI hard disk dump/restore utility");

	if (args.size() < 2 || string(args[1]) == "-h") {
		cout << "Usage: " << args[0] << " -t ID[:LUN] [-i BID] -f FILE [-v] [-r] [-s BUFFER_SIZE]\n"
				<< " ID is the target device ID (0-7).\n"
				<< " LUN is the optional target device LUN (0-7). Default is 0.\n"
				<< " BID is the RaSCSI board ID (0-7). Default is 7.\n"
				<< " FILE is the dump file path.\n"
				<< " BUFFER_SIZE is the transfer buffer size, at least "
				<< to_string(MINIMUM_BUFFER_SIZE / 1024) << " KiB. Default is 1 MiB.\n"
				<< " -v Enable verbose logging.\n"
				<< " -r Restore instead of dump.\n" << flush;

		return false;
	}

	return true;
}

bool RasDump::Init() const
{
	// Interrupt handler setting
	if (signal(SIGINT, KillHandler) == SIG_ERR || signal(SIGHUP, KillHandler) == SIG_ERR ||
			signal(SIGTERM, KillHandler) == SIG_ERR) {
		return false;
	}

	bus = GPIOBUS_Factory::Create(BUS::mode_e::INITIATOR);

	return bus != nullptr;
}

void RasDump::ParseArguments(const vector<char *>& args)
{
	int opt;

	int buffer_size = DEFAULT_BUFFER_SIZE;

	opterr = 0;
	while ((opt = getopt(static_cast<int>(args.size()), args.data(), "i:f:s:t:rv")) != -1) {
		switch (opt) {
			case 'i':
				if (!GetAsUnsignedInt(optarg, initiator_id) || initiator_id > 7) {
					throw parser_exception("Invalid RaSCSI board ID " + to_string(initiator_id) + " (0-7)");
				}
				break;

			case 'f':
				filename = optarg;
				break;

			case 's':
				if (!GetAsUnsignedInt(optarg, buffer_size) || buffer_size < MINIMUM_BUFFER_SIZE) {
					throw parser_exception("Buffer size must be at least " + to_string(MINIMUM_BUFFER_SIZE / 1024) + "KiB");
				}

				break;

			case 't': {
					const string error = ProcessId(optarg, 8, target_id, target_lun);
					if (!error.empty()) {
						throw parser_exception(error);
					}
				}
				break;

			case 'v':
				set_level(level::debug);
				break;

			case 'r':
				restore = true;
				break;

			default:
				break;
		}
	}

	if (target_id == initiator_id) {
		throw parser_exception("Target ID and RaSCSI board ID must not be identical");
	}

	if (filename.empty()) {
		throw parser_exception("Missing filename");
	}

	buffer = vector<uint8_t>(buffer_size);
}

void RasDump::WaitPhase(BUS::phase_t phase) const
{
	LOGDEBUG("Waiting for %s phase", BUS::GetPhaseStrRaw(phase))

	// Timeout (3000ms)
	const uint32_t now = SysTimer::GetTimerLow();
	while ((SysTimer::GetTimerLow() - now) < 3 * 1000 * 1000) {
		bus->Acquire();
		if (bus->GetREQ() && bus->GetPhase() == phase) {
			return;
		}
	}

	throw parser_exception("Expected " + string(BUS::GetPhaseStrRaw(phase)) + " phase, actual phase is "
			+ string(BUS::GetPhaseStrRaw(bus->GetPhase())));
}

void RasDump::Selection() const
{
	// Set initiator and target ID
	auto data = static_cast<byte>(1 << initiator_id);
	data |= static_cast<byte>(1 << target_id);
	bus->SetDAT(static_cast<uint8_t>(data));

	bus->SetSEL(true);

	WaitForBusy();

	bus->SetSEL(false);
}

void RasDump::Command(scsi_command cmd, vector<uint8_t>& cdb) const
{
	LOGDEBUG("Executing %s", command_mapping.find(cmd)->second.second)

	Selection();

	WaitPhase(BUS::phase_t::command);

	cdb[0] = static_cast<uint8_t>(cmd);
	cdb[1] = static_cast<uint8_t>(static_cast<byte>(cdb[1]) | static_cast<byte>(target_lun << 5));
	if (static_cast<int>(cdb.size()) != bus->SendHandShake(cdb.data(), static_cast<int>(cdb.size()), BUS::SEND_NO_DELAY)) {
		BusFree();

		throw parser_exception(command_mapping.find(cmd)->second.second + string(" failed"));
	}
}

void RasDump::DataIn(int length)
{
	WaitPhase(BUS::phase_t::datain);

	if (!bus->ReceiveHandShake(buffer.data(), length)) {
		throw parser_exception("DATA IN failed");
	}
}

void RasDump::DataOut(int length)
{
	WaitPhase(BUS::phase_t::dataout);

	if (!bus->SendHandShake(buffer.data(), length, BUS::SEND_NO_DELAY)) {
		throw parser_exception("DATA OUT failed");
	}
}

void RasDump::Status() const
{
	WaitPhase(BUS::phase_t::status);

	if (array<uint8_t, 256> buf; bus->ReceiveHandShake(buf.data(), 1) != 1) {
		throw parser_exception("STATUS failed");
	}
}

void RasDump::MessageIn() const
{
	WaitPhase(BUS::phase_t::msgin);

	if (array<uint8_t, 256> buf; bus->ReceiveHandShake(buf.data(), 1) != 1) {
		throw parser_exception("MESSAGE IN failed");
	}
}

void RasDump::BusFree() const
{
	bus->Reset();
}

void RasDump::TestUnitReady() const
{
	vector<uint8_t> cdb(6);
	Command(scsi_command::eCmdTestUnitReady, cdb);

	Status();

	MessageIn();

	BusFree();
}

void RasDump::RequestSense()
{
	vector<uint8_t> cdb(6);
	cdb[4] = 0xff;
	Command(scsi_command::eCmdRequestSense, cdb);

	DataIn(256);

	Status();

	MessageIn();

	BusFree();
}

void RasDump::Inquiry()
{
	vector<uint8_t> cdb(6);
	cdb[4] = 0xff;
	Command(scsi_command::eCmdInquiry, cdb);

	DataIn(256);

	Status();

	MessageIn();

	BusFree();
}

pair<uint64_t, uint32_t> RasDump::ReadCapacity()
{
	vector<uint8_t> cdb(10);
	Command(scsi_command::eCmdReadCapacity10, cdb);

	DataIn(8);

	Status();

	MessageIn();

	BusFree();

	uint64_t capacity = (static_cast<uint32_t>(buffer[0]) << 24) | (static_cast<uint32_t>(buffer[1]) << 16) |
			(static_cast<uint32_t>(buffer[2]) << 8) | static_cast<uint32_t>(buffer[3]);

	int sector_size_offset = 4;

	if (static_cast<int32_t>(capacity) == -1) {
		cdb.resize(16);
		// READ CAPACITY(16), not READ LONG(16)
		cdb[1] = 0x10;
		Command(scsi_command::eCmdReadCapacity16_ReadLong16, cdb);

		DataIn(14);

		Status();

		MessageIn();

		BusFree();

		capacity = (static_cast<uint64_t>(buffer[0]) << 56) | (static_cast<uint64_t>(buffer[1]) << 48) |
				(static_cast<uint64_t>(buffer[2]) << 40) | (static_cast<uint64_t>(buffer[3]) << 32) |
				(static_cast<uint64_t>(buffer[4]) << 24) | (static_cast<uint64_t>(buffer[5]) << 16) |
				(static_cast<uint64_t>(buffer[6]) << 8) | static_cast<uint64_t>(buffer[7]);

		sector_size_offset = 8;
	}

	const uint32_t sector_size = (static_cast<uint32_t>(buffer[sector_size_offset]) << 24) |
			(static_cast<uint32_t>(buffer[sector_size_offset + 1]) << 16) |
			(static_cast<uint32_t>(buffer[sector_size_offset +2]) << 8) |
			static_cast<uint32_t>(buffer[sector_size_offset + 3]);

	return make_pair(capacity, sector_size);
}

void RasDump::Read10(uint32_t bstart, uint32_t blength, uint32_t length)
{
	vector<uint8_t> cdb(10);
	cdb[2] = (uint8_t)(bstart >> 24);
	cdb[3] = (uint8_t)(bstart >> 16);
	cdb[4] = (uint8_t)(bstart >> 8);
	cdb[5] = (uint8_t)bstart;
	cdb[7] = (uint8_t)(blength >> 8);
	cdb[8] = (uint8_t)blength;
	Command(scsi_command::eCmdRead10, cdb);

	DataIn(length);

	Status();

	MessageIn();

	BusFree();
}

void RasDump::Write10(uint32_t bstart, uint32_t blength, uint32_t length)
{
	vector<uint8_t> cdb(10);
	cdb[2] = (uint8_t)(bstart >> 24);
	cdb[3] = (uint8_t)(bstart >> 16);
	cdb[4] = (uint8_t)(bstart >> 8);
	cdb[5] = (uint8_t)bstart;
	cdb[7] = (uint8_t)(blength >> 8);
	cdb[8] = (uint8_t)blength;
	Command(scsi_command::eCmdWrite10, cdb);

	DataOut(length);

	Status();

	MessageIn();

	BusFree();
}

void RasDump::WaitForBusy() const
{
	// Wait for busy for up to 2 s
	int count = 10000;
	do {
		// Wait 20 ms
		const timespec ts = { .tv_sec = 0, .tv_nsec = 20 * 1000};
		nanosleep(&ts, nullptr);
		bus->Acquire();
		if (bus->GetBSY()) {
			break;
		}
	} while (count--);

	// Success if the target is busy
	if(!bus->GetBSY()) {
		throw parser_exception("SELECTION failed");
	}
}

int RasDump::run(const vector<char *>& args)
{
	if (!Banner(args)) {
		return EXIT_SUCCESS;
	}

	if (!Init()) {
		cerr << "Error: Initializing. Are you root?" << endl;

		// Probably not root
		return EPERM;
	}

	try {
		ParseArguments(args);

#ifndef USE_SEL_EVENT_ENABLE
		cerr << "Error: No RaSCSI hardware support" << endl;
		return EXIT_FAILURE;
#endif

		return DumpRestore();
	}
	catch(const parser_exception& e) {
		cerr << "Error: " << e.what() << endl;

		CleanUp();

		return EXIT_FAILURE;
	}

	CleanUp();

	return EXIT_SUCCESS;
}

int RasDump::DumpRestore()
{
	const auto [capacity, sector_size] = GetDeviceInfo();

	fstream fs;
	fs.open(filename, (restore ? ios::in : ios::out) | ios::binary);

	if (fs.fail()) {
		throw parser_exception("Can't open image file '" + filename + "'");
	}

	if (restore) {
		cout << "Starting restore\n" << flush;

		// filesystem::file_size cannot be used here because gcc < 10.3.0 cannot handle more than 2 GiB
		off_t size;
		if (struct stat st; !stat(filename.c_str(), &st)) {
			size = st.st_size;
		}
		else {
			throw parser_exception("Can't determine file size");
		}

		cout << "Restore file size: " << size << " bytes\n";
		if (size > (off_t)(sector_size * capacity)) {
			cout << "WARNING: File size is larger than disk size\n" << flush;
		} else if (size < (off_t)(sector_size * capacity)) {
			throw parser_exception("File size is smaller than disk size");
		}
	}
	else {
		cout << "Starting dump\n" << flush;
	}

	// Dump by buffer size
	auto dsiz = static_cast<int>(buffer.size());
	const int duni = dsiz / sector_size;
	auto dnum = static_cast<int>((capacity * sector_size) / dsiz);

	int i;
	for (i = 0; i < dnum; i++) {
		if (restore) {
			fs.read((char *)buffer.data(), dsiz);
			Write10(i * duni, duni, dsiz);
		}
		else {
			Read10(i * duni, duni, dsiz);
			fs.write((const char *)buffer.data(), dsiz);
		}

		if (fs.fail()) {
			throw parser_exception("File I/O failed");
		}

		cout << ((i + 1) * 100 / dnum) << "%" << " (" << ( i + 1) * duni << "/" << capacity << ")\n" << flush;
	}

	// Rounding on capacity
	dnum = capacity % duni;
	dsiz = dnum * sector_size;
	if (dnum > 0) {
		if (restore) {
			fs.read((char *)buffer.data(), dsiz);
			if (!fs.fail()) {
				Write10(i * duni, dnum, dsiz);
			}
		}
		else {
			Read10(i * duni, dnum, dsiz);
			fs.write((const char *)buffer.data(), dsiz);
		}

		if (fs.fail()) {
			throw parser_exception("File I/O failed");
		}

		cout << "100% (" << capacity << "/" << capacity << ")\n" << flush;
	}

	return EXIT_SUCCESS;
}

pair<uint64_t, uint32_t> RasDump::GetDeviceInfo()
{
	// Assert RST for 1 ms
	bus->SetRST(true);
	const timespec ts = { .tv_sec = 0, .tv_nsec = 1000 * 1000};
	nanosleep(&ts, nullptr);
	bus->SetRST(false);

	cout << "Target device ID: " << target_id << ", LUN: " << target_lun << "\n";
	cout << "RaSCSI board ID: " << initiator_id << "\n" << flush;

	Inquiry();

	// Display INQUIRY information
	array<char, 17> str = {};
	memcpy(str.data(), &buffer[8], 8);
	cout << "Vendor:    " << str.data() << "\n";
	str.fill(0);
	memcpy(str.data(), &buffer[16], 16);
	cout << "Product:   " << str.data() << "\n";
	str.fill(0);
	memcpy(str.data(), &buffer[32], 4);
	cout << "Revision:  " << str.data() << "\n" << flush;

	if (auto type = static_cast<device_type>(buffer[0]);
		type != device_type::DIRECT_ACCESS && type != device_type::CD_ROM && type != device_type::OPTICAL_MEMORY) {
		throw parser_exception("Invalid device type, supported types are DIRECT ACCESS, CD-ROM and OPTICAL MEMORY");
	}

	TestUnitReady();

	RequestSense();

	const auto [capacity, sector_size] = ReadCapacity();

	cout << "Number of sectors: " << capacity << "\n"
			<< "Sector size:       " << sector_size << " bytes\n"
			<< "Capacity:          " << sector_size * capacity / 1024 / 1024 << " MiB ("
			<< sector_size * capacity << " bytes)\n\n" << flush;

	return make_pair(capacity, sector_size);
}