/*
 * scribiu -- read notebooks and voice memos from Livescribe pens
 * Copyright (C) 2015 Javier S. Pedro <javier@javispedro.com>
 *
 * 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
 * (at your option) 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 <QtCore/QDataStream>
#include <QtCore/QDebug>
#include <QtCore/QDeadlineTimer>
#include <QtCore/QThread>
#include <QtCore/QStringList>
#include <QtCore/QtEndian>
#include <libusb-1.0/libusb.h>
#include "xmlutils.h"
#include "smartpen.h"

#define PEN_MTU OBEX_MAXIMUM_MTU
#define PEN_TIMEOUT_SECONDS 5

#define INVALID_CID 0xFFFFFFFFU

static const char pen_serial_chars[] = "ABCDEFGHJKMNPQRSTUWXYZ23456789";
static const unsigned int pen_serial_num_chars = sizeof(pen_serial_chars) - 1;

Smartpen::Smartpen(QObject *parent) :
    QObject(parent), _obex(0), _connId(INVALID_CID), _reqComplete(false), _continueReceived(0)
{
}

Smartpen::~Smartpen()
{
	if (_connId != INVALID_CID || _obex) {
		disconnectFromPen();
	}
}

bool Smartpen::isConnected() const
{
	return _obex && _connId != INVALID_CID;
}

QByteArray Smartpen::getObject(const QString &name)
{
	qDebug() << "Getting object" << name;

	prepareRequest();

	obex_object_t *obj = OBEX_ObjectNew(_obex, OBEX_CMD_GET);
	Q_ASSERT(obj);

	addConnHeader(obj);

	obex_headerdata_t hd;
	QByteArray encodedName = encodeUtf16(name);
	hd.bs = reinterpret_cast<const uint8_t*>(encodedName.constData());
	if (OBEX_ObjectAddHeader(_obex, obj, OBEX_HDR_NAME, hd, encodedName.size(), 0) < 0) {
		qCritical("Could not add name header");
		OBEX_ObjectDelete(_obex, obj);
		return QByteArray();
	}

	if (OBEX_Request(_obex, obj) < 0) {
		qWarning() << "Get object request failed";
		OBEX_ObjectDelete(_obex, obj);
		return QByteArray();
	}

	waitForRequestComplete(PEN_TIMEOUT_SECONDS);

	QByteArray result;
	qSwap(_inBuf, result);

	return result;
}

QByteArray Smartpen::getParameter(Parameter parameter)
{
	QString objectName = QString("ppdata?key=pp%1").arg(uint(parameter), 4, 16, QChar('0'));
	QByteArray data = getObject(objectName);
	QXmlStreamReader r(data);

	advanceToFirstChildElement(r, "xml");
	advanceToFirstChildElement(r, "parameter");

	if (!r.atEnd()) {
		QXmlStreamAttributes attrs = r.attributes();
		QString value = attrs.value("value").toString();
		if (!value.isEmpty()) {
			if (value.startsWith("0x")) {
				return QByteArray::fromHex(value.mid(2).toLatin1());
			} else {
				qWarning() << "Unknown parameter return format: " << value;
			}
		}
	}

	return QByteArray();
}

Smartpen::PenId Smartpen::getPenId()
{
	PenId id;
	QByteArray value = getParameter(Parameter::Id);
	if (value.isEmpty() || value.size() != 1 + sizeof(Smartpen::PenId)) {
		qWarning() << "got invalid value for pen id: " << value.toHex();
		return 0;
	}
	QDataStream ds(value);
	ds.setByteOrder(QDataStream::BigEndian);
	ds.skipRawData(1); // Unclear what first byte is
	ds >> id;
	return id;
}

QString Smartpen::getPenSerial()
{
	return toPenSerial(getPenId());
}

QString Smartpen::getPenName()
{
	return QString::fromUtf8(getParameter(Parameter::Name));
}

Smartpen::PenTime Smartpen::getPenTime(Parameter parameter)
{
	PenTime time;
	QByteArray value = getParameter(parameter);
	if (value.isEmpty() || value.size() != sizeof(Smartpen::PenTime)) {
		qWarning() << "got invalid value for pen time: " << value.toHex();
		return 0;
	}
	QDataStream ds(value);
	ds.setByteOrder(QDataStream::LittleEndian);
	ds >> time;
	return time;
}

QVariantMap Smartpen::getPenInfo()
{
	QVariantMap result;
	QByteArray data = getObject("peninfo");
	QXmlStreamReader r(data);

	qDebug() << "PenInfo: " << QString::fromLatin1(data);

	advanceToFirstChildElement(r, "xml");
	advanceToFirstChildElement(r, "peninfo");

	if (!r.atEnd()) {
		Q_ASSERT(r.isStartElement() && r.name() == "peninfo");
		QString penId = r.attributes().value("penid").toString();
		result["penid"] = penId;
		result["penserial"] = toPenSerial(penId.mid(2).toULongLong(0, 16));

		while (r.readNextStartElement()) {
			if (r.name() == "battery") {
				result["battery"] = r.attributes().value("level").toString();
				r.skipCurrentElement();
			} else if (r.name() == "time") {
				result["time"] = r.attributes().value("absolute").toString();
				r.skipCurrentElement();
			} else {
				r.skipCurrentElement();
			}
		}
	} else {
		qWarning() << "Could not parse peninfo XML";
	}

	return result;
}

QList<Smartpen::ChangeReport> Smartpen::getChangeList(PenTime from)
{
	QList<ChangeReport> result;
	QByteArray data = getObject(QString("changelist?start_time=%1").arg(from));
	QXmlStreamReader r(data);

	qDebug() << "changelist:" << QString::fromLatin1(data);

	advanceToFirstChildElement(r, "xml");
	advanceToFirstChildElement(r, "changelist");

	if (!r.atEnd()) {
		Q_ASSERT(r.isStartElement() && r.name() == "changelist");

		while (r.readNextStartElement()) {
			if (r.name() == "lsp") {
				QXmlStreamAttributes attrs = r.attributes();
				ChangeReport report;
				if (attrs.hasAttribute("guid")) {
					report.guid = attrs.value("guid").toString();
					report.title = attrs.value("title").toString();

					// Figure out the change record endtime to enumerating the
					// endtime of all the record's changed pages
					report.endTime = 0;
					while (r.readNextStartElement()) {
						if (r.name() == "page") {
							QXmlStreamAttributes attrs = r.attributes();
							PenTime endTime = attrs.value("end_time").toString().toLongLong();
							if (endTime > report.endTime) report.endTime = endTime;
						}
						r.skipCurrentElement();
					}

					result.append(report);
				} else if (attrs.hasAttribute("classname")) {
					report.className = attrs.value("classname").toString();
					report.title = attrs.value("title").toString();
					report.endTime = attrs.value("end_time").toString().toLongLong();
					result.append(report);
					r.skipCurrentElement();
				} else {
					qWarning() << "Unknown change report format";
					r.skipCurrentElement();
				}
			} else {
				r.skipCurrentElement();
			}
		}

	} else {
		qWarning() << "Could not parse changelist XML";
	}

	return result;
}

QByteArray Smartpen::getLspData(const QString &name, PenTime from)
{
	return getObject(QString("lspdata?name=%1&start_time=%2").arg(name).arg(from));
}

QByteArray Smartpen::getPaperReplay(PenTime from)
{
	return getObject(QString("lspdata?name=com.livescribe.paperreplay.PaperReplay&start_time=%1&returnVersion=0.3&remoteCaller=WIN_LD_200").arg(from));
}

QDateTime Smartpen::fromPenTime(PenTime userTime, PenTime penTime)
{
	QDateTime dt = QDateTime::fromMSecsSinceEpoch(penTime + userTime, Qt::UTC);
	dt.setTimeSpec(Qt::LocalTime); // userTime is actually in LocalTime, so override tz conversion
	return dt;
}

QString Smartpen::toPenSerial(quint64 id)
{
	QString serial;
	serial.reserve(3 + 1 + 3 + 1 + 3 + 1 + 2 + 1);

	serial.append(toPenSerialSegment(id >> 32, 3));
	serial.append('-');
	serial.append(toPenSerialSegment(id, 6).mid(0, 3));
	serial.append('-');
	serial.append(toPenSerialSegment(id, 6).mid(3, 3));
	serial.append('-');
	serial.append(toPenSerialSegment(id % 0x36D, 2));

	return serial;
}

quint64 Smartpen::toPenId(const QString &serial)
{
	QStringList segments = serial.split('-');
	if (segments.size() != 4) {
		return 0;
	}

	quint64 id = quint64(fromPenSerialSegment(segments[0])) << 32;
	id |= fromPenSerialSegment(segments[1] + segments[2]) * 0x36D;
	id |= fromPenSerialSegment(segments[3]);
	return id;
}

bool Smartpen::reset(const Address &addr)
{
	libusb_context *ctx = 0;
	libusb_device **devlist = 0;
	libusb_device *dev = 0;
	libusb_device_handle *handle = 0;
	ssize_t ndevs;
	int err = 0;

	err = libusb_init(&ctx);
	if (err != 0) {
		qWarning() << "libusb_init failed:" << err;
		goto err0;
	}

	ndevs = libusb_get_device_list(ctx, &devlist);
	if (ndevs < 0) {
		qWarning() << "libusb_get_device_list failed:" << err;
		goto err1;
	}

	for (ssize_t i = 0; i < ndevs; ++i) {
		if (libusb_get_bus_number(devlist[i]) == addr.first &&
		        libusb_get_device_address(devlist[i]) == addr.second) {
			dev = devlist[i];
		}
	}

	if (!dev) {
		qWarning() << "could not find device in libusb";
		err = -ENODEV;
		goto err2;
	}

	err = libusb_open(dev, &handle);
	if (err != 0) {
		qWarning() << "libusb_open failed:" << err;
		goto err2;
	}

	err = libusb_reset_device(handle);
	if (err != 0) {
		qWarning() << "libusb_reset_device failed: " << err;
		goto err3;
	}

	qDebug() << "USB device resetted";

err3:
	libusb_close(handle);
err2:
	libusb_free_device_list(devlist, 1);
err1:
	libusb_exit(ctx);
err0:
	return err == 0;
}

bool Smartpen::connectToPen(const Address &addr)
{
	if (_obex) {
		qWarning() << "Already connected";
		return false;
	}

	_connId = INVALID_CID;

	_obex = OBEX_Init(OBEX_TRANS_USB, obexEventCb, OBEX_FL_CLOEXEC);
	Q_ASSERT(_obex);

	OBEX_SetUserData(_obex, this);
	OBEX_SetTransportMTU(_obex, PEN_MTU, PEN_MTU);

	obex_interface_t *ls_interface = 0;
	int count = OBEX_EnumerateInterfaces(_obex);
	for (int i = 0; i < count; i++) {
		obex_interface_t *intf = OBEX_GetInterfaceByIndex(_obex, i);
		if (intf->usb.bus_number == addr.first &&
		        intf->usb.device_address == addr.second) {
			ls_interface = intf;
		}
	}

	if (!ls_interface) {
		qWarning() << "Could not find Lightscribe interface on device:" << addr;
		return false;
	}

	qDebug() << "Connecting to" << ls_interface->usb.product;

	int err = OBEX_InterfaceConnect(_obex, ls_interface) ;
	if (err < 0) {
		qWarning() << "Could not connect to Livescribe interface" << strerror(-err);
		return false;
	}

	prepareRequest();

	static const char * livescribe_service = "LivescribeService";
	obex_object_t *object = OBEX_ObjectNew(_obex, OBEX_CMD_CONNECT);
	obex_headerdata_t hd;
	int hd_len;

	Q_ASSERT(object);

	hd.bs = reinterpret_cast<const quint8*>(livescribe_service);
	hd_len = strlen(livescribe_service) + 1;
	if (OBEX_ObjectAddHeader(_obex, object, OBEX_HDR_TARGET, hd, hd_len, 0) < 0) {
		qWarning() << "Failed to add Target header";
		OBEX_ObjectDelete(_obex, object);
		return false;
	}

	if (OBEX_Request(_obex, object) < 0) {
		qWarning() << "Failed to make connection request";
		OBEX_ObjectDelete(_obex, object);
		return false;
	}

	qDebug() << "Connection in progress";

	waitForRequestComplete(PEN_TIMEOUT_SECONDS);

	return _connId != INVALID_CID;
}

void Smartpen::disconnectFromPen()
{
	if (_connId != INVALID_CID) {
		if (_obex) {
			OBEX_CancelRequest(_obex, 0);

			prepareRequest();

			obex_object_t *object = OBEX_ObjectNew(_obex, OBEX_CMD_DISCONNECT);
			Q_ASSERT(object);
			addConnHeader(object);
			if (OBEX_Request(_obex, object) == 0) {
				qDebug() << "Send disconnect";
				waitForRequestComplete(PEN_TIMEOUT_SECONDS);
			}
		}
		_connId = INVALID_CID;
	}
	if (_obex) {
		OBEX_TransportDisconnect(_obex);
		OBEX_Cleanup(_obex);
		_obex = 0;
	}
	_inBuf.clear();
	qDebug() << "Disconnected";
}

void Smartpen::obexEventCb(obex_t *handle, obex_object_t *obj,
                           int mode, int event, int obex_cmd, int obex_rsp)
{
	Smartpen *smartpen = static_cast<Smartpen*>(OBEX_GetUserData(handle));
	Q_UNUSED(mode);
	smartpen->handleObexEvent(obj, event, obex_cmd, obex_rsp);
}

void Smartpen::handleObexEvent(obex_object_t *object,
                               int event, int obex_cmd, int obex_rsp)
{
	// Special flag used for temporarily ignoring the synthetic events generated during OBEX_CancelRequest
	static bool aborting_continue = false;
	if (aborting_continue) return;

	switch (event) {
	case OBEX_EV_PROGRESS:
		break;
	case OBEX_EV_REQDONE:
		qDebug() << "event reqdone cmd=" << obex_cmd << " rsp=" << OBEX_ResponseToString(obex_rsp);
		handleObexRequestDone(object, obex_cmd, obex_rsp);
		break;
	case OBEX_EV_LINKERR:
		qWarning() << "link error cmd=" << obex_cmd << " rsp=" << OBEX_ResponseToString(obex_rsp);
		emit linkError("Link error");
		break;
	case OBEX_EV_PARSEERR:
		qWarning() << "parse error cmd=" << obex_cmd << " rsp=" << OBEX_ResponseToString(obex_rsp);
		emit linkError("Protocol error");
		break;
	case OBEX_EV_CONTINUE:
		// The standard "Continue" messages sent by OpenObex "forget" to include the ConnectionID, confusing the pen
		// We're going to therefore implement the "continue" state machine on our own
		handleObexContinue(object, obex_cmd);

		// Cancel OpenObex's Continue message, avoiding the spurious events that generates
		Q_ASSERT(!aborting_continue);
		aborting_continue = true;
		OBEX_CancelRequest(_obex, 0);
		aborting_continue = false;
		break;
	default:
		qDebug() << "event unknown=" << event << " cmd=" << obex_cmd << " rsp=" << OBEX_ResponseToString(obex_rsp);
		break;
	}
}

void Smartpen::handleObexRequestDone(obex_object_t *object, int obex_cmd, int obex_rsp)
{
	quint8 header_id;
	obex_headerdata_t hdata;
	quint32 hlen;

	_reqComplete = true;

	switch (obex_cmd & ~OBEX_FINAL) {
	case OBEX_CMD_CONNECT:
		switch (obex_rsp) {
		case OBEX_RSP_SUCCESS:
			while (OBEX_ObjectGetNextHeader(_obex, object, &header_id, &hdata, &hlen)) {
				if (header_id == OBEX_HDR_CONNECTION) {
					Q_ASSERT(_connId == INVALID_CID);
					_connId = hdata.bq4;
					qDebug() << "Connection established, id:" << _connId;
				}
			}
			break;
		default:
			qWarning() << "Failed connection request:" << OBEX_ResponseToString(obex_rsp);
			emit linkError("OBEX connection error");
			break;
		}
		break;
	case OBEX_CMD_DISCONNECT:
		switch (obex_rsp) {
		case OBEX_RSP_SUCCESS:
			qDebug() << "Disconnected succesfully";
			_connId = INVALID_CID;
			break;
		default:
			qWarning() << "Failed disconnection request:" << OBEX_ResponseToString(obex_rsp);
			_connId = INVALID_CID;
			break;
		}

		break;
	case OBEX_CMD_GET:
		switch (obex_rsp) {
		case OBEX_RSP_SUCCESS:
			qDebug() << "GET request succesful";
			while (OBEX_ObjectGetNextHeader(_obex, object, &header_id, &hdata, &hlen)) {
				if (header_id == OBEX_HDR_BODY || header_id == OBEX_HDR_BODY_END) {
					_inBuf.append(reinterpret_cast<const char*>(hdata.bs), hlen);
				}
			}
			break;
		default:
			qWarning() << "Failed GET request:" << OBEX_ResponseToString(obex_rsp);
			break;
		}

		break;
	}
}

void Smartpen::handleObexContinue(obex_object_t *object, int obex_cmd)
{
	const uint8_t *data;
	int len;

	_continueReceived++;

	switch (obex_cmd & ~OBEX_FINAL) {
	case OBEX_CMD_GET:
		len = OBEX_ObjectReadStream(_obex, object, &data);
		if (len > 0) {
			_inBuf.append(reinterpret_cast<const char*>(data), len);
		}
		break;
	}
}

void Smartpen::prepareRequest()
{
	_reqComplete = false;
	_continueReceived = 0;
	_inBuf.clear();
}

bool Smartpen::waitForRequestComplete(int timeout)
{
	QDeadlineTimer timer(timeout * 1000UL);
	timer.setTimerType(Qt::CoarseTimer);

	int cmd = OBEX_ObjectGetCommand(_obex, NULL);

	do {
		if (OBEX_HandleInput(_obex, timer.remainingTime() / 1000) < 0) {
			qWarning() << "OBEX_HandleInput failed";
			break;
		}
		if (_continueReceived) {
			sendContinue(cmd);
			_continueReceived--;

			// Reset timeout
			timer.setRemainingTime(timeout * 1000UL);
		}
	} while (!_reqComplete && !timer.hasExpired());

	if (!_reqComplete) {
		qWarning() << "Did not complete request in" << timeout << "seconds";
		emit linkError("Timeout");
		return false;
	}

	return true;
}

void Smartpen::addConnHeader(obex_object_t *obj) const
{
	obex_headerdata_t hd;
	hd.bq4 = _connId;
	if (OBEX_ObjectAddHeader(_obex, obj, OBEX_HDR_CONNECTION, hd, sizeof(hd.bq4), OBEX_FL_FIT_ONE_PACKET) < 0) {
		qCritical() << "Could not add connection header";
	}
}

bool Smartpen::sendContinue(int obex_cmd)
{
	obex_object_t *obj = OBEX_ObjectNew(_obex, obex_cmd);
	Q_ASSERT(obj);

	addConnHeader(obj);

	if (OBEX_Request(_obex, obj) < 0) {
		qWarning() << "Send continue failed";
		OBEX_ObjectDelete(_obex, obj);
		return false;
	}

	return true;
}

QString Smartpen::toPenSerialSegment(quint32 id, int len)
{

	QString segment(len, Qt::Uninitialized);

	for (int i = 0; i < len; i++) {
		segment[len - (i + 1)] = pen_serial_chars[id % pen_serial_num_chars];
		id /= pen_serial_num_chars;
	}

	return segment;
}

quint32 Smartpen::fromPenSerialSegment(const QString &s)
{
	const int len = s.length();
	quint32 id = 0;

	for (int i = 0; i < len; i++) {
		uint val = std::find(&pen_serial_chars[0], &pen_serial_chars[pen_serial_num_chars], s[i]) - &pen_serial_chars[0];
		if (val >= pen_serial_num_chars) return 0;
		id = val + id * pen_serial_num_chars;
	}

	return id;
}

QByteArray Smartpen::encodeUtf16(const QString &s)
{
	const int size = s.size();
	QByteArray data((size + 1) * sizeof(quint16), Qt::Uninitialized);
	quint16 *p = reinterpret_cast<quint16*>(data.data());
	for (int i = 0; i < size; i++) {
		p[i] = qToBigEndian(s.at(i).unicode());
	}
	p[size] = 0;
	return data;
}