/*
 * parser.cpp - parse an XMPP "document"
 * Copyright (C) 2003  Justin Karneges
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

/*
  TODO:

  For XMPP::Parser to be "perfect", some things must be solved/changed in the
  Qt library:

  - Fix weird TQDomElement::haveAttributeNS() bug (patch submitted to
    Trolltech on Aug 31st, 2003).
  - Fix weird behavior in TQXmlSimpleReader of reporting endElement() when
    the '/' character of a self-closing tag is reached, instead of when
    the final '>' is reached.
  - Fix incremental parsing bugs in TQXmlSimpleReader.  At the moment, the
    only bug I've found is related to attribute parsing, but there might
    be more (search for '###' in $QTDIR/src/xml/qxml.cpp).

  We have workarounds for all of the above problems in the code below.

  - Deal with the <?xml?> processing instruction as an event type, so that we
    can feed it back to the application properly.  Right now it is completely
    untrackable and is simply tacked into the first event's actualString.  We
    can't easily do this because TQXmlSimpleReader eats an extra byte beyond
    the processing instruction before reporting it.

  - Make TQXmlInputSource capable of accepting data incrementally, to ensure
    proper text encoding detection and processing over a network.  This is
    technically not a bug, as we have our own subclass below to do it, but
    it would be nice if Qt had this already.
*/

#include"parser.h"

#include<tqtextcodec.h>
#include<tqptrlist.h>
#include<string.h>

using namespace XMPP;

static bool qt_bug_check = false;
static bool qt_bug_have;

//----------------------------------------------------------------------------
// StreamInput
//----------------------------------------------------------------------------
class StreamInput : public QXmlInputSource
{
public:
	StreamInput()
	{
		dec = 0;
		reset();
	}

	~StreamInput()
	{
		delete dec;
	}

	void reset()
	{
		delete dec;
		dec = 0;
		in.resize(0);
		out = "";
		at = 0;
		paused = false;
		mightChangeEncoding = true;
		checkBad = true;
		last = TQChar();
		v_encoding = "";
		resetLastData();
	}

	void resetLastData()
	{
		last_string = "";
	}

	TQString lastString() const
	{
		return last_string;
	}

	void appendData(const TQByteArray &a)
	{
		int oldsize = in.size();
		in.resize(oldsize + a.size());
		memcpy(in.data() + oldsize, a.data(), a.size());
		processBuf();
	}

	TQChar lastRead()
	{
		return last;
	}

	TQChar next()
	{
		if(paused)
			return EndOfData;
		else
			return readNext();
	}

	// NOTE: setting 'peek' to true allows the same char to be read again,
	//       however this still advances the internal byte processing.
	TQChar readNext(bool peek=false)
	{
		TQChar c;
		if(mightChangeEncoding)
			c = EndOfData;
		else {
			if(out.isEmpty()) {
				TQString s;
				if(!tryExtractPart(&s))
					c = EndOfData;
				else {
					out = s;
					c = out[0];
				}
			}
			else
				c = out[0];
			if(!peek)
				out.remove(0, 1);
		}
		if(c == EndOfData) {
#ifdef XMPP_PARSER_DEBUG
			printf("next() = EOD\n");
#endif
		}
		else {
#ifdef XMPP_PARSER_DEBUG
			printf("next() = [%c]\n", c.latin1());
#endif
			last = c;
		}

		return c;
	}

	TQByteArray unprocessed() const
	{
		TQByteArray a(in.size() - at);
		memcpy(a.data(), in.data() + at, a.size());
		return a;
	}

	void pause(bool b)
	{
		paused = b;
	}

	bool isPaused()
	{
		return paused;
	}

	TQString encoding() const
	{
		return v_encoding;
	}

private:
	TQTextDecoder *dec;
	TQByteArray in;
	TQString out;
	int at;
	bool paused;
	bool mightChangeEncoding;
	TQChar last;
	TQString v_encoding;
	TQString last_string;
	bool checkBad;

	void processBuf()
	{
#ifdef XMPP_PARSER_DEBUG
		printf("processing.  size=%d, at=%d\n", in.size(), at);
#endif
		if(!dec) {
			TQTextCodec *codec = 0;
			uchar *p = (uchar *)in.data() + at;
			int size = in.size() - at;

			// do we have enough information to determine the encoding?
			if(size == 0)
				return;
			bool utf16 = false;
			if(p[0] == 0xfe || p[0] == 0xff) {
				// probably going to be a UTF-16 byte order mark
				if(size < 2)
					return;
				if((p[0] == 0xfe && p[1] == 0xff) || (p[0] == 0xff && p[1] == 0xfe)) {
					// ok it is UTF-16
					utf16 = true;
				}
			}
			if(utf16)
				codec = TQTextCodec::codecForMib(1000); // UTF-16
			else
				codec = TQTextCodec::codecForMib(106); // UTF-8

			v_encoding = codec->name();
			dec = codec->makeDecoder();

			// for utf16, put in the byte order mark
			if(utf16) {
				out += dec->toUnicode((const char *)p, 2);
				at += 2;
			}
		}

		if(mightChangeEncoding) {
			while(1) {
				int n = out.find('<');
				if(n != -1) {
					// we need a closing bracket
					int n2 = out.find('>', n);
					if(n2 != -1) {
						++n2;
						TQString h = out.mid(n, n2-n);
						TQString enc = processXmlHeader(h);
						TQTextCodec *codec = 0;
						if(!enc.isEmpty())
							codec = TQTextCodec::codecForName(enc.latin1());

						// changing codecs
						if(codec) {
							v_encoding = codec->name();
							delete dec;
							dec = codec->makeDecoder();
						}
						mightChangeEncoding = false;
						out.truncate(0);
						at = 0;
						resetLastData();
						break;
					}
				}
				TQString s;
				if(!tryExtractPart(&s))
					break;
				if(checkBad && checkForBadChars(s)) {
					// go to the parser
					mightChangeEncoding = false;
					out.truncate(0);
					at = 0;
					resetLastData();
					break;
				}
				out += s;
			}
		}
	}

	TQString processXmlHeader(const TQString &h)
	{
		if(h.left(5) != "<?xml")
			return "";

		int endPos = h.find(">");
		int startPos = h.find("encoding");
		if(startPos < endPos && startPos != -1) {
			TQString encoding;
			do {
				startPos++;
				if(startPos > endPos) {
					return "";
				}
			} while(h[startPos] != '"' && h[startPos] != '\'');
			startPos++;
			while(h[startPos] != '"' && h[startPos] != '\'') {
				encoding += h[startPos];
				startPos++;
				if(startPos > endPos) {
					return "";
				}
			}
			return encoding;
		}
		else
			return "";
	}

	bool tryExtractPart(TQString *s)
	{
		int size = in.size() - at;
		if(size == 0)
			return false;
		uchar *p = (uchar *)in.data() + at;
		TQString nextChars;
		while(1) {
			nextChars = dec->toUnicode((const char *)p, 1);
			++p;
			++at;
			if(!nextChars.isEmpty())
				break;
			if(at == (int)in.size())
				return false;
		}
		last_string += nextChars;
		*s = nextChars;

		// free processed data?
		if(at >= 1024) {
			char *p = in.data();
			int size = in.size() - at;
			memmove(p, p + at, size);
			in.resize(size);
			at = 0;
		}

		return true;
	}

	bool checkForBadChars(const TQString &s)
	{
		int len = s.find('<');
		if(len == -1)
			len = s.length();
		else
			checkBad = false;
		for(int n = 0; n < len; ++n) {
			if(!s.at(n).isSpace())
				return true;
		}
		return false;
	}
};


//----------------------------------------------------------------------------
// ParserHandler
//----------------------------------------------------------------------------
namespace XMPP
{
	class ParserHandler : public QXmlDefaultHandler
	{
	public:
		ParserHandler(StreamInput *_in, TQDomDocument *_doc)
		{
			in = _in;
			doc = _doc;
			needMore = false;
		}

		~ParserHandler()
		{
			eventList.setAutoDelete(true);
			eventList.clear();
		}

		bool startDocument()
		{
			depth = 0;
			return true;
		}

		bool endDocument()
		{
			return true;
		}

		bool startPrefixMapping(const TQString &prefix, const TQString &uri)
		{
			if(depth == 0) {
				nsnames += prefix;
				nsvalues += uri;
			}
			return true;
		}

		bool startElement(const TQString &namespaceURI, const TQString &localName, const TQString &qName, const TQXmlAttributes &atts)
		{
			if(depth == 0) {
				Parser::Event *e = new Parser::Event;
				TQXmlAttributes a;
				for(int n = 0; n < atts.length(); ++n) {
					TQString uri = atts.uri(n);
					TQString ln = atts.localName(n);
					if(a.index(uri, ln) == -1)
						a.append(atts.qName(n), uri, ln, atts.value(n));
				}
				e->setDocumentOpen(namespaceURI, localName, qName, a, nsnames, nsvalues);
				nsnames.clear();
				nsvalues.clear();
				e->setActualString(in->lastString());

				in->resetLastData();
				eventList.append(e);
				in->pause(true);
			}
			else {
				TQDomElement e = doc->createElementNS(namespaceURI, qName);
				for(int n = 0; n < atts.length(); ++n) {
					TQString uri = atts.uri(n);
					TQString ln = atts.localName(n);
					bool have;
					if(!uri.isEmpty()) {
						have = e.hasAttributeNS(uri, ln);
						if(qt_bug_have)
							have = !have;
					}
					else
						have = e.hasAttribute(ln);
					if(!have)
						e.setAttributeNS(uri, atts.qName(n), atts.value(n));
				}

				if(depth == 1) {
					elem = e;
					current = e;
				}
				else {
					current.appendChild(e);
					current = e;
				}
			}
			++depth;
			return true;
		}

		bool endElement(const TQString &namespaceURI, const TQString &localName, const TQString &qName)
		{
			--depth;
			if(depth == 0) {
				Parser::Event *e = new Parser::Event;
				e->setDocumentClose(namespaceURI, localName, qName);
				e->setActualString(in->lastString());
				in->resetLastData();
				eventList.append(e);
				in->pause(true);
			}
			else {
				// done with a depth 1 element?
				if(depth == 1) {
					Parser::Event *e = new Parser::Event;
					e->setElement(elem);
					e->setActualString(in->lastString());
					in->resetLastData();
					eventList.append(e);
					in->pause(true);

					elem = TQDomElement();
					current = TQDomElement();
				}
				else
					current = current.parentNode().toElement();
			}

			if(in->lastRead() == '/')
				checkNeedMore();

			return true;
		}

		bool characters(const TQString &str)
		{
			if(depth >= 1) {
				TQString content = str;
				if(content.isEmpty())
					return true;

				if(!current.isNull()) {
					TQDomText text = doc->createTextNode(content);
					current.appendChild(text);
				}
			}
			return true;
		}

		/*bool processingInstruction(const TQString &target, const TQString &data)
		{
			printf("Processing: [%s], [%s]\n", target.latin1(), data.latin1());
			in->resetLastData();
			return true;
		}*/

		void checkNeedMore()
		{
			// Here we will work around TQXmlSimpleReader strangeness and self-closing tags.
			// The problem is that endElement() is called when the '/' is read, not when
			// the final '>' is read.  This is a potential problem when obtaining unprocessed
			// bytes from StreamInput after this event, as the '>' character will end up
			// in the unprocessed chunk.  To work around this, we need to advance StreamInput's
			// internal byte processing, but not the xml character data.  This way, the '>'
			// will get processed and will no longer be in the unprocessed return, but
			// TQXmlSimpleReader can still read it.  To do this, we call StreamInput::readNext
			// with 'peek' mode.
			TQChar c = in->readNext(true); // peek
			if(c == TQXmlInputSource::EndOfData) {
				needMore = true;
			}
			else {
				// We'll assume the next char is a '>'.  If it isn't, then
				// TQXmlSimpleReader will deal with that problem on the next
				// parse.  We don't need to take any action here.
				needMore = false;

				// there should have been a pending event
				Parser::Event *e = eventList.getFirst();
				if(e) {
					e->setActualString(e->actualString() + '>');
					in->resetLastData();
				}
			}
		}

		Parser::Event *takeEvent()
		{
			if(needMore)
				return 0;
			if(eventList.isEmpty())
				return 0;

			Parser::Event *e = eventList.getFirst();
			eventList.removeRef(e);
			in->pause(false);
			return e;
		}

		StreamInput *in;
		TQDomDocument *doc;
		int depth;
		TQStringList nsnames, nsvalues;
		TQDomElement elem, current;
		TQPtrList<Parser::Event> eventList;
		bool needMore;
	};
}


//----------------------------------------------------------------------------
// Event
//----------------------------------------------------------------------------
class Parser::Event::Private
{
public:
	int type;
	TQString ns, ln, qn;
	TQXmlAttributes a;
	TQDomElement e;
	TQString str;
	TQStringList nsnames, nsvalues;
};

Parser::Event::Event()
{
	d = 0;
}

Parser::Event::Event(const Event &from)
{
	d = 0;
	*this = from;
}

Parser::Event & Parser::Event::operator=(const Event &from)
{
	delete d;
	d = 0;
	if(from.d)
		d = new Private(*from.d);
	return *this;
}

Parser::Event::~Event()
{
	delete d;
}

bool Parser::Event::isNull() const
{
	return (d ? false: true);
}

int Parser::Event::type() const
{
	if(isNull())
		return -1;
	return d->type;
}

TQString Parser::Event::nsprefix(const TQString &s) const
{
	TQStringList::ConstIterator it = d->nsnames.begin();
	TQStringList::ConstIterator it2 = d->nsvalues.begin();
	for(; it != d->nsnames.end(); ++it) {
		if((*it) == s)
			return (*it2);
		++it2;
	}
	return TQString::null;
}

TQString Parser::Event::namespaceURI() const
{
	return d->ns;
}

TQString Parser::Event::localName() const
{
	return d->ln;
}

TQString Parser::Event::qName() const
{
	return d->qn;
}

TQXmlAttributes Parser::Event::atts() const
{
	return d->a;
}

TQString Parser::Event::actualString() const
{
	return d->str;
}

TQDomElement Parser::Event::element() const
{
	return d->e;
}

void Parser::Event::setDocumentOpen(const TQString &namespaceURI, const TQString &localName, const TQString &qName, const TQXmlAttributes &atts, const TQStringList &nsnames, const TQStringList &nsvalues)
{
	if(!d)
		d = new Private;
	d->type = DocumentOpen;
	d->ns = namespaceURI;
	d->ln = localName;
	d->qn = qName;
	d->a = atts;
	d->nsnames = nsnames;
	d->nsvalues = nsvalues;
}

void Parser::Event::setDocumentClose(const TQString &namespaceURI, const TQString &localName, const TQString &qName)
{
	if(!d)
		d = new Private;
	d->type = DocumentClose;
	d->ns = namespaceURI;
	d->ln = localName;
	d->qn = qName;
}

void Parser::Event::setElement(const TQDomElement &elem)
{
	if(!d)
		d = new Private;
	d->type = Element;
	d->e = elem;
}

void Parser::Event::setError()
{
	if(!d)
		d = new Private;
	d->type = Error;
}

void Parser::Event::setActualString(const TQString &str)
{
	d->str = str;
}

//----------------------------------------------------------------------------
// Parser
//----------------------------------------------------------------------------
class Parser::Private
{
public:
	Private()
	{
		doc = 0;
		in = 0;
		handler = 0;
		reader = 0;
		reset();
	}

	~Private()
	{
		reset(false);
	}

	void reset(bool create=true)
	{
		delete reader;
		delete handler;
		delete in;
		delete doc;

		if(create) {
			doc = new QDomDocument;
			in = new StreamInput;
			handler = new ParserHandler(in, doc);
			reader = new QXmlSimpleReader;
			reader->setContentHandler(handler);

			// initialize the reader
			in->pause(true);
			reader->parse(in, true);
			in->pause(false);
		}
	}

	TQDomDocument *doc;
	StreamInput *in;
	ParserHandler *handler;
	TQXmlSimpleReader *reader;
};

Parser::Parser()
{
	d = new Private;

	// check for evil bug in Qt <= 3.2.1
	if(!qt_bug_check) {
		qt_bug_check = true;
		TQDomElement e = d->doc->createElementNS("someuri", "somename");
		if(e.hasAttributeNS("someuri", "somename"))
			qt_bug_have = true;
		else
			qt_bug_have = false;
	}
}

Parser::~Parser()
{
	delete d;
}

void Parser::reset()
{
	d->reset();
}

void Parser::appendData(const TQByteArray &a)
{
	d->in->appendData(a);

	// if handler was waiting for more, give it a kick
	if(d->handler->needMore)
		d->handler->checkNeedMore();
}

Parser::Event Parser::readNext()
{
	Event e;
	if(d->handler->needMore)
		return e;
	Event *ep = d->handler->takeEvent();
	if(!ep) {
		if(!d->reader->parseContinue()) {
			e.setError();
			return e;
		}
		ep = d->handler->takeEvent();
		if(!ep)
			return e;
	}
	e = *ep;
	delete ep;
	return e;
}

TQByteArray Parser::unprocessed() const
{
	return d->in->unprocessed();
}

TQString Parser::encoding() const
{
	return d->in->encoding();
}