// Ryzom - MMORPG Framework <http://dev.ryzom.com/projects/ryzom/>
// Copyright (C) 2010  Winch Gate Property Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.


#include "stdpch.h"

#include <string>
#include <libxml/HTMLparser.h>

#include "nel/misc/types_nl.h"
#include "nel/gui/libwww.h"
#include "nel/gui/group_html.h"
#include "nel/gui/lua_ihm.h"

using namespace std;
using namespace NLMISC;

namespace NLGUI
{
	// ***************************************************************************
	void CGroupHTML::htmlElement(xmlNode *node, int element_number)
	{
		SGML_dtd *HTML_DTD = HTML_dtd ();

		if (element_number < HTML_ELEMENTS)
		{
			CXMLAutoPtr ptr;
			// load attributes into libwww structs
			std::vector<bool> present;
			std::vector<const char *>value;
			std::string strvalues[MAX_ATTRIBUTES];
			present.resize(30, false);
			value.resize(30);

			uint nbAttributes = std::min(MAX_ATTRIBUTES, HTML_DTD->tags[element_number].number_of_attributes);
			for(uint i=0; i<nbAttributes; i++)
			{
				std::string name;
				name = toLower(std::string(HTML_DTD->tags[element_number].attributes[i].name));
				ptr = xmlGetProp(node, (const xmlChar *)name.c_str());
				if (ptr)
				{
					// copy xmlChar to string (xmlChar will be released)
					strvalues[i] = (const char *)(ptr);
					// now use string pointer in value[] array
					value[i] = strvalues[i].c_str();
					present[i] = true;
				}
			}

			if (element_number == HTML_A)
			{
				addLink(element_number, present, value);
			}

			beginElement(element_number, present, value);
		}
		else
		{
			beginUnparsedElement((const char *)(node->name), xmlStrlen(node->name));
		}

		// recursive - text content / child nodes
		htmlWalkDOM(node->children);

		// closing tag
		if (element_number < HTML_ELEMENTS)
		{
			endElement(element_number);
		}
		else
		{
			endUnparsedElement((const char *)(node->name), xmlStrlen(node->name));
		}
	}

	// ***************************************************************************
	// recursive function to walk html document
	void CGroupHTML::htmlWalkDOM(xmlNode *a_node)
	{
		SGML_dtd *HTML_DTD = HTML_dtd ();

		uint element_number;
		xmlNode *node = a_node;
		while(node)
		{
			if (node->type == XML_TEXT_NODE)
			{
				addText((const char *)(node->content), xmlStrlen(node->content));
			}
			else
			if (node->type == XML_ELEMENT_NODE)
			{
				// find libwww tag
				for(element_number = 0; element_number<HTML_ELEMENTS; ++element_number)
				{
					if (xmlStrncasecmp(node->name, (const xmlChar *)HTML_DTD->tags[element_number].name.c_str(), xmlStrlen(node->name)) == 0)
						break;
				}

				htmlElement(node, element_number);
			}

			// move into next sibling
			node = node->next;
		}
	}

	// ***************************************************************************
	// http://stackoverflow.com/a/18335183
	static std::string correct_non_utf_8(const std::string &str)
	{
		int i,f_size=str.size();
		unsigned char c,c2,c3,c4;
		std::string to;
		to.reserve(f_size);

		for(i=0 ; i<f_size ; i++){
			c=(unsigned char)(str[i]);
			if(c<32){//control char
				if(c==9 || c==10 || c==13){//allow only \t \n \r
					to.append(1,c);
				}
				continue;
			}else if(c<127){//normal ASCII
				to.append(1,c);
				continue;
			}else if(c<160){//control char (nothing should be defined here either ASCI, ISO_8859-1 or UTF8, so skipping)
				if(c==128){//fix microsoft mess, add euro
					to.append(1,226);
					to.append(1,130);
					to.append(1,172);
				}
				if(c==133){//fix IBM mess, add NEL = \n\r
					to.append(1,10);
					to.append(1,13);
				}
				continue;
			}else if(c<192){//invalid for UTF8, converting ASCII
				to.append(1,(unsigned char)194);
				to.append(1,c);
				continue;
			}else if(c<194){//invalid for UTF8, converting ASCII
				to.append(1,(unsigned char)195);
				to.append(1,c-64);
				continue;
			}else if(c<224 && i+1<f_size){//possibly 2byte UTF8
				c2=(unsigned char)(str[i+1]);
				if(c2>127 && c2<192){//valid 2byte UTF8
					if(c==194 && c2<160){//control char, skipping
						;
					}else{
						to.append(1,c);
						to.append(1,c2);
					}
					i++;
					continue;
				}
			}else if(c<240 && i+2<f_size){//possibly 3byte UTF8
				c2=(unsigned char)(str[i+1]);
				c3=(unsigned char)(str[i+2]);
				if(c2>127 && c2<192 && c3>127 && c3<192){//valid 3byte UTF8
					to.append(1,c);
					to.append(1,c2);
					to.append(1,c3);
					i+=2;
					continue;
				}
			}else if(c<245 && i+3<f_size){//possibly 4byte UTF8
				c2=(unsigned char)(str[i+1]);
				c3=(unsigned char)(str[i+2]);
				c4=(unsigned char)(str[i+3]);
				if(c2>127 && c2<192 && c3>127 && c3<192 && c4>127 && c4<192){//valid 4byte UTF8
					to.append(1,c);
					to.append(1,c2);
					to.append(1,c3);
					to.append(1,c4);
					i+=3;
					continue;
				}
			}
			//invalid UTF8, converting ASCII (c>245 || string too short for multi-byte))
			to.append(1,(unsigned char)195);
			to.append(1,c-64);
		}
		return to;
	}

	// ***************************************************************************
	static void patchHtmlQuirks(std::string &htmlString)
	{
		size_t npos = std::string::npos;
		size_t pos;

		// get rid of BOM (some ingame help files does not show up otherwise)
		if (htmlString.substr(0, 3) == "\xEF\xBB\xBF")
		{
			htmlString.erase(0, 3);
		}

		// if any element is before <html>, then parser adds <html><body>
		// and original tags are ignored (their attributes not processed)
		//
		// only fix situation when there is <body> tag with attributes
		//
		// tags are considered to be lowercase

		pos = htmlString.find("<body ");
		if (pos != npos)
		{
			size_t start = htmlString.find("<");
			// skip <!doctype html>
			if (htmlString.substr(start, 2) == "<!")
				start = htmlString.find("<", start + 1);

			// if there is no html tag, then abort
			size_t end = htmlString.find("<html>");
			if (end != npos && start < end && end < pos)
			{
				// body tag end position
				size_t insert = htmlString.find(">", pos);
				if (insert != npos)
				{
					std::string str = htmlString.substr(start, end - start);
					htmlString.insert(insert+1, str);
					htmlString.erase(start, str.size());
				}
			}
		}

		// make sure </html> (if present) is last in document or tags coming after it are ignored
		pos = htmlString.find("</html>");
		if (pos != npos && htmlString.find("<", pos+1) > pos)
		{
			htmlString.erase(pos, 7);
			htmlString += "</html>";
		}

		// if there is invalid utf-8 chars, then libxml will break everything after first it finds.
		htmlString = correct_non_utf_8(htmlString);
	}

	// ***************************************************************************
	bool CGroupHTML::parseHtml(std::string htmlString)
	{
		htmlParserCtxtPtr parser = htmlCreatePushParserCtxt(NULL, NULL, NULL, 0, NULL, XML_CHAR_ENCODING_UTF8);
		if (!parser)
		{
			nlwarning("Creating html parser context failed");
			return false;
		}

		htmlCtxtUseOptions(parser, HTML_PARSE_NOBLANKS | HTML_PARSE_NOERROR | HTML_PARSE_NOWARNING | HTML_PARSE_NONET);

		// parser is little strict on tag order, so fix whats needed
		patchHtmlQuirks(htmlString);

		htmlParseChunk(parser, htmlString.c_str(), htmlString.size(), 0);
		htmlParseChunk(parser, "", 0, 1);

		bool success = true;
		if (parser->myDoc)
		{
			xmlNode *root = xmlDocGetRootElement(parser->myDoc);
			if (root)
			{
				htmlWalkDOM(root);
			}
			else
			{
				nlwarning("html root node failed");
				success = false;
			}
		}
		else
		{
			nlwarning("htmlstring parsing failed");
			success = false;
		}

		htmlFreeParserCtxt(parser);
		return success;
	}

	// ***************************************************************************
	int CGroupHTML::luaParseHtml(CLuaState &ls)
	{
		const char *funcName = "parseHtml";
		CLuaIHM::checkArgCount(ls, funcName, 1);
		CLuaIHM::checkArgType(ls, funcName, 1, LUA_TSTRING);
		std::string html = ls.toString(1);

		parseHtml(html);

		return 0;
	}

}