#include "precompiled.h"

#include <vector>
#include <set>
#include <map>
#include <stack>
#include <algorithm>

#include "ps/CLogger.h"
#include "ps/Filesystem.h"
#include "Xeromyces.h"

#define LOG_CATEGORY "xml"

#include "XML.h"


int CXeromyces::XercesLoaded = 0; // for once-only initialisation

// Convenient storage for the internal tree
typedef struct {
	std::string name;
	utf16string value;
} XMLAttribute;

typedef struct XMLElement {
	std::string name;
	int linenum;
	utf16string text;
	std::vector<XMLElement*> childs;
	std::vector<XMLAttribute*> attrs;
} XMLElement;

class XeroHandler : public DefaultHandler
{
public:
	XeroHandler() : m_locator(NULL), Root(NULL) {}
	~XeroHandler()
	{
		if (Root)
			DeallocateElement(Root);
	}

	// SAX2 event handlers:
	virtual void startDocument();
	virtual void endDocument();
	virtual void startElement(const XMLCh* const uri, const XMLCh* const localname, const XMLCh* const qname, const Attributes& attrs);
	virtual void endElement(const XMLCh* const uri, const XMLCh* const localname, const XMLCh* const qname);
	virtual void characters(const XMLCh* const chars, const unsigned int length);
	
	const Locator* m_locator;

	virtual void setDocumentLocator(const Locator* const locator)
	{
		m_locator = locator;
	}

	// Non-SAX2 stuff, used for storing the
	// parsed data and constructing the XMB:

	void CreateXMB();
	WriteBuffer writeBuffer;

private:
	std::set<std::string> ElementNames;
	std::set<std::string> AttributeNames;
	XMLElement* Root;
	XMLElement* CurrentElement;
	std::stack<XMLElement*> ElementStack;

	std::map<std::string, int> ElementID;
	std::map<std::string, int> AttributeID;

	void OutputElement(XMLElement* el);

	// Recursively frees memory
	void DeallocateElement(XMLElement* el);
};



CXeromyces::CXeromyces()
{
}

CXeromyces::~CXeromyces()
{
}

void CXeromyces::Terminate()
{
	if (XercesLoaded)
	{
		XMLPlatformUtils::Terminate();
		XercesLoaded = 0;
	}
}


// Find out write location of the XMB file corresponding to xmlFilename
void CXeromyces::GetXMBPath(const PIVFS& vfs, const VfsPath& xmlFilename, const VfsPath& xmbFilename, VfsPath& xmbActualPath)
{
	// rationale:
	// - it is necessary to write out XMB files into a subdirectory
	//   corresponding to the mod from which the XML file is taken.
	//   this avoids confusion when multiple mods are active -
	//   their XMB files' VFS filename would otherwise be indistinguishable.
	// - we group files in the cache/ mount point first by mod, and only
	//   then XMB. this is so that all output files for a given mod can
	//   easily be deleted. the operation of deleting all old/unused
	//   XMB files requires a program anyway (to find out which are no
	//   longer needed), so it's not a problem that XMB files reside in
	//   a subdirectory (which would make manually deleting all harder).

	// get real path of XML file (e.g. mods/official/entities/...)
	Path P_XMBRealPath;
	vfs->GetRealPath(xmlFilename, P_XMBRealPath);

	// extract mod name from that
	char modName[PATH_MAX];
	// .. NOTE: can't use %s, of course (keeps going beyond '/')
	int matches = sscanf(P_XMBRealPath.string().c_str(), "mods/%[^/]", modName);
	debug_assert(matches == 1);

	// build full name: cache, then mod name, XMB subdir, original XMB path
	xmbActualPath = VfsPath("cache/mods") / modName / "xmb" / xmbFilename;
}

PSRETURN CXeromyces::Load(const VfsPath& filename)
{
	// Make sure the .xml actually exists
	if (! FileExists(filename))
	{
		LOG(CLogger::Error, LOG_CATEGORY, "CXeromyces: Failed to find XML file %s", filename.string().c_str());
		return PSRETURN_Xeromyces_XMLOpenFailed;
	}

	// Get some data about the .xml file
	FileInfo fileInfo;
	if (g_VFS->GetFileInfo(filename, &fileInfo) < 0)
	{
		LOG(CLogger::Error, LOG_CATEGORY, "CXeromyces: Failed to stat XML file %s", filename.string().c_str());
		return PSRETURN_Xeromyces_XMLOpenFailed;
	}


	/*
	XMBs are stored with a unique name, where the name is generated from
	characteristics of the XML file. If a file already exists with the
	generated name, it is assumed that that file is a valid conversion of
	the XML, and so it's loaded. Otherwise, the XMB is created with that
	filename.

	This means it's never necessary to overwrite existing XMB files; since
	the XMBs are often in archives, it's not easy to rewrite those files,
	and it's not possible to switch to using a loose file because the VFS
	has already decided that file is inside an archive. So each XMB is given
	a unique name, and old ones are somehow purged.
	*/


	// Generate the filename for the xmb:
	//     <xml filename>_<mtime><size><format version>.xmb
	// with mtime/size as 8-digit hex, where mtime's lowest bit is
	// zeroed because zip files only have 2 second resolution.
	const int suffixLength = 22;
	char suffix[suffixLength+1];
	int ret = sprintf(suffix, "_%08x%08xB.xmb", (int)(fileInfo.MTime() & ~1), (int)fileInfo.Size());
	debug_assert(ret == suffixLength);
	VfsPath xmbFilename = change_extension(filename, suffix);

	VfsPath xmbPath;
	GetXMBPath(g_VFS, filename, xmbFilename, xmbPath);

	// If the file exists, use it
	if (FileExists(xmbPath))
	{
		if (ReadXMBFile(xmbPath))
			return PSRETURN_OK;
		// (no longer return PSRETURN_Xeromyces_XMLOpenFailed here because
		// failure legitimately happens due to partially-written XMB files.)
	}

	
	// XMB isn't up to date with the XML, so rebuild it:

	// Load Xerces if necessary
	if (! XercesLoaded)
	{
		XMLPlatformUtils::Initialize();
		XercesLoaded = 1;
	}

	// Open the .xml file
	CVFSInputSource source;
	if (source.OpenFile(filename) < 0)
	{
		LOG(CLogger::Error, LOG_CATEGORY, "CXeromyces: Failed to open XML file %s", filename.string().c_str());
		return PSRETURN_Xeromyces_XMLOpenFailed;
	}

	// Set up the Xerces parser
	SAX2XMLReader* Parser = XMLReaderFactory::createXMLReader();

	// Enable validation
	Parser->setFeature(XMLUni::fgSAX2CoreValidation, true);
	Parser->setFeature(XMLUni::fgXercesDynamic, true);

	XeroHandler handler;
	Parser->setContentHandler(&handler);

	CXercesErrorHandler errorHandler;
	Parser->setErrorHandler(&errorHandler);

	CVFSEntityResolver entityResolver(filename.string().c_str());
	Parser->setEntityResolver(&entityResolver);

	// Build a tree inside handler
	Parser->parse(source);

	// (It's horribly inefficient doing SAX2->tree then tree->XMB,
	// but the XML->XMB conversion should be done very rarely
	// anyway. If it's ever needed, the XMB writing can be done
	// directly from inside the SAX2 event handlers, although that's
	// a little more complex)

	delete Parser;

	if (errorHandler.GetSawErrors())
	{
		LOG(CLogger::Error, LOG_CATEGORY, "CXeromyces: Errors in XML file '%s'", filename.string().c_str());
		return PSRETURN_Xeromyces_XMLParseError;
		// The internal tree of the XeroHandler will be cleaned up automatically
	}

	// Convert the data structures into the XMB format
	handler.CreateXMB();

	// Save the file to disk, so it can be loaded quickly next time
	WriteBuffer& writeBuffer = handler.writeBuffer;
	g_VFS->CreateFile(xmbPath, writeBuffer.Data(), writeBuffer.Size());

	XMBBuffer = writeBuffer.Data();	// add a reference

	// Set up the XMBFile
	const bool ok = Initialise((const char*)XMBBuffer.get());
	debug_assert(ok);

	return PSRETURN_OK;
}

bool CXeromyces::ReadXMBFile(const VfsPath& filename)
{
	size_t size;
	if(g_VFS->LoadFile(filename, XMBBuffer, size) < 0)
		return false;
	debug_assert(size >= 42);	// else: invalid XMB file size. (42 bytes is the smallest possible XMB. (Well, maybe not quite, but it's a nice number.))

	// Set up the XMBFile
	if(!Initialise((const char*)XMBBuffer.get()))
		return false;

	return true;
}



void XeroHandler::startDocument()
{
	Root = new XMLElement;
	ElementStack.push(Root);
}

void XeroHandler::endDocument()
{
}

/*
// Silently clobbers non-ASCII characters
std::string lowercase_ascii(const XMLCh *a)
{
	std::string b;
	size_t len=XMLString::stringLen(a);
	b.resize(len);
	for (size_t i = 0; i < len; ++i)
		b[i] = (char)towlower(a[i]);
	return b;
}
*/

/**
 * Return an ASCII version of the given 16-bit string, ignoring
 * any non-ASCII characters.
 *
 * @param const XMLCh * a Input string.
 * @return std::string 8-bit ASCII version of <code>a</code>.
 **/
std::string toAscii( const XMLCh* a )
{
	std::string b;
	size_t len=XMLString::stringLen(a);
	b.reserve(len);
	for (size_t i = 0; i < len; ++i)
	{
		if(a[i] < 0x80)
			b += (char) a[i];
	}
	return b;
}

void XeroHandler::startElement(const XMLCh* const UNUSED(uri), const XMLCh* const localname, const XMLCh* const UNUSED(qname), const Attributes& attrs)
{
	std::string elementName = toAscii(localname);
	ElementNames.insert(elementName);

	// Create a new element
	XMLElement* e = new XMLElement;
	e->name = elementName;
	e->linenum = m_locator->getLineNumber();

	// Store all the attributes in the new element
	for (unsigned int i = 0; i < attrs.getLength(); ++i)
	{
		std::string attrName = toAscii(attrs.getLocalName(i));
		AttributeNames.insert(attrName);
		XMLAttribute* a = new XMLAttribute;
		a->name = attrName;
		const XMLCh *tmp = attrs.getValue(i);
		a->value = utf16string(tmp, tmp+XMLString::stringLen(tmp));
		e->attrs.push_back(a);
	}

	// Add the element to its parent
	ElementStack.top()->childs.push_back(e);

	// Set as parent of following elements
	ElementStack.push(e);
}

void XeroHandler::endElement(const XMLCh* const UNUSED(uri), const XMLCh* const UNUSED(localname), const XMLCh* const UNUSED(qname))
{
	ElementStack.pop();
}

void XeroHandler::characters(const XMLCh* const chars, const unsigned int UNUSED(length))
{
	ElementStack.top()->text += utf16string(chars, chars+XMLString::stringLen(chars));
}


void XeroHandler::CreateXMB()
{
	// Header
	writeBuffer.Append(UnfinishedHeaderMagicStr, 4);

	std::set<std::string>::iterator it;
	int i;

	// Element names
	i = 0;
	int ElementCount = (int)ElementNames.size();
	writeBuffer.Append(&ElementCount, 4);
	for (it = ElementNames.begin(); it != ElementNames.end(); ++it)
	{
		int TextLen = (int)it->length()+1;
		writeBuffer.Append(&TextLen, 4);
		writeBuffer.Append((void*)it->c_str(), TextLen);
		ElementID[*it] = i++;
	}

	// Attribute names
	i = 0;
	int AttributeCount = (int)AttributeNames.size();
	writeBuffer.Append(&AttributeCount, 4);
	for (it = AttributeNames.begin(); it != AttributeNames.end(); ++it)
	{
		int TextLen = (int)it->length()+1;
		writeBuffer.Append(&TextLen, 4);
		writeBuffer.Append((void*)it->c_str(), TextLen);
		AttributeID[*it] = i++;
	}

	// All the XML contents must be surrounded by a single element
	debug_assert(Root->childs.size() == 1);

	OutputElement(Root->childs[0]);

	delete Root;
	Root = NULL;

	// file is now valid, so insert correct magic string
	writeBuffer.Overwrite(HeaderMagicStr, 4, 0);
}

// Writes a whole element (recursively if it has children) into the buffer,
// and also frees all the memory that has been allocated for that element.
void XeroHandler::OutputElement(XMLElement* el)
{
	// Filled in later with the length of the element
	int Pos_Length = (int)writeBuffer.Size();
	writeBuffer.Append("????", 4);

	int NameID = ElementID[el->name];
	writeBuffer.Append(&NameID, 4);

	int AttrCount = (int)el->attrs.size();
	writeBuffer.Append(&AttrCount, 4);

	int ChildCount = (int)el->childs.size();
	writeBuffer.Append(&ChildCount, 4);

	// Filled in later with the offset to the list of child elements
	int Pos_ChildrenOffset = (int)writeBuffer.Size();
	writeBuffer.Append("????", 4);


	// Trim excess whitespace in the entity's text, while counting
	// the number of newlines trimmed (so that JS error reporting
	// can give the correct line number)

	std::string whitespaceA = " \t\r\n";
	utf16string whitespace (whitespaceA.begin(), whitespaceA.end());

	// Find the start of the non-whitespace section
	size_t first = el->text.find_first_not_of(whitespace);

	if (first == el->text.npos)
		// Entirely whitespace - easy to handle
		el->text = utf16string();

	else
	{
		// Count the number of \n being cut off,
		// and add them to the line number
		utf16string trimmed (el->text.begin(), el->text.begin()+first);
		el->linenum += (int)std::count(trimmed.begin(), trimmed.end(), (utf16_t)'\n');

		// Find the end of the non-whitespace section,
		// and trim off everything else
		size_t last = el->text.find_last_not_of(whitespace);
		el->text = el->text.substr(first, 1+last-first);
	}

	// Output text, prefixed by length in bytes
	if (el->text.length() == 0)
	{
		// No text; don't write much
		writeBuffer.Append("\0\0\0\0", 4);
	}
	else
	{
		// Write length and line number and null-terminated text
		int NodeLen = 4 + 2*((int)el->text.length()+1);
		writeBuffer.Append(&NodeLen, 4);
		writeBuffer.Append(&el->linenum, 4);
		writeBuffer.Append((void*)el->text.c_str(), NodeLen-4);
	}

	// Output attributes

	int i;

	for (i = 0; i < AttrCount; ++i)
	{
		int AttrName = AttributeID[el->attrs[i]->name];
		writeBuffer.Append(&AttrName, 4);

		int AttrLen = 2*((int)el->attrs[i]->value.length()+1);
		writeBuffer.Append(&AttrLen, 4);
		writeBuffer.Append((void*)el->attrs[i]->value.c_str(), AttrLen);

		// Free each attribute as soon as it's been dealt with
		delete el->attrs[i];
	}

	// Go back and fill in the child-element offset
	int ChildrenOffset = (int)writeBuffer.Size() - (Pos_ChildrenOffset+4);
	writeBuffer.Overwrite(&ChildrenOffset, 4, Pos_ChildrenOffset);

	// Output all child nodes
	for (i = 0; i < ChildCount; ++i)
		OutputElement(el->childs[i]);

	// Go back and fill in the length
	int Length = (int)writeBuffer.Size() - Pos_Length;
	writeBuffer.Overwrite(&Length, 4, Pos_Length);

	// Tidy up the parser's mess
	delete el;
}

void XeroHandler::DeallocateElement(XMLElement* el)
{
	size_t i;

	for (i = 0; i < el->attrs.size(); ++i)
		delete el->attrs[i];

	for (i = 0; i < el->childs.size(); ++i)
		DeallocateElement(el->childs[i]);

	delete el;
}