#include <stdexcept>

#include <memory>
#include <fstream>
#include <iomanip>
#include <exception>
#include "xml_article.h"

using namespace std;

void SaveWideBufferToFileUTF8(HANDLE hFile, LPCWSTR pwch, int cch)
{
	//Guess the size of contents in UTF-8 encoding is less than 120% of characters in Unicode.
	//This guess is usually correct, and is therefore faster than asking, allocating and converting. 06/18/01 BB
	int nBuffer(cch*6/5); //NOTE: Six-fifths == 120%

	//Convert bstrContents to UTF-8.
	auto_ptr<char> pBuffer(new char[nBuffer]);
	if (0 == (nBuffer = WideCharToMultiByte(CP_UTF8,0, pwch, cch, pBuffer.get(), nBuffer, NULL, NULL)))
	{
		if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
			throw runtime_error("Couldn't convert to UTF-8.");

		//Buffer size guess was wrong; take the time to ask API to give us the exact size. 
		nBuffer = WideCharToMultiByte(CP_UTF8,0,pwch, cch, NULL, 0, NULL, NULL);
		delete [] pBuffer.release();
		pBuffer = auto_ptr<char>(new char[nBuffer]);
		if (!WideCharToMultiByte(CP_UTF8,0,pwch, cch, pBuffer.get(), nBuffer, NULL, NULL))
			throw runtime_error("Couldn't convert to UTF-8.");
	}
	DWORD dwNumBytesWritten;

	//Write pBuffer to the file.
	if( !WriteFile( hFile, pBuffer.get(), nBuffer, &dwNumBytesWritten, NULL ) )
		throw runtime_error("Couldn't write file.");
}

IFileStream::IFileStream(LPCWSTR szFile): m_refCnt(0)
{
	m_hFile = CreateFileW( szFile, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
		
	if( m_hFile == INVALID_HANDLE_VALUE )
		throw std::logic_error("Could not open file.");
	AddRef();
}

IFileStream::~IFileStream()
{
	CloseHandle(m_hFile);
}

STDMETHODIMP IFileStream::Write(const void __RPC_FAR *pv,ULONG cb, ULONG __RPC_FAR *pcbWritten) 
{ 
	SaveWideBufferToFileUTF8(m_hFile, (LPCWSTR) pv, cb/2);
	*pcbWritten = cb;
	return S_OK;
}

long __stdcall IFileStream::QueryInterface(const struct _GUID &riid,void ** ppvObject)
{
    *ppvObject = NULL;
	if (riid == IID_IUnknown ||riid == __uuidof(IStream))
	{
		*ppvObject = static_cast<IStream *>(this);
		AddRef();
		return S_OK;
	}
	
	return E_NOINTERFACE;
}

unsigned long __stdcall IFileStream::AddRef()
{
     return ++m_refCnt; // NOT thread-safe
}

unsigned long __stdcall IFileStream::Release()
{
    --m_refCnt; // NOT thread-safe
   if (m_refCnt == 0) {
      delete this;
      return 0; // Can't return the member of a deleted object.
   }
   else return m_refCnt;
}


//NOTE: MXFileWriter is derived from IMXWriterPtr, so an instance of
//this class can be used in place of a standard IMXWriterPtr.
//The difference is, all output will be saved to the file specified
//in the constructor, or in the SetFileLocation method.
MXFileWriter::MXFileWriter(LPCWSTR szFile) : m_pFileStream(NULL)
{
	CreateInstance(__uuidof(MSXML2::MXXMLWriter)); 
	if (szFile)
		SetFileLocation(szFile);
}

MXFileWriter::~MXFileWriter()
{
	if (m_pFileStream)
		m_pFileStream->Release(); //self-deleting on zero reference count
}

//Start writing to a new file.
MXFileWriter::SetFileLocation(LPCWSTR szFile)
{
	if (m_pFileStream)
		m_pFileStream->Release(); //self-deleting on zero reference count
	m_pFileStream = NULL;
	m_pFileStream = new IFileStream(szFile);
	
	//Here's the $64,000 Line: Redirect output as a variant containing an IStream pointer.
	GetInterfacePtr()->put_output(_variant_t((IStream *)m_pFileStream));  
}