#include <memory>
#include <vector>

#include "data.h"
#include "win.h"

template <typename T>
inline unsigned char* ValToBuf(const T& val, unsigned char* const buf)
{
	memcpy(buf, &val, sizeof(val));
	return buf+sizeof(val);
}

template <typename T>
inline unsigned char* BufToVal(unsigned char* const buf, T& val)
{
	memcpy(&val, buf, sizeof(val));
	return buf+sizeof(val);
}

FileView::FileView(const wchar_t* const filename, const size_t cb)
{
	hf = CreateFile(filename, GENERIC_READ|GENERIC_WRITE,
	    0, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
	if (hf == INVALID_HANDLE_VALUE) {
		if (GetLastError() == ERROR_FILE_NOT_FOUND) {
			hf = CreateFile(filename, GENERIC_READ|GENERIC_WRITE,
			    0, nullptr, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, nullptr);
			if (hf == INVALID_HANDLE_VALUE)
				throw Win32Error{};
		} else
			throw Win32Error{};
	}

	LARGE_INTEGER cbMap;
	cbMap.QuadPart = cb;
	hm = CreateFileMapping(hf, nullptr, PAGE_READWRITE,
	    cbMap.HighPart, cbMap.LowPart, nullptr);
	if (!hm)
		throw Win32Error{};

	view = reinterpret_cast<unsigned char*>(MapViewOfFile(hm, FILE_MAP_ALL_ACCESS, 0, 0, 0));
	if (!view)
		throw Win32Error{};
}

FileView::~FileView()
{
	FlushViewOfFile(view, 0);
	UnmapViewOfFile(view);
	CloseHandle(hm);
	CloseHandle(hf);
}

void Write(unsigned char* buf, const ElvData& e)
{
	memcpy(buf, reinterpret_cast<const unsigned char*>(&e), sizeof(e));
}

ElvData* Read(unsigned char* const buf)
{
	if (buf[0] != 'a')
		return nullptr;
	return reinterpret_cast<ElvData*>(buf);
}