#include <wrl.h>
#include <string>
#include <DXGI.h>
#include <ppltasks.h>
#include <shcore.h>
#include <unordered_set>
#include "AsyncHelper.h"
#include "StringHelper.h"

#pragma comment(lib, "ShCore.lib")

#define PAL_PATH_NAME	"SDLPAL"

static const LARGE_INTEGER liZero = { 0 };
static const void* const _SIGNATURE = &liZero;

/*========================*/

typedef struct WRT_FILE WRT_FILE;

struct WRT_FILE
{
	const void* sig;
	IStream* stream;
	CRITICAL_SECTION cs;
	bool readable;
	bool writable;
	bool binary;

	WRT_FILE() : sig(&liZero), stream(nullptr), readable(false), writable(false), binary(false) { InitializeCriticalSectionEx(&cs, 4000, 0); }
	WRT_FILE(Windows::Storage::Streams::IRandomAccessStream^ s, bool r, bool w, bool b)
		: sig(&liZero), stream(nullptr), readable(r), writable(w), binary(b)
	{
		HRESULT hr;
		InitializeCriticalSectionEx(&cs, 4000, 0);
		if (FAILED(hr = CreateStreamOverRandomAccessStream(s, IID_PPV_ARGS(&stream))))
			throw ref new Platform::Exception(hr);
	}
	~WRT_FILE() { if (stream) stream->Release(); DeleteCriticalSection(&cs); }
};

class CriticalSection
{
public:
	CriticalSection(CRITICAL_SECTION& cs) : m_cs(cs) { EnterCriticalSection(&m_cs); }
	~CriticalSection() { LeaveCriticalSection(&m_cs); }

private:
	CRITICAL_SECTION& m_cs;
};

class Event
{
public:
	Event() : _eventHandle(CreateEventEx(NULL, NULL, 0, EVENT_ALL_ACCESS)) {}
	~Event() { CloseHandle(_eventHandle); }

	operator HANDLE() { return _eventHandle; }

private:
	HANDLE _eventHandle;
};

extern "C"
errno_t WRT_fopen_s(WRT_FILE ** pFile, const char * _Filename, const char * _Mode)
{
	if (nullptr == _Filename || nullptr == _Mode || nullptr == pFile) return EINVAL;

	std::wstring path;
	Platform::String^ filename;
	ConvertString(_Filename, path);
	auto ptr = (wchar_t*)path.c_str() + path.length();
	while (ptr >= path.c_str() && *ptr != L'/' && *ptr != L'\\') ptr--;
	filename = ref new Platform::String(ptr + 1);
	path = path.substr(0, ptr - path.c_str());
	size_t offset = 0;
	while ((offset = path.find(L'/', offset)) != std::wstring::npos)
		path[offset++] = L'\\';
	if (path.size() > 0)
	{
		if (path.back() == L':') path.append(L"\\");
	}
	else
	{
		path.assign(Windows::Storage::ApplicationData::Current->LocalFolder->Path->Data());
	}

	Windows::Storage::StorageFolder^ folder = nullptr;
	Event eventHandle;
	try
	{
		folder = AWait(Windows::Storage::StorageFolder::GetFolderFromPathAsync(ref new Platform::String(path.c_str())), eventHandle);
	}
	catch (Platform::AccessDeniedException^)
	{
		return EACCES;
	}
	catch (Platform::Exception^)
	{
		return EIO;
	}

	WRT_FILE* ret = nullptr;
	try
	{
		Windows::Storage::StorageFile^ file;
		bool r, w;
		switch (*_Mode)
		{
		case 'a': file = AWait(folder->CreateFileAsync(filename, Windows::Storage::CreationCollisionOption::OpenIfExists), eventHandle); w = true; r = false; break;
		case 'w': file = AWait(folder->CreateFileAsync(filename, Windows::Storage::CreationCollisionOption::ReplaceExisting), eventHandle); w = true; r = false; break;
		case 'r': file = AWait(folder->GetFileAsync(filename), eventHandle); w = false; r = true; break;
		default: CloseHandle(eventHandle); return EINVAL;
		}
		if (file)
		{
			bool b = false;
			for (size_t i = 1; i < strlen(_Mode); i++)
			{
				switch (_Mode[i])
				{
				case '+': r = w = true; break;
				case 'b': b = true; break;
				case 't': b = false; break;
				default: return EINVAL;
				}
			}
			ret = new WRT_FILE(AWait(file->OpenAsync(w ? Windows::Storage::FileAccessMode::ReadWrite : Windows::Storage::FileAccessMode::Read), eventHandle), r, w, b);
		}
	}
	catch (Platform::Exception^)
	{
		return EIO;
	}
	*pFile = ret;
	return 0;
}

extern "C"
WRT_FILE* WRT_fopen(const char * _Filename, const char * _Mode)
{
	WRT_FILE* ret;
	int err = WRT_fopen_s(&ret, _Filename, _Mode);
	_set_errno(err);
	return err ? nullptr : ret;
}

extern "C"
int WRT_fclose(WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fclose((FILE*)_File);
	delete _File;
	return 0;
}

extern "C"
int WRT_feof(WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return feof((FILE*)_File);

	STATSTG st;
	ULARGE_INTEGER uli;
	CriticalSection cs(_File->cs);

	if (SUCCEEDED(_File->stream->Seek(liZero, STREAM_SEEK_CUR, &uli)) &&
		SUCCEEDED(_File->stream->Stat(&st, STATFLAG_NONAME)))
		return uli.QuadPart >= st.cbSize.QuadPart;
	else
		return 1;
}

extern "C"
int WRT_fseeki64(WRT_FILE * _File, long long _Offset, int _Origin)
{
	if (!_File || _File->sig != _SIGNATURE) return _fseeki64((FILE*)_File, _Offset, _Origin);

	CriticalSection cs(_File->cs);
	LARGE_INTEGER liOffset;
	liOffset.QuadPart = _Offset;
	return SUCCEEDED(_File->stream->Seek(liOffset, _Origin, NULL)) ? 0 : -1;
}

extern "C"
int WRT_fseek(WRT_FILE * _File, long _Offset, int _Origin)
{
	return WRT_fseeki64(_File, _Offset, _Origin);
}

extern "C"
long long WRT_ftelli64(WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return _ftelli64((FILE*)_File);

	CriticalSection cs(_File->cs);
	unsigned long long pos;
	return SUCCEEDED(_File->stream->Seek(liZero, STREAM_SEEK_CUR, (PULARGE_INTEGER)&pos)) ? pos : -1;
}

extern "C"
size_t WRT_ftell(WRT_FILE * _File)
{
	return (size_t)WRT_ftelli64(_File);
}

extern "C"
size_t WRT_fread(void * _DstBuf, size_t _ElementSize, size_t _Count, WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fread(_DstBuf, _ElementSize, _Count, (FILE*)_File);
	if (!_File->readable || _ElementSize == 0 || _Count == 0 || !_DstBuf) return 0;

	CriticalSection cs(_File->cs);
	unsigned long cbRead;
	return SUCCEEDED(_File->stream->Read(_DstBuf, _ElementSize * _Count, &cbRead)) ? cbRead / _ElementSize : 0;
}

extern "C"
size_t WRT_fwrite(const void * _Str, size_t _Size, size_t _Count, WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fwrite(_Str, _Size, _Count, (FILE*)_File);
	if (!_File->writable || !_Str || _Size == 0 || _Count == 0) return 0;

	CriticalSection cs(_File->cs);
	unsigned long cbWrite;
	return SUCCEEDED(_File->stream->Write(_Str, _Size * _Count, &cbWrite)) ? cbWrite / _Size : 0;
}

extern "C"
int WRT_fflush(WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fflush((FILE*)_File);
	if (!_File->writable) return 0;

	CriticalSection cs(_File->cs);
	return SUCCEEDED(_File->stream->Commit(STGC_DEFAULT)) ? 0 : EOF;
}

static int WRT_fgetc_nolock(WRT_FILE * _File)
{
	unsigned long cbRead;
	unsigned char buf;
	return _File->stream->Read(&buf, 1, &cbRead) == S_OK ? buf : EOF;
}

extern "C"
int WRT_fgetc(WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fgetc((FILE*)_File);

	CriticalSection cs(_File->cs);
	return _File->readable ? WRT_fgetc_nolock(_File) : EOF;
}

extern "C"
char* WRT_fgets(char * _Buf, int _MaxCount, WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fgets(_Buf, _MaxCount, (FILE*)_File);
	if (!_File->readable || !_Buf || _MaxCount <= 0) return nullptr;

	CriticalSection cs(_File->cs);
	int n = 0, flag = 0, ch;
	while (n < _MaxCount - 1 && EOF != (ch = WRT_fgetc_nolock(_File)))
	{
		if (flag)
		{
			if (ch != '\n')
				_Buf[n++] = '\r';
			flag = 0;
		}
		if (ch != '\r')
		{
			_Buf[n++] = ch;
			if (ch == '\n') break;
		}
		else
			flag = 1;
	}
	if (n > 0)
	{
		_Buf[n] = '\0';
		return _Buf;
	}
	else
		return nullptr;
}

extern "C"
int WRT_fputc(int _Ch, WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fputc(_Ch, (FILE*)_File);

	CriticalSection cs(_File->cs);
	unsigned long cbWrite;
	return _File->writable && _File->stream->Write(&_Ch, 1, &cbWrite) == S_OK ? cbWrite : EOF;
}

extern "C"
int WRT_fputs(const char * _Str, WRT_FILE * _File)
{
	if (!_File || _File->sig != _SIGNATURE) return fputs(_Str, (FILE*)_File);
	if (!_File->writable || !_Str) return EOF;

	const char *start = _Str;
	int length = strlen(_Str);
	unsigned long cbWrite;
	const char crlf[] = { '\r', '\n' };
	CriticalSection cs(_File->cs);
	while (true)
	{
		const char *ptr = start;
		while (*ptr && *ptr != '\n') ptr++;
		if (_File->stream->Write(start, ptr - start, &cbWrite) != S_OK)
			return EOF;
		if (*ptr == '\n')
		{
			if (_File->stream->Write(crlf, 2, &cbWrite) != S_OK)
				return EOF;
			else
				start = ptr + 1;
		}
		else
			break;
	}
	return length;
}