#include "CUnicode.h"
#include <limits.h>
#include <string.h>

//
// local utility functions
//

inline
static
UInt16
decode16(const UInt8* n)
{
	union x16 {
		UInt8	n8[2];
		UInt16	n16;
	} c;
	c.n8[0] = n[0];
	c.n8[1] = n[1];
	return c.n16;
}

inline
static
UInt32
decode32(const UInt8* n)
{
	union x32 {
		UInt8	n8[4];
		UInt32	n32;
	} c;
	c.n8[0] = n[0];
	c.n8[1] = n[1];
	c.n8[2] = n[2];
	c.n8[3] = n[3];
	return c.n32;
}

inline
static
void
resetError(bool* errors)
{
	if (errors != NULL) {
		*errors = false;
	}
}

inline
static
void
setError(bool* errors)
{
	if (errors != NULL) {
		*errors = true;
	}
}

//
// CUnicode
//

UInt32					CUnicode::s_invalid     = 0x0000ffff;
UInt32					CUnicode::s_replacement = 0x0000fffd;

bool
CUnicode::isUTF8(const CString& src)
{
	// convert and test each character
	const UInt8* data = reinterpret_cast<const UInt8*>(src.c_str());
	for (UInt32 n = src.size(); n > 0; ) {
		if (fromUTF8(data, n) == s_invalid) {
			return false;
		}
	}
	return true;
}

CString
CUnicode::UTF8ToUCS2(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// get size of input string and reserve some space in output.
	// include UTF8's nul terminator.
	UInt32 n = src.size() + 1;
	CString dst;
	dst.reserve(2 * n);

	// convert each character
	const UInt8* data = reinterpret_cast<const UInt8*>(src.c_str());
	while (n > 0) {
		UInt32 c = fromUTF8(data, n);
		if (c == s_invalid) {
			c = s_replacement;
		}
		else if (c >= 0x00010000) {
			setError(errors);
			c = s_replacement;
		}
		UInt16 ucs2 = static_cast<UInt16>(c);
		dst.append(reinterpret_cast<const char*>(&ucs2), 2);
	}

	return dst;
}

CString
CUnicode::UTF8ToUCS4(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// get size of input string and reserve some space in output.
	// include UTF8's nul terminator.
	UInt32 n = src.size() + 1;
	CString dst;
	dst.reserve(4 * n);

	// convert each character
	const UInt8* data = reinterpret_cast<const UInt8*>(src.c_str());
	while (n > 0) {
		UInt32 c = fromUTF8(data, n);
		if (c == s_invalid) {
			c = s_replacement;
		}
		dst.append(reinterpret_cast<const char*>(&c), 4);
	}

	return dst;
}

CString
CUnicode::UTF8ToUTF16(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// get size of input string and reserve some space in output.
	// include UTF8's nul terminator.
	UInt32 n = src.size() + 1;
	CString dst;
	dst.reserve(2 * n);

	// convert each character
	const UInt8* data = reinterpret_cast<const UInt8*>(src.c_str());
	while (n > 0) {
		UInt32 c = fromUTF8(data, n);
		if (c == s_invalid) {
			c = s_replacement;
		}
		else if (c >= 0x00110000) {
			setError(errors);
			c = s_replacement;
		}
		if (c < 0x00010000) {
			UInt16 ucs2 = static_cast<UInt16>(c);
			dst.append(reinterpret_cast<const char*>(&ucs2), 2);
		}
		else {
			c -= 0x00010000;
			UInt16 utf16h = static_cast<UInt16>(c >> 10) + 0xd800;
			UInt16 utf16l = (static_cast<UInt16>(c) & 0x03ff) + 0xdc00;
			dst.append(reinterpret_cast<const char*>(&utf16h), 2);
			dst.append(reinterpret_cast<const char*>(&utf16l), 2);
		}
	}

	return dst;
}

CString
CUnicode::UTF8ToUTF32(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// get size of input string and reserve some space in output.
	// include UTF8's nul terminator.
	UInt32 n = src.size() + 1;
	CString dst;
	dst.reserve(4 * n);

	// convert each character
	const UInt8* data = reinterpret_cast<const UInt8*>(src.c_str());
	while (n > 0) {
		UInt32 c = fromUTF8(data, n);
		if (c == s_invalid) {
			c = s_replacement;
		}
		else if (c >= 0x00110000) {
			setError(errors);
			c = s_replacement;
		}
		dst.append(reinterpret_cast<const char*>(&c), 4);
	}

	return dst;
}

CString
CUnicode::UTF8ToText(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// convert to wide char
	wchar_t* tmp = UTF8ToWideChar(src, errors);

	// get length of multibyte string
	size_t len = 0;
	char mbc[MB_LEN_MAX];
	mbstate_t state;
	memset(&state, 0, sizeof(state));
	for (const wchar_t* scan = tmp; *scan != 0; ++scan) {
		size_t mblen = wcrtomb(mbc, *scan, &state);
		if (mblen == -1) {
			// unconvertable character
			setError(errors);
			len += 1;
		}
		else {
			len += mblen;
		}
	}

	// check if state is in initial state.  if not then count the
	// bytes for returning it to the initial state.
	if (mbsinit(&state) == 0) {
		len += wcrtomb(mbc, L'\0', &state) - 1;
	}
	assert(mbsinit(&state) != 0);

	// allocate multibyte string
	char* mbs = new char[len + 1];

	// convert to multibyte
	char* dst = mbs;
	for (const wchar_t* scan = tmp; *scan != 0; ++scan) {
		size_t mblen = wcrtomb(dst, *scan, &state);
		if (mblen == -1) {
			// unconvertable character
			*dst++ = '?';
		}
		else {
			dst += len;
		}
	}
	*dst = '\0';
	CString text(mbs);

	// clean up
	delete[] mbs;
	delete[] tmp;

	return text;
}

CString
CUnicode::UCS2ToUTF8(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// convert
	UInt32 n = src.size() >> 1;
	return doUCS2ToUTF8(reinterpret_cast<const UInt8*>(src.data()), n, errors);
}

CString
CUnicode::UCS4ToUTF8(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// convert
	UInt32 n = src.size() >> 2;
	return doUCS4ToUTF8(reinterpret_cast<const UInt8*>(src.data()), n, errors);
}

CString
CUnicode::UTF16ToUTF8(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// convert
	UInt32 n = src.size() >> 1;
	return doUTF16ToUTF8(reinterpret_cast<const UInt8*>(src.data()), n, errors);
}

CString
CUnicode::UTF32ToUTF8(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// convert
	UInt32 n = src.size() >> 2;
	return doUTF32ToUTF8(reinterpret_cast<const UInt8*>(src.data()), n, errors);
}

CString
CUnicode::textToUTF8(const CString& src, bool* errors)
{
	// default to success
	resetError(errors);

	// get length of multibyte string
	UInt32 n   = src.size();
	size_t len = 0;
	mbstate_t state;
	memset(&state, 0, sizeof(state));
	for (const char* scan = src.c_str(); n > 0 && *scan != 0; ) {
		size_t mblen = mbrtowc(NULL, scan, n, &state);
		switch (mblen) {
		case (size_t)-2:
			// incomplete last character.  convert to unknown character.
			setError(errors);
			len += 1;
			n    = 0;
			break;

		case (size_t)-1:
			// invalid character.  count one unknown character and
			// start at the next byte.
			setError(errors);
			len  += 1;
			scan += 1;
			n    -= 1;
			break;

		default:
			// normal character
			len  += 1;
			scan += mblen;
			n    -= mblen;
			break;
		}
	}
	memset(&state, 0, sizeof(state));

	// allocate wide character string
	wchar_t* wcs = new wchar_t[len + 1];

	// convert multibyte to wide char
	n = src.size();
	wchar_t* dst = wcs;
	for (const char* scan = src.c_str(); n > 0 && *scan != 0; ++dst) {
		size_t mblen = mbrtowc(dst, scan, n, &state);
		switch (mblen) {
		case (size_t)-2:
			// incomplete character.  convert to unknown character.
			*dst = (wchar_t)0xfffd;
			n    = 0;
			break;

		case (size_t)-1:
			// invalid character.  count one unknown character and
			// start at the next byte.
			scan += 1;
			n    -= 1;
			*dst = (wchar_t)0xfffd;
			break;

		default:
			// normal character
			scan += mblen;
			n    -= mblen;
			break;
		}
	}
	*dst = L'\0';

	// convert to UTF8
	CString utf8 = wideCharToUTF8(wcs, errors);

	// clean up
	delete[] wcs;

	return utf8;
}

wchar_t*
CUnicode::UTF8ToWideChar(const CString& src, bool* errors)
{
	// convert to platform's wide character encoding.
	// note -- this must include a wide nul character (independent of
	// the CString's nul character).
#if WINDOWS_LIKE
	CString tmp = UTF8ToUCS16(src);
	UInt32 size = tmp.size() >> 1;
#elif UNIX_LIKE
	CString tmp = UTF8ToUCS4(src);
	UInt32 size = tmp.size() >> 2;
#endif

	// copy to a wchar_t array
	wchar_t* dst = new wchar_t[size];
	::memcpy(dst, tmp.data(), sizeof(wchar_t) * size);
	return dst;
}

CString
CUnicode::wideCharToUTF8(const wchar_t* src, bool* errors)
{
	// convert from platform's wide character encoding.
	// note -- this must include a wide nul character (independent of
	// the CString's nul character).
#if WINDOWS_LIKE
	return doUCS16ToUTF8(reinterpret_cast<const UInt8*>(src),
								wcslen(src), errors);
#elif UNIX_LIKE
	return doUCS4ToUTF8(reinterpret_cast<const UInt8*>(src),
								wcslen(src), errors);
#endif
}

CString
CUnicode::doUCS2ToUTF8(const UInt8* data, UInt32 n, bool* errors)
{
	// make some space
	CString dst;
	dst.reserve(n);

	// convert each character
	for (; n > 0; data += 2, --n) {
		UInt32 c = decode16(data);
		toUTF8(dst, c, errors);
	}

	// remove extra trailing nul
	if (dst.size() > 0 && dst[dst.size() - 1] == '\0') {
		dst.resize(dst.size() - 1);
	}

	return dst;
}

CString
CUnicode::doUCS4ToUTF8(const UInt8* data, UInt32 n, bool* errors)
{
	// make some space
	CString dst;
	dst.reserve(n);

	// convert each character
	for (; n > 0; data += 4, --n) {
		UInt32 c = decode32(data);
		toUTF8(dst, c, errors);
	}

	// remove extra trailing nul
	if (dst.size() > 0 && dst[dst.size() - 1] == '\0') {
		dst.resize(dst.size() - 1);
	}

	return dst;
}

CString
CUnicode::doUTF16ToUTF8(const UInt8* data, UInt32 n, bool* errors)
{
	// make some space
	CString dst;
	dst.reserve(n);

	// convert each character
	for (; n > 0; data += 2, --n) {
		UInt32 c = decode16(data);
		if (c < 0x0000d800 || c > 0x0000dfff) {
			toUTF8(dst, c, errors);
		}
		else if (n == 1) {
			// error -- missing second word
			setError(errors);
			toUTF8(dst, s_replacement, NULL);
		}
		else if (c >= 0x0000d800 && c <= 0x0000dbff) {
			UInt32 c2 = decode16(data);
			data += 2;
			--n;
			if (c2 < 0x0000dc00 || c2 > 0x0000dfff) {
				// error -- [d800,dbff] not followed by [dc00,dfff]
				setError(errors);
				toUTF8(dst, s_replacement, NULL);
			}
			else {
				c = (((c - 0x0000d800) << 10) | (c2 - 0x0000dc00)) + 0x00010000;
				toUTF8(dst, c, errors);
			}
		}
		else {
			// error -- [dc00,dfff] without leading [d800,dbff]
			setError(errors);
			toUTF8(dst, s_replacement, NULL);
		}
	}

	// remove extra trailing nul
	if (dst.size() > 0 && dst[dst.size() - 1] == '\0') {
		dst.resize(dst.size() - 1);
	}

	return dst;
}

CString
CUnicode::doUTF32ToUTF8(const UInt8* data, UInt32 n, bool* errors)
{
	// make some space
	CString dst;
	dst.reserve(n);

	// convert each character
	for (; n > 0; data += 4, --n) {
		UInt32 c = decode32(data);
		if (c >= 0x00110000) {
			setError(errors);
			c = s_replacement;
		}
		toUTF8(dst, c, errors);
	}

	// remove extra trailing nul
	if (dst.size() > 0 && dst[dst.size() - 1] == '\0') {
		dst.resize(dst.size() - 1);
	}

	return dst;
}

UInt32
CUnicode::fromUTF8(const UInt8*& data, UInt32& n)
{
	assert(data != NULL);
	assert(n    != 0);

	// compute character encoding length, checking for overlong
	// sequences (i.e. characters that don't use the shortest
	// possible encoding).
	UInt32 size;
	if (data[0] < 0x80) {
		// 0xxxxxxx
		size = 1;
	}
	else if (data[0] < 0xc0) {
		// 10xxxxxx -- in the middle of a multibyte character.  skip
		// until we find a start byte and return error.
		do {
			--n;
			++data;
		} while (n > 0 && (data[0] & 0xc0) == 0x80);
		return s_invalid;
	}
	else if (data[0] < 0xe0) {
		// 110xxxxx
		size = 2;
	}
	else if (data[0] < 0xf0) {
		// 1110xxxx
		size = 3;
	}
	else if (data[0] < 0xf8) {
		// 11110xxx
		size = 4;
	}
	else if (data[0] < 0xfc) {
		// 111110xx
		size = 5;
	}
	else if (data[0] < 0xfe) {
		// 1111110x
		size = 6;
	}
	else {
		// invalid sequence.  dunno how many bytes to skip so skip one.
		--n;
		++data;
		return s_invalid;
	}

	// make sure we have enough data
	if (size > n) {
		data += n;
		n     = 0;
		return s_invalid;
	}

	// extract character
	UInt32 c;
	switch (size) {
	case 1:
		c = static_cast<UInt32>(data[0]);
		break;

	case 2:
		c = ((static_cast<UInt32>(data[0]) & 0x1f) <<  6) |
			((static_cast<UInt32>(data[1]) & 0x3f)      );
		break;

	case 3:
		c = ((static_cast<UInt32>(data[0]) & 0x0f) << 12) |
			((static_cast<UInt32>(data[1]) & 0x3f) <<  6) |
			((static_cast<UInt32>(data[2]) & 0x3f)      );
		break;

	case 4:
		c = ((static_cast<UInt32>(data[0]) & 0x07) << 18) |
			((static_cast<UInt32>(data[1]) & 0x3f) << 12) |
			((static_cast<UInt32>(data[1]) & 0x3f) <<  6) |
			((static_cast<UInt32>(data[1]) & 0x3f)      );
		break;

	case 5:
		c = ((static_cast<UInt32>(data[0]) & 0x03) << 24) |
			((static_cast<UInt32>(data[1]) & 0x3f) << 18) |
			((static_cast<UInt32>(data[1]) & 0x3f) << 12) |
			((static_cast<UInt32>(data[1]) & 0x3f) <<  6) |
			((static_cast<UInt32>(data[1]) & 0x3f)      );
		break;

	case 6:
		c = ((static_cast<UInt32>(data[0]) & 0x01) << 30) |
			((static_cast<UInt32>(data[1]) & 0x3f) << 24) |
			((static_cast<UInt32>(data[1]) & 0x3f) << 18) |
			((static_cast<UInt32>(data[1]) & 0x3f) << 12) |
			((static_cast<UInt32>(data[1]) & 0x3f) <<  6) |
			((static_cast<UInt32>(data[1]) & 0x3f)      );
		break;

	default:
		assert(0 && "invalid size");
	}

	// check that all bytes after the first have the pattern 10xxxxxx.
	// truncated sequences are treated as a single malformed character.
	bool truncated = false;
	switch (size) {
	case 6:
		if ((data[5] & 0xc0) != 0x80) {
			truncated = true;
			size = 5;
		}
		// fall through

	case 5:
		if ((data[4] & 0xc0) != 0x80) {
			truncated = true;
			size = 4;
		}
		// fall through

	case 4:
		if ((data[3] & 0xc0) != 0x80) {
			truncated = true;
			size = 3;
		}
		// fall through

	case 3:
		if ((data[2] & 0xc0) != 0x80) {
			truncated = true;
			size = 2;
		}
		// fall through

	case 2:
		if ((data[1] & 0xc0) != 0x80) {
			truncated = true;
			size = 1;
		}
	}

	// update parameters
	data += size;
	n    -= size;

	// invalid if sequence was truncated
	if (truncated) {
		return s_invalid;
	}

	// check for characters that didn't use the smallest possible encoding
	static UInt32 s_minChar[] = {
		0,
		0x00000000,
		0x00000080,
		0x00000800,
		0x00010000,
		0x00200000,
		0x04000000
	};
	if (c < s_minChar[size]) {
		return s_invalid;
	}

	// check for characters not in ISO-10646
	if (c >= 0x0000d800 && c <= 0x0000dfff) {
		return s_invalid;
	}
	if (c >= 0x0000fffe && c <= 0x0000ffff) {
		return s_invalid;
	}

	return c;
}

void
CUnicode::toUTF8(CString& dst, UInt32 c, bool* errors)
{
	UInt8 data[6];

	// handle characters outside the valid range
	if ((c >= 0x0000d800 && c <= 0x0000dfff) || c >= 0x80000000) {
		setError(errors);
		c = s_replacement;
	}

	// convert to UTF-8
	if (c < 0x00000080) {
		data[0] = static_cast<UInt8>(c);
		dst.append(reinterpret_cast<char*>(data), 1);
	}
	else if (c < 0x00000800) {
		data[0] = static_cast<UInt8>((c >>  6) & 0x0000001f) + 0xc0;
		data[1] = static_cast<UInt8>(c         & 0x0000003f) + 0x80;
		dst.append(reinterpret_cast<char*>(data), 2);
	}
	else if (c < 0x00010000) {
		data[0] = static_cast<UInt8>((c >> 12) & 0x0000000f) + 0xe0;
		data[1] = static_cast<UInt8>((c >>  6) & 0x0000003f) + 0x80;
		data[2] = static_cast<UInt8>(c         & 0x0000003f) + 0x80;
		dst.append(reinterpret_cast<char*>(data), 3);
	}
	else if (c < 0x00200000) {
		data[0] = static_cast<UInt8>((c >> 18) & 0x00000007) + 0xf0;
		data[1] = static_cast<UInt8>((c >> 12) & 0x0000003f) + 0x80;
		data[2] = static_cast<UInt8>((c >>  6) & 0x0000003f) + 0x80;
		data[3] = static_cast<UInt8>(c         & 0x0000003f) + 0x80;
		dst.append(reinterpret_cast<char*>(data), 4);
	}
	else if (c < 0x04000000) {
		data[0] = static_cast<UInt8>((c >> 24) & 0x00000003) + 0xf8;
		data[1] = static_cast<UInt8>((c >> 18) & 0x0000003f) + 0x80;
		data[2] = static_cast<UInt8>((c >> 12) & 0x0000003f) + 0x80;
		data[3] = static_cast<UInt8>((c >>  6) & 0x0000003f) + 0x80;
		data[4] = static_cast<UInt8>(c         & 0x0000003f) + 0x80;
		dst.append(reinterpret_cast<char*>(data), 5);
	}
	else if (c < 0x80000000) {
		data[0] = static_cast<UInt8>((c >> 30) & 0x00000001) + 0xfc;
		data[1] = static_cast<UInt8>((c >> 24) & 0x0000003f) + 0x80;
		data[2] = static_cast<UInt8>((c >> 18) & 0x0000003f) + 0x80;
		data[3] = static_cast<UInt8>((c >> 12) & 0x0000003f) + 0x80;
		data[4] = static_cast<UInt8>((c >>  6) & 0x0000003f) + 0x80;
		data[5] = static_cast<UInt8>(c         & 0x0000003f) + 0x80;
		dst.append(reinterpret_cast<char*>(data), 6);
	}
	else {
		assert(0 && "character out of range");
	}
}