/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public

    License along with this library; if not, write to the Free Software

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include "SDL_config.h"

/* This file contains portable iconv functions for SDL */

#include "SDL_stdinc.h"

#include "SDL_endian.h"

#ifdef HAVE_ICONV

/* Depending on which standard the iconv() was implemented with,

   iconv() may or may not use const char ** for the inbuf param.

   If we get this wrong, it's just a warning, so no big deal.

*/

#if defined(_XGP6) || \

    defined(__GLIBC__) && ((__GLIBC__ > 2) || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2))

#define ICONV_INBUF_NONCONST

#endif

#include <errno.h>

size_t SDL_iconv(SDL_iconv_t cd,

                 const char **inbuf, size_t *inbytesleft,

                 char **outbuf, size_t *outbytesleft)

{

	size_t retCode;

#ifdef ICONV_INBUF_NONCONST

	retCode = iconv(cd, (char **)inbuf, inbytesleft, outbuf, outbytesleft);

#else

	retCode = iconv(cd, inbuf, inbytesleft, outbuf, outbytesleft);

#endif

	if ( retCode == (size_t)-1 ) {

		switch(errno) {

		    case E2BIG:

			return SDL_ICONV_E2BIG;

		    case EILSEQ:

			return SDL_ICONV_EILSEQ;

		    case EINVAL:

			return SDL_ICONV_EINVAL;

		    default:

			return SDL_ICONV_ERROR;

		}

	}

	return retCode;

}

#else

/* Lots of useful information on Unicode at:

	http://www.cl.cam.ac.uk/~mgk25/unicode.html

*/

#define UNICODE_BOM	0xFEFF

#define UNKNOWN_ASCII	'?'

#define UNKNOWN_UNICODE	0xFFFD

enum {

	ENCODING_UNKNOWN,

	ENCODING_ASCII,

	ENCODING_LATIN1,

	ENCODING_UTF8,

	ENCODING_UTF16,		/* Needs byte order marker */

	ENCODING_UTF16BE,

	ENCODING_UTF16LE,

	ENCODING_UTF32,		/* Needs byte order marker */

	ENCODING_UTF32BE,

	ENCODING_UTF32LE,

	ENCODING_UCS2,		/* Native byte order assumed */

	ENCODING_UCS4,		/* Native byte order assumed */

};

#if SDL_BYTEORDER == SDL_BIG_ENDIAN

#define ENCODING_UTF16NATIVE	ENCODING_UTF16BE

#define ENCODING_UTF32NATIVE	ENCODING_UTF32BE

#else

#define ENCODING_UTF16NATIVE	ENCODING_UTF16LE

#define ENCODING_UTF32NATIVE	ENCODING_UTF32LE

#endif

struct _SDL_iconv_t

{

	int src_fmt;

	int dst_fmt;

};

static struct {

	const char *name;

	int format;

} encodings[] = {

	{ "ASCII",	ENCODING_ASCII },

	{ "US-ASCII",	ENCODING_ASCII },

	{ "8859-1",	ENCODING_LATIN1 },

	{ "ISO-8859-1",	ENCODING_LATIN1 },

	{ "UTF8",	ENCODING_UTF8 },

	{ "UTF-8",	ENCODING_UTF8 },

	{ "UTF16",	ENCODING_UTF16 },

	{ "UTF-16",	ENCODING_UTF16 },

	{ "UTF16BE",	ENCODING_UTF16BE },

	{ "UTF-16BE",	ENCODING_UTF16BE },

	{ "UTF16LE",	ENCODING_UTF16LE },

	{ "UTF-16LE",	ENCODING_UTF16LE },

	{ "UTF32",	ENCODING_UTF32 },

	{ "UTF-32",	ENCODING_UTF32 },

	{ "UTF32BE",	ENCODING_UTF32BE },

	{ "UTF-32BE",	ENCODING_UTF32BE },

	{ "UTF32LE",	ENCODING_UTF32LE },

	{ "UTF-32LE",	ENCODING_UTF32LE },

	{ "UCS2",	ENCODING_UCS2 },

	{ "UCS-2",	ENCODING_UCS2 },

	{ "UCS4",	ENCODING_UCS4 },

	{ "UCS-4",	ENCODING_UCS4 },

};

static const char *getlocale(char *buffer, size_t bufsize)

{

	const char *lang;

	char *ptr;

	lang = SDL_getenv("LC_ALL");

	if ( !lang ) {

		lang = SDL_getenv("LC_CTYPE");

	}

	if ( !lang ) {

		lang = SDL_getenv("LC_MESSAGES");

	}

	if ( !lang ) {

		lang = SDL_getenv("LANG");

	}

	if ( !lang || !*lang || SDL_strcmp(lang, "C") == 0 ) {

		lang = "ASCII";

	}

	/* We need to trim down strings like "en_US.UTF-8@blah" to "UTF-8" */

	ptr = SDL_strchr(lang, '.');

	if (ptr != NULL) {

		lang = ptr + 1;

	}

	SDL_strlcpy(buffer, lang, bufsize);

	ptr = SDL_strchr(buffer, '@');

	if (ptr != NULL) {

		*ptr = '\0';  /* chop end of string. */

	}

	return buffer;

}

SDL_iconv_t SDL_iconv_open(const char *tocode, const char *fromcode)

{

	int src_fmt = ENCODING_UNKNOWN;

	int dst_fmt = ENCODING_UNKNOWN;

	int i;

	char fromcode_buffer[64];

	char tocode_buffer[64];

	if ( !fromcode || !*fromcode ) {

		fromcode = getlocale(fromcode_buffer, sizeof(fromcode_buffer));

	}

	if ( !tocode || !*tocode ) {

		tocode = getlocale(tocode_buffer, sizeof(tocode_buffer));

	}

	for ( i = 0; i < SDL_arraysize(encodings); ++i ) {

		if ( SDL_strcasecmp(fromcode, encodings[i].name) == 0 ) {

			src_fmt = encodings[i].format;

			if ( dst_fmt != ENCODING_UNKNOWN ) {

				break;

			}

		}

		if ( SDL_strcasecmp(tocode, encodings[i].name) == 0 ) {

			dst_fmt = encodings[i].format;

			if ( src_fmt != ENCODING_UNKNOWN ) {

				break;

			}

		}

	}

	if ( src_fmt != ENCODING_UNKNOWN && dst_fmt != ENCODING_UNKNOWN ) {

		SDL_iconv_t cd = (SDL_iconv_t)SDL_malloc(sizeof(*cd));

		if ( cd ) {

			cd->src_fmt = src_fmt;

			cd->dst_fmt = dst_fmt;

			return cd;

		}

	}

	return (SDL_iconv_t)-1;

}

size_t SDL_iconv(SDL_iconv_t cd,

                 const char **inbuf, size_t *inbytesleft,

                 char **outbuf, size_t *outbytesleft)

{

	/* For simplicity, we'll convert everything to and from UCS-4 */

	const char *src;

	char *dst;

	size_t srclen, dstlen;

	Uint32 ch = 0;

	size_t total;

	if ( !inbuf || !*inbuf ) {

		/* Reset the context */

		return 0;

	}

	if ( !outbuf || !*outbuf || !outbytesleft || !*outbytesleft ) {

		return SDL_ICONV_E2BIG;

	}

	src = *inbuf;

	srclen = (inbytesleft ? *inbytesleft : 0);

	dst = *outbuf;

	dstlen = *outbytesleft;

	switch ( cd->src_fmt ) {

	    case ENCODING_UTF16:

		/* Scan for a byte order marker */

		{

			Uint8 *p = (Uint8 *)src;

			size_t n = srclen / 2;

			while ( n ) {

				if ( p[0] == 0xFF && p[1] == 0xFE ) {

					cd->src_fmt = ENCODING_UTF16BE;

					break;

				} else if ( p[0] == 0xFE && p[1] == 0xFF ) {

					cd->src_fmt = ENCODING_UTF16LE;

					break;

				}

				p += 2;

				--n;

			}

			if ( n == 0 ) {

				/* We can't tell, default to host order */

				cd->src_fmt = ENCODING_UTF16NATIVE;

			}

		}

		break;

	    case ENCODING_UTF32:

		/* Scan for a byte order marker */

		{

			Uint8 *p = (Uint8 *)src;

			size_t n = srclen / 4;

			while ( n ) {

				if ( p[0] == 0xFF && p[1] == 0xFE &&

				     p[2] == 0x00 && p[3] == 0x00 ) {

					cd->src_fmt = ENCODING_UTF32BE;

					break;

				} else if ( p[0] == 0x00 && p[1] == 0x00 &&

				            p[2] == 0xFE && p[3] == 0xFF ) {

					cd->src_fmt = ENCODING_UTF32LE;

					break;

				}

				p += 4;

				--n;

			}

			if ( n == 0 ) {

				/* We can't tell, default to host order */

				cd->src_fmt = ENCODING_UTF32NATIVE;

			}

		}

		break;

	}

	switch ( cd->dst_fmt ) {

	    case ENCODING_UTF16:

		/* Default to host order, need to add byte order marker */

		if ( dstlen < 2 ) {

			return SDL_ICONV_E2BIG;

		}

		*(Uint16 *)dst = UNICODE_BOM;

		dst += 2;

		dstlen -= 2;

		cd->dst_fmt = ENCODING_UTF16NATIVE;

		break;

	    case ENCODING_UTF32:

		/* Default to host order, need to add byte order marker */

		if ( dstlen < 4 ) {

			return SDL_ICONV_E2BIG;

		}

		*(Uint32 *)dst = UNICODE_BOM;

		dst += 4;

		dstlen -= 4;

		cd->dst_fmt = ENCODING_UTF32NATIVE;

		break;

	}

	total = 0;

	while ( srclen > 0 ) {

		/* Decode a character */

		switch ( cd->src_fmt ) {

		    case ENCODING_ASCII:

			{

				Uint8 *p = (Uint8 *)src;

				ch = (Uint32)(p[0] & 0x7F);

				++src;

				--srclen;

			}

			break;

		    case ENCODING_LATIN1:

			{

				Uint8 *p = (Uint8 *)src;

				ch = (Uint32)p[0];

				++src;

				--srclen;

			}

			break;

		    case ENCODING_UTF8: /* RFC 3629 */

			{

				Uint8 *p = (Uint8 *)src;

				size_t left = 0;

				SDL_bool overlong = SDL_FALSE;

				if ( p[0] >= 0xFC ) {

					if ( (p[0] & 0xFE) != 0xFC ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

					} else {

						if ( p[0] == 0xFC ) {

							overlong = SDL_TRUE;

						}

						ch = (Uint32)(p[0] & 0x01);

						left = 5;

					}

				} else if ( p[0] >= 0xF8 ) {

					if ( (p[0] & 0xFC) != 0xF8 ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

					} else {

						if ( p[0] == 0xF8 ) {

							overlong = SDL_TRUE;

						}

						ch = (Uint32)(p[0] & 0x03);

						left = 4;

					}

				} else if ( p[0] >= 0xF0 ) {

					if ( (p[0] & 0xF8) != 0xF0 ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

					} else {

						if ( p[0] == 0xF0 ) {

							overlong = SDL_TRUE;

						}

						ch = (Uint32)(p[0] & 0x07);

						left = 3;

					}

				} else if ( p[0] >= 0xE0 ) {

					if ( (p[0] & 0xF0) != 0xE0 ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

					} else {

						if ( p[0] == 0xE0 ) {

							overlong = SDL_TRUE;

						}

						ch = (Uint32)(p[0] & 0x0F);

						left = 2;

					}

				} else if ( p[0] >= 0xC0 ) {

					if ( (p[0] & 0xE0) != 0xC0 ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

					} else {

						if ( (p[0] & 0xCE) == 0xC0 ) {

							overlong = SDL_TRUE;

						}

						ch = (Uint32)(p[0] & 0x1F);

						left = 1;

					}

				} else {

					if ( (p[0] & 0x80) != 0x00 ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

					} else {

						ch = (Uint32)p[0];

					}

				}

				++src;

				--srclen;

				if ( srclen < left ) {

					return SDL_ICONV_EINVAL;

				}

				while ( left-- ) {

					++p;

					if ( (p[0] & 0xC0) != 0x80 ) {

						/* Skip illegal sequences

						return SDL_ICONV_EILSEQ;

						*/

						ch = UNKNOWN_UNICODE;

						break;

					}

					ch <<= 6;

					ch |= (p[0] & 0x3F);

					++src;

					--srclen;

				}

				if ( overlong ) {

					/* Potential security risk

					return SDL_ICONV_EILSEQ;

					*/

					ch = UNKNOWN_UNICODE;

				}

				if ( (ch >= 0xD800 && ch <= 0xDFFF) ||

				     (ch == 0xFFFE || ch == 0xFFFF) ||

				     ch > 0x10FFFF ) {

					/* Skip illegal sequences

					return SDL_ICONV_EILSEQ;

					*/

					ch = UNKNOWN_UNICODE;

				}

			}

			break;

		    case ENCODING_UTF16BE: /* RFC 2781 */

			{

				Uint8 *p = (Uint8 *)src;

				Uint16 W1, W2;

				if ( srclen < 2 ) {

					return SDL_ICONV_EINVAL;

				}

				W1 = ((Uint16)p[0] << 8) |

				      (Uint16)p[1];

				src += 2;

				srclen -= 2;

				if ( W1 < 0xD800 || W1 > 0xDFFF ) {

					ch = (Uint32)W1;

					break;

				}

				if ( W1 > 0xDBFF ) {

					/* Skip illegal sequences

					return SDL_ICONV_EILSEQ;

					*/

					ch = UNKNOWN_UNICODE;

					break;

				}

				if ( srclen < 2 ) {

					return SDL_ICONV_EINVAL;

				}

				p = (Uint8 *)src;

				W2 = ((Uint16)p[0] << 8) |

				      (Uint16)p[1];

				src += 2;

				srclen -= 2;

				if ( W2 < 0xDC00 || W2 > 0xDFFF ) {

					/* Skip illegal sequences

					return SDL_ICONV_EILSEQ;

					*/

					ch = UNKNOWN_UNICODE;

					break;

				}

				ch = (((Uint32)(W1 & 0x3FF) << 10) |

				      (Uint32)(W2 & 0x3FF)) + 0x10000;

			}

			break;

		    case ENCODING_UTF16LE: /* RFC 2781 */

			{

				Uint8 *p = (Uint8 *)src;

				Uint16 W1, W2;

				if ( srclen < 2 ) {

					return SDL_ICONV_EINVAL;

				}

				W1 = ((Uint16)p[1] << 8) |

				      (Uint16)p[0];

				src += 2;

				srclen -= 2;

				if ( W1 < 0xD800 || W1 > 0xDFFF ) {

					ch = (Uint32)W1;

					break;

				}

				if ( W1 > 0xDBFF ) {

					/* Skip illegal sequences

					return SDL_ICONV_EILSEQ;

					*/

					ch = UNKNOWN_UNICODE;

					break;

				}

				if ( srclen < 2 ) {

					return SDL_ICONV_EINVAL;

				}

				p = (Uint8 *)src;

				W2 = ((Uint16)p[1] << 8) |

				      (Uint16)p[0];

				src += 2;

				srclen -= 2;

				if ( W2 < 0xDC00 || W2 > 0xDFFF ) {

					/* Skip illegal sequences

					return SDL_ICONV_EILSEQ;

					*/

					ch = UNKNOWN_UNICODE;

					break;

				}

				ch = (((Uint32)(W1 & 0x3FF) << 10) |

				      (Uint32)(W2 & 0x3FF)) + 0x10000;

			}

			break;

		    case ENCODING_UTF32BE:

			{

				Uint8 *p = (Uint8 *)src;

				if ( srclen < 4 ) {

					return SDL_ICONV_EINVAL;

				}

				ch = ((Uint32)p[0] << 24) |

				     ((Uint32)p[1] << 16) |

				     ((Uint32)p[2] << 8) |

				      (Uint32)p[3];