/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1996 by Sun Microsystems, Inc.
 */


#include <stdlib.h>
#include <errno.h>
#include <widec.h>
#include "common_def.h"
#include "common_han.h"
#include "utf_euc_api.h"
#include "common_defs.h"

#define ESC             0x1B
#define SO              0x0E
#define SI              0x0F

typedef struct __conv_desc {
        enum { NOT_DEFINED_YET, KSC5601 }       designator;
        enum { ASCII, HANGUL }                  state;
} _conv_desc;

/****  _ I C V _ O P E N  ****/

void* _icv_open()
{
        _conv_desc* cd = (_conv_desc*)malloc(sizeof(_conv_desc));

        if (cd == (_conv_desc*)NULL)
        {
                errno = ENOMEM;
                return((void*)-1);
        }

        cd->designator = NOT_DEFINED_YET;
        cd->state = ASCII;

        return((void*)cd);
}  /* end of int _icv_open(). */


/****  _ I C V _ C L O S E  ****/

void _icv_close(_conv_desc* cd)
{
        if (!cd)
                errno = EBADF;
        else
                free((void*)cd);
}  /* end of void _icv_close(_conv_desc*). */


/****  _ I C V _ I C O N V  ****/

size_t _icv_iconv(_conv_desc* cd, char** inbuf, size_t* inbufleft,
                        char** outbuf, size_t* outbufleft)
{
        size_t          ret_val = 0;
        unsigned char*  ib;
        unsigned char*  ob;
        unsigned char*  ibtail;
        unsigned char*  obtail;

        if (!cd)
        {
                errno = EBADF;
                return((size_t)-1);
        }

        if (!inbuf || !(*inbuf))
        {
                if (cd->state == HANGUL)
                {
                        if (outbufleft && *outbufleft >= 1 && outbuf && *outbuf)
                        {
                                **outbuf = SI;
                                (*outbuf)++;
                                (*outbufleft)--;
                        }
                        else
                        {
                                errno = E2BIG;
                                return((size_t)-1);
                        }
                }

                cd->designator = NOT_DEFINED_YET;
                cd->state = ASCII;
                return((size_t)0);
        }

        ib = (unsigned char*)*inbuf;
        ob = (unsigned char*)*outbuf;
        ibtail = ib + *inbufleft;
        obtail = ob + *outbufleft;

        while (ib < ibtail)
        {
                if (!(*ib & 0x80))              /* 7 bits */
                {
                        if (ob >= obtail)
                        {
                                errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }

                        /* Hangul string ends */
                        if (cd->state == HANGUL) {
                                *ob++ = SI;
                                cd->state = ASCII;
                        }
                        *ob++ = *ib++;
                }
                else if ((*ib & 0xF0) == 0xE0)  /* 16 bits */
                {
                        hcode_type utf8_code, euc_code;

                        if ((ibtail - ib) < 3)
                        {
                                errno = EINVAL;
                                ret_val = (size_t)-1;
                                break;
                        }

                        if (!is_valid_utf8_string(ib, 3))
                        {
                                errno = EILSEQ;
                                ret_val = (size_t)-1;
                                break;
                        }

                        utf8_code.byte.byte1 = 0;
                        utf8_code.byte.byte2 = *ib;
                        utf8_code.byte.byte3 = *(ib + 1);
                        utf8_code.byte.byte4 = *(ib + 2);

                        euc_code = _utf8_to_wansung(utf8_code);

                        if (euc_code.code != 0) {
                                /* If find something -> EUC code */

                                /* if the first time of Hangul -> put Mark */
                                if (cd->designator ==  NOT_DEFINED_YET) {
                                        *ob++ = ESC;
                                        *ob++ = '$';
                                        *ob++ = ')';
                                        *ob++ = 'C';
                                        cd->designator = KSC5601;
                                }

                                /* if the first Hangul in a string */
                                if (cd->state == ASCII) {
                                        *ob++ = SO;
                                        cd->state = HANGUL;
                                }

                                /* MSB clear for 7-bits encoding */
                                euc_code.wansung.msb1 = 0;
                                euc_code.wansung.msb2 = 0;

                                *ob++ = euc_code.byte.byte3;
                                *ob++ = euc_code.byte.byte4;
                        }
                        else
                        {
                                /* Let's assume the code is non-identical. */
                                if ((obtail - ob) < 2)
                                {
                                        errno = E2BIG;
                                        ret_val = (size_t)-1;
                                        break;
                                }

                                /* non identical character == ASCII */
                                if (cd->state == HANGUL) {
                                        *ob++ = SI;
                                        cd->state = ASCII;
                                }
                                *ob++ = NON_IDENTICAL;
                                *ob++ = NON_IDENTICAL;
                                ret_val += 2;
                        }
                        ib += 3;
                }
                else  /* 11, 21, 26 & 31 bits codes won't be able to convert. */
                {
                        short int offset;

                        if ((*ib & 0xE0) == 0xC0)  /* 11 */
                                offset = 2;
                        else if ((*ib & 0xF0) == 0xE0)  /* 16 */
                                offset = 3;
                        else if ((*ib & 0xF8) == 0xF0)  /* 21 */
                                offset = 4;
                        else if ((*ib & 0xFC) == 0xF8)  /* 26 */
                                offset = 5;
                        else if ((*ib & 0xFE) == 0xFC)  /* 31 */
                                offset = 6;
                        else  /* Illegal sequence. */
                                offset = 1;

                        if ((ibtail - ib) < offset)
                        {
                                errno = EINVAL;
                                ret_val = (size_t)-1;
                                break;
                        }

                        if (!is_valid_utf8_string(ib, offset))
                        {
                                errno = EILSEQ;
                                ret_val = (size_t)-1;
                                break;
                        }

                        ib += offset;

                        /* Let's assume the code is non-identical. */
                        offset = (offset > 2) ? 2 : 1;
                        if ((obtail - ob) < offset)
                        {
                                errno = E2BIG;
                                ret_val = (size_t)-1;
                                break;
                        }

                        /* non identical character == ASCII */
                        if (cd->state == HANGUL) {
                                *ob++ = SI;
                                cd->state = ASCII;
                        }

                        *ob++ = NON_IDENTICAL;
                        if (offset > 1)
                                *ob++ = NON_IDENTICAL;
                        ret_val += offset;
                }
        }

        *inbuf = (char*)ib;
        *inbufleft = ibtail - ib;
        *outbuf = (char*)ob;
        *outbufleft = obtail - ob;

        return(ret_val);
}  /* end of size_t _icv_iconv(int*, char**, size_t*, char**, size_t*).*/