/*
  LibRCC - interface to iconv library

  Copyright (C) 2005-2018 Suren A. Chilingaryan <csa@suren.me>

  This library is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License version 2.1 or later
  as published by the Free Software Foundation.

  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 program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <iconv.h>

#include <string.h>
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */

#include "internal.h"
#include "rcciconv.h"

#define RCC_MAX_ERRORS 3

static void rccIConvCopySymbol(char **in_buf, size_t *in_left, char **out_buf, size_t *out_left) {
    if ((out_left>0)&&(in_left>0)) {
/*	(**out_buf)=(**in_buf);
	(*out_buf)++;
	(*out_left)--;*/
	(*in_buf)++;
	(*in_left)--;
    }
}

static int rccIConvUTFBytes(unsigned char c) {
    int j;
    if (c<128) return 1;

    for (j=6;j>=0;j--)
	if ((c&(1<<j))==0) break;
	    
    if ((j==0)||(j==6)) return 1;
    return 6-j;
}


rcc_iconv rccIConvOpen(const char *to, const char *from) {
    rcc_iconv icnv;
    
    if ((!from)||(!to)||(!strcasecmp(from,to))) return NULL;
    
    icnv = (rcc_iconv)malloc(sizeof(rcc_iconv_s));
    if (!icnv) return icnv;
    
    icnv->icnv = iconv_open(to, from);
    return icnv;
}

void rccIConvClose(rcc_iconv icnv) {
    if (icnv) {
	if (icnv->icnv != (iconv_t)-1) iconv_close(icnv->icnv);
	free(icnv);
    }
}

int rccIConvGetError(rcc_iconv icnv) {
    if ((!icnv)||(icnv->icnv == (iconv_t)-1)) return -1;
    return 0;
}

size_t rccIConvRecode(rcc_iconv icnv, char *outbuf, size_t outsize, const char *buf, size_t size) {
    char *in_buf, *out_buf, err;
    size_t in_left, out_left;
    int ub, utf_mode=0;
    int errors=0;
    
    if ((!buf)||(!outbuf)||(!outsize)||(!icnv)||(icnv->icnv == (iconv_t)-1)) return (size_t)-1;
    if (iconv(icnv->icnv, NULL, NULL, NULL, NULL) == -1) return (size_t)-1;

    if (!size) size = strlen(buf);
        
loop_restart:
    errors = 0;
    in_buf = (char*)buf; /*DS*/
    in_left = size;
    out_buf = outbuf;
    out_left = outsize;

loop:
    err=iconv(icnv->icnv, (char**)&in_buf, &in_left, &out_buf, &out_left);
    if (err<0) {
        if (errno==E2BIG) {
    	    *(int*)(outbuf+(RCC_MAX_STRING_CHARS-sizeof(int)))=0;
	} else if (errno==EILSEQ) {
	    if (errors++<RCC_MAX_ERRORS) {
		for (ub=utf_mode?rccIConvUTFBytes(*in_buf):1;ub>0;ub--)
		    rccIConvCopySymbol(&in_buf, &in_left, &out_buf, &out_left);
		if (in_left>0) goto loop;
	    } else if (!utf_mode) {
		utf_mode = 1;
		goto loop_restart;
	    } else {
	        return (size_t)-1;
	    }
	} else {
	    return (size_t)-1;
	}
    }
    
    outbuf[outsize - out_left] = 0;

    return outsize - out_left;
}

char *rccIConv(rcc_iconv icnv, const char *buf, size_t len, size_t *rlen) {
    char *res;
    size_t size;
    char tmpbuffer[RCC_MAX_STRING_CHARS+1];

    size = rccIConvRecode(icnv, tmpbuffer, RCC_MAX_STRING_CHARS, buf, len);
    if (size != (size_t)-1) {
	res = (char*)malloc((size+1)*sizeof(char));
	if (!res) return res;
	
	if (rlen) *rlen = size;
	memcpy(res, tmpbuffer, size);
	res[size] = 0;

	return res;
    }

    return NULL;
}

size_t rccIConvInternal(rcc_context ctx, rcc_iconv icnv, const char *buf, size_t len) {
    if (!ctx) return (size_t)-1;
    return rccIConvRecode(icnv, ctx->tmpbuffer, RCC_MAX_STRING_CHARS, buf, len);
}