/**
  * Copyright (c) 2009-2010 Mika Laitio <lamikr@pilppa.org>
  *
  * This file and library is covered by the LGPL version 3, read LICENSE for details.
  *
  * History:
  * - Created charencoding_internal.c on: Nov 25, 2009
  */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <locale.h>
#include <langinfo.h>
#include <stdarg.h>
#include <errno.h>
#include <iconv.h>
#include <limits.h>
#include <iconv.h>
#include <time.h>
#include <ctype.h>

#define SIZE_CALCULATION_TEMP_BUFFER_SIZE	8

static bool _locale_charset_initialized			= false;

const char *get_locale_charset_alias()
{
	if (_locale_charset_initialized == false) {
		setlocale(LC_ALL, "");
		_locale_charset_initialized = true;
	}
	return nl_langinfo(CODESET);
}

size_t calculate_target_charset_bytecount(iconv_t conversion_desc,
					const char *src,
					size_t bcount_src)
{
	size_t		ret_val;
	size_t 		err_flg;
	size_t		bcount_trgt;
	const char	*p_src;
	char		*p_trgt;
	char 		tmp_buf[SIZE_CALCULATION_TEMP_BUFFER_SIZE];

	ret_val		= 0;
	err_flg		= 0;
	// reset conversion descriptor to initial state
	iconv(conversion_desc,
		NULL,
		NULL,
		NULL,
		NULL);
	p_src	= src;
	while (bcount_src > 0) {
		p_trgt		= tmp_buf;
		bcount_trgt	= SIZE_CALCULATION_TEMP_BUFFER_SIZE;
		err_flg		= iconv(conversion_desc,
					(char **)&p_src,
					&bcount_src,
					&p_trgt,
					&bcount_trgt);
		if (err_flg == (size_t)(-1)) {
			if (errno == E2BIG) {
				// too small tmp_buf error can be skipped
				err_flg	= 0;
			}
			else {
				err_flg	= -1;
				break;
			}
		}
		ret_val	= ret_val + SIZE_CALCULATION_TEMP_BUFFER_SIZE - bcount_trgt;
	}
	if (err_flg != 0) {
		ret_val	=-1;
	}
	printf("size: %d\n", ret_val);
	return ret_val;
}

char *str_iconv_encode(iconv_t conversion_desc,
		const char *src,
		size_t bcount_src,
		size_t *p_bcount,
		int *err_flg)
{
	char		*ret_val;
	char		*p_ret_val;
	const char	*p_src;
	size_t		bcount_src_left;
	size_t		bcount_trgt_left;
	size_t 		ic_ret_val;

	ret_val		= NULL;
	*err_flg	= 0;
	*p_bcount	= calculate_target_charset_bytecount(conversion_desc,
						src,
						bcount_src);
	if (*p_bcount >= 0) {
		ret_val	= (char *)calloc(1, *p_bcount + 1);
		if (ret_val != NULL) {
			// reset conversion descriptor to initial state
			iconv(conversion_desc,
				NULL,
				NULL,
				NULL,
				NULL);
			p_src			= src;
			bcount_src_left		= bcount_src;
			p_ret_val		= ret_val;
			bcount_trgt_left	= *p_bcount;
			while (bcount_src_left > 0) {
				errno		= 0;
				ic_ret_val	= iconv(conversion_desc,
							(char **)&p_src,
							&bcount_src_left,
							&p_ret_val,
							&bcount_trgt_left);
				if (ic_ret_val == (size_t)(-1)) {
					free(ret_val);
					ret_val		= NULL;
					*err_flg	= -1;
					break;
				}
			}
		}
		else {
			*err_flg	= -1;
		}
	}
	else {
		// could not calculate the byte count
		*err_flg	= -1;
	}
	if (*err_flg != 0) {
		*p_bcount	= -1;
	}
	return ret_val;
}