/*
 *  Copyright (C) 2005 Kouji TAKAO <kouji@netlab.jp>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <glib/gi18n.h>

#include "gpass/pack.h"

void
gpass_pack_number(gint number, GString **buffer)
{
    if (number == 0) {
        *buffer = g_string_append_c(*buffer, 0);
        return;
    }
    
    number = GINT_TO_LE(number);
    while (number > 0) {
        div_t d;
        guchar c;
        
        d = div(number, 0x80);
        number = d.quot;
        c = (guchar) d.rem;
        if (number > 0) {
            c |= 0x80;
        }
        *buffer = g_string_append_c(*buffer, c);
    }
}

GError *
gpass_unpack_number(const guchar *buffer, gint len, gint *result,
                    gint *read_len)
{
    gint val = 0, base = 1, i = 0;
    const guchar *ptr = buffer, *ptr_end = buffer + len;
    GError *error = NULL;

    while (ptr < ptr_end && i <= 5) {
        if (*ptr & 0x80) {
            val += base * (*ptr & 0x7f);
            base *= 0x80;
            ptr++;
        }
        else {
            val += base * (*ptr);
            *result = GINT_FROM_LE(val);
            *read_len = (ptr + 1) - buffer;
            return NULL;
        }
        i++;
    }
    if (i <= 5) {
        g_set_error(&error, 0, 0, _("buffer is too short"));
    }
    else {
        g_set_error(&error, 0, 0, _("invalid buffer"));
    }
    return error;
}

void
gpass_pack_string(const gchar *str, GString **buffer)
{
    if (str == NULL || *str == '\0') {
        gpass_pack_number(0, buffer);
    }
    else {
        gint len;
        
        len = strlen(str);
        gpass_pack_number(len, buffer);
        *buffer = g_string_append_len(*buffer, str, len);
    }
}

GError *
gpass_unpack_string(const guchar *buffer, gint len,
                    GString **str, gint *read_len)
{
    gint str_len;
    GError *error;

    error = gpass_unpack_number(buffer, len, &str_len, read_len);
    if (error != NULL) {
        return error;
    }
    if (str_len == 0) {
        return NULL;
    }
    if (str_len > (len - *read_len)) {
        g_set_error(&error, 0, 0, _("buffer is too short"));
        return error;
    }
    *str = g_string_append_len(*str, buffer + *read_len, str_len);
    (*read_len) += str_len;
    return NULL;
}