/*
 * Copyright (c) 2011 Alex Hornung <alex@alexhornung.com>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <inttypes.h>
#include <ctype.h>
#include <errno.h>

#include "humanize.h"

static const char prefixes[] = " KMGTPE";
int
_humanize_number(char *buf, size_t bufsz, uint64_t num)
{
        const char *prefixp;
        int ret;
        uint64_t i, d;

        prefixp = prefixes;
        i = num;
        d = 0;

        while ((i > 1024) && (*prefixp != '\0')) {
                d = (i % 1024)/10;
                i /= 1024;
                ++prefixp;
        }

        if (d > 0)
                ret = snprintf(buf, bufsz, "%"PRIu64".%"PRIu64" %c",
                    i, d, *prefixp);
        else
                ret = snprintf(buf, bufsz, "%"PRIu64" %c", i, *prefixp);


        if ((ret < 0) || ((size_t)ret >= bufsz)) {
                errno = ENOMEM;
                return -1;
        } else {
                return 0;
        }
}

int
_dehumanize_number(const char *buf, uint64_t *dest)
{
        char *endptr;
        uint64_t n, n_check, d;
        uint64_t multiplier;
        size_t len;

        if (*buf == '\0') {
                errno = EINVAL;
                return -1;
        }

        len = strlen(buf);
        if (tolower(buf[len-1]) == 'b')
                --len;

        multiplier = 1;

        switch (tolower(buf[len-1])) {
        case 'y':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 'z':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 'e':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 'p':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 't':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 'g':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 'm':
                multiplier *= 1024;
                /* FALLTHROUGH */
        case 'k':
                multiplier *= 1024;
                break;
        default:
                /*
                 * only set error if string ends in a character that
                 * is not a valid unit.
                 */
                if (isalpha(buf[len-1])) {
                        errno = EINVAL;
                        return -1;
                }
        }

        d = 0;
        n = n_check = strtoull(buf, &endptr, 10);
        if (endptr) {
                if ((*endptr != '.') && (*endptr != '\0') &&
                    (*endptr != ' ') && (endptr != &buf[len-1])) {
                        errno = EINVAL;
                        return -1;
                }

                if (*endptr == '.') {
                        d = strtoull(endptr+1, &endptr, 10);
                        if (endptr && (*endptr != '\0') &&
                            (*endptr != ' ') &&
                            (endptr != &buf[len-1])) {
                                errno = EINVAL;
                                return -1;
                        }
                }
        }

        if (d != 0) {
                while (d < 100)
                        d *= 10;

                while (d > 1000)
                        d /= 10;
        }

        d *= (multiplier/1024);
        n *= multiplier;

        if ((uint64_t)(n/multiplier) != n_check) {
                errno = ERANGE;
                return -1;
        }

        n += d;
        *dest = n;

        return 0;
}

#ifdef __TEST_HUMANIZE__

#include <assert.h>
int main(int argc, char *argv[])
{
        char buf[1024];
        uint64_t n, out;
        int err;

        if (argc < 3)
                return -1;

        n = strtoull(argv[1], NULL, 10);

        err = _humanize_number(buf, 1024, n);
        assert(err == 0);

        err = _dehumanize_number(buf, &out);
        assert(err == 0);

        printf("Converting: %"PRIu64" => %s => %"PRIu64"\n", n, buf, out);

        err = _dehumanize_number(argv[2], &out);
        assert (err == 0);

        printf("Converting: %s => %"PRIu64"\n", argv[2], out);

        return 0;
}

#endif