/*
 * Copyright (c) 2015 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @addtogroup libfdisk
 * @{
 */
/**
 * @file Disk management library.
 */

#include <errno.h>
#include <fdisk.h>
#include <imath.h>
#include <stdio.h>
#include <str.h>

/** Simplified capacity parameters */
enum {
	/** Simplified capacity maximum integer digits */
	scap_max_idig = 3,
	/** Simplified capacity maximum significant digits */
	scap_max_sdig = 4
};

static const char *cu_str[] = {
	[cu_byte] = "B",
	[cu_kbyte] = "kB",
	[cu_mbyte] = "MB",
	[cu_gbyte] = "GB",
	[cu_tbyte] = "TB",
	[cu_pbyte] = "PB",
	[cu_ebyte] = "EB",
	[cu_zbyte] = "ZB",
	[cu_ybyte] = "YB"
};

void fdisk_cap_from_blocks(uint64_t nblocks, size_t block_size,
    fdisk_cap_t *cap)
{
	uint64_t tsize;

	tsize = nblocks * block_size;
	cap->m = tsize;
	cap->dp = 0;
	cap->cunit = cu_byte;
}

/** Convert capacity to blocks.
 *
 * If the value of bytes is not integer, it is properly rounded. If the number
 * of bytes is not divisible by the number of blocks, it is rounded
 * up to an integer number of blocks.
 */
int fdisk_cap_to_blocks(fdisk_cap_t *cap, size_t block_size,
    uint64_t *blocks)
{
	int exp;
	uint64_t bytes;
	uint64_t f;
	int rc;

	// XXX Check for overflow

	exp = cap->cunit * 3 - cap->dp;
	if (exp < 0) {
		rc = ipow10_u64(-exp, &f);
		if (rc != EOK)
			return ERANGE;
		bytes = (cap->m + (f / 2)) / f;
	} else {
		rc = ipow10_u64(exp, &f);
		if (rc != EOK)
			return ERANGE;
		bytes = cap->m * f;
	}

	*blocks = (bytes + block_size - 1) / block_size;
	return EOK;
}

/** Simplify and round capacity to a human-friendly form.
 *
 * Change unit and round the number so that we have at most three integer
 * digits and at most two fractional digits, e.g abc.xy <unit>.
 */
void fdisk_cap_simplify(fdisk_cap_t *cap)
{
	uint64_t div;
	uint64_t maxv;
	unsigned sdig;
	unsigned rdig;
	int rc;

	printf("before: m=%" PRIu64 " dp=%u cunit=%d\n",
	    cap->m, cap->dp, cap->cunit);

	/* Change units so that we have at most @c scap_max_idig integer digits */
	rc = ipow10_u64(scap_max_idig, &maxv);
	assert(rc == EOK);

	rc = ipow10_u64(cap->dp, &div);
	assert(rc == EOK);

	while (cap->m / div >= maxv) {
		++cap->cunit;
		cap->dp += 3;
		div = div * 1000;
	}

	/* Round the number so that we have at most @c scap_max_sdig significant digits */
	sdig = 1 + ilog10_u64(cap->m); /* number of significant digits */
	if (sdig > scap_max_sdig) {
		/* Number of digits to remove */
		rdig = sdig - scap_max_sdig;
		if (rdig > cap->dp)
			rdig = cap->dp;

		rc = ipow10_u64(rdig, &div);
		assert(rc == EOK);

		cap->m = (cap->m + (div / 2)) / div;
		cap->dp -= rdig;
	}

	printf("after: m=%" PRIu64 " dp=%u cunit=%d\n",
	    cap->m, cap->dp, cap->cunit);
}

int fdisk_cap_format(fdisk_cap_t *cap, char **rstr)
{
	int rc;
	const char *sunit;
	uint64_t ipart;
	uint64_t fpart;
	uint64_t div;

	sunit = NULL;

	if (cap->cunit < 0 || cap->cunit >= CU_LIMIT)
		assert(false);

	rc = ipow10_u64(cap->dp, &div);
	if (rc != EOK)
		return rc;

	ipart = cap->m / div;
	fpart = cap->m % div;

	sunit = cu_str[cap->cunit];
	if (cap->dp > 0) {
		rc = asprintf(rstr, "%" PRIu64 ".%0*" PRIu64 " %s", ipart,
		    (int)cap->dp, fpart, sunit);
	} else {
		rc = asprintf(rstr, "%" PRIu64 " %s", ipart, sunit);
	}
	if (rc < 0)
		return ENOMEM;

	return EOK;
}

int fdisk_cap_parse(const char *str, fdisk_cap_t *cap)
{
	char *eptr;
	char *p;
	unsigned long val;
	int i;

	val = strtoul(str, &eptr, 10);

	while (*eptr == ' ')
		++eptr;

	if (*eptr == '\0') {
		cap->cunit = cu_byte;
	} else {
		for (i = 0; i < CU_LIMIT; i++) {
			if (str_lcasecmp(eptr, cu_str[i],
			    str_length(cu_str[i])) == 0) {
				p = eptr + str_size(cu_str[i]);
				while (*p == ' ')
					++p;
				if (*p == '\0')
					goto found;
			}
		}

		return EINVAL;
found:
		cap->cunit = i;
	}

	cap->m = val;
	cap->dp = 0;
	return EOK;
}

/** @}
 */