/*

 *  LibXDiff by Davide Libenzi ( File Differential Library )

 *  Copyright (C) 2003	Davide Libenzi

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Lesser General Public

 *  License as published by the Free Software Foundation; either

 *  version 2.1 of the License, or (at your option) any later version.

 *

 *  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 library; if not, see

 *  <http://www.gnu.org/licenses/>.

 *

 *  Davide Libenzi <davidel@xmailserver.org>

 *

 */

#include <limits.h>

#include <assert.h>

#include "xinclude.h"

long xdl_bogosqrt(long n) {

	long i;

	/*

	 * Classical integer square root approximation using shifts.

	 */

	for (i = 1; n > 0; n >>= 2)

		i <<= 1;

	return i;

}

int xdl_emit_diffrec(char const *rec, long size, char const *pre, long psize,

		     xdemitcb_t *ecb) {

	int i = 2;

	mmbuffer_t mb[3];

	mb[0].ptr = (char *) pre;

	mb[0].size = psize;

	mb[1].ptr = (char *) rec;

	mb[1].size = size;

	if (size > 0 && rec[size - 1] != '\n') {

		mb[2].ptr = (char *) "\n\\ No newline at end of file\n";

		mb[2].size = strlen(mb[2].ptr);

		i++;

	}

	if (ecb->outf(ecb->priv, mb, i) < 0) {

		return -1;

	}

	return 0;

}

void *xdl_mmfile_first(mmfile_t *mmf, long *size)

{

	*size = mmf->size;

	return mmf->ptr;

}

long xdl_mmfile_size(mmfile_t *mmf)

{

	return mmf->size;

}

int xdl_cha_init(chastore_t *cha, long isize, long icount) {

	cha->head = cha->tail = NULL;

	cha->isize = isize;

	cha->nsize = icount * isize;

	cha->ancur = cha->sncur = NULL;

	cha->scurr = 0;

	return 0;

}

void xdl_cha_free(chastore_t *cha) {

	chanode_t *cur, *tmp;

	for (cur = cha->head; (tmp = cur) != NULL;) {

		cur = cur->next;

		xdl_free(tmp);

	}

}

void *xdl_cha_alloc(chastore_t *cha) {

	chanode_t *ancur;

	void *data;

	if (!(ancur = cha->ancur) || ancur->icurr == cha->nsize) {

		if (!(ancur = (chanode_t *) xdl_malloc(sizeof(chanode_t) + cha->nsize))) {

			return NULL;

		}

		ancur->icurr = 0;

		ancur->next = NULL;

		if (cha->tail)

			cha->tail->next = ancur;

		if (!cha->head)

			cha->head = ancur;

		cha->tail = ancur;

		cha->ancur = ancur;

	}

	data = (char *) ancur + sizeof(chanode_t) + ancur->icurr;

	ancur->icurr += cha->isize;

	return data;

}

long xdl_guess_lines(mmfile_t *mf, long sample) {

	long nl = 0, size, tsize = 0;

	char const *data, *cur, *top;

	if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {

		for (top = data + size; nl < sample && cur < top; ) {

			nl++;

			if (!(cur = memchr(cur, '\n', top - cur)))

				cur = top;

			else

				cur++;

		}

		tsize += (long) (cur - data);

	}

	if (nl && tsize)

		nl = xdl_mmfile_size(mf) / (tsize / nl);

	return nl + 1;

}

int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)

{

	if (s1 == s2 && !memcmp(l1, l2, s1))

		return 1;

}

unsigned long xdl_hash_record(char const **data, char const *top, long flags) {

	unsigned long ha = 5381;

	char const *ptr = *data;

	for (; ptr < top && *ptr != '\n'; ptr++) {

		ha += (ha << 5);

		ha ^= (unsigned long) *ptr;

	}

	*data = ptr < top ? ptr + 1: ptr;

	return ha;

}

unsigned int xdl_hashbits(unsigned int size) {

	unsigned int val = 1, bits = 0;

	for (; val < size && bits < CHAR_BIT * sizeof(unsigned int); val <<= 1, bits++);

	return bits ? bits: 1;

}

int xdl_num_out(char *out, long val) {

	char *ptr, *str = out;

	char buf[32];

	ptr = buf + sizeof(buf) - 1;

	*ptr = '\0';

	if (val < 0) {

		*--ptr = '-';

		val = -val;

	}

	for (; val && ptr > buf; val /= 10)

		*--ptr = "0123456789"[val % 10];

	if (*ptr)

		for (; *ptr; ptr++, str++)

			*str = *ptr;

	else

		*str++ = '0';

	*str = '\0';

	return str - out;

}

int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,

		      const char *func, long funclen, xdemitcb_t *ecb) {

	int nb = 0;

	mmbuffer_t mb;

	char buf[128];

	memcpy(buf, "@@ -", 4);

	nb += 4;

	nb += xdl_num_out(buf + nb, c1 ? s1: s1 - 1);

	if (c1 != 1) {

		memcpy(buf + nb, ",", 1);

		nb += 1;

		nb += xdl_num_out(buf + nb, c1);

	}

	memcpy(buf + nb, " +", 2);

	nb += 2;

	nb += xdl_num_out(buf + nb, c2 ? s2: s2 - 1);

	if (c2 != 1) {

		memcpy(buf + nb, ",", 1);

		nb += 1;

		nb += xdl_num_out(buf + nb, c2);

	}

	memcpy(buf + nb, " @@", 3);

	nb += 3;

	if (func && funclen) {

		buf[nb++] = ' ';

		if (funclen > sizeof(buf) - nb - 1)

			funclen = sizeof(buf) - nb - 1;

		memcpy(buf + nb, func, funclen);

		nb += funclen;

	}

	buf[nb++] = '\n';

	mb.ptr = buf;

	mb.size = nb;

	if (ecb->outf(ecb->priv, &mb, 1) < 0)

		return -1;

	return 0;

}

int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,

		int line1, int count1, int line2, int count2)

{

	/*

	 * This probably does not work outside Git, since

	 * we have a very simple mmfile structure.

	 *

	 * Note: ideally, we would reuse the prepared environment, but

	 * the libxdiff interface does not (yet) allow for diffing only

	 * ranges of lines instead of the whole files.

	 */

	mmfile_t subfile1, subfile2;

	xdfenv_t env;

	subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;

	subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +

		diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;

	subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;

	subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +

		diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;

	if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)

		return -1;

	memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);

	memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);

	xdl_free_env(&env);

	return 0;

}