/*
** folder_realloc.c -- realloc a folder/msgs structure
**
** This code is Copyright (c) 2002, by the authors of nmh.  See the
** COPYRIGHT file in the root directory of the nmh distribution for
** complete copyright information.
*/

#include <sysexits.h>
#include <h/mh.h>
#include <h/utils.h>

/*
** Reallocate some of the space in the folder
** structure (currently just message status array).
**
** Return pointer to new folder structure.
** If error, return NULL.
*/

struct msgs *
folder_realloc(struct msgs *mp, int lo, int hi)
{
	int msgnum;

	/* sanity checks */
	if (lo < 1)
		adios(EX_SOFTWARE, NULL, "BUG: called folder_realloc with lo (%d) < 1", lo);
	if (hi < 1)
		adios(EX_SOFTWARE, NULL, "BUG: called folder_realloc with hi (%d) < 1", hi);
	if (mp->nummsg > 0 && lo > mp->lowmsg)
		adios(EX_SOFTWARE, NULL, "BUG: called folder_realloc with lo (%d) > mp->lowmsg (%d)",
				lo, mp->lowmsg);
	if (mp->nummsg > 0 && hi < mp->hghmsg)
		adios(EX_SOFTWARE, NULL, "BUG: called folder_realloc with hi (%d) < mp->hghmsg (%d)",
				hi, mp->hghmsg);

	/* Check if we really need to reallocate anything */
	if (lo == mp->lowoff && hi == mp->hghoff)
		return mp;

	if (lo == mp->lowoff) {
		/*
		** We are just extending (or shrinking) the end of message
		** status array.  So we don't have to move anything and can
		** just realloc the message status array.
		*/
		mp->msgstats = mh_xrealloc(mp->msgstats, MSGSTATSIZE(mp, lo, hi));
	} else {
		/*
		** We are changing the offset of the message status
		** array.  So we will need to shift everything.
		*/
		seqset_t *tmpstats;

		/* first allocate the new message status space */
		tmpstats = mh_xcalloc(MSGSTATSIZE(mp, lo, hi), 1);

		/* then copy messages status array with shift */
		if (mp->nummsg > 0) {
			for (msgnum=mp->lowmsg; msgnum<=mp->hghmsg; msgnum++) {
				tmpstats[msgnum - lo] = mp->msgstats[msgnum - mp->lowoff];
			}
		}
		mh_free0(&(mp->msgstats));
		mp->msgstats = tmpstats;
	}

	mp->lowoff = lo;
	mp->hghoff = hi;

	/*
	** Clear all the flags for entries outside
	** the current message range for this folder.
	*/
	if (mp->nummsg > 0) {
		for (msgnum = mp->lowoff; msgnum < mp->lowmsg; msgnum++)
			clear_msg_flags(mp, msgnum);
		for (msgnum = mp->hghmsg + 1; msgnum <= mp->hghoff; msgnum++)
			clear_msg_flags(mp, msgnum);
	} else {
		/* no messages, so clear entire range */
		for (msgnum = mp->lowoff; msgnum <= mp->hghoff; msgnum++)
			clear_msg_flags(mp, msgnum);
	}

	return mp;
}
