/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Main functions of the program.
 *
 * Copyright (C) 2007-2008 David Härdeman <david@hardeman.nu>
 * Copyright (C) 2012-2016 Przemyslaw Pawelczyk <przemoc@gmail.com>
 * Copyright (C) 2014-2015 Dan Fandrich <dan@coneharvesters.com>
 *
 * 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; only version 2 of the License is applicable.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#define _BSD_SOURCE
#define _DEFAULT_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <getopt.h>
#include <utime.h>
#include <sys/xattr.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include "metastore.h"
#include "settings.h"
#include "utils.h"
#include "metaentry.h"

/* metastore settings */
static struct metasettings settings = {
	.metafile = METAFILE,
	.do_mtime = false,
	.do_emptydirs = false,
	.do_removeemptydirs = false,
	.do_git = false,
};

/* Used to create lists of dirs / other files which are missing in the fs */
static struct metaentry *missingdirs = NULL;
static struct metaentry *missingothers = NULL;

/* Used to create lists of dirs / other files which are missing in metadata */
static struct metaentry *extradirs = NULL;

/*
 * Inserts an entry in a linked list ordered by pathlen
 */
static void
insert_entry_plist(struct metaentry **list, struct metaentry *entry)
{
	struct metaentry **parent;

	for (parent = list; *parent; parent = &((*parent)->list)) {
		if ((*parent)->pathlen > entry->pathlen)
			break;
	}

	entry->list = *parent;
	*parent = entry;
}

/*
 * Inserts an entry in a linked list ordered by pathlen descendingly
 */
static void
insert_entry_pdlist(struct metaentry **list, struct metaentry *entry)
{
	struct metaentry **parent;

	for (parent = list; *parent; parent = &((*parent)->list)) {
		if ((*parent)->pathlen < entry->pathlen)
			break;
	}

	entry->list = *parent;
	*parent = entry;
}

/*
 * Prints differences between real and stored actual metadata
 * - for use in mentries_compare
 */
static void
compare_print(struct metaentry *real, struct metaentry *stored, int cmp)
{
	if (!real && (!stored || (cmp == DIFF_NONE || cmp & DIFF_ADDED))) {
		msg(MSG_ERROR, "%s called with incorrect arguments\n", __func__);
		return;
	}

	if (cmp == DIFF_NONE) {
		msg(MSG_DEBUG, "%s:\tno difference\n", real->path);
		return;
	}

	msg(MSG_QUIET, "%s:\t", real ? real->path : stored->path);

	if (cmp & DIFF_ADDED)
		msg(MSG_QUIET, "added ", real->path);
	if (cmp & DIFF_DELE)
		msg(MSG_QUIET, "removed ", stored->path);
	if (cmp & DIFF_OWNER)
		msg(MSG_QUIET, "owner ");
	if (cmp & DIFF_GROUP)
		msg(MSG_QUIET, "group ");
	if (cmp & DIFF_MODE)
		msg(MSG_QUIET, "mode ");
	if (cmp & DIFF_TYPE)
		msg(MSG_QUIET, "type ");
	if (cmp & DIFF_MTIME)
		msg(MSG_QUIET, "mtime ");
	if (cmp & DIFF_XATTR)
		msg(MSG_QUIET, "xattr ");
	msg(MSG_QUIET, "\n");
}

/*
 * Tries to change the real metadata to match the stored one
 * - for use in mentries_compare
 */
static void
compare_fix(struct metaentry *real, struct metaentry *stored, int cmp)
{
	struct group *group;
	struct passwd *owner;
	gid_t gid = -1;
	uid_t uid = -1;
	struct utimbuf tbuf;
	unsigned i;

	if (!real && !stored) {
		msg(MSG_ERROR, "%s called with incorrect arguments\n", __func__);
		return;
	}

	if (!real) {
		if (S_ISDIR(stored->mode))
			insert_entry_plist(&missingdirs, stored);
		else
			insert_entry_plist(&missingothers, stored);

		msg(MSG_NORMAL, "%s:\tremoved\n", stored->path);
		return;
	}

	if (!stored) {
		if (S_ISDIR(real->mode))
			insert_entry_pdlist(&extradirs, real);
		msg(MSG_NORMAL, "%s:\tadded\n", real->path);
		return;
	}

	if (cmp == DIFF_NONE) {
		msg(MSG_DEBUG, "%s:\tno difference\n", real->path);
		return;
	}

	if (cmp & DIFF_TYPE) {
		msg(MSG_NORMAL, "%s:\tnew type, will not change metadata\n",
		    real->path);
		return;
	}

	msg(MSG_QUIET, "%s:\tchanging metadata\n", real->path);

	while (cmp & (DIFF_OWNER | DIFF_GROUP)) {
		if (cmp & DIFF_OWNER) {
			msg(MSG_NORMAL, "%s:\tchanging owner from %s to %s\n",
			    real->path, real->group, stored->group);
			owner = xgetpwnam(stored->owner);
			if (!owner) {
				msg(MSG_DEBUG, "\tgetpwnam failed: %s\n",
				    strerror(errno));
				break;
			}
			uid = owner->pw_uid;
		}

		if (cmp & DIFF_GROUP) {
			msg(MSG_NORMAL, "%s:\tchanging group from %s to %s\n",
			    real->path, real->group, stored->group);
			group = xgetgrnam(stored->group);
			if (!group) {
				msg(MSG_DEBUG, "\tgetgrnam failed: %s\n",
				    strerror(errno));
				break;
			}
			gid = group->gr_gid;
		}

		if (lchown(real->path, uid, gid)) {
			msg(MSG_DEBUG, "\tlchown failed: %s\n",
			    strerror(errno));
			break;
		}
		break;
	}

	if (cmp & DIFF_MODE) {
		msg(MSG_NORMAL, "%s:\tchanging mode from 0%o to 0%o\n",
		    real->path, real->mode & 07777, stored->mode & 07777);
		if (chmod(real->path, stored->mode & 07777))
			msg(MSG_DEBUG, "\tchmod failed: %s\n", strerror(errno));
	}

	/* FIXME: Use utimensat here, or even better - lutimensat */
	if ((cmp & DIFF_MTIME) && S_ISLNK(real->mode)) {
		msg(MSG_NORMAL, "%s:\tsymlink, not changing mtime\n", real->path);
	} else if (cmp & DIFF_MTIME) {
		msg(MSG_NORMAL, "%s:\tchanging mtime from %ld to %ld\n",
		    real->path, real->mtime, stored->mtime);
		tbuf.actime = stored->mtime;
		tbuf.modtime = stored->mtime;
		if (utime(real->path, &tbuf)) {
			msg(MSG_DEBUG, "\tutime failed: %s\n", strerror(errno));
			return;
		}
	}

	if (cmp & DIFF_XATTR) {
		for (i = 0; i < real->xattrs; i++) {
			/* Any attrs to remove? */
			if (mentry_find_xattr(stored, real, i) >= 0)
				continue;

			msg(MSG_NORMAL, "%s:\tremoving xattr %s\n",
			    real->path, real->xattr_names[i]);
			if (lremovexattr(real->path, real->xattr_names[i]))
				msg(MSG_DEBUG, "\tlremovexattr failed: %s\n",
				    strerror(errno));
		}

		for (i = 0; i < stored->xattrs; i++) {
			/* Any xattrs to add? (on change they are removed above) */
			if (mentry_find_xattr(real, stored, i) >= 0)
				continue;

			msg(MSG_NORMAL, "%s:\tadding xattr %s\n",
			    stored->path, stored->xattr_names[i]);
			if (lsetxattr(stored->path, stored->xattr_names[i],
			              stored->xattr_values[i],
			              stored->xattr_lvalues[i], XATTR_CREATE)
			   )
				msg(MSG_DEBUG, "\tlsetxattr failed: %s\n",
				    strerror(errno));
		}
	}
}

/*
 * Tries to fix any empty dirs which are missing from the filesystem by
 * recreating them.
 */
static void
fixup_emptydirs(void)
{
	struct metaentry *entry;
	struct metaentry *cur;
	struct metaentry **parent;
	char *bpath;
	char *delim;
	size_t blen;
	struct metaentry *new;

	if (!missingdirs)
		return;
	msg(MSG_DEBUG, "\nAttempting to recreate missing dirs\n");

	/* If directory x/y is missing, but file x/y/z is also missing,
	 * we should prune directory x/y from the list of directories to
	 * recreate since the deletition of x/y is likely to be genuine
	 * (as opposed to empty dir pruning like git/cvs does).
	 *
	 * Also, if file x/y/z is missing, any child directories of
	 * x/y should be pruned as they are probably also intentionally
	 * removed.
	 */

	msg(MSG_DEBUG, "List of candidate dirs:\n");
	for (cur = missingdirs; cur; cur = cur->list)
		msg(MSG_DEBUG, " %s\n", cur->path);

	for (entry = missingothers; entry; entry = entry->list) {
		msg(MSG_DEBUG, "Pruning using file %s\n", entry->path);
		bpath = xstrdup(entry->path);
		delim = strrchr(bpath, '/');
		if (!delim) {
			msg(MSG_NORMAL, "No delimiter found in %s\n", bpath);
			free(bpath);
			continue;
		}
		*delim = '\0';

		parent = &missingdirs;
		for (cur = *parent; cur; cur = cur->list) {
			if (strcmp(cur->path, bpath)) {
				parent = &cur->list;
				continue;
			}

			msg(MSG_DEBUG, "Prune phase 1 - %s\n", cur->path);
			*parent = cur->list;
		}

		/* Now also prune subdirs of the base dir */
		*delim++ = '/';
		*delim = '\0';
		blen = strlen(bpath);

		parent = &missingdirs;
		for (cur = *parent; cur; cur = cur->list) {
			if (strncmp(cur->path, bpath, blen)) {
				parent = &cur->list;
				continue;
			}

			msg(MSG_DEBUG, "Prune phase 2 - %s\n", cur->path);
			*parent = cur->list;
		}

		free(bpath);
	}
	msg(MSG_DEBUG, "\n");

	for (cur = missingdirs; cur; cur = cur->list) {
		msg(MSG_QUIET, "%s:\trecreating...", cur->path);
		if (mkdir(cur->path, cur->mode)) {
			msg(MSG_QUIET, "failed (%s)\n", strerror(errno));
			continue;
		}
		msg(MSG_QUIET, "ok\n");

		new = mentry_create(cur->path);
		if (!new) {
			msg(MSG_QUIET, "Failed to get metadata for %s\n");
			continue;
		}

		compare_fix(new, cur, mentry_compare(new, cur, &settings));
	}
}

/*
 * Deletes any empty dirs present in the filesystem that are missing
 * from the metadata.
 * An "empty" dir is one which either:
 *  - is empty; or
 *  - only contains empty dirs
 */
static void
fixup_newemptydirs(void)
{
	struct metaentry **cur;
	int removed_dirs = 1;

	if (!extradirs)
		return;

	/* This is a simpleminded algorithm that attempts to rmdir() all
	 * directories discovered missing from the metadata. Naturally, this will
	 * succeed only on the truly empty directories, but depending on the order,
	 * it may mean that parent directory removal are attempted to be removed
	 * *before* the children. To circumvent this, keep looping around all the
	 * directories until none have been successfully removed.  This is a
	 * O(N**2) algorithm, so don't try to remove too many nested directories
	 * at once (e.g. thousands).
	 *
	 * Note that this will succeed only if each parent directory is writable.
	 */
	while (removed_dirs) {
		removed_dirs = 0;
		msg(MSG_DEBUG, "\nAttempting to delete empty dirs\n");
		for (cur = &extradirs; *cur;) {
			msg(MSG_QUIET, "%s:\tremoving...", (*cur)->path);
			if (rmdir((*cur)->path)) {
				msg(MSG_QUIET, "failed (%s)\n", strerror(errno));
				cur = &(*cur)->list;
				continue;
			}
			/* No freeing, because OS will do the job at the end. */
			*cur = (*cur)->list;
			removed_dirs++;
			msg(MSG_QUIET, "ok\n");
		}
	}
}

/* Outputs version information and exits */
static void
version(void)
{
	printf("metastore %s\n", METASTORE_VER);

	exit(EXIT_SUCCESS);
}

/* Prints usage message and exits */
static void
usage(const char *arg0, const char *message)
{
	if (message) {
		msg(MSG_CRITICAL, "%s: %s\n", arg0, message);
		msg(MSG_ERROR, "\n");
	}

	msg(message ? MSG_ERROR : MSG_QUIET,
"Usage: %s ACTION [OPTION...] [PATH...]\n",
	    arg0);
	msg(message ? MSG_ERROR : MSG_QUIET,
"\n"
"Where ACTION is one of:\n"
"  -c, --compare            Show differences between stored and real metadata\n"
"  -s, --save               Save current metadata\n"
"  -a, --apply              Apply stored metadata\n"
"  -d, --dump               Dump stored (if no PATH is given) or real metadata\n"
"                           (if PATH is present, e.g. ./) in human-readable form\n"
"  -V, --version            Output version information and exit\n"
"  -h, --help               Help message (this text)\n"
"\n"
"Valid OPTIONS are:\n"
"  -v, --verbose            Print more verbose messages\n"
"  -q, --quiet              Print less verbose messages\n"
"  -m, --mtime              Also take mtime into account for diff or apply\n"
"  -e, --empty-dirs         Recreate missing empty directories\n"
"  -E, --remove-empty-dirs  Remove extra empty directories\n"
"  -g, --git                Do not omit .git directories\n"
"  -f, --file=FILE          Set metadata file (" METAFILE " by default)\n"
	    );

	exit(message ? EXIT_FAILURE : EXIT_SUCCESS);
}

/* Options */
static struct option long_options[] = {
	{ "compare",           no_argument,       NULL, 'c' },
	{ "save",              no_argument,       NULL, 's' },
	{ "apply",             no_argument,       NULL, 'a' },
	{ "dump",              no_argument,       NULL, 'd' },
	{ "version",           no_argument,       NULL, 'V' },
	{ "help",              no_argument,       NULL, 'h' },
	{ "verbose",           no_argument,       NULL, 'v' },
	{ "quiet",             no_argument,       NULL, 'q' },
	{ "mtime",             no_argument,       NULL, 'm' },
	{ "empty-dirs",        no_argument,       NULL, 'e' },
	{ "remove-empty-dirs", no_argument,       NULL, 'E' },
	{ "git",               no_argument,       NULL, 'g' },
	{ "file",              required_argument, NULL, 'f' },
	{ NULL, 0, NULL, 0 }
};

/* Main function */
int
main(int argc, char **argv)
{
	int i, c;
	struct metahash *real = NULL;
	struct metahash *stored = NULL;
	int action = 0;

	/* Parse options */
	i = 0;
	while (1) {
		int option_index = 0;
		c = getopt_long(argc, argv, "csadVhvqmeEgf:",
		                long_options, &option_index);
		if (c == -1)
			break;
		switch (c) {
		case 'c': /* compare */           action |= ACTION_DIFF;  i++;   break;
		case 's': /* save */              action |= ACTION_SAVE;  i++;   break;
		case 'a': /* apply */             action |= ACTION_APPLY; i++;   break;
		case 'd': /* dump */              action |= ACTION_DUMP;  i++;   break;
		case 'V': /* version */           action |= ACTION_VER;   i++;   break;
		case 'h': /* help */              action |= ACTION_HELP;  i++;   break;
		case 'v': /* verbose */           adjust_verbosity(1);           break;
		case 'q': /* quiet */             adjust_verbosity(-1);          break;
		case 'm': /* mtime */             settings.do_mtime = true;      break;
		case 'e': /* empty-dirs */        settings.do_emptydirs = true;  break;
		case 'E': /* remove-empty-dirs */ settings.do_removeemptydirs = true;
			                              break;
		case 'g': /* git */               settings.do_git = true;        break;
		case 'f': /* file */              settings.metafile = optarg;    break;
		default:
			usage(argv[0], "unknown option");
		}
	}

	/* Make sure only one action is specified */
	if (i != 1)
		usage(argv[0], "incorrect option(s)");

	/* Make sure --empty-dirs is only used with apply */
	if (settings.do_emptydirs && action != ACTION_APPLY)
		usage(argv[0], "--empty-dirs is only valid with --apply");

	/* Make sure --remove-empty-dirs is only used with apply */
	if (settings.do_removeemptydirs && action != ACTION_APPLY)
		usage(argv[0], "--remove-empty-dirs is only valid with --apply");

	if (action == ACTION_VER)
		version();

	if (action == ACTION_HELP)
		usage(argv[0], NULL);

	/* Perform action */
	if (action & ACTIONS_READING && !(action == ACTION_DUMP && optind < argc)) {
		mentries_fromfile(&stored, settings.metafile);
		if (!stored) {
			msg(MSG_CRITICAL, "Failed to load metadata from %s\n",
			    settings.metafile);
			exit(EXIT_FAILURE);
		}
	}

	if (optind < argc) {
		while (optind < argc)
			mentries_recurse_path(argv[optind++], &real, &settings);
	} else if (action != ACTION_DUMP) {
		mentries_recurse_path(".", &real, &settings);
	}

	if (!real && (action != ACTION_DUMP || optind < argc)) {
		msg(MSG_CRITICAL,
		    "Failed to load metadata from file system\n");
		exit(EXIT_FAILURE);
	}

	switch (action) {
	case ACTION_DIFF:
		mentries_compare(real, stored, compare_print, &settings);
		break;
	case ACTION_SAVE:
		mentries_tofile(real, settings.metafile);
		break;
	case ACTION_APPLY:
		mentries_compare(real, stored, compare_fix, &settings);
		if (settings.do_emptydirs)
			fixup_emptydirs();
		if (settings.do_removeemptydirs)
			fixup_newemptydirs();
		break;
	case ACTION_DUMP:
		mentries_dump(real ? real : stored);
		break;
	}

	exit(EXIT_SUCCESS);
}