/*
    clsync - file tree sync utility based on inotify/kqueue

    Copyright (C) 2013-2014 Dmitry Yu Okunev <dyokunev@ut.mephi.ru> 0x8E30679C

    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, either version 3 of the License, or
    (at your option) any later version.

    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/>.
 */

#include "common.h"

#include <glib.h>	// g_hash_table_*

#include "rules.h"
#include "error.h"

int rule_complete ( rule_t *rule_p, char *expr, size_t *rules_count_p )
{
	debug ( 3, "<%s>.", expr );
#ifdef VERYPARANOID

	if ( rule_p->mask == RA_NONE ) {
		error ( "Received a rule with rule_p->mask == 0x00. Exit." );
		return EINVAL;
	}

#endif
	char buf[BUFSIZ];
	int ret = 0;

	if ( rule_p->num >= MAXRULES ) {
		error ( "Too many rules (%i >= %i).", rule_p->num, MAXRULES );
		return ENOMEM;
	}

	if ( ( ret = regcomp ( &rule_p->expr,       expr, REG_EXTENDED | REG_NOSUB ) ) ) {
		regerror ( ret, &rule_p->expr, buf, BUFSIZ );
		error ( "Invalid regexp pattern <%s>: %s (regex-errno: %i).", expr, buf, ret );
		return ret;
	}

	( *rules_count_p )++;
	return ret;
}

int parse_rules_fromfile ( ctx_t *ctx_p )
{
	int ret = 0;
	char *rulfpath = ctx_p->rulfpath;
	rule_t *rules  = ctx_p->rules;
	size_t *rules_count_p = &ctx_p->rules_count;
	char *line_buf = NULL;
	FILE *f = fopen ( rulfpath, "r" );

	if ( f == NULL ) {
		rules->mask   = RA_NONE;		// Terminator. End of rules' chain.
		rules->perm   = DEFAULT_RULES_PERM;
		error ( "Cannot open \"%s\" for reading.", rulfpath );
		return errno;
	}

	GHashTable *autowrules_ht = g_hash_table_new_full ( g_str_hash,	g_str_equal,	free,    0 );
	int i = 0;
	ssize_t linelen;
	size_t size = 0;

	while ( ( linelen = getline ( &line_buf, &size, f ) ) != -1 ) {
		if ( linelen > 1 ) {
			uint8_t sign = 0;
			char *line = line_buf;
			rule_t *rule;
			rule = &rules[i];
#ifdef VERYPARANOID
			memset ( rule, 0, sizeof ( *rule ) );
#endif
			rule->num = i++;
			line[--linelen] = 0;

			// Parsing the first character of the line
			switch ( *line ) {
				case '+':
					sign = RS_PERMIT;
					break;

				case '-':
					sign = RS_REJECT;
					break;

				case '#':	// Comment?
					i--;	// Canceling new rule
					continue;

				default:
					error ( "Wrong rule action <%c>.", *line );
					return EINVAL;
			}

			line++;
			linelen--;
			// Parsing the second character of the line
			*line |= 0x20;	// lower-casing
			// Default rule->mask and rule->perm
			// rule->mask - sets bitmask of operations that are affected by the rule
			// rule->perm - sets bitmask of permit/reject for every operation. Effect have only bits specified by the rule->mask.
			rule->mask = RA_ALL;

			switch ( sign ) {
				case RS_REJECT:
					rule->perm = RA_NONE;
					break;

				case RS_PERMIT:
					rule->perm = RA_ALL;
					break;
			}

			switch ( *line ) {
				case '*':
					rule->objtype = 0;	// "0" - means "of any type"
					break;
#ifdef DETAILED_FTYPE

				case 's':
					rule->objtype = S_IFSOCK;
					break;

				case 'l':
					rule->objtype = S_IFLNK;
					break;

				case 'b':
					rule->objtype = S_IFBLK;
					break;

				case 'c':
					rule->objtype = S_IFCHR;
					break;

				case 'p':
					rule->objtype = S_IFIFO;
					break;
#endif

				case 'f':
					rule->objtype = S_IFREG;
					break;

				case 'd':
					rule->objtype = S_IFDIR;
					break;

				case 'W':
				case 'w':
				case 'm':
				case 's':
					if (
					    ( ctx_p->flags[MODE] == MODE_RSYNCDIRECT ) ||
					    ( ctx_p->flags[MODE] == MODE_RSYNCSHELL )  ||
					    ( ctx_p->flags[MODE] == MODE_RSYNCSO )
					)
						warning ( "Used \"w\" or/and \"m\" or/and \"s\" rule in rsync \"--monitor\" case."
						          " This may cause unexpected problems." );

					rule->objtype = S_IFDIR;

					switch ( *line ) {
						case 'W':
							rule->mask    = RA_WALK | RA_MONITOR;
							break;

						case 'w':
							rule->mask    = RA_WALK;
							break;

						case 'm':
							rule->mask    = RA_MONITOR;
							break;

						case 's':
							rule->mask    = RA_SYNC;
							break;
					}

					break;

				default:
					warning ( "Cannot parse the rule <%s>", &line[-1] );
					i--;	// Canceling new rule
					continue;
			}

			line++;
			linelen--;
			// Parsing the rest part of the line
			debug ( 1, "Rule #%i <%c>[0x%02x 0x%02x] <%c>[0x%04x] pattern <%s> (length: %i).", rule->num, line[-2], rule->perm, rule->mask, line[-1], rule->objtype, line, linelen );

			if ( ( ret = rule_complete ( rule, line, rules_count_p ) ) )
				goto l_parse_rules_fromfile_end;

			// Post-processing:
			line--;
			linelen++;
#ifdef AUTORULESW

			if ( *line != 'w' ) {
				// processing --auto-add-rules-w
				if ( ctx_p->flags[AUTORULESW] && ( sign == RS_PERMIT ) ) {
					// Preparing to add appropriate w-rules
					char skip = 0;
					char *expr = alloca ( linelen + 2 );
					memcpy ( expr, line, linelen + 1 );
					size_t exprlen = linelen;

					// Making expr to be starting with '^'
					if ( line[1] == '^' ) {
						expr++;
						exprlen--;
					} else
						*expr = '^';

					char *end;

					if ( *line == 'd' || *line == '*' ) {
						// "d" rule already doing what we need, so we can skip the last level
						end = &expr[exprlen];

						if ( end[-1] != '$' )
							* ( end++ ) = '$';

						*end = 0;
//						debug(3, "Don't adding w-rule for \"%s\" due to [*d]-rule for \"%s\"",
//							expr, &line[1]);
						g_hash_table_insert ( autowrules_ht, strdup ( expr ), GINT_TO_POINTER ( 1 ) );
					}

					if ( !skip ) {
						do {
							// Decreasing directory level and make the '$' ending
							end = strrchr ( expr, '/' );

							if ( end != NULL ) {
								if ( end[-1] != '$' )
									* ( end++ ) = '$';

								*end = 0;
								exprlen = ( size_t ) ( end - expr );
							} else {
								expr[1] = '$';
								expr[2] = 0;
								exprlen = 2;
							}

							// Checking if it not already set
							if ( !g_hash_table_lookup ( autowrules_ht, expr ) ) {
								// Switching to next rule:
								rule = &rules[i];
								rule->num = i++;
								// Adding the rule
								rule->objtype = S_IFDIR;
								rule->mask    = RA_WALK;
								rule->perm    = RA_WALK;
								debug ( 1, "Rule #%i <+> <w> pattern <%s> (length: %i) [auto].",
								        rule->num, expr, exprlen );

								if ( ( ret = rule_complete ( rule, expr, rules_count_p ) ) )
									goto l_parse_rules_fromfile_end;

								g_hash_table_insert ( autowrules_ht, strdup ( expr ), GINT_TO_POINTER ( 1 ) );
							}
						} while ( end != NULL );
					}
				}
			}

#endif
		}
	}

l_parse_rules_fromfile_end:

	if ( size )
		free ( line_buf );

	fclose ( f );
	debug ( 3, "Adding tail-rule #%u (effective #%u).", -1, i );
	rules[i].mask   = RA_NONE;		// Terminator. End of rules' chain.
	rules[i].perm   = DEFAULT_RULES_PERM;
	g_hash_table_destroy ( autowrules_ht );
#ifdef _DEBUG_FORCE
	debug ( 3, "Total (p == %p):", rules );
	i = 0;

	do {
		debug ( 4, "\t%i\t%i\t%p/%p", i, rules[i].objtype, ( void * ) ( long ) rules[i].perm, ( void * ) ( long ) rules[i].mask );
		i++;
	} while ( rules[i].mask != RA_NONE );

#endif
	return ret;
}

/**
 * @brief 			Checks file path by rules' expressions (parsed from file)
 *
 * @param[in]       fpath		Path to file of directory
 * @param[in]       st_mode		st_mode received via *stat() functions
 * @param[in]       rules_p		Pointer to start of rules array
 * @param[in]       ruleaction	Operaton ID (see ruleaction_t)
 * @param[in,out]   rule_pp		Pointer to pointer to rule, where the last search ended. Next search will be started from the specified rule. Can be "NULL" to disable this feature.
 *
 * @retval	perm		Permission bitmask
 *
 */
// Checks file path by rules' expressions (parsed from file)
// Return: RS_PERMIT or RS_REJECT for the "file path" and specified ruleaction

ruleaction_t rules_search_getperm ( const char *fpath, mode_t st_mode, rule_t *rules_p, const ruleaction_t ruleaction, rule_t **rule_pp )
{
	debug ( 3, "rules_search_getperm(\"%s\", %p, %p, %p, %p)",
	        fpath, ( void * ) ( unsigned long ) st_mode, rules_p,
	        ( void * ) ( long ) ruleaction, ( void * ) ( long ) rule_pp
	      );
	int i;
	i = 0;
	rule_t *rule_p = rules_p;
	mode_t ftype = st_mode & S_IFMT;
#ifdef _DEBUG_FORCE
	debug ( 3, "Rules (p == %p):", rules_p );
	i = 0;

	do {
		debug ( 3, "\t%i\t%i\t%p/%p", i, rules_p[i].objtype, ( void * ) ( long ) rules_p[i].perm, ( void * ) ( long ) rules_p[i].mask );
		i++;
	} while ( rules_p[i].mask != RA_NONE );

#endif
	i = 0;

	if ( rule_pp != NULL )
		if ( *rule_pp != NULL ) {
			debug ( 3, "Previous position is set." );

			if ( rule_p->mask == RA_NONE )
				return rule_p->perm;

			rule_p = ++ ( *rule_pp );
			i = rule_p->num;
		}

	debug ( 3, "Starting from position %i", i );

	while ( rule_p->mask != RA_NONE ) {
		debug ( 3, "%i -> %p/%p: type compare: %p, %p -> %i",
		        i,
		        ( void * ) ( long ) rule_p->perm, ( void * ) ( long ) rule_p->mask,
		        ( void * ) ( unsigned long ) ftype, ( void * ) ( unsigned long ) rule_p->objtype,
		        ( unsigned char ) ! ( rule_p->objtype && ( rule_p->objtype != ftype ) )
		      );

		if ( ! ( rule_p->mask & ruleaction ) ) {	// Checking wrong operation type
			debug ( 3, "action-mask mismatch. Skipping." );
			rule_p++;
			i++;// = &rules_p[++i];
			continue;
		}

		if ( rule_p->objtype && ( rule_p->objtype != ftype ) ) {
			debug ( 3, "objtype mismatch. Skipping." );
			rule_p++;
			i++;// = &rules_p[++i];
			continue;
		}

		if ( !regexec ( &rule_p->expr, fpath, 0, NULL, 0 ) )
			break;

		debug ( 3, "doesn't match regex. Skipping." );
		rule_p++;
		i++;// = &rules_p[++i];
	}

	debug ( 2, "matched to rule #%u for \"%s\":\t%p/%p (queried: %p).", rule_p->mask == RA_NONE ? -1 : i, fpath,
	        ( void * ) ( long ) rule_p->perm, ( void * ) ( long ) rule_p->mask,
	        ( void * ) ( long ) ruleaction
	      );

	if ( rule_pp != NULL )
		*rule_pp = rule_p;

	return rule_p->perm;
}

ruleaction_t rules_getperm ( const char *fpath, mode_t st_mode, rule_t *rules_p, ruleaction_t ruleactions )
{
	rule_t *rule_p = NULL;
	ruleaction_t gotpermto  = 0;
	ruleaction_t resultperm = 0;
	debug ( 3, "rules_getperm(\"%s\", %p, %p (#%u), %p)",
	        fpath, ( void * ) ( long ) st_mode, rules_p, rules_p->num, ( void * ) ( long ) ruleactions );

	while ( ( gotpermto & ruleactions ) != ruleactions ) {
		rules_search_getperm ( fpath, st_mode, rules_p, ruleactions, &rule_p );

		if ( rule_p->mask == RA_NONE ) { // End of rules' list
			resultperm |= rule_p->perm & ( gotpermto ^ RA_ALL );
			break;
		}

		resultperm |= rule_p->perm & ( ( gotpermto ^ rule_p->mask ) &rule_p->mask );	// Adding perm bitmask of operations that was unknown before
		gotpermto  |= rule_p->mask;						// Adding the mask
	}

	debug ( 3, "rules_getperm(\"%s\", %p, rules_p, %p): result perm is %p",
	        fpath, ( void * ) ( long ) st_mode, ( void * ) ( long ) ruleactions, ( void * ) ( long ) resultperm );
	return resultperm;
}