/*
 * reg.c - "glob"-like wildcard pattern matching (not regexes)
 *
 * Copyright (c) 1992 Troy Rollo.
 * Copyright 1997, 2002 EPIC Software Labs.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notices, the above paragraph (the one permitting redistribution),
 *    this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The names of the author(s) may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``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 AUTHORS 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.
 */

/*
 * [Original note from Troy]
 * The original was spagetti. I have replaced Michael's code with some of
 * my own which is a thousand times more readable and can also handle '%',
 * which substitutes anything except a space. This should enable people
 * to position things better based on argument. I have also added '?', which
 * substitutes to any single character. And of course it still handles '*'.
 * this should be more efficient than the previous version too.
 */
/*
 * [Note from EPIC Software Labs]
 * I had seen that phone had written a non-recursive pattern matcher for ircII,
 * so I decided to see if I could write one too without peeking at his 
 * implementation.  The matcher I came up with ("new_match") is iterative and 
 * is bug-for-bug compatable with troy's recursive matcher ("old_match"). 
 * It's a lot more complicated, but it's also a lot faster.  (jfn)
 */

#include "irc.h"
#include "ircaux.h"
#include "output.h"
#include "reg.h"

static	int	total_explicit;

/*
 * The following #define is here because we *know* its behaviour.
 * The behaviour of toupper tends to be undefined when it's given
 * a non lower case letter.
 * All the systems supported by IRCII should be ASCII
 */
#define	mkupper(c)	(((c) >= 'a' && (c) <= 'z') ? ((c) - 'a' + 'A') : c)

static int	old_match(const char *pattern, const char *string)
{
	char	type = 0;

	while (*string && *pattern && *pattern != '*' && *pattern != '%')
	{
		if (*pattern == '\\' && pattern[1])
		{
			if (!*++pattern || !(mkupper(*pattern) == mkupper(*string)))
				return 0;
			else
				pattern++, string++, total_explicit++;
			continue;	/* Erf! try $match(\\* *) */
		}

		if (*pattern == '?')
			pattern++, string++;
		else if (mkupper(*pattern) == mkupper(*string))
			pattern++, string++, total_explicit++;
		else
			break;
	}
	if (*pattern == '*' || *pattern == '%')
	{
		type = (*pattern++);
		while (*string)
		{
			if (old_match(pattern, string))
				return 1;
			else if (type == '*' || !isspace(*string))
				string++;
			else
				break;
		}
	}

	/* Slurp up any trailing *'s or %'s... */
	if (!*string && (type == '*' || type == '%'))
		while (*pattern && (*pattern == '*' || *pattern == '%'))
			pattern++;

	if (!*string && !*pattern)
		return 1;

	return 0;
}

static int new_match (const char *pattern, const char *string)
{
	int		count = 1;
	int 		asterisk = 0;
	int		percent = 0;
	const char	*last_asterisk_point = NULL;
	const char	*last_percent_point = NULL;
	int		last_asterisk_count = 0;
	int		last_percent_count = 0;
	const char	*after_wildcard = NULL;
	int		sanity = 0;

	if (x_debug & DEBUG_REGEX_DEBUG)
		privileged_yell("Matching [%s] against [%s]", pattern, string);

	for (;;)
	{
		if (sanity++ > 100000)
		{
			privileged_yell("Infinite loop in match! -- Returning [0]");
			return 0;
		}

		/*
		 * If the last character in the pattern was a *, then
		 * we walk the string until we find the next instance int
		 * string, of the character that was after the *.
		 * If we get to the end of string, then obviously there
		 * is no match.  A * at the end of the pattern is handled
		 * especially, so we dont need to consider that.
		 */
		if (asterisk)
		{
			/*
			 * More pattern, no source.  Obviously this
			 * asterisk isnt going to cut it.  Try again.
			 * This replaces an 'always failure' case. 
			 * In 99% of the cases, we will try again and it
			 * will fail anyhow, but 1% of the cases it would
			 * have succeeded, so we need that retry.
			 *
			 * Except that ircII always failed on this case, so
			 * the attempted retry would return the "wrong" (cough)
			 * answer.  So we just always fail.  Oh well.
			 */
			if (!*string)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("More pattern, no source, Failure.  Returning [0]");
				return 0;
			}

			if (*pattern == '\\')
			{
                          if (x_debug & DEBUG_REGEX_DEBUG)
                             privileged_yell("Trying to match [%d] after the backslash "
                                   "against [%d]", (int)*(pattern + 1), 
                                                  (int)*string);

                          if (tolower(*string) == tolower(*(pattern+1)))
                          {
                               if (x_debug & DEBUG_REGEX_DEBUG)
                                  privileged_yell("It matches!  Releasing the backslash");

                               pattern++;
                               asterisk = 0;
                               last_asterisk_point = string;
                               last_asterisk_count = count;

                               pattern++;
                               string++;
                          }
                          else
                               string++;               /* Not this char */
			}

			/*
			 * If the character in the pattern immediately
			 * following the asterisk is a qmark, then we
			 * save where we're at and we allow the ? to be
			 * matched.  If we find it doesnt work later on,
			 * then we will come back to here and try again.
			 *     OR 
			 * We've found the character we're looking for!
			 * Save some state information about how to recover
			 * if we dont match
			 */
			else if (*pattern == '?' || 
				(tolower(*string) == tolower(*pattern)))
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Found a [%d] in the source", *pattern);

				asterisk = 0;
				last_asterisk_point = string;
				last_asterisk_count = count;
			}

			/*
			 * This is not the character we're looking for.
			 */
			else
				string++;

			continue;
		}

		/*
		 * Ok.  If we're dealing with a percent, but not a asterisk,
		 * then we need to look for the character after the percent.
		 * BUT, if we find a space, then we stop anyways.
		 */
		if (percent)
		{
			/*
			 * Ran out of string.  If there is more to the 
			 * pattern, then we failed.  Otherwise if the %
			 * was at the end of the pattern, we havent found
			 * a space, so it succeeds!
			 */
			if (!*string)
			{
				if (*pattern)
				{
					if (x_debug & DEBUG_REGEX_DEBUG)
						privileged_yell("Ran out of source matching after %%.  Returning [0]");
					return 0;
				}
				else
				{
					if (x_debug & DEBUG_REGEX_DEBUG)
						privileged_yell("Success!  Returning [%d]", count);
					return count;
				}
			}

			/*
			 * XXXX Skip over any backslashes...
			 */
			if (*pattern == '\\')
			{
                          if (x_debug & DEBUG_REGEX_DEBUG)
                             privileged_yell("Trying to match [%d] after the backslash "
                                   "against [%d]", (int)*(pattern + 1), 
                                                  (int)*string);

                          if (tolower(*string) == tolower(*(pattern+1)))
                          {
                               if (x_debug & DEBUG_REGEX_DEBUG)
                                  privileged_yell("It matches!  Releasing the backslash");

                               pattern++;
                               percent = 0;
                               last_percent_point = string;
                               last_percent_count = count;

                               pattern++;
                               string++;
                          }
                          else if (isspace(*string))
                          {
                               if (x_debug & DEBUG_REGEX_DEBUG)
                               {
                                  privileged_yell("Found a space trying to match the [%d] after a %%\\, so this doesn't match.  Returning [0]", (int)*(pattern + 1));
                                  return 0;
                               }
                          }
                          else
                               string++;               /* Not this char */
			}

			/*
			 * If we find a space, then we stop looking at the
			 * percent.  We're definitely done with it.  We also
			 * go back to normal parsing mode, presumably with
			 * the space after the %.
			 */
			else if (isspace(*string))
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Found a space");
				percent = 0;
				last_percent_point = NULL;
			}

			/*
			 * If this is not the char we're looking for, then
			 * keep looking.
			 */
			else if (tolower(*string) != tolower(*pattern))
				string++;

			/*
			 * We found it!  Huzzah!
			 */
			else
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Found a [%d]", *pattern);

				percent = 0;
				last_percent_point = string;
				last_percent_count = count;
			}

			continue;
		}


		/*
		 * Ok.  So at this point, we know we're not handling an
		 * outstanding asterisk or percent request.  So we look
		 * to see what the next char is in the pattern and deal
		 * with it.
		 */
		switch (*pattern)
		{

		/*
		 * If its an asterisk, then we just keep some info about
		 * where we're at. 
		 */
		case ('*') : case ('%') :
		{
			asterisk = 0, percent = 0;
			do
			{
				if (*pattern == '*')
					asterisk = 1;
				pattern++;
			}
			while (*pattern == '*' || *pattern == '%');

			after_wildcard = pattern;
			if (asterisk)
			{
				last_asterisk_point = string;
				last_asterisk_count = count;
			}
			else
			{
				percent = 1;
				last_percent_point = string;
				last_percent_count = count;
			}

			/*
			 * If there's nothing in the pattern after the
			 * asterisk, then it slurps up the rest of string,
			 * and we're definitely done!
			 */
			if (asterisk && !*pattern)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Wildcard at end of pattern. success!  Returning [%d]", count);
				return count;
			}

			break;
		}

		/*
		 * If its a question mark, then we have to slurp up one 
		 * character from the pattern and the string.
		 */
		case ('?') :
		{
			pattern++;

			/*
			 * If there is nothing left in string, then we
			 * definitely fail.
			 */
			if (!*string)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Ran out of source matching ?. Returning [0]");
				return 0;
			}
			string++;
			break;
		}

		/*
		 * De-quote any \'s in the pattern.
		 */
		case ('\\') :
		{
			/*
			 * ircII says that a single \ at the end of a pattern
			 * is defined as a failure. (must quote SOMETHING)
			 */
			pattern++;
			if (!*pattern)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Lone \\ at end of pattern, failed.  Returning [0]");
				return 0;
			}

			if (x_debug & DEBUG_REGEX_DEBUG)
				privileged_yell("Comparing dequoted [%d] with [%d]",
					*pattern, *string);

			/*
			 * Check to see if the dequoted character and
			 * the next string character are the same.
			 */
			if (tolower(*pattern) != tolower(*string))
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("characters [%d] and [%d] after \\ dont match.  Returning [0]", tolower(*pattern), tolower(*string));
				return 0;
			}

			if (x_debug & DEBUG_REGEX_DEBUG)
				privileged_yell("Apparantly they match");

			count++, string++, pattern++;
			break;
		}

		/*
		 * If there is nothing left in the pattern and string,
		 * then we've definitely succeeded.  Return the number of
		 * non-wildcard characters.
		 */
		default:
		{
			if (!*pattern && !*string)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Success!  Returning [%d]", count);
				return count;
			}

			/*
			 * There are regular characters next in the pattern 
			 * and string.  Are they the same?  If they are, walk 
			 * past them and go to the next character.
			 */
			if (tolower(*pattern) == tolower(*string))
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("characters match");

				count++, pattern++, string++;
			}

			/*
			 * The two characters are not the same.  If we're 
			 * currently trying to match a wildcard, go back to 
			 * where we started after the wildcard and try looking
			 * again from there.  If we are not currently matching
			 * a wildcard, then the entire match definitely fails.
			 */
			else if (last_asterisk_point)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("last_asterisk_point");

                                asterisk = 1;
                                string = last_asterisk_point + 1;
                                pattern = after_wildcard;
                                count = last_asterisk_count;
			}
			else if (last_percent_point)
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("last_percent_point");

                                percent = 1;
                                string = last_percent_point + 1;
                                pattern = after_wildcard;
                                count = last_percent_count;
			}
			else
			{
				if (x_debug & DEBUG_REGEX_DEBUG)
					privileged_yell("Characters [%d] and [%d] dont match.  Returning [0]", tolower(*pattern), tolower(*string));
				return 0;
			}

			break;
		}
		}
	}

	/* NOTREACHED */
	if (x_debug & DEBUG_REGEX_DEBUG)
		privileged_yell("ABAONDON SHIP!  Returning [0]");
	return 0;
}

/*
 * wild_match: calculate the "value" of str when matched against pattern.
 * The "value" of a string is always zero if it is not matched by the pattern.
 * In all cases where the string is matched by the pattern, then the "value"
 * of the match is 1 plus the number of non-wildcard characters in "str".
 *
 * \\[ and \\] handling is an epic extension.
 */
int wild_match (const char *p, const char *str)
{
	total_explicit = 0;

	/*
	 * Is there a \[ in the pattern to be expanded? 
	 * 
	 * This stuff here just reduces the \[ \] set into a series of
	 * one-simpler patterns and then recurses over the options.
	 */
	if (strstr(p, "\\["))
	{
		char *pattern, *ptr, *ptr2, *arg, *placeholder;
		int nest = 0;

		/*
		 * Only make the copy if we're going to be tearing it apart.
		 */
		pattern = LOCAL_COPY(p);

		/*
		 * We will have to null this out, but not until we've used it
		 * XXX This seems to be a no-op.  Why bother?
		 */
		placeholder = ptr = strstr(pattern, "\\[");

		/*
		 * Look for the matching \].
		 */
		do
		{
			switch (ptr[1]) 
			{
					/* step over it and add to nest */
				case '[' :  ptr2 = ptr + 2 ;
					    nest++;
					    break;
					/* step over it and remove nest */
				case ']' :  ptr2 = ptr + 2;
					    nest--;
					    break;
				default:
					    ptr2 = ptr + 2;
					    break;
			}
		}
		while (nest && (ptr = strchr(ptr2, '\\')));

		/*
		 * Right now, we know that ptr points to a \] or to a NULL.
		 * Remember that '&&' short circuits and that ptr will
		 * not be set to NULL if (nest) is zero.
		 */
		if (ptr)
		{
			int best_total = 0;

			*ptr = 0;
			ptr += 2;
			*placeholder = 0;
			placeholder += 2;

			/* 
			 * grab words ("" sets or space words) one at a time
			 * and attempt to match all of them.  The best value
			 * matched is the one used.
			 */
			while ((arg = new_next_arg(placeholder, &placeholder)))
			{
				int tmpval;
				char my_buff[BIG_BUFFER_SIZE + 1];

				strlcpy(my_buff, pattern, sizeof my_buff);
				strlcat(my_buff, arg, sizeof my_buff);
				strlcat(my_buff, ptr, sizeof my_buff);

				/*
				 * The total_explicit we return is whatever
				 * sub-pattern has the highest total_explicit
				 */
				if ((tmpval = wild_match(my_buff, str)))
				{
					if (tmpval > best_total)
						best_total = tmpval;
				}
			}

			return best_total; /* end of expansion section */
		}

		/*
		 * Possibly an unmatched \[ \] set.  Just wing it.
		 */
		else
		{
			total_explicit = 0;
			if (!(x_debug & DEBUG_REGEX))
				return new_match(pattern, str);
			else
			{
				if (old_match(pattern, str))
					return total_explicit + 1;
				else
					return 0;
			}
		}
	}

	/*
	 * Trivial case -- No \[ \] sets, just do the match.
	 */
	else
	{
		if (!(x_debug & DEBUG_REGEX))
			return new_match(p, str);
		else
		{
			if (old_match(p, str))
				return total_explicit + 1;
			else
				return 0;
		}
	}
}


/*
 * Hrm.  Here's the plan -- can we convert ircII patterns to normal
 * regexes?  Well, the syntax should be pretty simple, right?
 *
 * 	ircII Char:			regex char:
 *	-----------			-----------
 *	    ?				    .
 *	    %				    [^ \r\n\t]*
 *	    *				    .*
 *	    \[a b\]			    (a|b)
 */

int	pattern_regcomp (regex_t *preg, const char *pattern, int cflags)
{
	char *	regex;
	int	retval;
	int	weight;

	regex = pattern2regex(pattern, &weight);
	retval = regcomp(preg, regex, cflags);
	new_free(&regex);
	if (retval < 0)
		return -1;
	return weight;
}

char *	pattern2regex (const char *pattern, int *weight)
{
	char *	retval = NULL;
	const char *	pat;
	size_t	retsize;

	*weight = 0;

	retsize = strlen(pattern) * 11 + 4;	/* big enough? */
	retval = new_malloc(retsize);
	*retval = 0;
	strlcat(retval, "^", retsize);

	for (pat = pattern; *pat; pat++)
	{
	    switch (*pat)
	    {
		case '.' :
		case '{' : case '}' :
		case '(' : case ')' :
		case '[' : case ']' :
		case '^' : case '$' :
		case '|' : case '+' :
			strextend(retval, '\\', 1);
			strextend(retval, *pat, 1);
			break;
		case '?' :
			strextend(retval, '.', 1);
			break;
		case '%' :
			strlcat(retval, "[^ \t]*", retsize);
			break;
		case '*' :
			strlcat(retval, ".*", retsize);
			break;
		case '\\' :
			if (pat[1] != '[')
				goto end;
		{
			char *ptr, *ptr2, *arg, *placeholder;
			int nest = 1;

			placeholder = ptr = strstr(pattern, "\\[");
			do
			{
				switch (ptr[1]) 
				{
					/* step over it and add to nest */
					case '[' :  ptr2 = ptr + 2 ;
					    nest++;
					    break;
					/* step over it and remove nest */
					case ']' :  ptr2 = ptr + 2;
					    nest--;
					    break;
					default:
					    ptr2 = ptr + 2;
					    break;
				}
			}
			while (nest && (ptr = strchr(ptr2, '\\')));

			if (!ptr)
				goto end;

			*ptr = 0;
			/* ptr += 2; */
			*placeholder = 0;
			placeholder += 2;

			arg = new_next_arg(placeholder, &placeholder);
			strlcat(retval, "(", retsize);
			strlcat(retval, arg, retsize);

			while ((arg = new_next_arg(placeholder, &placeholder)))
			{
				strlcat(retval, "|", retsize);
				strlcat(retval, arg, retsize);
			}
			strlcat(retval, ")", retsize);
			break;
		   }
		   end:
			strextend(retval, *pat++, 1);
			if (*pat)
				strextend(retval, *pat, 1);
			break;
		default :
			strextend(retval, *pat, 1);
			(*weight)++;
			break;
	    }
	}
	strlcat(retval, "$", retsize);

	(*weight)++;		/* The nul counts towards the weight */

	if (x_debug & DEBUG_REGEX_DEBUG)
		privileged_yell("[%s] -> [%s]", pattern, retval);
	return retval;
}