/*
    Copyright (c) 2006-2020 Chung, Hyung-Hwan. 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
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.

    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "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 AUTHOR 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.
 */

/*
  tre-match-parallel.c - TRE parallel regex matching engine

This is the license, copyright notice, and disclaimer for TRE, a regex
matching package (library and tools) with support for approximate
matching.

Copyright (c) 2001-2009 Ville Laurikari <vl@iki.fi>
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
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS
``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 COPYRIGHT
HOLDER OR CONTRIBUTORS 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.
*/

/*
  This algorithm searches for matches basically by reading characters
  in the searched string one by one, starting at the beginning.	 All
  matching paths in the TNFA are traversed in parallel.	 When two or
  more paths reach the same state, exactly one is chosen according to
  tag ordering rules; if returning submatches is not required it does
  not matter which path is chosen.

  The worst case time required for finding the leftmost and longest
  match, or determining that there is no match, is always linearly
  dependent on the length of the text being searched.

  This algorithm cannot handle TNFAs with back referencing nodes.
  See `tre-match-backtrack.c'.
*/

#include "tre-prv.h"
#include "tre-match-ut.h"

typedef struct
{
	tre_tnfa_transition_t *state;
	int *tags;
} tre_tnfa_reach_t;

typedef struct
{
	int pos;
	int **tags;
} tre_reach_pos_t;


#ifdef TRE_DEBUG
static void
tre_print_reach(const tre_tnfa_t *tnfa, tre_tnfa_reach_t *reach, int num_tags)
{
	int i;

	while (reach->state != NULL)
	{
		DPRINT((" %p", (void *)reach->state));
		if (num_tags > 0)
		{
			DPRINT(("/"));
			for (i = 0; i < num_tags; i++)
			{
				DPRINT(("%d:%d", i, reach->tags[i]));
				if (i < (num_tags-1))
					DPRINT((","));
			}
		}
		reach++;
	}
	DPRINT(("\n"));

}
#endif /* TRE_DEBUG */

reg_errcode_t
tre_tnfa_run_parallel(hawk_gem_t* gem, const tre_tnfa_t *tnfa, const void *string, int len,
                      tre_str_type_t type, int *match_tags, int eflags,
                      int *match_end_ofs)
{
	/* State variables required by GET_NEXT_WCHAR. */
	tre_char_t prev_c = 0, next_c = 0;
	const char *str_byte = string;
	int pos = -1;
	unsigned int pos_add_next = 1;
#ifdef TRE_WCHAR
	const hawk_uch_t *str_wide = string;
#ifdef TRE_MBSTATE
	hawk_mbstate_t mbstate;
#endif
#endif /* TRE_WCHAR */
	int reg_notbol = eflags & REG_NOTBOL;
	int reg_noteol = eflags & REG_NOTEOL;
	int reg_newline = tnfa->cflags & REG_NEWLINE;
	int str_user_end = 0;

	char *buf;
	tre_tnfa_transition_t *trans_i;
	tre_tnfa_reach_t *reach, *reach_next, *reach_i, *reach_next_i;
	tre_reach_pos_t *reach_pos;
	int *tag_i;
	int num_tags, i;

	int match_eo = -1;	   /* end offset of match (-1 if no match found yet) */
	int new_match = 0;
	int *tmp_tags = NULL;
	int *tmp_iptr;

#ifdef TRE_MBSTATE
	HAWK_MEMSET(&mbstate, '\0', sizeof(mbstate));
#endif /* TRE_MBSTATE */

	DPRINT(("tre_tnfa_run_parallel, input type %d\n", type));

	if (!match_tags)
		num_tags = 0;
	else
		num_tags = tnfa->num_tags;

	/* Allocate memory for temporary data required for matching.	This needs to
	   be done for every matching operation to be thread safe.  This allocates
	   everything in a single large block from the stack frame using alloca()
	   or with malloc() if alloca is unavailable. */
	{
		int tbytes, rbytes, pbytes, xbytes, total_bytes;
		char *tmp_buf;
		/* Compute the length of the block we need. */
		tbytes = sizeof(*tmp_tags) * num_tags;
		rbytes = sizeof(*reach_next) * (tnfa->num_states + 1);
		pbytes = sizeof(*reach_pos) * tnfa->num_states;
		xbytes = sizeof(int) * num_tags;
		total_bytes =
		    (sizeof(long) - 1) * 4 /* for alignment paddings */
		    + (rbytes + xbytes * tnfa->num_states) * 2 + tbytes + pbytes;

		/* Allocate the memory. */
		buf = xmalloc(gem, (unsigned)total_bytes);
		if (buf == NULL) return REG_ESPACE;
		HAWK_MEMSET(buf, 0, (size_t)total_bytes);

		/* Get the various pointers within tmp_buf (properly aligned). */
		tmp_tags = (void *)buf;
		tmp_buf = buf + tbytes;
		tmp_buf += ALIGN(tmp_buf, hawk_uintptr_t);
		reach_next = (void *)tmp_buf;
		tmp_buf += rbytes;
		tmp_buf += ALIGN(tmp_buf, hawk_uintptr_t);
		reach = (void *)tmp_buf;
		tmp_buf += rbytes;
		tmp_buf += ALIGN(tmp_buf, hawk_uintptr_t);
		reach_pos = (void *)tmp_buf;
		tmp_buf += pbytes;
		tmp_buf += ALIGN(tmp_buf, hawk_uintptr_t);
		for (i = 0; i < tnfa->num_states; i++)
		{
			reach[i].tags = (void *)tmp_buf;
			tmp_buf += xbytes;
			reach_next[i].tags = (void *)tmp_buf;
			tmp_buf += xbytes;
		}
	}

	for (i = 0; i < tnfa->num_states; i++)
		reach_pos[i].pos = -1;

	/* If only one character can start a match, find it first. */
	if (tnfa->first_char >= 0 && type == STR_BYTE && str_byte)
	{
		const char *orig_str = str_byte;
		int first = tnfa->first_char;

		if (len >= 0)
			str_byte = hawk_find_bchar_in_bchars(orig_str, (size_t)len, first);
		else
			str_byte = hawk_find_bchar_in_bcstr(orig_str, first);
		if (str_byte == NULL)
		{
			if (buf) xfree(gem, buf);
			return REG_NOMATCH;
		}
		DPRINT(("skipped %lu chars\n", (unsigned long)(str_byte - orig_str)));
		if (str_byte >= orig_str + 1)
			prev_c = (unsigned char)*(str_byte - 1);
		next_c = (unsigned char)*str_byte;
		pos = str_byte - orig_str;
		if (len < 0 || pos < len)
			str_byte++;
	}
	else
	{
		GET_NEXT_WCHAR();
		pos = 0;
	}

#if 0
	/* Skip over characters that cannot possibly be the first character
	   of a match. */
	if (tnfa->firstpos_chars != NULL)
	{
		char *chars = tnfa->firstpos_chars;

		if (len < 0)
		{
			const char *orig_str = str_byte;
			/* XXX - use strpbrk() and wcspbrk() because they might be
			   optimized for the target architecture.  Try also strcspn()
			   and wcscspn() and compare the speeds. */
			while (next_c != HAWK_T('\0') && !chars[next_c])
			{
				next_c = *str_byte++;
			}
			prev_c = *(str_byte - 2);
			pos += str_byte - orig_str;
			DPRINT(("skipped %d chars\n", str_byte - orig_str));
		}
		else
		{
			while (pos <= len && !chars[next_c])
			{
				prev_c = next_c;
				next_c = (unsigned char)(*str_byte++);
				pos++;
			}
		}
	}
#endif

	DPRINT(("length: %d\n", len));
	DPRINT(("pos:chr/code | states and tags\n"));
	DPRINT(("-------------+------------------------------------------------\n"));

	reach_next_i = reach_next;
	while (/*CONSTCOND*/1)
	{
		/* If no match found yet, add the initial states to `reach_next'. */
		if (match_eo < 0)
		{
			DPRINT((" init >"));
			trans_i = tnfa->initial;
			while (trans_i->state != NULL)
			{
				if (reach_pos[trans_i->state_id].pos < pos)
				{
					if (trans_i->assertions
					        && CHECK_ASSERTIONS(trans_i->assertions))
					{
						DPRINT(("assertion failed\n"));
						trans_i++;
						continue;
					}

					DPRINT((" %p", (void *)trans_i->state));
					reach_next_i->state = trans_i->state;
					for (i = 0; i < num_tags; i++)
						reach_next_i->tags[i] = -1;
					tag_i = trans_i->tags;
					if (tag_i)
						while (*tag_i >= 0)
						{
							if (*tag_i < num_tags)
								reach_next_i->tags[*tag_i] = pos;
							tag_i++;
						}
					if (reach_next_i->state == tnfa->final)
					{
						DPRINT(("	 found empty match\n"));
						match_eo = pos;
						new_match = 1;
						for (i = 0; i < num_tags; i++)
							match_tags[i] = reach_next_i->tags[i];
					}
					reach_pos[trans_i->state_id].pos = pos;
					reach_pos[trans_i->state_id].tags = &reach_next_i->tags;
					reach_next_i++;
				}
				trans_i++;
			}
			DPRINT(("\n"));
			reach_next_i->state = NULL;
		}
		else
		{
			if (num_tags == 0 || reach_next_i == reach_next)
				/*?We have found a match. */
				break;
		}

		/* Check for end of string. */
		if (len < 0)
		{
			if (next_c == HAWK_T('\0'))
				break;
		}
		else
		{
			if (pos >= len)
				break;
		}

		GET_NEXT_WCHAR();

#ifdef TRE_DEBUG
		DPRINT(("%3d:%2lc/%05d |", pos - 1, (tre_cint_t)prev_c, (int)prev_c));
		tre_print_reach(tnfa, reach_next, num_tags);
		DPRINT(("%3d:%2lc/%05d |", pos, (tre_cint_t)next_c, (int)next_c));
		tre_print_reach(tnfa, reach_next, num_tags);
#endif /* TRE_DEBUG */

		/* Swap `reach' and `reach_next'. */
		reach_i = reach;
		reach = reach_next;
		reach_next = reach_i;

		/* For each state in `reach', weed out states that don't fulfill the
			 minimal matching conditions. */
		if (tnfa->num_minimals && new_match)
		{
			new_match = 0;
			reach_next_i = reach_next;
			for (reach_i = reach; reach_i->state; reach_i++)
			{
				int skip = 0;
				for (i = 0; tnfa->minimal_tags[i] >= 0; i += 2)
				{
					int end = tnfa->minimal_tags[i];
					int start = tnfa->minimal_tags[i + 1];
					DPRINT(("  Minimal start %d, end %d\n", start, end));
					if (end >= num_tags)
					{
						DPRINT(("	 Throwing %p out.\n", reach_i->state));
						skip = 1;
						break;
					}
					else if (reach_i->tags[start] == match_tags[start]
					         && reach_i->tags[end] < match_tags[end])
					{
						DPRINT(("	 Throwing %p out because t%d < %d\n",
						        reach_i->state, end, match_tags[end]));
						skip = 1;
						break;
					}
				}
				if (!skip)
				{
					reach_next_i->state = reach_i->state;
					tmp_iptr = reach_next_i->tags;
					reach_next_i->tags = reach_i->tags;
					reach_i->tags = tmp_iptr;
					reach_next_i++;
				}
			}
			reach_next_i->state = NULL;

			/* Swap `reach' and `reach_next'. */
			reach_i = reach;
			reach = reach_next;
			reach_next = reach_i;
		}

		/* For each state in `reach' see if there is a transition leaving with
			 the current input symbol to a state not yet in `reach_next', and
			 add the destination states to `reach_next'. */
		reach_next_i = reach_next;
		for (reach_i = reach; reach_i->state; reach_i++)
		{
			for (trans_i = reach_i->state; trans_i->state; trans_i++)
			{
				/* Does this transition match the input symbol? */
				if (trans_i->code_min <= (tre_cint_t)prev_c && trans_i->code_max >= (tre_cint_t)prev_c)
				{
					if (trans_i->assertions && 
					    (CHECK_ASSERTIONS(trans_i->assertions) || 
					     CHECK_CHAR_CLASSES(trans_i, tnfa, eflags)))
					{
						DPRINT(("assertion failed\n"));
						continue;
					}

					/* Compute the tags after this transition. */
					for (i = 0; i < num_tags; i++) tmp_tags[i] = reach_i->tags[i];
					tag_i = trans_i->tags;
					if (tag_i != NULL)
					{
						while (*tag_i >= 0)
						{
							if (*tag_i < num_tags)
								tmp_tags[*tag_i] = pos;
							tag_i++;
						}
					}

					if (reach_pos[trans_i->state_id].pos < pos)
					{
						/* Found an unvisited node. */
						reach_next_i->state = trans_i->state;
						tmp_iptr = reach_next_i->tags;
						reach_next_i->tags = tmp_tags;
						tmp_tags = tmp_iptr;
						reach_pos[trans_i->state_id].pos = pos;
						reach_pos[trans_i->state_id].tags = &reach_next_i->tags;

						if (reach_next_i->state == tnfa->final
						        && (match_eo == -1 || (num_tags > 0 && reach_next_i->tags[0] <= match_tags[0])))
						{
							DPRINT(("  found match %p\n", trans_i->state));
							match_eo = pos;
							new_match = 1;
							for (i = 0; i < num_tags; i++) match_tags[i] = reach_next_i->tags[i];
						}
						reach_next_i++;

					}
					else
					{
						assert(reach_pos[trans_i->state_id].pos == pos);
						/* Another path has also reached this state.  We choose
									 the winner by examining the tag values for both
									 paths. */
						if (tre_tag_order(num_tags, tnfa->tag_directions,
						                  tmp_tags,
						                  *reach_pos[trans_i->state_id].tags))
						{
							/* The new path wins. */
							tmp_iptr = *reach_pos[trans_i->state_id].tags;
							*reach_pos[trans_i->state_id].tags = tmp_tags;
							if (trans_i->state == tnfa->final)
							{
								DPRINT(("	 found better match\n"));
								match_eo = pos;
								new_match = 1;
								for (i = 0; i < num_tags; i++)
									match_tags[i] = tmp_tags[i];
							}
							tmp_tags = tmp_iptr;
						}
					}
				}
			}
		}
		reach_next_i->state = NULL;
	}

	DPRINT(("match end offset = %d\n", match_eo));

	if (buf) xfree(gem, buf);

	*match_end_ofs = match_eo;
	return match_eo >= 0 ? REG_OK : REG_NOMATCH;
}

/* EOF */