/*
 * Copyright (C) 1984-2000  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


#include "less.h"

#define	WHITESP(c)	((c)==' ' || (c)=='\t')

#if TAGS

#include "queue.h"

char *tags = "tags";

static int total;
static int curseq;

extern int linenums;
extern int sigs;
extern int jump_sline;

/*
 * tag type
 */
enum {
	T_CTAGS,	/* 'tags': standard and extended format (ctags) */
	T_CTAGS_X,	/* stdin: cross reference format (ctags) */
	T_GTAGS,	/* 'GTAGS': function defenition (global) */
	T_GRTAGS,	/* 'GRTAGS': function reference (global) */
	T_GSYMS,	/* 'GSYMS': other symbols (global) */
	T_GPATH		/* 'GPATH': path name (global) */
};

static void findctag(), findgtag();
static char *nextgtag(), *prevgtag();
static POSITION ctagsearch(), gtagsearch();
static int getentry();

/*
 * The queue of tags generated by the last findgtag() call.
 *
 * Use either pattern or line.
 * findgtag() use line, so pattern is always NULL.
 * findctag() useally use pattern, then line is 0 but sometimes use
 * line (old style tags format) instead of pattern. In such case,
 * pattern is NULL.
 */
static CIRCLEQ_HEAD(tag_q, tag) tag_q;
struct tag {
	CIRCLEQ_ENTRY(tag) ptrs;
	char *tagfile;		/* source file containing the tag */
	int taglinenum;		/* appropriate line number of source file */
	char *tagpattern;	/* pattern which should be used to find the tag */
	char tagendline;	/* 1: the pattern include '$' */
};
static struct tag *curtag;
/*
 * Cleanup loading tag structure.
 */
	public void
cleantags()
{
	struct tag *tag_p, *tag_save_p;

	/* Clear any existing tag circle queue */
	/* XXX Ideally, we wouldn't do this until after we know that we
	 * can load some other tag information. */
	curtag = NULL;
	tag_p = CIRCLEQ_FIRST(&tag_q);
	if (tag_p) {
		while (tag_p != (void *)&tag_q) {
			tag_save_p = CIRCLEQ_NEXT(tag_p, ptrs);
			free(tag_p);
			tag_p = tag_save_p;
		}
	}
	CIRCLEQ_INIT(&tag_q);
	total = curseq = 0;
}
/*
 * Make new tag entry.
 *
 * return 0 when result is OK, -1 when memory allocation error.
 */
static struct tag *
maketagent(name, file, line, pattern, end)
char *name;
char *file;
int line;
char *pattern;
int end;
{
	struct tag *tag_p;

	tag_p = calloc(sizeof(struct tag), 1);
	if (!tag_p)
		goto err;
	tag_p->tagfile = malloc(strlen(file) + 1);
	if (!tag_p->tagfile)
		goto err;
	strcpy(tag_p->tagfile, file);
	if (pattern) {
		tag_p->tagpattern = malloc(strlen(pattern) + 1);
		if (!tag_p->tagpattern)
			goto err;
		strcpy(tag_p->tagpattern, pattern);
		tag_p->tagendline = end;
	} else {
		tag_p->taglinenum = line;
	}
	return tag_p;
err:
	if (tag_p) {
		/* These pointers are cleaned by default. */
		if (tag_p->tagfile)
			free(tag_p->tagfile);
		if (tag_p->tagpattern)
			free(tag_p->tagpattern);
		free(tag_p);
	}
	return NULL;
}

/*
 * Get tag mode.
 *
 * Tag file name tell us the mode.
 */
#include <sys/stat.h>
	public int
gettagtype()
{
	int type;
	struct stat sb;

	if (!strcmp(tags, "GTAGS"))
		type = T_GTAGS;
	else if (!strcmp(tags, "GRTAGS"))
		type = T_GRTAGS;
	else if (!strcmp(tags, "GSYMS"))
		type = T_GSYMS;
	else if (!strcmp(tags, "GPATH"))
		type = T_GPATH;
	else if (!strcmp(tags, "-"))
		type = T_CTAGS_X;
	else if (stat(tags, &sb) == 0)
		type = T_CTAGS;
	else
		type = T_GTAGS;
	return type;
}
/*
 * Find tags in tag file.
 */
	public void
findtag(tag)
	register char *tag;
{
	int type = gettagtype();
	switch (type) {
	case T_CTAGS:
		findctag(tag);
		break;
	case T_GTAGS:
	case T_GRTAGS:
	case T_GSYMS:
	case T_GPATH:
	case T_CTAGS_X:
		findgtag(tag, type);
		break;
	}
}

/*
 * Search for a tag.
 */
	public POSITION
tagsearch()
{
	if (!curtag)
		return (NULL_POSITION);  /* No gtags loaded! */
	if (curtag->taglinenum)
		return gtagsearch();
	else
		return ctagsearch();
}
/*
 * Go to the next tag.
 *
 * return file name which should be read.
 */
	public char *
nexttag(number)
int number;
{
	char *tagfile;

	while (number--) tagfile = nextgtag();
	return tagfile;
}
/*
 * Go to the previous tag.
 *
 * return file name which should be read.
 */
	public char *
prevtag(number)
int number;
{
	char *tagfile;

	while (number--) tagfile = prevgtag();
	return tagfile;
}

/*
 * return the total number of tag.
 */
	public int
ntags()
{
	return total;
}
/*
 * return the sequence number of current tag.
 */
	public int
curr_tag()
{
	return curseq;
}
/*******************************************************************************
 *
 * ctags
 *
 */

/*
 * Find tags in the "tags" file.
 * Sets curtag to the first tag entry.
 */
static void
findctag(tag)
	register char *tag;
{
	char *p;
	char *q;
	register FILE *f;
	register int taglen;
	register int taglinenum;
	char *tagfile;
	char *tagpattern;
	int tagendline;
	int search_char;
	int err;
	char tline[TAGLINE_SIZE];
	struct tag *tag_p;

	p = unquote_file(tags);
	f = fopen(p, "r");
	free(p);
	if (f == NULL)
	{
		error("No tags file", NULL_PARG);
		return;
	}

	/* Cleanup loading tag structure if any. */
	cleantags();
	total = 0;

	taglen = strlen(tag);

	/*
	 * Search the tags file for the desired tag.
	 */
	while (fgets(tline, sizeof(tline), f) != NULL)
	{
		/*
		 * It's header of extended format. Skip.
		 */
		if (tline[0] == '!')
			continue;
		if (strncmp(tag, tline, taglen) != 0 || !WHITESP(tline[taglen]))
			continue;

		/*
		 * Found it.
		 * The line contains the tag, the filename and the
		 * location in the file, separated by white space.
		 * The location is either a decimal line number, 
		 * or a search pattern surrounded by a pair of delimiters.
		 * Parse the line and extract these parts.
		 */
		tagfile = NULL;
		taglinenum = 0;
		tagpattern = NULL;

		/*
		 * Skip over the whitespace after the tag name.
		 */
		p = skipsp(tline+taglen);
		if (*p == '\0')
			/* File name is missing! */
			continue;

		/*
		 * Save the file name.
		 * Skip over the whitespace after the file name.
		 */
		tagfile = p;
		while (!WHITESP(*p) && *p != '\0')
			p++;
		*p++ = '\0';
		p = skipsp(p);
		if (*p == '\0')
			/* Pattern is missing! */
			continue;

		/*
		 * First see if it is a line number. 
		 */
		taglinenum = getnum(&p, 0, &err);
		if (err)
		{
			/*
			 * No, it must be a pattern.
			 * Delete the initial "^" (if present) and 
			 * the final "$" from the pattern.
			 * Delete any backslash in the pattern.
			 */
			taglinenum = 0;
			search_char = *p++;
			if (*p == '^')
				p++;
			tagpattern = p;
			while (*p != search_char && *p != '\0')
			{
				if (*p == '\\')
					p++;
				p++;
			}
			tagendline = (p[-1] == '$');
			if (tagendline)
				p--;
			*p = '\0';
		}
		/* Make new entry and add to queue */
		tag_p = maketagent(tag, tagfile, taglinenum, tagpattern, tagendline);
		if (tag_p) {
			CIRCLEQ_INSERT_TAIL(&tag_q, tag_p, ptrs);
		} else {
			error("malloc() failed", NULL_PARG);
			if (f != stdin)
				pclose(f);
			return;
		}
		total++;
	}
	fclose(f);
	if (total == 0) {
		error("No such tag in tags file", NULL_PARG);
		return;
	}
	curtag = CIRCLEQ_FIRST(&tag_q);
	curseq = 1;
}
/*
 * Edit current tagged file.
 */
	public int
edit_tagfile()
{
	int r;

	if (curtag == NULL)
		return (1);
	return edit(curtag->tagfile);
}

/*
 * Search for a tag.
 * This is a stripped-down version of search().
 * We don't use search() for several reasons:
 *   -	We don't want to blow away any search string we may have saved.
 *   -	The various regular-expression functions (from different systems:
 *	regcmp vs. re_comp) behave differently in the presence of 
 *	parentheses (which are almost always found in a tag).
 */
static POSITION
ctagsearch()
{
	POSITION pos, linepos;
	int linenum;
	int len;
	char *line;

	pos = ch_zero();
	linenum = find_linenum(pos);

	for (;;)
	{
		/*
		 * Get lines until we find a matching one or 
		 * until we hit end-of-file.
		 */
		if (ABORT_SIGS())
			return (NULL_POSITION);

		/*
		 * Read the next line, and save the 
		 * starting position of that line in linepos.
		 */
		linepos = pos;
		pos = forw_raw_line(pos, &line);
		if (linenum != 0)
			linenum++;

		if (pos == NULL_POSITION)
		{
			/*
			 * We hit EOF without a match.
			 */
			error("Tag not found", NULL_PARG);
			return (NULL_POSITION);
		}

		/*
		 * If we're using line numbers, we might as well
		 * remember the information we have now (the position
		 * and line number of the current line).
		 */
		if (linenums)
			add_lnum(linenum, pos);

		/*
		 * Test the line to see if we have a match.
		 * Use strncmp because the pattern may be
		 * truncated (in the tags file) if it is too long.
		 * If tagendline is set, make sure we match all
		 * the way to end of line (no extra chars after the match).
		 */
		len = strlen(curtag->tagpattern);
		if (strncmp(curtag->tagpattern, line, len) == 0 &&
		    (!curtag->tagendline || line[len] == '\0' || line[len] == '\r')) {
			/*
			 * Set line number to tag entry while forwarding.
			 * It can be used while back fowarding.
			 */
			curtag->taglinenum = find_linenum(linepos);
			jump_back(curtag->taglinenum);
			break;
		}
	}

	return (linepos);
}

/*******************************************************************************
 *
 * gtags
 *
 */

/*
 * Find tags in the GLOBAL's tag file.
 * The findgtag() will try and load information about the requested tag.
 * It does this by calling "global -x tag" and storing the parsed output
 * for future use by gtagsearch().
 * Sets curtag to the first tag entry.
 */
static void
findgtag(tag, type)
	char *tag;		/* tag to load */
	int type;		/* tags type */
{
	char command[512];
	char *flag;
	char buf[256];
	int status;
	FILE *fp;
	struct tag *tag_p;

	if (type != T_CTAGS_X && !tag) {
		return;
	}

	/* Cleanup loading tag structure if any. */
	cleantags();
	total = 0;

	/*
	 * If type == T_CTAGS_X then read ctags's -x format from stdin
	 * else execute global(1) and read from it;
	 */
	if (type == T_CTAGS_X) {
		fp = stdin;
		/*
		 * Set tag default because we cannot read stdin again.
		 */
		tags = "tags";
	} else {
		/* Get suitable flag value for global(1). */
		switch (type) {
		case T_GTAGS:
			flag = "" ;
			break;
		case T_GRTAGS:
			flag = "r";
			break;
		case T_GSYMS:
			flag = "s";
			break;
		case T_GPATH:
			flag = "P";
			break;
		default:
			error("unknown tag type", NULL_PARG);
		}

		/* Get our data from global(1) */
#ifdef HAVE_SNPRINTF
		snprintf(command, sizeof(command),
#else
		sprintf(command,
#endif /* HAVE_SNPRINTF */
			"global -x%s '%s' 2>/dev/null", flag, tag);
		fp = popen(command, "r");
	}
	if (fp) {
		while (fgets(buf, sizeof(buf), fp)) {
			char *name, *file, *line;

			if (sigs) {
				if (fp != stdin)
					pclose(fp);
				return;
			}
				
			/* chop(buf) */
			if (buf[strlen(buf) - 1] == '\n')
				buf[strlen(buf) - 1] = 0;
			else
				while (fgetc(fp) != '\n')
					;

 			if (getentry(buf, &name, &file, &line)) {
				/*
				 * Couldn't parse this line for some reason.
				 * We'll just pretend it never happened.
				 */
				break;
			}

			/* Make new entry and add to queue */
			tag_p = maketagent(name, file, atoi(line), NULL, 0);
			if (tag_p) {
				CIRCLEQ_INSERT_TAIL(&tag_q, tag_p, ptrs);
			} else {
				error("malloc() failed", NULL_PARG);
				if (fp != stdin)
					pclose(fp);
				return;
			}
			total++;
		}
		if (fp != stdin) {
			status = pclose(fp);
			if (status) {
				error("No tags file", NULL_PARG);
				curtag = NULL;
				total = curseq = 0;
				return;
			}
		}
	}

	/* Check to see if we found anything. */
	if (CIRCLEQ_EMPTY(&tag_q))
		return;  /* Nope! */

	curtag = CIRCLEQ_FIRST(&tag_q);
	curseq = 1;
}

static int circular = 0;	/* 1: circlular tag structure */
/*
 * Return the filename required for the next gtag in the queue that was setup
 * by findgtag().  The next call to gtagsearch() will try to position at the
 * appropriate tag.
 */
static char *
nextgtag()
{
	if (!curtag)
		/* No tag loaded */
		return NULL;

	/*
	 * It is the last tag entry.
	 */
	if (CIRCLEQ_NEXT(curtag, ptrs) == (void *)&tag_q) {
		if (!circular)
			return NULL;
		/* Wrapped around to the head of the queue */
		curtag = CIRCLEQ_FIRST(&tag_q);
		curseq = 1;
	} else {
		curtag = CIRCLEQ_NEXT(curtag, ptrs);
		curseq++;
	}
	return curtag->tagfile;
}

/*
 * Return the filename required for the previous gtag in the queue that was
 * setup by findgtat().  The next call to gtagsearch() will try to position
 * at the appropriate tag.
 */
static char *
prevgtag()
{
	if (!curtag)
		/* No tag loaded */
		return NULL;

	/*
	 * It is the first tag entry.
	 */
	if (CIRCLEQ_PREV(curtag, ptrs) == (void *)&tag_q) {
		if (!circular)
			return NULL;
		/* Wrapped around to the tail of the queue */
		curtag = CIRCLEQ_LAST(&tag_q);
		curseq = total;
	} else {
		curtag = CIRCLEQ_PREV(curtag, ptrs);
		curseq--;
	}
	return curtag->tagfile;
}

/*
 * Position the current file at at what is hopefully the tag that was chosen
 * using either findtag() or one of nextgtag() and prevgtag().  Returns -1
 * if it was unable to position at the tag, 0 if succesful.
 */
static POSITION
gtagsearch()
{
	if (!curtag)
		return (NULL_POSITION);  /* No gtags loaded! */

	jump_back(curtag->taglinenum);

	/*
	 * XXX We'll assume we were successful --- jump_back() will call error()
	 * if it fails, so the user will receive some kind of notification.
	 * Eventually, jump_back() should do its work silently and let us
	 * perform the error notification, eventually allowing our caller
	 * (presumably tagsearch()) to go error("Could not locate tag.");
	 */
	return (find_pos(curtag->taglinenum));
}

/*
 * The getentry() parses both standard and extended ctags -x format.
 *
 * [standard format]
 * <tag>   <lineno>  <file>         <image>
 * +------------------------------------------------
 * |main     30      main.c         main(argc, argv)
 * |func     21      subr.c         func(arg)
 *
 * The following commands write this format.
 *	o Traditinal Ctags with -x option
 *	o Global with -x option
 *		See <http://www.tamacom.com/global>
 *
 * [extended format]
 * <tag>   <type>  <lineno>   <file>        <image>
 * +----------------------------------------------------------
 * |main     function 30      main.c         main(argc, argv)
 * |func     function 21      subr.c         func(arg)
 *
 * The following commands write this format.
 *	o Exuberant Ctags with -x option
 *		See <http://ctags.sourceforge.net>
 *
 * Returns 0 on success, -1 on error.
 * The tag, file, and line will each be NUL-terminated pointers
 * into buf.
 */
static int
getentry(buf, tag, file, line)
	char *buf;	/* standard or extended ctags -x format data */
	char **tag;	/* name of the tag we actually found */
	char **file;	/* file in which to find this tag */
	char **line;	/* line number of file where this tag is found */
{
	char *p = buf;

	for (*tag = p; *p && !isspace(*p); p++)		/* tag name */
		;
	if (*p == 0)
		goto err;
	*p++ = 0;
	for (; *p && isspace(*p); p++)			/* (skip blanks) */
		;
	if (*p == 0)
		goto err;
	/*
	 * If the second part begin with other than digit,
	 * it is assumed tag type. Skip it.
	 */
	if (!isdigit(*p)) {
		for (; *p && !isspace(*p); p++)		/* (skip tag type) */
			;
		for (; *p && isspace(*p); p++)		/* (skip blanks) */
			;
	}
	if (!isdigit(*p))
		goto err;
	*line = p;					/* line no */
	for (*line = p; *p && !isspace(*p); p++)
		;
	if (*p == 0)
		goto err;
	*p++ = 0;
	for (; *p && isspace(*p); p++)			/* (skip blanks) */
		;
	if (*p == 0)
		goto err;
	*file = p;					/* file name */
	for (*file = p; *p && !isspace(*p); p++)
		;
	if (*p == 0)
		goto err;
	*p = 0;

	/* value check */
	if (strlen(*tag) && strlen(*line) && strlen(*file) && atoi(*line) > 0)
		return (0);	/* OK */
err:
	return (-1);		/* ERROR */
}

#endif