/*-
 * Copyright (c) 1999 Chris Costello
 * 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 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 AUTHOR 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.
 *
 * $Id: rtfm.c,v 1.9 2000/01/18 05:06:29 chris Exp $
 *
 */

#include <sys/types.h>
#include <sys/param.h>

#include <ctype.h>
#include <dirent.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void	 chomp(char *);
void	 search_manuals(void);
void	 search_texinfo(void);
void	 usage(void);
char	*add_spaces(char *);
char	*Rstrcasestr(char *, char *);
char	*Rstrstr(char *, char *);

static char *prog, *keyword;
extern char *__progname;

static int cflag, dflag, iflag, mflag, tflag, wflag;

/* From /usr/src/contrib/texinfo/info/filesys.h */
const char *info_paths[] = {
	"/usr/local/info",
	"/usr/info",
	"/usr/local/lib/info",
	"/usr/lib/info",
	"/usr/local/gnu/info",
	"/usr/local/gnu/lib/info",
	"/usr/gnu/info",
	"/usr/gnu/lib/info",
	"/opt/gnu/info",
	"/usr/share/info",
	"/usr/share/lib/info",
	"/usr/local/share/info",
	"/usr/local/share/lib/info",
	"/usr/gnu/lib/emacs/info",
	"/usr/local/gnu/lib/emacs/info",
	"/usr/local/lib/emacs/info",
	"/usr/local/emacs/info",
	".",
	NULL
};

int ninfo_paths = sizeof(info_paths) / sizeof(info_paths[0]);

/*
 * Match strings depending on iflag
 */
char *
Rstrstr(char *s, char *find)
{
	if (iflag)
		return Rstrcasestr(s, find);
	return strstr(s, find);
}

char *
Rstrcasestr(char *s, char *find)
{
	register char c, sc;
	register size_t len;

	if ((c = *find++) != 0) {
		len = strlen(find);
		do {
			do {
				if ((sc = *s++) == 0)
					return (NULL);
			} while (toupper(sc) != toupper(c));
		} while (strncasecmp(s, find, len) != 0);
		s--;
	}
	return ((char *)s);
}

/*
 * Put a space at the beginning and end of a string.
 */
char *
add_spaces(char *s)
{
	char *ret = calloc(sizeof(char), strlen(s) +3);

	sprintf(ret, " %s ", s);

	return ret;
}

/*
 * This function cuts off any trailing line terminators.
 */
void
chomp(char *s)
{
	size_t loc = strlen(s) - 1;

	if (s[loc] == '\n')
		s[loc--] = 0;
	if (s[loc] == '\r')
		s[loc--] = 0;
}

void
usage(void)
{
	fprintf(stderr, "usage: %s [-cdimtw] keyword\n", __progname);
	exit(1);
}

/*
 * Searches the manuals.
 */
void
search_manuals(void)
{
	FILE *p;
	char *sp, *prog_args;
	char fbuf[BUFSIZ];
	char *bad_val = NULL;
	int printed_header = 0;

	/*
	 * Create what we'll compare to prog's output so we can check if
	 * anything was found.
	 */
	asprintf(&bad_val, "%s: nothing appropriate", keyword);

	/* Create the command string that we'll pass to popen(3) */
	prog_args = malloc(strlen(prog) + strlen(keyword) + 1);
	sprintf(prog_args, "%s %s", prog, keyword);

	if ((p = popen(prog_args, "r")) == NULL) {
		free(prog_args);
		err(1, "popen: %s", prog);
		return;
	}
	while (fgets(fbuf, sizeof(fbuf), p)) {
		register char *paren, *name;

		if (!printed_header) {
			printed_header++;
			printf("Manual pages found:\n");
		}
		chomp(fbuf);

		if (!strcmp(fbuf, bad_val)) {
			if (bad_val)
				free(bad_val);
			return;
		}

		name = fbuf;
		paren = strchr(fbuf, '(');

		if (paren == NULL)
			return;

		*paren = 0;
		paren++;

		sp = paren;
		paren = strchr(sp, ')');
		if (paren == NULL)
			return;
			
		*paren = 0;

		if (cflag)
			printf("  man %s %s\n", sp, name);
		else
			printf("  %s(%s)\n", name, sp);

		if (dflag) {
			char *dash;

			dash = strchr(paren + 1, '-');
			if (dash == NULL)
				continue;

			dash += 2;
			if (*(dash - 1) == '\0' || *dash == '\0')
				continue;

			printf("    %s\n", dash);
		}
	}

	if (bad_val)
		free(bad_val);

	free(prog_args);
}

/*
 * Search GNU Texinfo pages
 */
void
search_texinfo()
{
	DIR *dir;
	struct dirent *ent;
	int printed_header = 0, i;
	char startdir[MAXPATHLEN];

	/* Preserve original directory. */
	getcwd(startdir, sizeof(startdir));

	for (i = 0; i < ninfo_paths; i++) {
		if (!printed_header) {
			printed_header++;
			printf("\nGNU Texinfo pages found:\n");
		}
		if ((dir = opendir(info_paths[i])) == NULL)
			continue;

		/*
		 * Change to the directory so we can more easily access
		 * files.
		 */
		chdir(info_paths[i]);

		while ((ent = readdir(dir)) != NULL) {
			if (ent->d_type == DT_REG) {
				char *command, c;
				int matches = 0;
				FILE *p;

				/*
				 * Anything that does not end in '.info.gz'
				 * is not a Texinfo page.
				 */
				if (strcasecmp(".info.gz", &ent->d_name[ent->d_namlen - 8])
				    && strcasecmp(".info", &ent->d_name[ent->d_namlen - 5]))
					continue;

				/*
				 * See if we can read it.  We don't want
				 * confusing stderr from zgrep annoying the
				 * user.
				 */
				if (access(ent->d_name, R_OK) < 0)
					continue;

				/*
				 * Create the string we'll be passing to
				 * popen(3)
				 */
				command = calloc(sizeof(char), strlen(ent->d_name) +
						 strlen(keyword) + 8);

				(void)sprintf(command, "zgrep %s %s %s %s",
				       wflag ? "-w" : "", iflag ? "-i" : "",
					       keyword, ent->d_name);

				if ((p = popen(command, "r")) == NULL) {
					warn("popen");
					return;
				}
				while ((c = fgetc(p)) != EOF)
					if (c == '\n')
						matches++;

				pclose(p);

				if (!matches)
					continue;

				if (cflag) {
					char *iptr;

					/*
					 * Strip the .info.gz from the end of
					 * the string to create a command the
					 * user can type at his shell prompt.
					 */
					iptr = strchr(ent->d_name, '.');
					if (iptr)
						*iptr = 0;
					(void)printf("  info %s\n", ent->d_name);
				} else
					(void)printf("  %s (%d matches)\n", ent->d_name,
						      matches);
			}
		}
		(void)closedir(dir);
	}

	/* Switch back to the original directory. */
	chdir(startdir);

}

int
main(int argc, char **argv)
{
	int c;

	prog = "apropos";

	while ((c = getopt(argc, argv, "cdimtw")) != -1)
		switch (c) {
		case 'c':
			cflag = 1;
			break;
		case 'd':
			dflag = 1;
			break;
		case 'i':
			iflag = 1;
			break;
		case 'm':
			mflag = 1;
			break;
		case 't':
			tflag = 1;
			break;
		case 'w':
			wflag = 1;
			prog = "whatis";
			break;
		default:
			usage();
			/* NOTREACHED */
		}

	argc -= optind;
	argv += optind;

	if (argc < 1) {
		usage();
		/* NOTREACHED */
	}
	keyword = argv[0];

	if (wflag)
		keyword = add_spaces(keyword);

	/* Search manuals only */
	if (mflag) {
		search_manuals();
		exit(0);
	}
	/* Search texinfo only */
	if (tflag) {
		search_texinfo();
		exit(0);
	}
	search_manuals();
	search_texinfo();

	return 0;
}