/* vim:set ts=4 sw=4:
 *
 * This program makes a tags file for help text.
 *
 * Usage: doctags *.txt ... >tags
 *
 * A tag in this context is an identifier between stars, e.g. *c_files*
 */

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

#define LINELEN 200

	int
main(int argc, char **argv)
{
	char	line[LINELEN];
	char	*p1, *p2;
	char	*p;
	FILE	*fd;

	if (argc <= 1)
	{
		fprintf(stderr, "Usage: doctags docfile ... >tags\n");
		exit(1);
	}
	printf("help-tags\ttags\t1\n");
	while (--argc > 0)
	{
		++argv;
		fd = fopen(argv[0], "r");
		if (fd == NULL)
		{
			fprintf(stderr, "Unable to open %s for reading\n", argv[0]);
			continue;
		}
		while (fgets(line, LINELEN, fd) != NULL)
		{
			p1 = strchr(line, '*');				/* find first '*' */
			while (p1 != NULL)
			{
				p2 = strchr(p1 + 1, '*');		/* find second '*' */
				if (p2 != NULL && p2 > p1 + 1)	/* skip "*" and "**" */
				{
					for (p = p1 + 1; p < p2; ++p)
						if (*p == ' ' || *p == '\t' || *p == '|')
							break;
					/*
					 * Only accept a *tag* when it consists of valid
					 * characters, there is white space before it and is
					 * followed by a white character or end-of-line.
					 */
					if (p == p2
							&& (p1 == line || p1[-1] == ' ' || p1[-1] == '\t')
								&& (strchr(" \t\n\r", p[1]) != NULL
									|| p[1] == '\0'))
					{
						*p2 = '\0';
						++p1;
						printf("%s\t%s\t/*", p1, argv[0]);
						while (*p1)
						{
							/* insert backslash before '\\' and '/' */
							if (*p1 == '\\' || *p1 == '/')
								putchar('\\');
							putchar(*p1);
							++p1;
						}
						printf("*\n");
						p2 = strchr(p2 + 1, '*');		/* find next '*' */
					}
				}
				p1 = p2;
			}
		}
		fclose(fd);
	}
	return 0;
}
