/* dir.c -- How to build a special "dir" node from "localdir" files. */

/* This file is part of GNU Info, a program for reading online documentation
   stored in Info format.

   Copyright (C) 1993 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

   Written by Brian Fox (bfox@ai.mit.edu). */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/errno.h>
#include "info-utils.h"
#include "filesys.h"
#include "tilde.h"

/* The "dir" node can be built from the contents of a file called "dir",
   with the addition of the menus of every file called "localdir" found in
   INFOPATH. */

static void add_menu_to_file_buffer (), insert_text_into_fb_at_binding ();

void
maybe_build_dir_node (dirname, from_files_named)
     char *dirname;
     char *from_files_named;
{
  FILE_BUFFER *dir_buffer;

  /* See if the file has already been loaded and exists. */
  dir_buffer = info_find_file (dirname);

  /* If there is no "dir" in the current info path, we cannot build one
     from nothing. */
  if (!dir_buffer)
    return;

  /* If this directory has already been built, return now. */
  if (dir_buffer->flags & N_CannotGC)
    return;

  dir_buffer->flags |= N_CannotGC;

  /* For every file named FROM_FILES_NAMED in the search path, add the
     contents of that file's menu to our "dir" node. */
  {
    struct stat finfo;
    char *this_dir;
    int namelen, path_index;
    int update_tags = 0;

    namelen = strlen (from_files_named);
    path_index = 0;

    /* Using each element of the path, check for "localdir".  Do not check
       for "localdir.info.Z" or anything else.  Only files explictly named
       "localdir" are eligible.  This is a design decision.  There can be
       an info file name "localdir.info" which contains information on the
       setting up of "localdir" files. */
    while (this_dir = extract_colon_unit (infopath, &path_index))
      {
	char *fullpath;
	int statable;

	/* Expand a leading tilde if one is present. */
	if (*this_dir == '~')
	  {
	    char *tilde_expanded_dirname;

	    tilde_expanded_dirname = tilde_expand_word (this_dir);
	    free (this_dir);
	    this_dir = tilde_expanded_dirname;
	  }

	fullpath = (char *)xmalloc (3 + strlen (this_dir) + namelen);
	strcpy (fullpath, this_dir);
	if (fullpath[strlen (fullpath) - 1] != '/')
	  strcat (fullpath, "/");
	strcat (fullpath, from_files_named);

	statable = (stat (fullpath, &finfo) == 0);

	if (statable && S_ISREG (finfo.st_mode))
	  {
	    long filesize;
	    char *contents;

	    contents = filesys_read_info_file (fullpath, &filesize, &finfo);

	    if (contents)
	      {
		update_tags++;
		add_menu_to_file_buffer (contents, filesize, dir_buffer);
		free (contents);
	      }
	  }

	free (fullpath);
	free (this_dir);
      }
    if (update_tags)
      build_tags_and_nodes (dir_buffer);
  }
}

/* Given CONTENTS and FB (a file buffer), add the menu found in CONTENTS
   to the menu found in FB->contents.  Second argument SIZE is the total
   size of CONTENTS. */
static void
add_menu_to_file_buffer (contents, size, fb)
     char *contents;
     long size;
     FILE_BUFFER *fb;
{
  SEARCH_BINDING contents_binding, fb_binding;
  long contents_offset, fb_offset;

  contents_binding.buffer = contents;
  contents_binding.start = 0;
  contents_binding.end = size;
  contents_binding.flags = S_FoldCase | S_SkipDest;

  fb_binding.buffer = fb->contents;
  fb_binding.start = 0;
  fb_binding.end = fb->filesize;
  fb_binding.flags = S_FoldCase | S_SkipDest;

  /* Move to the start of the menus in CONTENTS and FB. */
  contents_offset = search_forward (INFO_MENU_LABEL, &contents_binding);
  fb_offset = search_forward (INFO_MENU_LABEL, &fb_binding);

  /* If there is no menu in CONTENTS, quit now. */
  if (contents_offset == -1)
    return;

  /* If there is no menu in FB, make one. */
  if (fb_offset == -1)
    {
      /* Find the start of the second node in this file buffer.  If there
	 is only one node, we will be adding the contents to the end of
	 this node. */
      fb_offset = find_node_separator (&fb_binding);

      /* If not even a single node separator, give up. */
      if (fb_offset == -1)
	return;

      fb_binding.start = fb_offset;
      fb_binding.start +=
	skip_node_separator (fb_binding.buffer + fb_binding.start);

      /* Try to find the next node separator. */
      fb_offset = find_node_separator (&fb_binding);

      /* If found one, consider that the start of the menu.  Otherwise, the
	 start of this menu is the end of the file buffer (i.e., fb->size). */
      if (fb_offset != -1)
	fb_binding.start = fb_offset;
      else
	fb_binding.start = fb_binding.end;

      insert_text_into_fb_at_binding
	(fb, &fb_binding, INFO_MENU_LABEL, strlen (INFO_MENU_LABEL));

      fb_binding.buffer = fb->contents;
      fb_binding.start = 0;
      fb_binding.end = fb->filesize;
      fb_offset = search_forward (INFO_MENU_LABEL, &fb_binding);
      if (fb_offset == -1)
	abort ();
    }

  /* CONTENTS_OFFSET and FB_OFFSET point to the starts of the menus that
     appear in their respective buffers.  Add the remainder of CONTENTS
     to the end of FB's menu. */
  fb_binding.start = fb_offset;
  fb_offset = find_node_separator (&fb_binding);
  if (fb_offset != -1)
    fb_binding.start = fb_offset;
  else
    fb_binding.start = fb_binding.end;

  insert_text_into_fb_at_binding
    (fb, &fb_binding, contents + contents_offset, size - contents_offset);
}

static void
insert_text_into_fb_at_binding (fb, binding, text, textlen)
     FILE_BUFFER *fb;
     SEARCH_BINDING *binding;
     char *text;
     int textlen;
{
  char *contents;
  long start, end;

  start = binding->start;
  end = fb->filesize;

  contents = (char *)xmalloc (fb->filesize + textlen + 1);
  memcpy (contents, fb->contents, start);
  memcpy (contents + start, text, textlen);
  memcpy (contents + start + textlen, fb->contents + start, end - start);
  free (fb->contents);
  fb->contents = contents;
  fb->filesize += textlen;
  fb->finfo.st_size = fb->filesize;
}