############################################################################
#
#	File:     hotedit.icn
#
#	Subject:  Program to edit a Mosaic hotlist
#
#	Author:   Gregg M. Townsend
#
#	Date:     June 23, 2000
#
############################################################################
#
#   This file is in the public domain.
#
############################################################################
#
#  ===> IMPORTANT NOTE:  This program was written for "NCSA Mosaic 2.4"
#  ===> and is incompatible with the current version of Mosaic.
#
#  Hotedit makes it easy to edit the "hotlist" used with NCSA Mosaic,
#  a program for grazing the Wide World Web (WWW).  The Mosaic hotlist
#  is a text file, and it can be edited directly, but this is difficult
#  and error-prone.  Pairs of lines must be kept together, and the long
#  "Uniform Record Locator" (URL) lines make it hard to pick out the
#  title lines, which are of more interest.
#
#  Hotedit works by extracting the titles, bringing up an editor of the
#  user's choice, then processing the results when the editor exits.
#  The user can reorder, retitle, or delete lines; adding new entries
#  is best done within NCSA Mosaic.  It is vital that any editing 
#  preserve the three-digit number at the front of each line; hotedit
#  uses this to reconnect the titles with the corresponding URLs.
#
#  The editor is determined by the environment variable VISUAL (or, if
#  that is missing, EDITOR).  The hotlist file is assumed to be in the
#  usual place, $HOME/.mosaic-hotlist-default.  Because not all editors
#  return a reasonable exit status, the hotlist is *always* rewritten;
#  the previous edition is saved in $HOME/.mosaic-hotlist-backup.
#
#  Hotedit shouldn't be run while NCSA Mosaic is running; when Mosaic
#  exits, it is likely to overwrite the edited hotlist.
#
############################################################################
#
#  Requires:  Unix, NCSA Mosaic
#
############################################################################

$define TMPFILE "hotlist.tmp"
$define HOTFILE ".mosaic-hotlist-default"
$define HOTOLD ".mosaic-hotlist-backup"
$define HOTNEW ".mosaic-hotlist-revised"
$define HOTFORMAT "ncsa-xmosaic-hotlist-format-1"

procedure main()
   local home, f, t, line, n, editor, command, urllist

   home := getenv("HOME")	| stop("no $HOME value")
   chdir(home)			| stop("can't chdir to ", home)

   f := open(HOTFILE)		| stop("can't open ", HOTFILE)
   line := read(f)		| stop("empty hotlist file")
   line == HOTFORMAT		| stop("unrecognized hotlist format")
   line := read(f)		| stop("truncated hotlist file")
   line == "Default"		| stop("unrecognized hotlist format")

   t := open(TMPFILE, "w")	| stop("can't write ", TMPFILE)

   urllist := []
   while put(urllist, read(f)) do {
      line := read(f)		| stop("ill-formated hotlist file")
      if *urllist < 1000 then
         n := right(*urllist, 3, "0")
      else
         n := *urllist
      write(t, n, " ", line)
      }
   close(f)
   close(t)

   f := open(HOTNEW, "w")	| stop("can't write ", HOTNEW)

   editor := getenv("VISUAL") | getenv("EDITOR") | "/bin/vi"
   command := editor || " " || TMPFILE

   system(command)

   t := open(TMPFILE)		| stop("can't reopen ", TMPFILE)
   write(f, HOTFORMAT)
   write(f, "Default")
   while line := read(t) do line ? {
      if write(f, urllist[tab(many(&digits))]) then
         write(f, move(1) & tab(0))
      else 
         write(&errout, "invalid index: ", line)
      }

   remove(HOTOLD)
   (rename(HOTFILE, HOTOLD) & rename(HOTNEW, HOTFILE)) |
      stop("couldn't rename files; new file left in ", HOTNEW)
end