#!/usr/local/bin/bash
#
# $Id: xbiff-checkcommand-maildir,v 1.1 2004/06/19 11:50:37 suter Exp $
# Copyright (C) 2004 Mark Suter <suter@humbug.org.au>
#
# 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
# of the License, 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

# This will allow you to continue using xbiff(1) after you changed from
# mbox to maildir for your email.  From the manpage:
#
#     checkCommand (class CheckCommand)
#         Specifies a shell command to be executed to check for new
#         mail rather than examining the size of file.  The specified
#         string value is used as the argument to a system(3) call and
#         may therefore contain i/o redirection.  An exit status of 0
#         indicates that new mail is waiting, 1 indicates that there has
#         been no change in size, and 2 indicates that the mail has been
#         cleared.  By default, no shell command is provided.
#
# Here's an example usage from my ~/.Xresources:
#
#     xbiff*checkCommand: /home/suter/bin/xbiff-checkcommand-maildir /home/suter/mail/In/inbox/
#     xbiff*update: 45
#

## Our "die" function (think perl)
die () { echo "$@" 1>&2 ; exit 3 ; }

## Check for our needed binaries
hash test basename cat find wc touch || die $0: required binaries not present

## We expect one arguemnt, the maildir directory
maildir="$1"
test -n "$maildir"	|| die Usage: $(basename $0) maildir
test -d $maildir	|| die $0: Thing \"$maildir\" is not a directory.
test -d $maildir/new	|| die $0: Directory \"$maildir\" does not have a new subdir.

## We need to keep state
count=${TMPDIR:-/tmp}/.xbiff-checkcommand-maildir.count
state=${TMPDIR:-/tmp}/.xbiff-checkcommand-maildir.state

## Read the stored count (zero on error)
old=$(cat $count 2>/dev/null)
test -n "$old" || old=0

## Get current count of emails newer than our state file
if test -e $state ; then
    new=$(find $maildir/new/ -type f -newer $state -print | wc -l)
else
    new=$(find $maildir/new/ -type f -print | wc -l)
fi

## Write the count for next time
echo $new > $count	|| die $0: error writing state

## Exit correctly (according the man page above)
test $new -eq 0 -a $old -ne 0 && touch $state && exit 2 # new emails cleared
test $old -ge $new                            && exit 1 # no new arrivals since last check
test $old -lt $new                            && exit 0 # more new emails than last check

## Catch fallthough
die $0: should never be reached