#!/bin/sh
#
# mailmonth - outputs a mail folder name for X months ago
# Copyright (C) 2000,2001 Chris Gushue <chris@blackplasma.net>
#
#     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., 675 Mass Ave, Cambridge, MA 02139, USA.
#
# $Id: mailmonth,v 1.8 2001/01/03 15:45:07 seymour Exp $

# I made this little shell script so I wouldn't have to keep changing
# the monthly mail folders for Mutt (used in conjunction with my procmail
# scripts, available from the place you obtained this script) manually.
#
# eg. "./mailmonth 2" will display the folder for two months ago
#     "./mailmonth 1" will display the folder for last month
#     "./mailmonth" will display the folder for the current month
#
# To be used in .muttrc as follows:
#
# mailboxes +`~/.mutt/mailmonth`/Inbox
# mailboxes +`~/.mutt/mailmonth 2`
# mailboxes +`~/.mutt/mailmonth 1`
#
# Visit http://mutt.lazygenes.net for more of my Mutt stuff

GNUDATE="yes" # Change to "no" if you aren't using the GNU date util

if [ $# -eq 0 ]; then
  echo `date +%Y/%m`
else
  if [ $GNUDATE = "yes" ]; then 
    echo `date -d "$1 months ago" +%Y/%m`
  else
    echo `date -v -$1m +"%Y/%m"`
  fi
fi

exit 0

## ** This method has problems still **
# Method which doesn't rely on GNU date, thanks to BinarySoul <binary@b1n.org>
m=`date +%m`
y=`date +%Y`

if [ $# -eq 0 ] ; then
  dt="$y/$m"
else
  d=$1
  m=$(($m - $d))
  if [ $m -eq 0 ] ; then
    m=12
    y=$(($y - 1))
  elif [ $m -lt 0 -a $m -gt -12 ] ; then
    m=$((12 - $d + 1))
    y=$(($y - 1))
  elif [ $m -le -12 ] ; then
    m=$((  $m * -1))
    y2=$(( $m/12 - 1 ))
    y=$(( $y - $y2 ))
    m=$(( 12 - ($m%12) ))
  fi
  dt="$y/$m"
fi

echo $dt