#!/bin/bash
#
# $Id: trimmbox,v 1.1 2002/12/21 17:06:56 adicvs Exp $
#
# This script will trim mbox files to the number of messages specified.
# It assumes that messages are deliverd into the mbox via procmail.
# Lock files are maintained appropriately,
#

maxmsg="100"
mboxmatch="$HOME/mail/Junkmail"

lockext=".lock"
tempext=".temp"

date=`date`

if [ "$1" = "-v" ]; then
    verbose="1"
fi

# Test mbox properties
test_mbox ()
{
    # Omit anything but files
    if [ ! -f "$mbox" ]; then
        [ "$verbose" ] && echo "$mbox is directory, skipping"
        return 1
    fi

    # Omit lock files and temp files
    case "$mbox" in
      *$lockext)
        [ "$verbose" ] && echo "$mbox is lockfile, skipping"
        return 1
        ;;
      *$tempext)
        [ "$verbose" ] && echo "$mbox is temporary file, skipping"
        return 1
        ;;
    esac

    return 0
}

# Append trim message to mbox
msg_mbox ()
{
    cat<<EOF
From trimmbox $date
Date: $date
From: trimmbox
Subject: Removed $skip messages

Removed $skip messages from this mailbox.
$date

EOF
}

# Process files in list directory
for mbox in $mboxmatch ; do

    # Skip failed mbox
    test_mbox || continue

    lock="$mbox$lockext"
    temp="$mbox$tempext"

    # Attempt to lock the mbox
    lockfile -10 -r 6 "$lock"
    if [ "$?" != "0" ]; then
        echo "$mbox locking failed!"
        continue
    fi
    
    # Determine the number of messages in the mbox file
    nummsg=`formail -X 'From ' -s < "$mbox" | wc -l`

    # Trim mbox if maxmsg exceeded
    if [ "$nummsg" -gt "$maxmsg" ]; then
        skip=$(( nummsg - maxmsg ))
        msg_mbox > "$temp"
        formail +"$skip" -s < "$mbox" >> "$temp"
        cat "$temp" > "$mbox"
        rm -f "$temp"
    fi

    # Remove lockfile
    rm -f "$lock"
    
done