!/bin/bash
#====================================================================
# filename: getARNL
#
# This script will download the latest copy of Amateur Radio Newsline
# MP3 file. Since ARNewsline no longer makes available a "generic"
# copy of the MP3 file, this script must first compute the volume 
# number for the latest release. This script uses the epoch date of 
# "2012-02-03" with a volume number of "1799" as its base for 
# omputing the current volume number.
#
# history:
# 20120316	kc6hur	Initial release
#====================================================================
#--------------------------------------------------------------------
# Date Functions
#--------------------------------------------------------------------
#----- Generate a Unix timestamp from a date
date2stamp () {
    /bin/date --utc --date "$1" +%s
}

#----- Calculate the difference between two dates in weeks
dateDiff (){
    sec=604800            # seconds per week
    date1=$(date2stamp $1)
    date2=$(date2stamp $2)
    diffSec=$((date2-date1))
    if ((diffSec < 0)); then abs=-1; else abs=1; fi
    echo $((diffSec/sec*abs))
}

#--------------------------------------------------------------------
# Main
#--------------------------------------------------------------------
#
#----- Make sure we are user repeater!!!
#
if [ `/usr/bin/whoami` != "repeater" ] ; then
  echo This program must be run as user REPEATER!
  exit 1
fi
#
#----- Make sure we have sourced the environment file
#
if [ "$RUN_ENV" != "TRUE" ] ; then
  echo -n "Loading IRLP environment..."
  . /home/irlp/custom/environment
  echo "DONE"
fi

NEWS="$AUDIO/custom/news" # Save the mp3 here
edate="2012-02-03"       # epoch date
erels="1799"             # epoch release
#
#----- Compute the latest ARNewsline release number
#
let "rels = $erels + $(dateDiff $edate now)"
#
#----- Generate URL for the latest ARNewsline release
#
URL="http://www.arnewsline.org/storage/audio/nsln$rels.mp3"
#
#----- Download the latest ARNewsline release
#
/usr/bin/wget -q -O ${NEWS}/newsline.mp3 ${URL}
exit 1