#!/bin/bash
#
# calcweek.sh - calculate the current week of the semester
#

##
## Configuration - set dates to the MONDAY of the week in question
##
start="20100125"
break1="20100301"
break2="20100412"
duration="14"
boffset="0"
breakweek=0

##
## Obtain offsets
##
sem_start="`date +'%j' -d $start`"
sem_break1="`date +'%j' -d $break1`"
sem_break2="`date +'%j' -d $break2`"
sem_today="`date +'%j'`"

##
## Some debugging
##
#sem_today=95
#echo "sem_today: $sem_today"
#echo "sem_break1: $sem_break1"
#echo "sem_break2: $sem_break2"

##
## Determine break week offsets
##
if [ "$sem_today" -ge "$sem_break1" ]; then
    boffset=1
    let endofweek=${sem_break1}+6
    if [ "$sem_today" -le "$endofweek" ]; then
        breakweek=1
    fi
fi

if [ "$sem_today" -ge "$sem_break2" ]; then
    boffset=2
    let endofweek=${sem_break2}+6
    if [ "$sem_today" -le "$endofweek" ]; then
        breakweek=2
    fi
fi

##
## Perform THE calculation
##
week="$(((((${sem_today}-${sem_start})/7)+1)-$boffset))"

# If we're in a breakweek, week is set to 0.
if [ "$breakweek" -gt 0 ]; then
    week=0
fi

##
## If we're past the end of the semester, do nothing (set to 0, treat like breakweek)
##  
if [ "$week" -gt "$duration" ]; then
    week=0
fi      
    
##
## Produce output for other scripts to use
## 
echo "$week"
exit 0