#!/bin/sh
# Reads a delimited text file containing a daily Bible reading plan,
# finds the line corresponding to the current date, extracts each
# passage to be read, and sends them sequentially to the "kjv" program.
# If given a date on $1, finds the reading for that date instead.
# The -l option prints the passages listed for that date instead of
# sending them to kjv.

filedetails() {
  delim=";" # character that separates fields in reading plan file
  plandir="/usr/local/share/bibleplan" # path of plan directory
  planfile="plan.txt" # name of plan file
  case "$1" in
    show) echo $plandir/$planfile ;;
    edit) $EDITOR $plandir/$planfile ;;
    make) makeplan $2 ;;
  esac 
}

checkkjv() {
  [ -z $(which kjv) ] && echo "bibleplan: Couldn't find kjv(1). Is it installed and in your \$PATH?" && exit
}

printweekdays() {
  year="$1" && i=0
  dayone="Mon"
  daysperweek=5
  while [ "$day" != "$dayone" ]
  do
    i=$((i+1)) && day=$(date -d "$year-01-0$i" +%a)
  done
  day="$year-01-0$i" && i=0 && j=0
  while [ "$j" -lt 52 ]
  do
    i=0 && printf "\n"
    while [ "$i" -lt $daysperweek ]
    do
      k=$((i+j*7)) && echo "$(date -d "$day + $k days" +%d%^b);" && i=$((i+1))
    done
    j=$((j+1)) && printf "\n"
  done
}

makeplan() {
  printweekdays $1 | paste - $plandir/5daytemplate.txt -d\  | sed -e 's/^ //g'
}

makeuppercase() {
  echo "$1" | tr [:lower:] [:upper:]
}

todaydtg() {
  month=`date +%^b` # current month in the form "JAN" "FEB" etc
  day=`date +%d`    # day of month in the form "01" "31" etc
  dtg=$day$month
  echo $dtg
}

findpassages() {
  # to do: implement regex handling for proper dates
  dtg=$(makeuppercase $dtg)
  todaysreading=$(cat $plandir/$planfile | grep $dtg)
  [ -z "$todaysreading" ] && echo "No passages for $(echo $dtg | cut -c1,2) $(echo $dtg | cut -c3,4,5)." && exit 1
}

listpassages() {
  filedetails
  [ $# -eq 1 ] && dtg=$(paddtg $1) || dtg=$(todaydtg)
  dtg=$(makeuppercase $dtg)
  findpassages
  echo "$todaysreading"
  exit 0
}

paddtg() {
  [ $(echo "$1" | wc -m ) = 5 ] && echo 0$1 || echo $1
}

readpassages() {
  checkkjv
  filedetails
  [ $# -eq 1 ] && dtg=$(paddtg $1) || dtg=$(todaydtg)
  dtg=$(makeuppercase $dtg)
  [ $(echo -n "$dtg" | wc -c) = 4 ] && dtg=0$dtg
  findpassages
  i=1
  numberofpassages=$(echo "$todaysreading" | grep -o $delim | wc -l)
  while [ $i -lt $((numberofpassages+1)) ]
  do
    passage=$(echo $todaysreading | cut -f$((i+1)) -d$delim) # read j-th field
    kjv $passage
    i=$((i+1)) 
  done
}

help() {
  cat << EOF
bibleplan - Follow a Bible-reading plan with kjv(1).
Written 2020 by Ray Patrick.

Usage:
        $ bibleplan [date]
                If assigned reading exists for [date], opens it in kjv(1).
                If [date] is not given, looks up today's reading by
                default. Dates may be of the form: 1jan, 01jan, 1JAN,
                01JAN, etc.

        $ bibleplan -l, --list [date]
                Lists the assigned reading for [date]. If [date] is not
                given, looks up today's reading by default.

        $ bibleplan -f, --file
                Shows the plan file that bibleplan is using.

        $ bibleplan -e, --edit
                Opens the current plan file in \$EDITOR.

        $ bibleplan -m, --make [year]
                Will make a new 5-day-per-week plan for [year].
                The new plan will be emitted to stdout. You can do
                something like:
                          $ bibleplan -m 2021 > 2021plan.txt
                to write the plan to a text file.

        $ bibleplan -h, --help
                Print this help and exit. See 'man bibleplan' for more
                in-depth documentation.

EOF
}

case "$1" in
  -l|--list) listpassages $2 ;;
  -f|--file) filedetails show ;; 
  -e|--edit) filedetails edit ;;
  -m|--make) filedetails make $2 ;;
  -h|--help) help ;;
  #*) readpassages $1 ;;
  *) case "$2" in
    -l|--list) listpassages $1 ;;
    *) readpassages $1 ;;
  esac
esac