#!/usr/bin/env sh
# shows due entries of bibtex file passed in
# HACK: brittle! will break on various bibfile abnormities (even just on due date w/o priority)
# FIXME: reimplementation with real library needed
#

fields="due|priority|\bauthor\b|\btitle\b"
filterby="due"

main() {
  # use system default bib file or passed argument
  if [ -n "$1" ]; then
    file="$1"
  elif [ -n "$BIBFILE" ]; then
    file="$BIBFILE"
  else
    echo "Requires a bibtex file as argument."
    exit 1
  fi

  # filter all entries for those containing filterby field (default: due)
  # retain values of all fields mentioned in fields variable
  entries=$(grep -E "^@|$fields" "$file" | awk 1 ORS=' ' | sed -E 's/@\w+\{/\n/g' | grep $filterby | tail -n +2 | sed -E 's/(,\s+(\w+)\s+=\s+|,\s*$)/\t/g' | awk -F'\t' '{ print $4 "\t" $5 "\t" $2 "\t" $3 "\t" $1 }')

  # prettify and sort the entries for display (remove {}, order by date,prio,author,title)
  entries=$(echo "$entries" | awk -F'\t' '{ gsub(/{/,""); gsub(/}/,""); gsub(/prio/,"",$2) } { print $1 " (" $2 "): " $3 " -- " $4 " (" $5 ")"}' | sort)

  echo "$entries"
}

main "$@"