countdown

#!/bin/sh
help() {
  echo 'Like `sleep` but counts down visually when interactive and unpiped'
  echo "Usage: ${0##*/} [-i|--interactive] [MESSAGE] TIME"
  echo ""
  echo "  -i, --interactive  Force interactivity rather than determining it"
  echo ""
  version
}

version() {
  echo "Part of misc-scripts: https://github.com/adamhotep/misc-scripts"
  echo "countdown 0.3.20240811.0 Copyright 2003+ by Adam Katz, GPL v2+"
  exit
}

case $1 in
  ( -h | --help )		help ;;
  ( -i | --interactive )	interactive=1; shift ;;
  ( -v | --version )		version ;;
esac

# (unpiped, interactive, and neither linux console nor a dumb terminal) or -i
if [ -t 1 ] && [ -z "${-##*i*}" ] && [ "${TERM%inux}" = "${TERM%dumb}" ] \
|| [ -n "$interactive" ]; then
  titlebar() {
    printf '\033]0;%s\033\\%s' "$*" ''
  }
  sec2time() {
    local d= h= m= s="$1" o= neg= u=
    # The $((...)) construct is truncates to integers, which is perfect here.
    if [ $1 -ge 86400 ]; then d=$((s/86400)); o="%dd "; s=$((s-d*86400)); fi
    if [ $1 -ge 3600 ]; then h=$((s/3600)); o="$o%d:"; s=$((s-h*3600)); fi
    if [ $1 -ge 60 ]; then m=$((s/60)); o="$o%02d:%02d"; s=$((s-m*60)); fi
    if [ $1 -lt 60 ]; then u=s; fi
    printf "%s${o:-%d}%s\n" "$neg" $d $h $m $s $u
  }
  countdown() {
    local t="$2" text='\r%s, waiting %-5s'
    titlebar "$1"
    while [ "$t" -gt 0 ]; do
      printf "$text" "$1" "$(sec2time $t)"
      t=$((t-1))
      sleep 1
    done
    printf "$text" "$1" "...  "
  }
else
  countdown() { echo "$1"; sleep "$2"; }
fi

if [ $# = 1 ]; then set -- "Counting down from $1" "$1"; fi

if ! [ "$2" -ge 0 ] 2>/dev/null; then
  t="$2"
  if command -v timecalc >/dev/null 2>&1; then
    set -- "$1" "$(timecalc "$t" 2>/dev/null)"
  fi
  if ! [ "$2" -ge 0 ] 2>/dev/null; then
    echo "Invalid time '$t'" >&2
    exit 2
  fi
fi

countdown "$@"