Turn on 'Do Not disturb' for a time period on macOS

hush-for

#!/bin/bash

# See `showUsage` for desciption

# requires `gsed` via `brew install gnu-sed`
# requires `dnd` via `npm install --global do-not-disturb-cli`

function showUsage() {
  cat <<EOS
Usage: $(basename "${0}") "<time_description>"

Turns on 'Do Not disturb' for a time period on macOS

time_description examples:
- "1h 30m"
- "1 hour 30 minutes 15 seconds"
- "20 min"
- "2m"
EOS
}

function durationToSeconds () {
  # modified from https://stackoverflow.com/a/58617630/2443614

  set -f
  local value
  local fallback

  normalize () { echo "$1" | tr '[:upper:]' '[:lower:]' | tr -d "\"\\\'" | sed 's/ *y\(ear\)\{0,1\} */y /g; s/ *d\(ay\)\{0,1\} */d /g; s/ *h\(our\)\{0,1\} */h /g; s/ *m\(in\(ute\)\{0,1\}\)\{0,1\} */m /g; s/ *s\(ec\(ond\)\{0,1\}\)\{0,1\} */s /g; s/\([ydhms]\) s/\1/g'; }

  value=$(normalize "$1")
  fallback=$(normalize "$2")

  if (echo "$value" | grep -q -v '^[-+*/0-9ydhms ]\{0,30\}$');
  then
    >&2 echo Invalid duration pattern \""$value"\"
  else
    if [ "$value" = "" ]; then
      [ "$fallback" != "" ] && durationToSeconds "$fallback"
    else
      local template
      sedtmpl () { echo "s/\([0-9]\+\)$1/(0\1 * $2)/g;"; }
      template="$(sedtmpl '\( \|$\)' 1) $(sedtmpl y '365 * 86400') $(sedtmpl d 86400) $(sedtmpl h 3600) $(sedtmpl m 60) $(sedtmpl s 1) s/) *(/) + (/g;"

      echo "$value" | gsed "$template" | bc
    fi
  fi
  set +f
}

if ((!${#})); then
  showUsage;
  exit 1;
fi

seconds="$(durationToSeconds "$@")"

echo "Setting 'Do Not Disturb' until $(gdate --date="+$seconds seconds" '+%T')"
dnd on
sleep "$seconds"
dnd off
echo "'Do Not Disturb' ended"