#! /bin/bash

main() {
  case "$1" in
    (--help)
      echo "report temperature in K, °C, °R, or °F."
    ;;
    (-C|--celsius)
      echo `temp 'x - 273.15'` Grad Zelsius | to_espeak
    ;;
    (-F|--fahrenheit)
      echo `temp 'x * 9/5 - 459.67'` Grad Fahrenheit | to_espeak
    ;;
    (-R|--rankine)
      echo `temp 'x * 9/5'` Grad Renkin | to_espeak
    ;;
    (-K|--kelvin|*)
      echo `temp` Kelvin | to_espeak
    ;;
  esac
}

## temp [<formula with temperature as x>]
## Echo temperature in K.  If formula is given then return that result instead.
temp() {
  echo "scale=2; x=`dig +short txt outside.elwood.temp.citecs.de |
          sed 's/^"DEG \([0-9]\+\.[0-9]\+\)"$/\1/'
       ` + 273.15; ${1-x}" | bc
}

to_espeak() {
  sed '
    s/\(\.[0-9]\)0\+/\1/g
    s/\(\.[0-9]\)\([0-9]\)[0-9]*/ \1 \2 /;
    s/^-/minus /;
    s/\./ komma /;
    s:^:/espeak -v Die Außen-tempera-tur beträgt :;
  ' >$NOISE_linefeed
}

main "$@"