Resize with imagemagick

#!/bin/zsh

VERBOSE=0
QUIET=0

if [ "x$1" = "x-q" ]
then
  shift
  QUIET=1
elif [ "x$1" = "x-v" ]
then
  shift
  VERBOSE=1
fi

sailoop=0
arquivo="$1"
raio="$2"

if [[ $# -eq 1 ]] # Only file as argument
then
  sailoop=0 # don't exit the loop
  minsize=480000
  maxsize=512000
elif [[ $raio -lt 20.0 ]] # Two arguments, second is is the desired ratio
then
  sailoop=1 # exit the loop after changing the picture's size
else
  sailoop=0
  minsize=$raio # the second parameter was not the ratio, but the minimum size
  raio=""
  if [[ "$3" == "" ]]
  then
    maxsize=512000
  else
    maxsize=$3
  fi
fi

desiredsize=$(((maxsize+minsize)/2)) # this number is integer

[ -f "$arquivo" ] || {
  echo "**** Erro! Primeiro parametro \"$1\" precisa ser um arquivo legivel!" >&2
  exit 1
}

[[ $sailoop -eq 1 && "$raio" -lt 0.1 ]] && {
  echo "**** Erro! Segundo parametro \"$2\" precisa ser o raio (numerico) de contracao!" >&2
  exit 2
}

destino="${arquivo//./-pequeno.}"
largura=$(identify "$arquivo" | head -1 | sed 's/.* \([0-9].[0-9]*x[0-9].[0-9]*\) .*/\1/' | cut -f1 -dx)
altura=$(identify "$arquivo" | head -1 | sed 's/.* \([0-9].[0-9]*x[0-9].[0-9]*\) .*/\1/' | cut -f2 -dx)

while [[ $sailoop -lt 2 ]]
do
  if [[ $sailoop == 1 ]]
  then
    sailoop=2 # raio was provided.
  else
    if [[ "$raio" == "" ]] # Initial raio
    then
      inputsize=$(/usr/bin/stat "$arquivo" | awk '($1=="Size:") {print $2}')
      raio=$(echo -e "scale=3\nsqrt($inputsize/$desiredsize)" | bc -l) # rough estimate, square root of pictures ratio.
    fi
  fi

  novalargura=$((largura/raio))
  novaaltura=$((altura/raio))
  novalargura=${novalargura%%.*}
  novaaltura=${novaaltura%.*}

  intermediario=$(/bin/mktemp)
  /usr/bin/convert -resize ${novalargura}x${novaaltura}\! $arquivo "$intermediario"
  /usr/bin/gifsicle --colors 256 -O2 "$intermediario" > "$destino"
  rm -f "$intermediario"

  destsize=$(/usr/bin/stat "$destino" | awk '($1=="Size:") {print $2}')

  if [[ $destsize -gt $minsize && $destsize -lt $maxsize ]]
  then
    sailoop=2
  elif [[ $destsize -ge $maxsize || $destsize -le $minsize ]]
  then
    proporcao=$(echo -e "scale=3\n($destsize/$desiredsize)" | bc -l) # let's fix up our ratio.
    if [[ $VERBOSE -eq 1 ]]
    then
      echo "*** Not yet: size ${novalargura}x${novaaltura}, ratio $raio, target size $destsize"
    fi
    raio=$((((raio*proporcao)+raio)/2)) # we went bigger than expected, let's make the ratio bigger (this the target picture smaller)
  else
    echo "*** Internal error calculating sizes. Please check script. destsize=$destsize maxsize=$maxsize minsize=$minsize"
    exit 1
  fi
done

if [[ $VERBOSE -eq 1 ]]
then
  echo "*** Final: size ${novalargura}x${novaaltura}, ratio $raio, target size $destsize"
fi
if [[ $QUIET == 1 ]]
then
  echo $(ls -lh "$destino" | awk '{print $5}')
else
  echo "*** $destino file size is $(ls -lh "$destino" | awk '{print $5}')."
fi