#!/bin/sh

USAGE="Usage: $0 dep old new"

if [ $# -ne 3 ]; then
    echo "$USAGE"
    exit 1
fi

CABALFILE=*.cabal

if [ $(ls $CABALFILE | wc -l) -ne 1 ]; then
   echo "There needs to be one .cabal file in the current dir!"
   exit 1
fi

if ! grep -q "$1.*$2" $CABALFILE; then
   echo "$CABALFILE does not match: $1 $2" 
   exit 1
fi

sed -i.$1 -e "s/\($1.*\)$2/\1$3/g" $CABALFILE