#!/bin/sh

set -e +x

function fail {
    echo "$0: $1" >&2
    exit 1
}

USAGE="Usage: $0 dep"

if [ $# -ne 1 ]; then
    fail "$USAGE"
fi

DEP=$1

CABALFILE=$(ls *.cabal)

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

if [ ! -f $CABALFILE.orig ]; then
    BACKUP=.orig
fi

if grep "$DEP" $CABALFILE | sed -e "s/$DEP//" | grep -q -e "[A-Za-z]"; then
    fail "$0: deleting whole $DEP lines not safe - try more precise pattern"
fi

sed -i$BACKUP -e "/$DEP/d" $CABALFILE