#!/usr/bin/env zsh

normaluser=$1
(( $# < 1 ))  && {
    print -- "usage: ${0:t} \$USER" >&2
    exit 1
}

userhome="$(sudo -u $normaluser echo $HOME)"
echo $userhome

if [[ -e $userhome/.cabal ]]; then
    print -- "Moving your ~/.cabal to ~/old.cabal"
    sudo -u $normaluser mv $HOME/{,old}.cabal
fi

if [[ -e $userhome/.ghc ]]; then
    print -- "Moving your ~/.ghc to ~/old.ghc"
    sudo -u $normaluser mv $HOME/{,old}.ghc
fi

ghcversion="7.8.3"
cabalversion="1.20.0.3"
archi=$(uname -m)
if [[ $(uname -s) = "Darwin" ]]; then
    os="apple-darwin"
    cabalos="apple-darwin-mavericks"
else
    cabalversion="1.20.0.1"
    os="unknown-linux-deb7"
    cabalos="unknown-linux"
    # -------------------------
    # apt-get install libgmp-dev
fi

tmpdir=/tmp/install-haskell
mkdir -p $tmpdir

cd $tmpdir
ghctar=ghc-${ghcversion}-${archi}-${os}.tar.xz
if [[ ! -e $ghctar ]]; then
    echo "Downloading GHC..."
    curl -O http://www.haskell.org/ghc/dist/${ghcversion}/$ghctar
else
    echo "Using already downloaded GHC ($tmpdir)..."
fi
echo "Installing GHC..."
tar xJf $ghctar
cd ghc-${ghcversion}
./configure && make install

cd $tmpdir
echo "Downloading cabal..."
cabaltar=cabal-${cabalversion}-${archi}-${cabalos}.tar.gz
[[ $cabalos = "unknown-linux" ]] && cabaltar=cabal-${archi}-${cabalos}.tar.gz
if [[ ! -e $cabaltar ]]; then
    curl -O http://www.haskell.org/cabal/release/cabal-install-$cabalversion/$cabaltar
else
    echo "Using already downloaded cabal ($tmpdir)..."
fi
tar xzf $cabaltar
echo "Installing cabal..."
if [[ -e ./cabal ]]; then
    mv cabal /usr/local/bin
else
    mv ./dist/build/cabal/cabal /usr/local/bin
fi

echo "Init cabal..."
sudo -u $normaluser cabal info >/dev/null 2>&1

echo "Using Stackage build for GHC 7.8, 2014-08-17 exclusive..."
stackageurl="stackage:http://www.stackage.org/stackage/44dd460d063f344de0da3bfe984e1ac816f18469"

# use exclusive snapshot by default.
sudo -u $normaluser perl -pi.bak -e 's#^remote-repo: .*$#remote-repo: '$stackageurl'#' $HOME/.cabal/config
sudo -u $normaluser cabal update
echo "Install useful binaries"
sudo -u $normaluser cabal install -j alex happy

echo "Update your PATH in .profile for cabal binaries"
sudo -u $normaluser echo 'export PATH=$HOME/.cabal/bin:$PATH' >> $HOME/.profile

echo "[Stackage build] "
echo $stackageurl
echo
echo "If some package are missing, that means they are not considered stable."
echo "Ask gently the package maintainer to add its package to stackage."
echo
print -P -- "You could also use an %Binclusive%b build."
echo "Packages not in exclusive build aren't be garanteed to build thought."
echo
echo "================"
echo "Congratulations\!"
echo "================"
echo
echo "You should start using Haskell like a pro now"
echo "You shouldn't use cabal sandbox except if you know what you are doing."
echo "So if you follow a tutorial that use cabal sandbox, don't use it."
echo "Unless you don't mind killing some white bear and waiting a lot."
echo