#!/bin/bash

# Script to perform a manual install of GHC generic Linux version
# to a specific directory.
# The script will also build cabal-install into this same location.

# The goal here is to end up with a usable base Haskell toolchain
# for distros that do not provide new enough versions of these things.


set -e

# These can be overridden by setting environment variables
: ${GHC_VERSION:=7.10.2}
: ${ARCH:=x86_64}             # Optionally: i386
: ${DISTRO:=deb7}             # Optionally: centos66
: ${CABAL_VERSION:=1.22.6.0}
: ${PREFIX:=/}                # Optionally: /opt/haskell

# Temporary location where source downloading and builds will occur
buildDir=$(mktemp --directory --tmpdir ghc-install.XXXX)

ghcPkgDb="${buildDir}/packages.conf.d"

ghcArchive="ghc-${GHC_VERSION}-${ARCH}-unknown-linux-${DISTRO}.tar.xz"
cabalArchivePrefix="cabal-install-${CABAL_VERSION}"
cabalArchive="${cabalArchivePrefix}.tar.gz"

cat <<VARS
Here's what we're about to do:

Install $ghcArchive
and $cabalArchive
into $PREFIX
using the temp build directory $buildDir

Read this script's source for info on changing these values

VARS

read -r -p "Continue? [y/n] " response
case $response in
   [yY]) ;;
   *)
      echo "Aborted."
      rm -rf $buildDir
      exit 0
      ;;
esac

mkdir -p $PREFIX
cd $buildDir

# Download and install the GHC

echo "Download the GHC binary installation"
wget "http://downloads.haskell.org/~ghc/${GHC_VERSION}/${ghcArchive}"

echo "Unpack the GHC binary installation files"
tar xJf ${ghcArchive}

echo "Configure the GHC for this sytem"
pushd "${buildDir}/ghc-${GHC_VERSION}"
./configure --prefix=$PREFIX

echo "Install the GHC"
make install

echo "Temporarily adding new GHC binaries' location to the PATH"
export PATH="${PREFIX}/bin:$PATH"

popd


# Download, build and install cabal-install

echo "Download cabal-install source code"
wget "http://hackage.haskell.org/package/${cabalArchivePrefix}/${cabalArchive}"

echo "Unpack the cabal-install source"
tar xzf $cabalArchive

echo "Initialize a custom ghc package db"
ghc-pkg init $ghcPkgDb

echo "Build and install cabal-install (bootstrap.sh script method)"
pushd "${buildDir}/${cabalArchivePrefix}"
export SCOPE_OF_INSTALLATION="--package-db=${ghcPkgDb}"
export PREFIX=${PREFIX}
./bootstrap.sh

popd


echo "GHC and cabal-install installed into $PREFIX"
echo "You probably want to add $PREFIX/bin to your PATH environment variable"
echo "It is also now probably a good idea to rm the $buildDir directory"