#! @shell@

# Syntax: installer.sh <DEVICE> <NIX-EXPR>
# (e.g., installer.sh /dev/hda1 ./my-machine.nix)

# - mount target device
# - make Nix store etc.
# - copy closure of rescue env to target device
# - register validity
# - start the "target" installer in a chroot to the target device
#   * do a nix-pull
#   * nix-env -p system-profile -i <nix-expr for the configuration>
#   * run hook scripts provided by packages in the configuration?
# - install/update grub

targetDevice="$1"

if test -z "$targetDevice"; then
    echo "syntax: installer.sh <targetDevice>"
    exit 1
fi


# Make sure that the target device isn't mounted.
umount "$targetDevice" 2> /dev/null


# Check it.
fsck "$targetDevice" || exit 1


# Mount the target device.
mountPoint=/tmp/inst-mnt
mkdir -p $mountPoint
mount "$targetDevice" $mountPoint || exit 1

mkdir -p $mountPoint/dev $mountPoint/proc $mountPoint/sys || exit 1
mount --bind /dev $mountPoint/dev || exit 1
mount --bind /proc $mountPoint/proc || exit 1
mount --bind /sys $mountPoint/sys || exit 1

trap "umount $mountPoint/dev; umount $mountPoint/proc; umount $mountPoint/sys; umount $mountPoint" EXIT

mkdir -p $mountPoint/tmp
mkdir -p $mountPoint/var


# Create the necessary Nix directories on the target device, if they
# don't already exist.
mkdir -p \
    $mountPoint/nix/store \
    $mountPoint/nix/var/nix/gcroots \
    $mountPoint/nix/var/nix/temproots \
    $mountPoint/nix/var/nix/manifests \
    $mountPoint/nix/var/nix/userpool \
    $mountPoint/nix/var/nix/profiles \
    $mountPoint/nix/var/nix/db \
    $mountPoint/nix/var/log/nix/drvs


# Copy Nix to the Nix store on the target device.
echo "copying Nix to $targetDevice...."
for i in $(cat @nixClosure@); do
    echo "  $i"
    rsync -a $i $mountPoint/nix/store/ || exit 1
done


# Register the paths in the Nix closure as valid.  This is necessary
# to prevent them from being deleted the first time we install
# something.  (I.e., Nix will see that, e.g., the glibc path is not
# valid, delete it to get it out of the way, but as a result nothing
# will work anymore.)
for i in $(cat @nixClosure@); do
    echo $i
    echo # deriver
    echo 0 # nr of references
done \
| chroot $mountPoint @nix@/bin/nix-store --register-validity || exit 1


# Create the required /bin/sh symlink; otherwise lots of things
# (notably the system() function) won't work.
mkdir -p $mountPoint/bin
ln -sf $(type -tp sh) $mountPoint/bin/sh


# Enable networking in the chroot.
mkdir -p $mountPoint/etc
cp /etc/resolv.conf $mountPoint/etc/


# Do a nix-pull.
nixpkgsURL=http://nix.cs.uu.nl/dist/nix/nixpkgs-0.11pre6984
chroot $mountPoint @nix@/bin/nix-pull $nixpkgsURL/MANIFEST


# Install some packages.
rm -rf $mountPoint/scratch
mkdir $mountPoint/scratch
curl $nixpkgsURL/nixexprs.tar.bz2 | tar xj -C $mountPoint/scratch

nixpkgsName=$(cd $mountPoint/scratch && ls)

chroot $mountPoint @nix@/bin/nix-env -f /scratch/$nixpkgsName -i aterm