#!/bin/sh

if [ $# -ne 2 ]; then
    echo "$0 disk ssh-keyfile"
    echo "   disk: which disk to install to"
    echo "   ssh-keyfile: ssh keys to add into the image"
    exit 1
fi

set -e
set -x

DISK=$1; shift
SSH_KEYS=$1; shift

MAJOR_VERSION=3.14
MINOR_VERSION=0
IMAGE=alpine-minirootfs-$MAJOR_VERSION.$MINOR_VERSION-x86_64.tar.gz

RESOLVCONF=/etc/resolv.conf

working_directory=$(pwd -P)
rootfs_tmpdir=$(mktemp -d)

rootfs_url="http://dl-cdn.alpinelinux.org/alpine/v$MAJOR_VERSION/releases/x86_64/$IMAGE"

case $DISK in
    /dev/sd*)
        partition=${DISK}1
        ;;
    /dev/mmcblk*|/dev/nvme*)
        partition=${DISK}p1
        ;;
    *)
        echo "Unsupported disk - edit this script" >&2
        exit 1
        ;;
esac

run_root () {
    sudo chroot $rootfs_tmpdir /usr/bin/env \
        PATH=/sbin:/bin:/usr/sbin:/usr/bin \
        /bin/sh -c "$*"
}

wget -c "$rootfs_url" -O "$IMAGE"

# Clean the first 2M - getting rid of old things
# in the gap and also the paritition table
dd if=/dev/zero of=${DISK} bs=1M count=2

# Partition disk with 1 Linux partition
sudo sfdisk "$DISK" <<EOF
label: dos
,,L
EOF

# For creation, if an existing filesystem is on the partitions
sudo mkfs.ext4 -F ${partition}

sudo mount ${partition} $rootfs_tmpdir

# keep right permissions, use sudo
sudo tar xf $IMAGE -C $rootfs_tmpdir

# These are required by grub-install
# And also for generating grub config that contains rootfstype
for dir in dev proc sys; do
    sudo mount --bind /${dir} ${rootfs_tmpdir}/${dir}
done

# Add SSH keys
run_root mkdir -p root/.ssh
sudo cp $SSH_KEYS $rootfs_tmpdir/root/.ssh/authorized_keys
run_root chown root:root /root/.ssh/authorized_keys
run_root chmod 0600 /root/.ssh/authorized_keys
run_root chmod 0700 /root/.ssh

# Import local resolv.conf.
sudo cp "$RESOLVCONF" $rootfs_tmpdir/etc/resolv.conf

# Generate fstab which is later included in the initramfs

# Add filesystem to fstab, because busybox mount does not work
# without -t ext4 for mounting and returns "No such file or directory"
# nb2:~# blkid| grep ^${DISK}1 | awk '{ print $2 }'
# UUID="fecf4182-f6dd-4d2c-9af7-8f36444ee25c"
eval $(blkid | grep ^${DISK}1 | awk '{ print $2 }')
echo "UUID=$UUID / ext4 defaults 0 1" >> ${rootfs_tmpdir}/etc/fstab

run_root apk update
run_root apk add linux-lts openrc udev openssh e2fsprogs

run_root rc-update add udev
run_root rc-update add udev-trigger
run_root rc-update add sshd
run_root rc-update add networking
run_root rc-update add hostname
run_root rc-update add sysctl
run_root rc-update add modules
run_root sed -i 's/root:!::0:::::/root:*::0:::::/' /etc/shadow

sudo tee "$rootfs_tmpdir/etc/network/interfaces" <<EOF
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet6 manual
  up /sbin/ip link set \$IFACE up

EOF

sudo tee "$rootfs_tmpdir/etc/hostname" <<EOF
alpine-unconfigured
EOF

# Setup bootloader

run_root apk add grub-bios
echo 'GRUB_CMDLINE_LINUX_DEFAULT="quiet rootfstype=ext4"' >> ${rootfs_tmpdir}/etc/default/grub
run_root grub-mkconfig -o /boot/grub/grub.cfg
run_root grub-install --target=i386-pc ${DISK}

# Cleanup
run_root rm -f /etc/resolv.conf
for dir in dev proc sys; do
    sudo umount ${rootfs_tmpdir}/${dir}
done
sudo umount  $rootfs_tmpdir

sync
rmdir ${rootfs_tmpdir}

echo "${DISK} has been setup with Alpine Linux"

exit 0