#!/bin/sh
# vim: set sw=4 ts=4 sts=4 et :

SUBVOLUMES='
    /var
    /var/log
    /var/tmp
    /etc
'

cleanup() {
    if [ -n "${tmpdir}" ] && [ "${tmpdir}" != / ]; then
        if mountpoint -q "${tmpdir}"; then
            umount "${tmpdir}"
        fi
        rm -rf "${tmpdir}"
        unset tmpdir
    fi
}

copy_vol() {
    dev="$1"
    vol=$2

    printf 'Copying %s contents to data volume\n' "${vol}" >&2
    mount -o subvol="${vol#/}" "${dev}" "${tmpdir}" || exit
    cp -au${VERBOSE+v} /sysroot/${vol#/}/. "${tmpdir}" || exit
    umount "${tmpdir}"
}

find_part() {
    _i=0
    while [ $_i -lt 5 ]; do
        findfs "$1" 2>/dev/null && return
        _i=$((_i + 1))
        sleep 1
    done
    findfs "$1"
}

format_dev() {
    dev="$1"
    partno=$(partition_number "${dev}")
    if [ -n "${partno}" ]; then
        disk="$(get_disk "${dev}")"
        if [ -n "${disk}" ]; then
            printf 'Resizing partition %d on disk %s\n' \
                "${partno}" \
                "${disk}" \
                >&2
            resize_partition "${disk}" "${partno}"
        else
            printf 'Could not find disk for device %s\n' \
                "${dev}" \
                >&2
        fi
    fi

    printf 'Creating BTRFS filesystem on %s\n' "${dev}" >&2
    mkfs.btrfs --quiet "${dev}" || exit

    mount "${dev}" "${tmpdir}" || exit
    for vol in ${SUBVOLUMES}; do
        mkdir -p "${tmpdir}${vol%/*}" || exit
        btrfs subvolume create "${tmpdir}${vol}" || exit
    done
    relabel_all
    umount "${dev}" || exit
}

get_disk() {
    _syspath=/sys/class/block/${1##*/}
    [ -d "${_syspath}" ] || return 1
    if [ ! -f "${_syspath}"/partition ]; then
        readlink -f "${1}"
        return $?
    fi
    _disk=$(readlink -f "${_syspath}"/..)
    if [ -n "${_disk}" ]; then
        printf '/dev/%s\n' "${_disk##*/}"
        return 0
    fi
    return 1
}

has_fs() {
    dev="$1"
    fstype=$(blkid -o value -s TYPE "${dev}")
    [ -n "${fstype}" ]
}

last_partition() {
    cat /sys/class/block/"${1##*/}"/*/partition \
        | sort -n \
        | tail -n1
}

partition_number() {
    cat /sys/class/block/${1##*/}/partition
}

relabel_all() {
    if [ ! -d /sys/fs/selinux ] || [ ! -f /etc/selinux/config ]; then
        return
    fi
    selinuxtype=$(. /etc/selinux/config && echo ${SELINUXTYPE})
    find "${tmpdir}" | \
    setfiles \
        -v \
        -F \
        -m \
        -r "${tmpdir}" \
        -s \
        /etc/selinux/${selinuxtype}/contexts/files/file_contexts
}

resize_partition() {
    _disk="${1}"
    _part="${2}"
    _lastpart=$(last_partition "${_disk}")
    if [ "${_part}" -ne "${_lastpart}" ]; then
        printf 'Cannot resize %s, it is not the last partition on the disk\n' \
            "${_dev}" \
            >&2
        return 1
    fi
    _uuid=$(sfdisk --part-uuid "${_disk}" "${_part}") || return $?
    _type=$(sfdisk --part-type "${_disk}" "${_part}") || return $?
    _label=$(sfdisk --part-label "${_disk}" "${_part}") || return $?
    sfdisk --delete "${_disk}" "${_part}" || return $?
    printf 'type=%s, uuid=%s, name="%s"\n' \
        "${_type}" \
        "${_uuid}" \
        "${_label}" \
        | sfdisk -N "${_part}" "${_disk}" --quiet --force \
        || return $?
    partx -u "${_disk}"
}

setup_etc() {
    dev="$1"

    echo 'Initializing /etc overlay' >&2
    mkdir -p /run/aimeeos/etc || return
    mount -o subvol=etc "${dev}" /run/aimeeos/etc || return
    mkdir -p /run/aimeeos/etc/rw /run/aimeeos/etc/work || return
    mount -t overlay \
        -o lowerdir=/sysroot/etc,upperdir=/run/aimeeos/etc/rw,workdir=/run/aimeeos/etc/work \
        overlay \
        /sysroot/etc
}

rootdev=$(find_part "$1")
datapart=$(find_part "${2:-PARTLABEL=aimeeos-data}")
if [ -b "${datapart}" ]; then
    printf 'Found data partition: %s\n' "${datapart}" >&2
else
    echo 'Could not identify data partition' >&2
    exit 1
fi

trap cleanup INT TERM QUIT EXIT
tmpdir=/run/storinit
mkdir -p "${tmpdir}"

if ! has_fs "${datapart}"; then
    format_dev "${datapart}"
fi

mkdir -p /sysroot
mount -o ro "${rootdev}" /sysroot || exit

setup_etc "${datapart}"
copy_vol "${datapart}" /var
exit 0