#!/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_var() {
    dev="$1"

    echo 'Copying /var contents to data volume'
    mount -o subvol=var "${dev}" "${tmpdir}" || exit
    cp -acuv /var/. "${tmpdir}" || exit
    umount "${tmpdir}"
}

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' "${dev}"
    mkfs.btrfs "${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() {
    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}" --force \
        || return $?
    partx -u "${_disk}"
}

setup_etc() {
    dev="$1"

    echo 'Initializing writable paths in /etc'
    mount -o subvol=etc "${dev}" "${tmpdir}" || exit
    if [ ! -f "${tmpdir}"/shadow ]; then
        cp -ca /etc/shadow "${tmpdir}"/shadow || exit
    fi
    mount -o bind "${tmpdir}"/shadow /etc/shadow || exit
    if [ -f /etc/aimee-os/writable-etc ]; then
        while read type path; do
            if [ ! -e "${tmpdir}/${path}" ]; then
                if [ -e /etc/"${path}" ]; then
                    case "${path}" in
                    */*)
                        mkdir -p "${tmpdir}/${path%/*}"
                        ;;
                    esac
                    cp -ca /etc/"${path}" "${tmpdir}/${path}"
                elif [ "${type}" = d ]; then
                    mkdir -p "${tmpdir}/${path}"
                elif [ "${type}" = f ]; then
                    : > "${tmpdir}/${path}"
                else
                    printf 'Invalid path type %s for %s\n' \
                        "${type}" \
                        "${path}" \
                        >&2
                    continue
                fi
            fi
            mount -o bind "${tmpdir}/${path}" /etc/"${path}"
        done < /etc/aimee-os/writable-etc
    fi
    umount "${tmpdir}"
}

datapart=$(findfs $(awk '$2=="/var"{print $1}' /etc/fstab))
if [ -b "${datapart}" ]; then
    printf 'Found data partition: %s\n' "${datapart}"
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

setup_etc "${datapart}"
copy_var "${datapart}"