#!/bin/bash
die()
{
    printf 'Error: %s\n' "$*" >&2
    exit 1
}
KiB()
{
    printf %s $(("$1" * 1024))
}
MiB()
{
    KiB $(KiB "$1")
}

initialize_target()
{
    rm -f "$target"
    if [ "$ROOTFS" ]
    then
        fallocate -l $(($(KiB 17) + $(MiB $end_keys) + $(MiB $rootfs_size))) "$target"
    else
        fallocate -l $(($(KiB 17) + $(MiB $end_keys))) "$target"
    fi
}

# TODO: Use GUID type tags for each Samizdat partition type.
partition_target()
{
    parted "$target" -sm -a optimal                             \
           unit MiB                                             \
           mklabel gpt                                          \
           mkpart samizdat-grub 1 8                             \
           set 1 bios_grub on                                   \
           mkpart samizdat-keys btrfs ${start_keys} ${end_keys}

    if [ "$ROOTFS" ]
    then
        parted "$target" -sm -a optimal                         \
               mkpart samizdat-rootfs btrfs ${end_keys}MiB 100%
    fi
}

make_target_bootable()
{
    losetup -f "$target"
    dev=$(losetup -j "$target" -O NAME --noheadings)

    kpartx -vasas "$dev"
    kdev=/dev/mapper/${dev##*/}

    mnt=$target.mnt

    mkfs.btrfs --mixed "$kdev"p2
    mkdir -p "$mnt"
    mount "$kdev"p2 "$mnt"

    mkdir -p "$mnt"/boot/grub
    cp -aL "$GRUB_CONFIG" "$mnt"/boot/grub

    eatmydata -- grub-install -v --boot-directory "$mnt"/boot "$dev"
    sync
}

release_target_kernel_resources()
{
    umount "$mnt"
    kpartx -d "$dev"
    losetup -d "$dev"
}

with_target()
{
    local mnt dev target="$1"
    shift

    mnt=$target.mnt
    mkdir -p "$mnt"
    losetup -f "$target" -o $(MiB $start_keys)
    dev=$(losetup -j "$target" -O NAME --noheadings)
    mount "$dev" "$mnt"
    "$@"
    umount "$mnt"
    losetup -d "$dev"
}

add_keys()
{
    rsync  -a  --info=STATS  "$GPG_INPUT_DIR"/ "$mnt"/gnupghome/
}

initrd_suffix=.samizdat
add_initrd()
{
    mkdir -p "$mnt"/linux
    rsync  -aL --info=STATS "${1}vmlinuz${2}" "$mnt"/linux/vmlinuz
    rsync  -aL --info=STATS "${1}initrd.img${2}${initrd_suffix}" "$mnt"/linux/initrd.img
}

add_grub_cfg()
{
    mkdir -p "$mnt"/boot/grub
    cp -aL "$GRUB_CONFIG" "$mnt"/boot/grub
}

individualize()
{
    add_keys
    add_initrd "$samizdat_linux_dir"/ "${version_suffix}"
    add_grub_cfg
}

sanity_checks()
{
    [[ $UID = 0 ]] || die "You are not root."
    for d in "$samizdat_linux_dir" "$GPG_INPUT_DIR"
    do
        [ -d "$d" ] || die "Not a directory: $d"
    done
}

create_template()
{
    local target="${1}.tmp"

    if [ ! -e "${target%.tmp}" ]
    then
        initialize_target
        partition_target
        make_target_bootable
        release_target_kernel_resources
        mv -T "$target" "${target%.tmp}"
    fi
}

individualize_target_from()
{
    cp -T --reflink=always "$1" "$target"
    with_target "$target" individualize
}

. samizdat-paths.sh || die 'samizdat-paths.sh not found'
samizdat_linux_dir=/boot
: ${GPG_INPUT_DIR:=/cdrom/gnupghome}
: ${GRUB_CONFIG:=conf/grub.cfg}
start_keys=64 # megs
end_keys=256 # megs

if [ "$1" ]
then
    version_suffix=-$1
fi


sanity_checks
set -e
template=boot-disk.template.img
target=boot-disk.img.tmp
final=${target%.tmp}
create_template "$template"
individualize_target_from "$template"
mv -T "$target" "$final"


installer_target=target-disk.img
rm -f "$installer_target"
if [ ! -e "$installer_target" ]
then
    fallocate -l 10G "$installer_target"
fi

qemu-system-x86_64 -enable-kvm -smp 2 -m 512 -k en-us -vga qxl -drive file="$final",format=raw -drive file="$installer_target",format=raw