#!/bin/sh

set -e

grub_install="/usr/sbin/grub2-install"
grub_probe="/usr/sbin/grub2-probe"
grub_script_check="/usr/bin/grub2-script-check"
btrfs_util="/sbin/btrfs"

# Get GRUB_DISTRIBUTOR.
if test -f "/etc/default/grub" ; then
    . "/etc/default/grub"
fi

root_fstype=`$grub_probe -t fs /`
boot_fstype=`$grub_probe -t fs /boot`
if [ "x$SUSE_BTRFS_SNAPSHOT_BOOTING" != "xtrue" ] ||
   [ "x${root_fstype}" != "xbtrfs" ] ||
   [ "x${boot_fstype}" != "xbtrfs" ] ; then
    echo "requirement not met" >&2
    exit 1;
fi

make_grubcfg () {

prefix="$1"
descriptive_config="snapshot_submenu.cfg"

if [ "x${platform}" = "xpc" ]; then
cat <<EOF
insmod part_gpt
insmod part_msdos
insmod acpi
insmod btrfs
insmod multiboot
insmod configfile
insmod linux
insmod search
insmod search_fs_uuid
insmod search_fs_file
insmod search_label
insmod chain
insmod sleep
insmod test
insmod echo
insmod all_video
insmod regexp
insmod font
insmod terminal
insmod terminfo
insmod sleep
insmod ls
insmod minicmd
insmod png
insmod gzio
insmod boot
insmod read
insmod cat
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
insmod gettext
insmod true
insmod reboot
insmod password
insmod password_pbkdf2
insmod loadenv
insmod legacycfg
insmod jpeg
insmod gfxmenu
insmod gfxterm_background
insmod gfxterm_menu
insmod gfxterm
EOF
fi

cat <<EOF

set btrfs_relative_path="y"
set extra_cmdline=""
btrfs_subvolid=""
btrfs_subvol="/"

export btrfs_relative_path
export extra_cmdline
EOF

if [ "x${platform}" = "xpc" ]; then
cat <<EOF

set prefix="(\$root)${prefix}"
EOF
elif [ "x${platform}" = "xefi" ]; then
cat <<EOF

set prefix="(\$root)${prefix}"
search --fs-uuid --set=root `"$grub_probe" --target=fs_uuid /boot/grub2`
EOF
fi

cat <<EOF

terminal_input console
terminal_output console

set timeout=0

menuentry 'default' {
  btrfs_subvol=""
  configfile /boot/grub2/grub.cfg
  btrfs_subvol="/"
}

if [ -f "/.snapshots/${descriptive_config}" ]; then
  source "/.snapshots/${descriptive_config}"
else
  submenu 'Available Snapshots' {
    for i in /.snapshots/*; do
    if [ -f "\$i/${descriptive_config}" ]; then
      source "\$i/${descriptive_config}" 
    elif [ -f "\$i/snapshot/boot/grub2/grub.cfg" ]; then
      menuentry "\$i" "/.snapshots\$i/snapshot" {
        btrfs_subvol="\$2"
        extra_cmdline="rootflags=subvol=\$2"
        configfile /boot/grub2/grub.cfg
        btrfs_subvol="/"
      }
    fi
    done
  }
fi
EOF

}

case x"`uname -m`" in
  x"powerpc"* | x"ppc"*)
    target="powerpc-ieee1275";;
  x"sparc"*)
    target="sparc64-ieee1275";;
  x"mips"*"el")
    target="mipsel-loongson";;
  x"mips"*)
    target="mips-arc";;
  x"ia64"*)
    target="ia64-efi";;
  x"x86_64"* | x"amd64"*)
    modprobe -q efivars 2>/dev/null || true
    if [ -d /sys/firmware/efi ]; then
      target="x86_64-efi"
    else
      target=i386-pc
    fi
  ;;
  x"i"?"86"*)
    modprobe -q efivars 2>/dev/null || true 
    if [ -d /sys/firmware/efi ]; then
      target="i386-efi"
    elif [ -e /proc/device-tree ]; then
      target=i386-pc
      for x in /proc/device-tree/*; do
        if [ -e "$x" ]; then
          target="i386-ieee1275"
        fi
      done
    else
      target=i386-pc
    fi
  ;;
  *)
    target=""
  ;;
esac

if [ "x${target}" = "xi386-pc"  ]; then
  platform="pc"
elif [ "x${target}" = "xx86_64-efi" ] ||
     [ "x${target}" = "xi386-efi" ]; then
  platform="efi"
else
  exit 0
fi

if [ "x${platform}" = "xefi" ]; then
  bootloader_id="$(echo "$GRUB_DISTRIBUTOR" | tr 'A-Z' 'a-z' | cut -d' ' -f1)"
  if test -z "$bootloader_id"; then
    bootloader_id=grub
  fi
  boot_directory="/boot/efi/EFI/${bootloader_id}"

  if echo "$@" | grep -q '--boot-directory='; then
    ${grub_install} $@
  else
    ${grub_install} --boot-directory="${boot_directory}" --efi-directory="/boot/efi" $@
    make_grubcfg "/EFI/${bootloader_id}/grub2"  >"${boot_directory}/grub2/grub.cfg.new"
  fi
elif [ "x${platform}" = "xpc" ]; then
  boot_directory="/.boot"
  if [ ! -d "$boot_directory" ]; then
    ${btrfs_util} subvolume create "$boot_directory"
    echo "UUID=`$grub_probe -t fs_uuid /` /.boot             btrfs      subvol=@/.boot        0 0" >>/etc/fstab
  fi
  if echo "$@" | grep -q '--boot-directory='; then
    ${grub_install} $@
  else
    ${grub_install} --boot-directory="${boot_directory}" $@
    make_grubcfg "${boot_directory}/grub2"  >"${boot_directory}/grub2/grub.cfg.new"
  fi
fi

if $grub_script_check "${boot_directory}/grub2/grub.cfg.new"; then
  mv -f "${boot_directory}/grub2/grub.cfg.new" "${boot_directory}/grub2/grub.cfg"
fi