#!/bin/bash

# Configure grub. Note that the various conditionals here are to handle
# different distributions gracefully.

set -e
set -x

# FIXME:
[ -n "$IMAGE_BLOCK_DEVICE" ]
PART_DEV=$IMAGE_BLOCK_DEVICE
BOOT_DEV=$(echo $IMAGE_BLOCK_DEVICE | sed -e 's#p1##' | sed -e 's#mapper/##')

function install_extlinux {
    install-packages extlinux

    echo "Installing Extlinux..."

    MBR=/usr/share/syslinux/mbr.bin
    if [ ! -f $MBR ]; then
        MBR=/usr/lib/syslinux/mbr.bin
        if [ ! -f $MBR ]; then
            echo "mbr.bin (from SYSLINUX) not found."
            exit 1
        fi
    fi

    dd if=$MBR of=$BOOT_DEV

    mkdir -p /boot/syslinux
    extlinux --install /boot/syslinux

    if [ -f /etc/redhat-release ]; then
        kernel=$(ls -1rv /boot/vmlinuz* | head -1)
        initrd=$(ls -1rv /boot/initramfs* | head -1)
    elif [ -f /etc/debian_version ]; then
        kernel=$(ls -1rv /boot/vmlinuz*generic | head -1)
        initrd=$(ls -1rv /boot/initrd*generic | head -1)
    else
        echo "Unable to find kernel and initram"
        exit 1
    fi

    cat > /boot/syslinux/syslinux.cfg<<_EOF_
DEFAULT linux

LABEL linux
  KERNEL $kernel
  APPEND rw root=LABEL=cloudimg-rootfs
  INITRD  $initrd
_EOF_
}

function install_grub2 {

    # Check for offline installation of grub
    if [ -f "/tmp/grub/install" ] ; then
        source /tmp/grub/install
    else
        install-packages grub-pc
    fi

    # XXX: grub-probe on the nbd0/loop0 device returns nothing - workaround, manually
    # specify modules. https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1073731
    GRUBNAME=`which grub-install` || echo "trying grub2-install"
    if [ -z "$GRUBNAME" ]; then
        GRUBNAME="bash -x `which grub2-install`"
    fi

    # If no GRUB2 is found, fallback to extlinux
    if [ -z "$GRUBNAME" ] || [ $($GRUBNAME --version | grep "0.97" | wc -l) -ne 0 ]; then
        echo "No GRUB2 found. Fallback to Extlinux..."
        install_extlinux
        exit 0
    fi

    echo "Installing GRUB2..."

    GRUB_OPTS=${GRUB_OPTS:""}
    # XXX: This is buggy:
    # - --target=i386-pc is invalid for non-i386/amd64 architectures
    # - and for UEFI too.
    #    GRUB_OPTS="$GRUB_OPTS --target=i386-pc"
    if [[ ! $GRUB_OPTS == *--target* ]]; then
      # /sys/ comes from the host machine. If the host machine is using EFI
      # but the image being built doesn't have EFI boot-images installed we
      # should set the --target to use a BIOS-based boot-image.
      #
      # * --target tells grub what's the target platform
      # * the boot images are placed in /usr/lib/grub/<cpu>-<platform>
      # * i386-pc is used for BIOS-based machines
      # http://www.gnu.org/software/grub/manual/grub.html#Installation
      #
      if [ -d /sys/firmware/efi ]; then
        if [ ! -d /usr/lib/grub/*-efi ]; then
          case $ARCH in
            "x86_64"|"amd64")
               GRUB_OPTS="$GRUB_OPTS --target=i386-pc"
              ;;
            "i386")
               target=i386-pc
               if [ -e /proc/device-tree ]; then
                 for x in /proc/device-tree/*; do
                   if [ -e "$x" ]; then
                     target="i386-ieee1275"
                   fi
                 done
               fi
               GRUB_OPTS="$GRUB_OPTS --target=$target"
              ;;
          esac
        fi
      fi
    fi

    $GRUBNAME --modules="biosdisk part_msdos" $GRUB_OPTS $BOOT_DEV

    # This might be better factored out into a per-distro 'install-bootblock'
    # helper.
    if [ -f "/boot/grub/grub.cfg" ] ; then
      GRUB_CFG=/boot/grub/grub.cfg
    elif [ -f "/boot/grub2/grub.cfg" ] ; then
      GRUB_CFG=/boot/grub2/grub.cfg
    fi

    # If GRUB configuration file does not exist, generate one
    if [ ! $GRUB_CFG ]; then
      if [ -d /boot/grub2 ]; then
        GRUB_CFG=/boot/grub2/grub.cfg
      elif [ -d /boot/grub ]; then
        GRUB_CFG=/boot/grub/grub.cfg
      fi
      grub2-mkconfig -o $GRUB_CFG
    fi;

    DIST=`lsb_release -is`
    [ -n "$DIST" ]
    RELEASE=`lsb_release -cs`
    [ -n "$RELEASE" ]
    # grub-mkconfig generates a config with the device in it,
    # This shouldn't be needed, but old code has bugs
    if [ $RELEASE = 'precise' ] ; then
      # Replace the search attempt with a hardcoded root as the Ubuntu reference
      # images use.
      sed -i "s%search --no.*%%" $GRUB_CFG
      sed -i "s%set root=.*%set root=(hd0,1)%" $GRUB_CFG
    fi
    # force use of a LABEL:
    # NOTE: Updating the grub config by hand once deployed should work, its just
    # prepping it in a different environment that needs fiddling.
    sed -i "s%$PART_DEV%LABEL=cloudimg-rootfs%" $GRUB_CFG
    sed -i "s%search --no-floppy --fs-uuid --set=root .*$%search --no-floppy --set=root --label cloudimg-rootfs%" $GRUB_CFG
    sed -i "s%root=UUID=[A-Za-z0-9\-]*%root=LABEL=cloudimg-rootfs%" $GRUB_CFG
    if [ $DIST = 'Fedora' ] ; then
      # enable serial console
      sed -i "s%LABEL=cloudimg-rootfs%LABEL=cloudimg-rootfs console=tty0 console=ttyS0,115200%" $GRUB_CFG
      if [ $(lsb_release -rs) = '19' ]; then
        sed -i "s%UUID=[A-Za-z0-9\-]*%LABEL=cloudimg-rootfs%" /etc/fstab
      fi
    fi
}

DIB_EXTLINUX=${DIB_EXTLINUX:-0}
if [ "$DIB_EXTLINUX" != "0" ]; then
    install_extlinux
else
    install_grub2
fi