#!/bin/bash

set -eu

[ -n "$ARCH" ]
[ -n "$TARGET_ROOT" ]

if [ 'amd64' = "$ARCH" ] ; then
  ARCH="x86_64"
fi

DIB_RELEASE=${DIB_RELEASE:-latest}
DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://rhn.redhat.com}
BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-rhel-server-x86_64-kvm-6.4_20130130.0-4.qcow2}
BASE_IMAGE_TAR=$DIB_RELEASE-rhel-server-$ARCH-latest.tgz
CACHED_TAR=$DIB_IMAGE_CACHE/$BASE_IMAGE_TAR

if [ -n "$DIB_OFFLINE" -a -f "$CACHED_TAR" ] ; then
    echo "Not checking freshness of cached $CACHED_TAR."
else
    echo "Fetching Base Image"
    $TMP_HOOKS_PATH/bin/cache-url $DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE $DIB_IMAGE_CACHE/$BASE_IMAGE_FILE

    if [ ! -f $CACHED_TAR -o \
        $DIB_IMAGE_CACHE/$BASE_IMAGE_FILE -nt $CACHED_TAR ] ; then
        echo "Repacking base image as tarball."
        WORKING=$(mktemp -d)
        EACTION="rm -r $WORKING"
        trap "$EACTION" EXIT
        RAW_FILE=$(basename $BASE_IMAGE_FILE)
        RAW_FILE=${RAW_FILE#.qcow2}.raw
        qemu-img convert -f qcow2 -O raw $DIB_IMAGE_CACHE/$BASE_IMAGE_FILE $WORKING/$RAW_FILE
        MAGIC_BIT=p1
        # NOTE: On RHEL, partprobe of /dev/loop0 does not create /dev/loop0p2,
        # while kpartx at least creates /dev/mapper/loop0p2.
        LOOPDEV=$(sudo kpartx -av $WORKING/$RAW_FILE | awk "/loop[0-9]+$MAGIC_BIT/ {print \$3}")
        export LOOPDEV=$LOOPDEV
        echo "Loop device is set to: $LOOPDEV"
        if ! timeout 5 sh -c "while ! [ -e /dev/mapper/$LOOPDEV ]; do sleep 1; done"; then
            echo "Error: Could not find /dev/mapper/$LOOPDEV"
            exit 1
        fi
        EACTION="sudo kpartx -d $WORKING/$RAW_FILE;$EACTION"
        trap "$EACTION" EXIT
        mkdir $WORKING/mnt
        sudo mount /dev/mapper/$LOOPDEV $WORKING/mnt
        EACTION="sudo umount -f $WORKING/mnt;$EACTION"
        trap "$EACTION" EXIT
        # Chroot in so that we get the correct uid/gid
        sudo chroot $WORKING/mnt bin/tar -cz . > $WORKING/tmp.tar
        mv $WORKING/tmp.tar $DIB_IMAGE_CACHE/$BASE_IMAGE_TAR
    fi
fi
# Extract the base image (use --numeric-owner to avoid UID/GID mismatch between
# image tarball and host OS e.g. when building RHEL image on an openSUSE host)
sudo tar -C $TARGET_ROOT --numeric-owner -xzf $DIB_IMAGE_CACHE/$BASE_IMAGE_TAR
sudo rmdir $TARGET_ROOT/lost+found