#!/bin/bash

set -e

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

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

IMG_PATH=~/.cache/image-create
DIB_CLOUD_IMAGES=${DIB_CLOUD_IMAGES:-http://mattdm.fedorapeople.org/cloud-images/}
DIB_RELEASE=${DIB_RELEASE:-Fedora18}
BASE_IMAGE_FILE=${BASE_IMAGE_FILE:-$DIB_RELEASE-Cloud-$ARCH-latest.qcow2}
BASE_IMAGE_TAR=$DIB_RELEASE-Cloud-$ARCH-latest.tgz

mkdir -p $IMG_PATH
# TODO: don't cache forever.
if [ ! -f $IMG_PATH/$BASE_IMAGE_FILE ] ; then
   echo "Fetching Base Image"
   wget $DIB_CLOUD_IMAGES/$BASE_IMAGE_FILE -O $IMG_PATH/$BASE_IMAGE_FILE.tmp
   mv $IMG_PATH/$BASE_IMAGE_FILE.tmp $IMG_PATH/$BASE_IMAGE_FILE
fi
if [ ! -f $IMG_PATH/$BASE_IMAGE_TAR ] ; then
    echo "Repacking base image as tarball."
    WORKING=$(mktemp -d)
    EACTION="rm -r $WORKING"
    trap "$EACTION" EXIT
    echo "Working in $WORKING"
    RAW_FILE=$(basename $BASE_IMAGE_FILE)
    RAW_FILE=${RAW_FILE#.qcow2}.raw
    qemu-img convert -f qcow2 -O raw $IMG_PATH/$BASE_IMAGE_FILE $WORKING/$RAW_FILE
    # WARNING: The mattdm image has the root filesystem on the second
    #          partition (p2). If he changes the image the MAGIC_BIT
    #          might also need to change.
    MAGIC_BIT=p2
    # XXX: Parsing stdout is dangerous, would like a better way to discover
    #      the device used for the image.
    # NOTE: On F17 (parted-3.0-10.fc17.x86_64), partprobe of
    #       /dev/loop0 does not create /dev/loop0p2, while kpartx at
    #       least creates /dev/mapper/loop0p2.
    LOOPDEV=$(sudo kpartx -avr $WORKING/$RAW_FILE | awk "/loop[0-9]+$MAGIC_BIT/ {print \$3}")
    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 $IMG_PATH/$BASE_IMAGE_TAR
fi
# Extract the base image
sudo tar -C $TARGET_ROOT -xzf $IMG_PATH/$BASE_IMAGE_TAR
sudo rmdir $TARGET_ROOT/lost+found