#!/bin/bash
# vim: set sw=4 sts=4 et :


# Directory from which we will rsync portage to chroot
PORTAGE_DIR=/usr/portage

# stage tarball path
STAGE_TARBALL=""


# ==================================================================
#                       CODE
# ===================================================================


help()
{
    echo "Usage: `basename $0` OPTIONS BASE_CHROOT_DIR WORK_CHROOT_DIR"
    echo
    echo "   -c                 force clean BASE_CHROOT if it exists and start over from scratch"
    echo "   -p PORTAGE_DIR     directory where portage is (default is /usr/portage)"
    echo "   -s STAGE_FILE      stage file used to create base chroot directory"
    echo "   -m                 prepare mounts and chroot to BASE_CHROOT for its modification (update)"
    exit 1
}

clean_work_chroot()
{
    echo -n "Cleaning work chroot..."
    if [ -d $WORK_CHROOT ];then
        umount_all_dirs $WORK_CHROOT
        rm -rf --one-file-system "$WORK_CHROOT"
    fi
    echo Done
}

clean_base_chroot()
{
    echo -n "Cleaning base chroot..."
    if [ -d "$BASE_CHROOT" ];then
        rm -rf --one-file-system "$BASE_CHROOT"
    fi
    if [ -f "$BASE_CHROOT.tar" ];then
        rm -f "$BASE_CHROOT.tar"
    fi
    echo Done
}

mount_all_dirs()
{
    ROOTDIR=$1
    echo -n "Mounting filesystems..."
    mount -t proc none "$ROOTDIR/proc"
    mount -o bind /dev "$ROOTDIR/dev"
    mount -o bind /sys "$ROOTDIR/sys"

    mkdir -p "$ROOTDIR/$PORTAGE_DIR"
    mount -o bind "$PORTAGE_DIR" "$ROOTDIR/$PORTAGE_DIR"
    # this is bug/issue with current kernels, ro binds don't work so we have to remount
    mount -o remount,ro "$ROOTDIR/usr/portage"


    mount_dir "DISTDIR" $ROOTDIR
    mount_dir "PKGDIR" $ROOTDIR
    echo Done
}

umount_all_dirs()
{
    ROOTDIR=$1
    for dir in {"PKGDIR","DISTDIR"};do
        umount_dir $dir $ROOTDIR
    done
    for dir in $ROOTDIR/{"/dev","/proc","/sys","$PORTAGE_DIR"};do
        umount "$dir" || umount -l "$dir"
    done
}

GPSRET=""
get_portage_setting()
{
    setting=`grep $1 "$BASE_CHROOT/etc/make.conf" | sed -e "s/.*$1[[:space:]]*=[[:space:]]*//;s/\"//g;"`
    if [ "y$setting" == "y" ];then
        case $1 in
          "PORTDIR" )
                GPSRET=`portageq portdir`
                return 0;;
          "DISTDIR" )
                GPSRET=`portageq distdir`
                return 0;;
          "PKGDIR" )
                GPSRET=`portageq pkgdir`
                return 0;;
          * )
                return 1;;
        esac
    fi
    GPSRET=$setting
    return 0;
}

mount_dir()
{
    ROOTDIR=$2
    get_portage_setting $1
    if [ $? -eq 0 ];then
        if [ ! -e "$GPSRET" ];then
            mkdir -p "$GPSRET"
        fi
        mkdir -p "$ROOTDIR/$GPSRET"
        mount -o bind "$GPSRET" "$ROOTDIR/$GPSRET"
    else
        echo "Unable to get setting for $1 variable"
        exit 1
    fi
}

umount_dir()
{
    ROOTDIR=$2
    get_portage_setting $1
    umount "$ROOTDIR/$GPSRET" || umount -l "$ROOTDIR/$GPSRET"
}

FORCE_CLEAN_BASE=0

while getopts "p:s:cm" Option
do
  case $Option in
    p ) PORTAGE_DIR="$OPTARG";;
    s ) STAGE_TARBALL="$OPTARG";;
    c ) FORCE_CLEAN_BASE=1;;
    m ) MODIFY_BASE_CHROOT=1;;
    * ) echo "Unimplemented option chosen.";;   # DEFAULT
  esac
done


shift $(($OPTIND - 1))

if [ $# -ne 2 ];then
    echo "Wrong number of arguments"
    help
fi

BASE_CHROOT="$1"
WORK_CHROOT="$2"

echo "Using settings:"
echo "base chroot directory: $BASE_CHROOT"
echo "work chroot directory: $WORK_CHROOT"
echo "portage directory:     $PORTAGE_DIR"
echo "stage tarball:         $STAGE_TARBALL"


if [ $FORCE_CLEAN_BASE -eq 1 ];then
    clean_base_chroot    
fi

if [ -d "$BASE_CHROOT" ];then 
    echo "We found $BASE_CHROOT directory, assuming it's ready"
else
    if [ -z "$STAGE_TARBALL" ];then
        echo "We need stage tarball to create base chroot!! (option -s)"
        help
    fi

    # we will need to create usr/ anyway so why not do it at once
    mkdir -p "$BASE_CHROOT/usr"

    echo -n "Unpacking stage tarball..."
    tar xf "$STAGE_TARBALL" -C "$BASE_CHROOT"
    if [ $? -ne 0 ];then
        echo "Errors unpacking stage tarball, bailing out!!!"
        rm -rf "$BASE_CHROOT"
        exit 1
    fi
    echo Done

    rm -rf --one-file-system "$BASE_CHROOT/etc/portage/"
    mkdir -p "$BASE_CHROOT/etc/portage"

    echo -n "Copying settings..."
    cp -L /etc/resolv.conf "$BASE_CHROOT/etc"
    cp -L /etc/make.conf "$BASE_CHROOT/etc"
    cp -RL /etc/portage "$BASE_CHROOT/etc"
    echo Done

fi

if [ $MODIFY_BASE_CHROOT -eq 1 ];then
    mount_all_dirs $BASE_CHROOT
    chroot $BASE_CHROOT /bin/bash
    umount_all_dirs $BASE_CHROOT
    rm "$BASE_CHROOT.tar"
    exit 0;
fi

if [ ! -f "$BASE_CHROOT.tar" ];then
    echo -n "Creating tar from $BASE_CHROOT..."
    tar cf "$BASE_CHROOT.tar" -C "$BASE_CHROOT" .
    if [ $? -ne 0 ];then
        echo "Creating tar from $BASE_CHROOT failed, bailing out!!!"
        rm -rf "$BASE_CHROOT"
        exit 1
    fi
    echo Done
fi

clean_work_chroot

echo -n "Untaring base chroot to work chroot now"
mkdir -p "$WORK_CHROOT"
tar pxf "$BASE_CHROOT.tar" -C "$WORK_CHROOT"
if [ $? -ne 0 ];then
    echo "There were problems unpacking base chroot to work chroot!!"
    exit 1
fi
echo Done


mount_all_dirs $WORK_CHROOT



echo -n "Chrooting and updating env..."
# so that we can run env-update 
chroot "$WORK_CHROOT" /usr/sbin/env-update
echo Done

exit 0