#!/bin/bash


#!-
. /etc/shlib
#!-


DOCKER_UPDATE_PATH=${DOCKER_UPDATE_PATH:-/srv/docker-updates}


include common
include pretty

usage="$exname COMPONENT MASTER_IMAGE_NAME BRANCH UPDATED_IMAGE_NAME"


COMPONENT_NAME="$1"
MASTER_IMAGE_NAME="$2"
BRANCH="$3"
UPDATED_IMAGE_NAME="$4"

## Note: we will need in the DOCKER_UPDATE_HOST:
##  - git-sub

## should we check for aufs ?

mkdir -p "$DOCKER_UPDATE_PATH"
cd "$DOCKER_UPDATE_PATH"
if ! [ -d "$COMPONENT_NAME" ]; then
   echo "ERROR: repository $DOCKER_UPDATE_PATH//$COMPONENT_NAME is not existent."
   echo "You should build it on this host prior to run this hook."
   echo "As a remainder: this host is supposed to keep the reference git that"
   echo "was used to built the master image."
   exit 1
fi

if [ -e "$COMPONENT_NAME.locked" ]; then
   echo "Master is being updated."
   echo "Or '$COMPONENT_NAME.locked' file was left dangling over."
   exit 1
fi


clean_all() {
   cd /
   mountpoint "$tmpdir_root" 2>/dev/null && umount "$tmpdir_root"
   [ -d "$tmpdir_root" ] && rmdir "$tmpdir_root"
   [ -d "$tmpdir_changes" ] && rm -rf "$tmpdir_changes"
}

tmpdir_changes=$(mktemp -d /tmp/$COMPONENT_NAME.changes.XXXXXX)
tmpdir_root=$(mktemp -d /tmp/$COMPONENT_NAME.root.XXXXXX)

trap "clean_all" EXIT
mount -t aufs -o br=$tmpdir_changes:$DOCKER_UPDATE_PATH/$COMPONENT_NAME -o udba=none  none "$tmpdir_root"
cd "$tmpdir_root"

## XXXvlab: We probably would need to:
##   - fetch only the module concerned
##   - fetch only the ref concerned
git fetch origin "$BRANCH"
git checkout "$BRANCH"
git sub update

cd / &&
umount "$tmpdir_root" &&
rmdir "$tmpdir_root"
if [ "$?" != 0 ]; then
    echo "Uh oh... could not umount aufs $tmpdir_root or delete it."
    exit 1
fi
cd "$tmpdir_changes"

echo "Cleaning the change layer."
find  . -name .git -type d -exec  rm -rf {} \; -prune

## XXXvlab: if we produced it we shouldn't have to pull it
echo "Pulling $MASTER_IMAGE_NAME"
docker pull "$MASTER_IMAGE_NAME" >/dev/null 2>&1

container_id=$(docker run -d \
    -v $tmpdir_changes:/mnt/changes \
    "$MASTER_IMAGE_NAME" \
    /bin/bash -c "
        mkdir -p /srv/app/{root,changes}
        cp -a /mnt/changes /srv/app/changes/0000
        ls /srv/app/changes/0000
    ")

if [ "$(docker wait "$container_id")" != "0" ]; then
    echo "Copy of changes to docker images failed !"
    echo "Log of container:"
    docker logs $container_id
    exit 1
fi

docker commit --author "$exname" \
    --message "Automatic Updater" \
    "$container_id" \
    "$UPDATED_IMAGE_NAME"

docker push "$UPDATED_IMAGE_NAME"